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Maintenance & Technical (165)

Pre- and Post-overhaul:  Engine Removal & Installation

Pre- and Post-overhaul: Engine Removal & Installation


Wise owners (and mechanics) know that a successful overhaul starts with careful engine removal. The overhaul process isn’t finished until after the engine has been reinstalled and the break-in period completed. A&P Jacqueline Shipe walks you through best practices to ensure start-to-finish success.

An engine overhaul is a daunting repair that usually takes several weeks to complete. In addition to the engine overhaul itself, there are several maintenance tasks that are associated with pulling the engine and reinstalling it after the overhaul. (For more about what comprises an engine overhaul, see “A Step-by-Step Guide to Overhauls” in the February 2018 issue. —Ed.)



Engine removal location and airframe storage

Once the decision to overhaul the engine has been made, the next step for an owner is to decide on the location for the engine removal. Some owners have their mechanic pull the engine and ship it to an overhaul facility. Other owners fly the airplane to the overhaul location and let the overhaul specialists remove, overhaul and reinstall the engine. 


The next task is to find out where the airplane will be stored while the engine is off the airframe. Hangar space is typically at a premium for both overhaul shops and general maintenance shops. 


Some shops place the airplane outside for the duration of time that the engine is off the airframe. The airframe is unbalanced and hard to secure on a tiedown once the engine has been removed. It is also much lighter than normal, leaving the aircraft more vulnerable to windy weather. 


Make sure to have a clear understanding with whomever is doing the engine removal and installation about where the airplane will be stored while the overhaul is taking place. 


Engine removal

Removing an engine from the airplane is typically not that time-consuming. The engine can be pulled easily enough in most cases in less than a day. 


Once the cowling and propeller are removed, the next step should be to take lots of pictures from all different angles of every section of the engine. This will help to determine the routing of hoses and control cables later on during the reinstallation process. 


The exact location of clamps is not usually specified by the maintenance manual and is left up to the mechanic. Knowing where the old clamps and supports were located helps ensure that everything fits properly during reinstallation.


Once all the engine components are disconnected from the airframe, the engine is stripped of everything that is not sent with the engine for the overhaul. The exhaust system, alternator, starter, vacuum pump and engine baffling typically don’t get sent in with the engine for overhaul. These components are either replaced or refurbished as needed by specialty shops. 


After all the necessary items are removed or disconnected from the engine, the engine itself is removed from the airframe. The tail of the airplane should be secured on a support that will hold it up once the heavy engine is removed. Most engines have permanent lifting eyes installed on one or more of the upper crankcase bolts. If an engine doesn’t have a lifting eye, one will have to be temporarily installed. 


A chain is most often used to attach an engine hoist to the lifting eye. Once the chain is secured, the engine hoist is raised until the chain has all the slack removed from it. Then, the bolts that secure the engine to the mount are removed from the vibration isolators and the engine can be lifted out of its mount. 


Once removed, the engine is either wheeled into the overhaul shop for disassembly or prepared for shipping if the overhaul is to take place elsewhere.


Engines that are shipped out by means of a freight company are generally bolted to a shipping pallet with a prefabricated mount. 


Owners that are having their engines sent out can save money by taking it themselves to the overhaul shop. The engine is often placed on a layer of used tires in the back of a truck and secured to four different tiedowns to keep it from shifting. 


In addition to saving money, the owner can have peace of mind knowing that he or she has overseen the engine shipment the entire time. Careless handling can damage expensive engine components and shipping companies do occasionally drop or damage items. 


If the overhaul facility is located a long distance from the aircraft location, shipping with a freight company may be the only option. In those cases, the shipment should be insured for the full replacement value of the engine. 


After the engine overhaul is underway, attention can be shifted to the repair or refurbishment of all the parts that are now easily accessible with the engine removed. 


Engine mount

Once the engine has been removed, the engine mount is easily accessible and can be thoroughly inspected for cracks and pitted areas. 

Even if the mount itself is in good shape, remove the mount from the
airframe and inspect all the attachment areas on the airframe and mount
for corrosion. 

Mounts that are free of corrosion and have good paint are often reused as-is. Mounts that are in need of repainting should be cleaned, lightly sanded and painted with a high-quality primer and then a coat of paint. 

In addition, any corroded areas on the airframe should be cleaned and treated or repaired as needed. 

Engine mounts that have pitted areas, excessive corrosion or cracks are usually sent to specialized welding shops like Acorn Welding or Kosola (now Aerospace Welding) for repair. These shops have special jigs and can cut out bad sections of tubing and weld in reinforced sections without distorting the shape of the mount. 

The firewall of the airframe is easily accessible with the engine and the mount removed. Now is an ideal time to clean and paint the firewall. Painting areas such as the firewall and the inside of the cowling with a bright color (usually white) helps to spot leaks easier. It also makes the airplane look better, and adds another layer of protection against corrosion.



Controllable-pitch propellers and propeller governors are often overhauled at the same time as the engine. This ensures that the engine will be able to develop its maximum power within the proper limits without being held back by a sluggish or malfunctioning propeller or governor.



Metal engine baffles should be repaired as needed, and any worn baffle seals should be replaced to maximize engine cooling. 


Effective engine cooling is particularly important for overhauled engines because the new cylinder rings have to wear in and seat themselves against the cylinder walls during the first few engine runs. The extra friction will generate more heat than normal, especially in the cylinder heads. 


The air that the cylinders need for cooling should flow in through the front of the cowling, through the cylinder cooling fins, then down and out the bottom of the cowling. Any air leaks in the engine compartment that aren’t sealed off will allow cooling air to escape through a gap or hole instead of being ducted through the fins where it is most needed. 


Exhaust system

Exhaust system components are sent out for repair or are replaced if they are corroded, cracked or deformed in any way. Excessively thin or leaking pipes will only cause trouble later on. Leaking exhaust gases from warped exhaust flanges at the cylinder head connection will corrode and ruin the cylinder heads over time. 


Some overhaul facilities recommend replacing the exhaust system whenever the engine is overhauled. Turbochargers and wastegate assemblies should always be sent out for overhaul or replaced whenever the engine is overhauled. 




All fluid-carrying hoses connected to the engine should be replaced at overhaul. Hoses become hardened and brittle after being heated and cooled during engine operation. A ruptured hose can cause a fire hazard or starve internal engine components of precious oil pressure. 


Also, tiny amounts of metal and debris can remain in old hoses even after they are rinsed and blown out and can contaminate the new engine. Many engine overhaul facilities will deem the engine warranty null and void if the fluid-carrying hoses aren’t replaced. 


It is also good idea to replace the SCAT hoses, but they aren’t critical like the fluid-carrying hoses are.


Oil coolers

Oil coolers should be replaced with new units or sent to an oil cooler specialty shop that can thoroughly clean the oil passageways. The oil passageways through the cooler have 180-degree turns in them that cause contaminants to precipitate out of the oil flow and build up in the turn areas.


It is impossible to get all the sludge, metal particles and dirt out of the old cooler by rinsing it in a parts cleaning vat. It’s not worth risking contaminating a freshly-overhauled engine with debris from the old engine in order to save a few dollars on the oil cooler. Clean oil coolers also have better oil flow through them and cool the oil more efficiently. 


Rubber vibration isolators

Most engines are mounted with the four attachments for securing the engine to the mount located on the rear of the engine. The rubber vibration isolators (often called “rubber engine mounts”) that are installed between the engine mounting pads and the engine mount should always be replaced whenever the engine is removed.


Vibration isolators lose elasticity over time and will begin to sag under the weight of the engine. Once the isolators start to age, they allow the front of the engine and the propeller to not only sag, but also to tilt down. 


The cowling is secured to the airframe and the propeller is connected directly to the engine, so as the engine mount isolators droop, the clearance between the bottom of the spinner bulkhead and the cowling becomes smaller while the gap between the top of the spinner bulkhead and the top cowling gets larger.


Isolators that are severely aged and distorted on these types of engine mounts can cause the engine to droop so much that the bottom of the spinner bulkhead actually starts rubbing on the lower engine cowling. 


In addition, rubber engine mounts are easily damaged and prematurely age if they are exposed to leaking oil or hot exhaust leaks. Constant oil leaks soften the rubber, causing it to swell and bulge. Exhaust leaks overheat the rubber, making it brittle and prone to cracking.


The isolators play a critical role in helping to secure the engine to the engine mount. They are typically not that expensive in comparison to other parts, and are easily accessible any time the engine is removed from the airframe—but difficult or impossible to replace without pulling the engine. 


Engine installation

The engine installation process takes longer to complete and is much more detailed than the engine removal process. Installing the engine mount on the airframe and then hanging the engine on the mount can be done quickly in most cases because there are usually only four bolts and nuts that secure the engine mount to the airframe, and an additional four bolts and nuts that secure the engine to the mount. 


Sometimes it is difficult to get the engine hoist adjusted just right so that the engine lines up correctly when attaching it to the mount. It can take a few attempts to get the bolts inserted through the mount and isolators. Components like the magnetos, fuel servo or carburetor may have to be removed to provide enough clearance to get the engine into the proper position on the mount. 


Engine mount bolts should always be torqued to the specified setting listed in the airframe maintenance manual and any specified torque sequence should be adhered to.


Once the engine has been hung, the baffling, accessories, hoses, oil coolers and all remaining parts can be installed. Clamping and securing hoses, wires and ignition leads is one of the most time-consuming tasks in this phase of the project. 


The exhaust system and propeller are usually two of the last items that are installed because once they are installed, they block access to other parts of the engine. 


Many overhaul shops run an engine on a test cell for an hour or so before sending the engine out. Some shops send the engine out with no run time on it at all. 


After reinstallation on the airplane, the engine should be started and run on the ground for the minimum time needed to ensure that there are no leaks; that the magnetos have the proper rpm drop when checked; and, if a controllable-pitch propeller is installed, that the propeller changes pitch as it should. 


Idle mixture and idle speeds should be checked and adjusted if necessary—but ground runs should be kept to a minimum, especially if the engine has not been on a test cell. 


After an overhaul, the rings are not seated. In order for the rings to seat properly, they must be blown out against the cylinder walls. The rings need high manifold pressures to force them to have metal-to-metal contact with the cylinder walls so they seat properly. 


Running an overhauled engine at too low of a throttle setting for any length of time (on the ground or in the air) increases the likelihood of glazing the cylinder walls. Glazing results from the oil oxidizing on the cylinder walls and creating a hardened surface that prevents the rings from ever seating properly. 


After the first flight, the cowling should be completely removed and the entire engine looked over for leaks and to make sure nothing has vibrated loose. Some shops will change the oil at this time if the test flight was the first run on the engine. 


The recommended break-in oil is generally used for the first 50 hours. After the 50-hour mark, there should be no metal in the oil filter when it is inspected. Metal found in the oil filter after this time may be indicative of an internal problem with the engine. 


Most overhauled engines perform well and provide many hours of trouble-free flight time and it is generally a relief for owners to have this major expense behind them.


Know your FAR/AIM and check with your mechanic before starting any work. Always get instruction from an A&P prior to attempting preventive maintenance tasks.

Jacqueline Shipe grew up in an aviation home; her dad was a flight instructor. She soloed at age 16 and went on to get her CFII and ATP certificate. Shipe also attended Kentucky Tech and obtained an airframe and powerplant license. She has worked as a mechanic for the airlines and on a variety of General Aviation planes. She’s also logged over 5,000 hours of flight instruction time. Send question or comments to .








Acorn Welding Ltd. – PFA supporter



Aerospace Welding Minneapolis, Inc.



To find resources for other components and services for engine overhauls, please go to the Piper Flyer Yellow Pages at piperflyer.org/piper-yellow-pages.html, or contact Kent Dellenbusch at Email or phone 626-844-0215. 



Coming Unglued: Replacing Cable Seals on Fabric Aircraft

A step-by-step guide for making and installing cable seals on a PA-18.

When my 1952 Piper PA-18 Super Cub Special was restored in 2014, no detail was too small—even the black faux-leather cable seals where the control cables pass through the fabric skin were new and perfectly applied. However, after three years of heat, cold, exhaust gases and cleaning solutions, plus the buffeting of the slipstream, the edges of those seals started to dry, curl and peel away.

After pulling off a few of the seals and inspecting the material, it was obvious that their lack of flexibility and the old, dried adhesive would make them difficult to glue back in place. The seals seemed to be made of a plasticized fabric. The fabric had a woven backing coated with a black vinyl embossed in a faux leather pattern and was about 1 millimeter thick. 

I wondered if the original 1950s seals were leather, or if by that time they had been replaced by synthetic materials. Artificial leather, such as the brand-name material Naugahyde, was available as early as the 1930s. It’s likely that in the very earliest days of aviation this sort of item would have been genuine leather glued to the fabric, but I have no idea when Piper made the changeover to plastics. (Maybe a former factory worker will know?)

What are these things?

These cable seals might more precisely be called grommets, which is anything inserted around the edges of a hole through a thin material, which could be wing fabric, sheet metal, fiberglass, wood, paper or almost anything at all. 

Grommets perform several functions. They may be applied to prevent tearing of the pierced thin material, or to discourage abrasion by whatever passes through the hole. Or, it might be the other way around: to protect the wire, cable or whatever is passing through the hole from abrasion. Grommets can help keep dirt and water out of an opening, especially if the grommet is made of a flexible material, essentially making a big hole into a smaller hole. Since it doesn’t completely seal the opening from the elements, I wouldn’t call it a seal, exactly. 

Grommets are also used to cover the sharp edges of a hole so you don’t cut yourself. 

Often a grommet performs all these functions, which certainly seems to be the case for the fabric grommets used where control cables pass through the fabric on vintage airplanes. 

When most people think of a grommet, they envision a metal or plastic ring that’s pressed, like a rivet, into a fragile surface. But a grommet could also be something as lightweight as those self-sticking reinforcements students use for three-ring notebook paper. The stitching around a buttonhole could be considered a grommet in that it keeps the buttonhole from fraying. 

In the electrical business, rubber grommets are often known as “insulating bushings” and are commonly made of molded rubber. There are certainly a few of these on most aircraft. For large and irregular openings, long strips of cushioning materials may be applied to sharp edges. This is known as grommet edging.

Fabric airplane control cable grommets

On my Super Cub, the control cables pass through the fabric in four pairs of places—where the lower aileron cable passes from the floor of the cockpit and runs upward along the wing strut; where that cable enters the bottom of the wing (it emerges from the top of the wing under a metal shield); where the upper aileron cable running inside the wing passes out through the bottom surface of the wing to the aileron; and where the rudder cables exit the fuselage in front of the empennage to connect to the rudder arms. Two of these pairs of grommets are circular; two are elongated shapes. They are meant to prevent chafing along the fabric.

Retail suppliers

If you prefer premade grommets, Wag-Aero sells a Piper Naugahyde Cable Seal Kit (part No. M-423-003) for $7.50. The kit consists of “two slotted fuselage and two aileron punched cable seals. Set of 4.” Aircraft Spruce has a similar item on its website (part No. 09-00335) for $9.55 per set of four. The seals from Aircraft Spruce and Wag-Aero are all teardrop-shaped. 

To replace all the seals (i.e., grommets) on my Super Cub, I would need two kits. Depending on which company I order from, pricing would run $15 to $19, plus tax and shipping. 

However, I enjoy working on my airplane, so I decided to take a shot at making the grommets myself. 

Can you legally DIY?

My local mechanic said making these homemade grommets falls under FAR Part 43, Appendix A, which allows “preventive maintenance to be performed by a certificated pilot, holding at least a Private certificate, on an aircraft owned or operated by that pilot, provided the aircraft is not used in commercial service.” FAR Part 43, Appendix A, subpart (c), item No. 7 specifically mentions “making simple fabric patches not requiring rib stitching or the removal of structural parts or control surfaces.” 

My mechanic said he would consider these grommets no different than a pilot performing a small fabric repair job. 

I visited a nearby fabric store to look for replacement material. I found a few rolls of black vinyl in the upholstery section. One was called “marine vinyl” and the tag revealed it had a -10 F cold-crack rating. (“Marine” also led me to think that if it’s a good material for boat upholstery, it might be good for airplanes.) 

Since I was making just a few small grommets, I needed a minimal amount of material. The vinyl comes on a yard-wide roll. You must buy the material by length off the roll and the smallest amount I could buy was 1/8th of a yard, or 4.5 inches. At $19.99 per yard, it cost $2.50 plus tax.

After getting the material home, I checked the fabric store’s website and discovered the fabric’s brand name was Spradling. I researched a bit and learned that Spradling is a company that specializes in upholstery materials for automotive, marine and general upholstery. According to Spradling, marine vinyl is essentially the same as regular vinyl, with the addition of UV inhibitors and mildew or antifungal additives, all of which seem like good attributes for airplanes sitting inside damp hangars or out in the weather. 

Making and installing grommets: step by step

1. Carefully peel the old grommets from the fabric surfaces. I suppose if they didn’t come off reasonably easily, you wouldn’t be replacing them. Mine peeled right off.

2. Use the old grommet as a template and trace the shape onto the back side of the new vinyl. I used a fine point Sharpie marker, which made a 1/16-inch thick line.

3. Cut out the new vinyl with scissors or a sharp knife. I cut around the outer edge of the black line, making the new grommet about 1/8th of an inch larger than the original. This helps to cover any old glue that may be on the fabric and will give a clean look to the new installation.

4. Glue the new grommets in place. I chose original Gorilla Glue to adhere my newly-cut grommets. Make sure you keep this glue warm; put the bottle in your pocket for a while, otherwise it’ll be very thick and hard to spread. To use it, you must first wet the surfaces and then apply the glue. I used a small brush to spread the glue over the grommet’s surface to its edges. Gorilla Glue also comes in a “clear” version that I would select if I was buying glue again. It might also be good to use a spray adhesive, which would provide an even and thin application that wouldn’t squeeze out when the grommet is pressed on, keeping things neat. 

5. Wipe off any excess glue that gets squeezed from under the grommet before taping it in place (I used masking tape) until the glue sets. Be careful or you’ll glue the tape to the fabric.

6. After the glue dries, remove the tape and ensure that none of your control wires were glued to anything and they move freely. It’s also worth paying special attention to the “controls free and correct” item on your checklist in your next few flights. 

7. Admire your handiwork. 

From start to finish—including my travel time to the stores for the fabric and the glue—this project took around two hours. 


Know your FAR/AIM and check with your mechanic before starting any work.

Dennis K. Johnson is a writer and a New York City-based travel photographer, shooting primarily for Getty Images and select clients. He spends months each year traveling, flies sailplanes whenever possible and is the owner of N105T, a newly-restored Piper Super Cub Special. Send questions or comments to .



Spradling International, Inc.




Aircraft Spruce & Specialty Co.







Q&A: Adding A/C to a Navajo, Fuel Flow & Adjusting K-factor, Annual Inspection Checklist for a Cherokee

Q: Hi Steve,

I’m looking for recommendations regarding the best aftermarket air conditioning for a 1968 Piper PA-31 Navajo. Any ideas?


A: Hi Jeff,

My research shows that Air Center in Chattanooga markets its Cool Air system for many singles and twins. The company claims it can install a Cool Air system in any 28-volt airplane. However, the PA-31 is not listed on the Air Center website as an aircraft they have converted. Contact Gary Gadberry to see if he can do your Navajo. (The website and telephone number are in Resources at the end of this article. —Ed.)

Just to be clear, I did not see the Cool Air system in the FAA Supplemental Type Certificate listing; but STC listings are not always up-to-date. Since it’s not on the STC listing, make sure you ask how Air Center certifies Cool Air AC systems.

One company that is listed in the STC listings for your aircraft is Air Comm; the STC holder is listed as ACC-KP LLC in Addison, Texas. However, as I wrote above, the STC listings are not always up-to-date. It turns out that Air Comm (now in Colorado) purchased Meggitt, which had previously purchased Keith Air Conditioners.

For what it’s worth, I once installed a Keith air conditioning system in a Cessna Skymaster. The compressor and fan are electrically-powered. Unfortunately, the current draw was very high; something like 50 amps. 

Since the two alternators on that Skymaster were 38-amp units, we had to get FAA field approvals to install larger alternators to ensure that there would never be too great a draw on the airplane’s electrical system generating capacity.

Frankly, we were surprised that an STC was granted for this installation without forewarning us of the need to update the alternators. And so was the owner when we explained the need for larger alternators.

In the end, the system worked well, and I have to say it was a very comprehensive and well-engineered installation kit.

Happy flying,


Q: Hi Steve,

I see about 16 gph fuel flow on my Piper PA-28R-200 Arrow 200 at sea level takeoff power. Strangely, this puts me at about only 75 F rich of peak. I’m seeing 1,400 to 1,450 F egt during takeoff.

Is there a way to increase the takeoff power fuel flow? What fuel flow should I see at full rated power in my Arrow 200?


A: Hi Baris,

Great question. Let’s look at some statistics about the systems involved.

The Lycoming Operators Manual: O-360 and Associated Models is chock full of information about your engine and other Lycoming 360-series engines.

Figure 3.5 in the manual cites a fuel consumption at full rated power (200 hp) of 93.5 pph. 100LL Avgas weighs 6 pounds per gallon at standard temperature. If you divide 93.5 by 6, you’ll see a full-power fuel flow of 15.58 gph.

Based on the data from the performance charts published by Lycoming, you are getting a little more than full-power fuel flow at takeoff.

You said you were seeing a fuel flow of 16 gph at takeoff. I’m going to assume that you’re getting that number from a fuel flow gauge. If your fuel flow gauge is an aftermarket stand-alone gauge or is part of an aftermarket engine monitor such as the ones from Insight, Electronics International or JP Instruments, the fuel flow gph reading will be correct if what’s called the “K-factor” has been properly set during the installation of the gauge. 

You can verify the correctness of the K-factor by filling each of your tanks to a recognizable spot; on the filler neck, for instance. Then after taking off on one tank (we will call this tank No. 1), climb to an altitude you’re comfortable with for cruising and leaning. After leveling off, lean the engine in accordance with your normal practice at your normal cruise power setting. Note the time and switch to the other fuel tank (tank No. 2). 

Fly without touching the throttle or mixture knobs or climbing or descending for an hour. Note the fuel flow gauge gph reading during the flight. At the end of exactly one hour, switch from tank No. 2 back to tank No. 1 and return to base. When fueling tank No. 2, the amount of the fill should match the gph reading you noted on the fuel flow gauge. 

If it doesn’t, you need to adjust the gauge’s K-factor setting. It’s an easy task, though the exact procedure varies by gauge manufacturer. You’ll want to consult the manual for your specific gauge. Continue to adjust the K-factor and check its accuracy with the procedure I just described until you’re within a few tenths of a gallon per hour.

Regarding your temperature readings: you’ll be better served watching your CHT numbers instead of EGTs. Cylinder head temperatures are the most important number during high-power operations. Exhaust gas temperatures should not be of much concern.

If your CHT numbers stay below 400 F during high power operations, you’re getting sufficient fuel flow, no matter what your fuel flow gauge reads.

EGT numbers are used to establish peak EGT when leaning at 75 percent power or lower. Due to many variables such as installation orientation and distance from the cylinder exhaust flange, the actual numeric value of EGTs is not important.

My suggestion is that you pay attention to your CHTs and do the K-factor calibration flight and adjust the K-factor if necessary.

Happy flying,


Q: Do you have an annual checklist for a Piper PA-28-180 Cherokee that you can send me?

A: You’ll want to get ahold of a copy of the Piper Cherokee Service Manual. The Inspection Report checklist for the Cherokee series begins on the first page of Table III-I (Page 68).

Be sure to read the helpful notes at the end of the checklist—but realize that this list does not include other must-do annual inspection items such as AD research and compliance for airframe, engine, propeller and accessories such as magnetos, spark plugs, induction air filters and so on.

14 CFR Part 43, Appendix D states what items must be inspected in the course of an annual inspection. However, there is no “FAA-approved” annual inspection checklist for your (or any other) airframe. Each repair station or independent shop creates a checklist or uses the checklist in the service manual as a general guideline.

Happy flying,


Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, California with his wife Audrey. Send questions and comments to





Air Center, Inc.

Gary Gadberry
(423) 893-5444


Air Comm Corp.



Insight Instruments Corp.



Electronics International, Inc.


JP Instruments


What Can ADS-B Out Do for Me?

Steve Ells extols the benefits of ADS-B Out and provides information on a couple of new products in the field.

The Jan. 1, 2020 ADS-B mandate is coming for GA airplane owners. This mandate requires the installation of equipment to broadcast coded information to ATC, and to other aircraft in a format known as Automatic Dependent Surveillance-Broadcast, or ADS-B. 

Why do we need to upgrade to an ADS-B system? 

Simply put, every aircraft equipped with an ADS-B datalink will automatically transmit its precise position, its velocity (both vertical and horizontal), as well as its altitude and other information to controllers and to other nearby aircraft. 

I believe few understand how much safety is enhanced when pilots can display other nearby aircraft in real time on a panel-mounted or portable pictorial display. Prior to the installation of ADS-B Out equipment in my Comanche, I hadn’t grasped how much this benefit would affect my sense of safety while aloft.

Is ADS-B Out required?

Does every owner need to install ADS-B Out equipment to comply with the mandate? The answer is no, but if you’re having trouble with the decision, one rule of thumb suggests that if you are now flying into and out of airspace that requires a Mode C transponder, you’ll need to equip with ADS-B Out. 

The following defines where ADS-B Out is needed after Jan. 1, 2020:

 • All Class A, B and C airspace

• All airspace at and above 10,000 feet MSL over the 48 contiguous United States and the District of Columbia 

• Within 30 nautical miles of airports listed in 14 CFR §91.225, from the surface up to 10,000 feet MSL

• For Class E airspace over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles, at and above 3,000 feet MSL.

In versus Out

The broadcast part of ADS-B known as Out is the sticking point for mandate compliance.

Editor’s note: There is no requirement that aircraft be able to receive ADS-B In information. However, the traffic and weather information provided by ADS-B In are incredibly useful, and you will want to be able to view them in the cockpit. 

Some (but not all) ADS-B Out devices also have In capability and can display traffic and weather data on their own screens. Others can send traffic and weather data to a MFD/PFD or GPS or wirelessly to an iPad or other tablet.

If it’s just ADS-B In you’re looking for, data is easy to capture by using a wide variety of small, relatively inexpensive battery-powered portable receivers from companies such as Garmin, Dual, Appareo (Stratus), Levil and Radenna. There’s even a kit for an In receiver that features what’s known as a Raspberry Pi processor running PiAware software. 

I’ve used a portable Dual XGPS170 978 UAT receiver in the past and have recently upgraded to a Stratux Merlin by Seattle Avionics that has 978 UAT and 1090 ES receivers as well as an internal GPS and an AHRS. The Merlin AHRS provides reference information that syncs with terrain software to provide synthetic vision of the terrain. I use my Apple iPad Mini loaded with FlyQ electronic flight bag (EFB) software from Seattle Avionics to view ADS-B information.

There are still almost two years left to comply with the ADS-B Out mandate. That seems like a long time, but it’s hard to ignore the tick-tock of the clock as days speed by.

978 UAT ADS-B Out solutions

If you never fly above 18,000 feet MSL and don’t see yourself crossing international borders, then a simple 978 UAT (Universal Access Transceiver) installation is sufficient to meet the ADS-B Out mandate.

978 UAT (operating on a frequency of 978 MHz) was enacted to provide a path for small airplane owners to comply with the ADS-B mandate without adding thousands more users to the already saturated 1090 MHz transponder frequency.

The biggest advantage of installing 978 UAT equipment is the additional bandwidth of the frequency (compared to the 1090 MHz frequency). The “bait” the FAA hung out there to convince pilots to install 978 UAT equipment is a better data transfer rate on 978 MHz and the promise of in-cabin weather and traffic info.

Recently a Palo Alto, California company called uAvionix introduced a very simple ADS-B Out system that’s so ingenious it’s laughable. The uAvionix SkyBeacon looks like the left navigation light assembly with a small white blade projecting downward. There’s almost no installation cost since all that’s required is to remove the existing nav light assembly before connecting the existing power and ground wires to the SkyBeacon. Pricing is reported to be targeted at $1,400. Alas, it’s not yet approved for installation in certified airplanes, but the folks at uAvionix assured me that the paperwork is moving through the certification grinder.

Another relatively low-cost 978 UAT solution is the Garmin GDL 82. It’s a small box with a built-in WAAS GPS receiver that is installed in line with the existing transponder coaxial cable. A supplied ADS-B antenna and coaxial cable must be installed on top of the airplane to complete the installation. It is compatible with a wide range of existing transponders. Prices start at around $1,800.

The KGX 150 line of BendixKing 978 UAT Out transmitters start at around $2,400.

The combination of low acquisition cost and simple installations removes the financial roadblock that seemed to be part and parcel of the ADS-B mandate compliance a few years ago.

1090 ES ADS-B Out solutions

If you need to fly above 18,000 feet MSL and/or travel internationally, then you must install a system that transmits on 1090 MHz to comply with the ADS-B mandate. This is often referred to as a 1090 ES system; with the ES standing for “Extended Squitter.” The following definition from an online post on the Garmin website explains squitting: “By definition, the word ‘squitter’ refers to a periodic burst or broadcast of aircraft-tracking data that is transmitted periodically by a Mode S transponder without interrogation from controller’s radar.” 

Even my ancient King KT-76A Mode C transponder shot out a three-parameter squit. A Mode S transponder can squit up to seven parameters, while ES transponders can squit up to 49 parameters of data. 

1090 ES transponders are available from Garmin, BendixKing, Appareo (Stratus), Trig and other companies. 

Is it worth it?

Prior to installing ADS-B Out equipment late last year, I flew for a couple of years displaying ADS-B In data gathered by the Dual XGPS170 mentioned earlier. Data was displayed on my iPad and I was happy to get free traffic and weather information in my cockpit. 

I installed a 1090 ES system from Trig Avionics in my Comanche. In addition to complying with the mandate, what did I gain by installing ADS-B Out?

More than I thought I would, as it turns out. Just to verify my conclusions, I sent the following questions to around 20 of my flying friends: 1.) Why do you like ADS-B Out? 2.) What do you feel is the real advantage of ADS-B Out? and 3.) How do you feel ADS-B Out has enhanced ADS-B In?

Mike Jesch, a flight instructor, big iron captain for American and a Cessna 182 pilot wrote:

Why do I like ADS-B Out? What do I feel is the real advantage?

Two closely related questions. I like the Out because it improves the accuracy of the In data I receive. The real advantage is going to be the ability to receive traffic advisories in areas which don’t have radar coverage like mountainous areas. Even if not talking to ATC, it’ll be great to have accurate traffic information available in our cockpits. Once everybody gets equipped, the accuracy and validity of the data provided to the pilot in real time will be truly amazing.

ADS-B Out has and will enhance ADS-B In, by improving the accuracy and completeness of the traffic information available.

And, it’s important to remember that ADS-B In is not just about traffic. Weather information is now available in near-real time. That can provide amazing strategic planning capability in the GA cockpit.

Mike Filucci, a retired airline pilot, formation flight instructor and VP of the Pilot Information Center and Flight Ops at the Aircraft Owners and Pilots Association (AOPA) answered:

I’ve been flying my RV4 with ADS-B In and Out for the last year and eight months (225 hours) and really like both the In and the Out features. The biggest advantage I find for the Out is really tied to the In on other airplanes—I know other pilots can see me on their screens if they are equipped with ADS-B In and, of course, I can see their airplanes because I have In. Traffic awareness is an important aspect, particularly here on the East Coast where we have a high-density environment. The other big plus of In, as you know, is the ability to see weather radar returns, albeit delayed and access weather information.

Amy Laboda, freelance writer and former editor of Women in Aviation International’s magazine, has been flying ADS-B for years (the mandate was first published in 2010). She wrote:

This [ADS-B Out] is the only way to be sure you are getting accurate traffic info. Period. And that accurate traffic info has been enlightening. Perhaps lifesaving, but who would know, right?

I like that others know where I am, even if just seeing my 1200 squawk and a trend line. And of course, as I said above, I like having accurate traffic info on where others are if they are close to my “bubble” of airspace.

Can’t state it enough: accurate traffic position info.

It has been fascinating watching the ADS-B system build out and watching others adopt a tech that, by the time it is mandatory, I will have been using for nine years.

Eyeball-based traffic avoidance

There’s a segment of the flying public that may argue that their Mark I eyeball provides all the traffic protection they will ever need. That doesn’t work for me.

Years ago, Audrey and I were flying west up the wide and clear Antelope Valley east of Palmdale (California) VOR on our way home from one of AOPA’s famous Palm Springs Fly-ins. We were in AOPA’s completely refurbished Sweepstakes Commander 112. (For more information on that sweepstakes, see Resources at the end of this article. —Ed.)

Displayed on the screen of the then-new Garmin MX 20 MFD was traffic detected by the latest version of Ryan’s traffic advisory system (TAS). The screen showed four aircraft out there. We knew where they were and what altitude they were flying in relation to our altitude. We looked and looked but never saw any of them. To be honest, my eyes have needed correction since I was in fifth grade so maybe an eagle-eyed pilot could have seen them, but I remain unconvinced.

ADS-B Out enhances the ability of ADS-B In receivers to detect other airplanes 

Ken Foster, a retired engineer and pilot of a Cessna 182 who I’ve known for over 20 years wrote:

The real advantage of the system is demonstrated when you see close, sometimes very close, traffic on the panel [display] and cannot find it out the windshield. I am convinced that I have observed conflicting traffic on ADS-B and avoided a midair by varying my course. This has happened three times.

If you don’t have Out you are really not getting the In that will keep you safer. You’re kidding yourself, at least until 2020.

My experience is like Foster’s. Prior to installing ADS-B Out, I always requested flight following from ATC. Since my home airport is in a low traffic area, I almost always got it. But I knew that separating me from other traffic is pretty low on ATC’s priority of services. So, I knew that I had to keep using my “not-so-good” vision as my first defense against midair mishaps. Before ADS-B, what other tool did I have?

ADS-B Out provides a very clear picture of traffic near me. I have altered course when my “enhanced” ADS-B In showed what I felt was converging traffic. I had a transponder code for flight following during that flight, but ATC did not advise me of what I felt was conflicting traffic. 

Today I am more confident due my ability to personally control the responsibility of traffic conflict avoidance. Ensuring separation of VFR traffic is not ATC’s primary job. ADS-B Out puts the responsibility back on me; and provides just the tool I need to take care of business.

Now or later?

There are now several relatively inexpensive methods of complying with the ADS-B Out mandate. Will prices come down more in the next two years? No one knows, but avionics shops tell me that they’re busy now—so the sooner you get on a schedule to get your Out the sooner you’ll have a tool to enhance your In experience with all its benefits, as well as the best existing tool to avoid conflicts with other airplanes. 

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, California with his wife Audrey. Send questions and comments to  


Garmin, Ltd

Honeywell International, Inc.

Dual Electronics

Appareo Systems, LLC

Levil Aviation

Radenna, LLC

Sandia Aerospace


Seattle Avionics, Inc.

uAvionix Corporation

Trig Avionics Limited 



Aircraft Owners and Pilots Association

A Step-by-Step Guide to Overhauls

A Step-by-Step Guide to Overhauls


Most engines are “sent out” to specialty shops for overhaul. Peek behind the doors at Triad Aviation as author Jacqueline Shipe guides you through engine overhaul procedures.

The single biggest repair expense most airplane owners will ever face is an engine overhaul. Overhaul costs increase every year along with parts prices. The engine overhaul process has become somewhat of a specialized procedure. Most mechanics won’t consider overhauling an engine themselves. The engine is typically removed and sent out for overhaul. 


When is an overhaul necessary?

The first step in the overhaul process is determining that an engine does in fact need an overhaul. Mere time since the last overhaul doesn’t always equate to needing to overhaul an engine. Part 135 operators must legally comply with engine manufacturers’ recommended times between overhauls. However, the only legal requirement for everyone else is engine condition. 

An engine that is run regularly (at least once a week) with cylinders that have good compressions with no exhaust valve leakage is a good candidate to keep running. Regular oil changes must consistently demonstrate that no excessive metal is being produced by the engine. Such an engine can safely and legally go beyond the manufacturer’s recommended time between overhauls (TBO). 

Cylinder issues can be resolved by replacing the affected cylinder, or by completing a “top” overhaul and replacing all the cylinders.

So, what might indicate it’s time for an overhaul? Excessive amounts of metal that have been determined to be coming from the bottom end parts (camshaft, lifter bodies, gears or crankshaft bearings) is one sign. If an engine has crankcase cracks that are outside allowable limits, it’s time. If an engine has problems producing its rated power even though cylinder compressions are good and fuel and ignition systems are within limits and working properly, an overhaul is likely needed in the near future.  (For more, see “Is Your Engine Worn Out?” by Steve Ells in the October 2017 issue of Piper Flyer. —Ed.)

The overhaul process

An overhaul always includes a complete disassembly of the engine, thorough cleaning and inspection of parts, repair of parts as needed and disposal of defective parts. 

Major items such as the crankshaft, crankcase and connecting rods are subject to special inspections. 

Parts that are subjects of Airworthiness Directives or Service Bulletins are typically replaced or repaired in accordance with the steps outlined in the AD or bulletin. 

Parts are measured for excessive wear and proper clearances. The allowable dimensions and clearances are given in the manufacturer’s overhaul manual in two separate columns; one for manufacture (new) limits and one for service limits. The service limits are larger and allow for looser fits than manufacture limits. Some shops rebuild engines based on manufacture limits, while others use service limits. 


The crankshaft is arguably the most important component in an aircraft engine. It absorbs the force generated by the reciprocating strokes of the pistons and rods and transforms it into rotational force for the propeller. The crankshaft is continuously subjected to loads and stresses from engine operation and the rotating propeller. Cracks or defects on a crankshaft can cause sudden engine failure or excessive, premature wear on the bearings. As a result, the crankshaft is probably the most inspected, measured and scrutinized part in the entire engine during the overhaul.

After engine disassembly, the crankshaft is cleaned and degreased in a chemical vat, dried and inspected. Most shops have a Magnaflux machine to inspect the crankshaft for cracks. 

The crankshaft is clamped between two copper-plated pads and an electric current is sent through the crankshaft to magnetize it. 

The crankshaft is then coated with a fluorescent solution containing magnetic particles. If there is a fracture in the crankshaft, the magnetic particles will align along the edges of the fracture. The fluorescent solution makes cracks easy to see under a black light. 

Once the magnetic particle inspection is complete, the crankshaft is cleaned again, and each journal is polished. Some shops have a machine that spins the crankshaft while a polishing rag is held stationary on one journal at a time with a special tool. Other shops use a machine with a circular cloth that is spun around each journal. The polishing process removes light scoring and surface corrosion as well as providing a clean journal surface so that good measurements can be obtained of each journal. 

Excessive scoring or pits caused by corrosion that cannot be removed by polishing the crankshaft can usually be removed by grinding off a specified amount of material. The manufacturer sets the sizes to which the crank can be reground, and it varies based on the engine model. Most Lycoming crankshafts can be ground to three-thousandths, six-thousandths or ten-thousandths of an inch undersize. Continental usually allows five-thousandths or ten-thousandths undersize. 

Once the crankshaft has been ground down to limits (referred to in the field as “ten under”), any further scoring or pitting defects in the journals will most likely result in the crankshaft being scrapped at the next overhaul. Reground crankshafts require oversize bearings to maintain proper clearances.

When all the machining and polishing processes are complete, the diameters of the main bearing journals and connecting rod bearing journals are measured with a micrometer at several points around the circumference of each journal. The smallest measured diameter is used to determine if each journal is within limits. 

The inside diameters of the connecting rod and crankcase main bearings are measured by installing the bearings and temporarily installing the bolts and nuts, securing the case halves and connecting rod halves together. A telescoping gauge is then used to measure the inside diameter of the bearings. Clearances are obtained by subtracting the journal diameter from the bearing internal diameter. Clearances must fall within the limits set by the manufacturer.

The crankshaft is also measured for straightness (or run-out) using a dial indicator. The crankshaft is placed in a holder that supports the crankshaft while still allowing it to rotate. A dial indicator reading is then usually taken on the rear main journal as well as the crankshaft flange. The readings must not exceed allowable limits. 

It is a fairly rare occurrence when a crankshaft is rejected. Aircraft crankshafts are constructed with high-quality metals at manufacture and, barring misuse or a prop strike, generally pass inspections through multiple overhauls.

If the crankshaft needs to be replaced for any reason, it adds a significant amount to the cost of an overhaul. Some shops try to help owners by finding a serviceable used crankshaft, which is usually one-half to one-third the cost of a new crankshaft. 


The crankcase provides the housing to hold all the internal components (crankshaft, camshaft, rods) as well as providing a place to attach the cylinders, accessory case and oil sump. The crankcase is made of cast aluminum and must be strong enough to absorb all the opposing forces of the engine as it is in operation. 

Crankcases receive a thorough cleaning and inspection at overhaul. 

Some shops use abrasive media to clean the case and some use a chemical vat. Chemical-only cleaning processes are preferred because residue from blast material is difficult to remove from all the creases and recesses in the case. Any leftover media causes scratching and scoring once the engine is placed back in operation. 

Crankcases are inspected for cracks using a dye penetrant inspection. The case is saturated in fluorescent colored penetrant, then rinsed. The penetrant seeps into cracks making them easily seen once the case is sprayed with developer or examined under a black light.

Some cases are more prone to cracking than others. As an example, Lycoming “narrow deck” cases crack far more often than the thicker “wide deck” cases. Narrow deck cases utilize cylinders that have a thinner hold-down flange. The cylinder base nuts are Allen head (internal wrenching) types; while the wide deck cases have cylinders with thicker hold-down flange with standard six-sided nuts. Cracks can sometimes be welded and repaired depending on their location. 

Cases can have fretting damage or small areas of corrosion where the case halves are joined, especially near through-bolts. Cases with damage are generally sent to specialized machine shops such as DivCo or Crankcase Services to have the mating surfaces machined smooth. Some shops “line bore” the center bearing areas so that the crankshaft main bearings are perfectly straight and aligned with the each other. 

Regardless of whether the case is simply cleaned and inspected or sent out for further machine work, the mating surfaces of the case halves must be smooth and perfectly flat to ensure a proper seal once they are assembled. A silk thread is used to seal the case halves along with a special non-hardening compound designed to hold the thread in place as the case halves are assembled. Any irregularities in the mating surfaces will result in case leaks. 

Crankcases, like crankshafts, are expensive to replace and can add significantly to the cost of an overhaul if replacement is required. 

Connecting rods

Connecting rods are Magnafluxed, cleaned and dimensionally checked at overhaul. Connecting rod bearings along with the bolts and nuts that secure the rod halves are always replaced at overhaul. Connecting rod bushings are not always replaced, depending on the wear and condition on the bushings. 

The rods are checked with special dowel tools to be sure they aren’t bent or twisted. The connecting rod is turned sideways and held in a vertical plane. One dowel slides through the connecting rod bushing and the other through the crankshaft bearing. After they are inserted, the ends of the dowels are laid on perfectly-matched metal blocks. The four ends of each dowel pin should lay perfectly flat if the rod is not twisted at all. 

The dowels are left in place and a special gauge is attached to the end of the crankshaft bearing dowel. This gauge telescopes and it is extended until it touches the end of the shorter connecting rod bushing dowel.

After this measurement is made, the gauge is removed and placed on the opposite end of the crankshaft bearing dowel. If the rod is square and not bent, the gauge will line up and touch the short dowel on the opposite side without being extended or shortened.

Camshaft and lifters

The camshaft and lifter bodies are generally replaced or sent out to be reground to remove any light scoring marks or surface deformities. The camshaft lobes go through a carburizing process to harden them at manufacture. The depth of the carburized layer of metal is not very deep (about fifteen-thousandths of an inch) and it is possible for machine shops to accidentally grind below that layer. The camshaft lobe would wear down rapidly once placed in use if that happened. Additionally, the lobes are not only elliptically shaped, but they have a slight taper across the top of the lobe to ensure that the lifter body spins as it contacts the lobe. It takes very precise machine work when grinding the lobe to maintain its original shape and the taper across the top. Camshafts should only be sent to high-quality, experienced machine shops like Aircraft Specialties for machining work.  

Camshafts are not terribly expensive when purchased new (compared to major parts like crankshafts or cases). Typically, the cost of buying a new camshaft and all the lifters is only a few hundred dollars more than having the old ones reground. 

(For more on camshafts and lifters, see Jacqueline Shipe’s July 2017 article in Piper Flyer. —Ed.)
Accessory case, oil sump, gears

The accessory case and oil sump are typically cleaned, inspected and reused. The Lycoming oil sumps that have intake pipes routed through the sump are reswedged around the intake pipe end to ensure there are no leaks down the road. This involves using a special tool which swells the pipe back out a little so that it forms a better seal when it is inserted into the sump opening.

The accessory case is inspected with dye penetrant and cleaned. The gears in the accessory case are cleaned, Magnafluxed and reused. 


Individual cylinder assemblies can be overhauled, but by the time the valves, guides and seats are replaced, the cost is almost equal to the cost of a new cylinder. Most overhaul facilities that I’m familiar with install new cylinders rather than overhauling the old ones. 

The cylinder must absorb the heat and pressure of combustion every time it completes a cycle while in operation. Metal fatigues over time and with a relatively low cost difference between new and overhauled cylinders, new cylinders are the best choice for long-lasting operation. They also typically come with their own warranties, so shops like them. 

It’s important to note that there is no logbook tracking for individual cylinder assemblies. Times in operation are kept of engines, but not of the individual engine parts. Therefore, it is impossible to really know how much operating time cylinders have on them when purchasing overhauled cylinders outright. The times that are on the existing installed cylinders on an engine can be difficult to trace unless they were new at the time of installation. 

Fuel system

The fuel injection system or carburetor is generally sent out for overhaul at a specialty shop or replaced with a new unit. Very few overhaul facilities overhaul the fuel system components in-house. Even Lycoming gets all the fuel injection system components and carburetors for both their new and rebuilt engines from Avstar Fuel Systems in Florida. 

Accessories and other items

All other accessories are typically sent to specialty shops for an overhaul or are replaced with new. Magnetos, ignition harnesses and vacuum pumps are generally replaced with new units. Alternators and starters are generally rebuilt. 

Oil coolers should always be sent out for specialized porting and cleaning to be sure all metal particles and sludge buildup is completely removed. The oil passages through the coolers make several 180-degree turns. Small metal particles and contaminants build up in the coolers around the curves and it is impossible to remove all the debris with just a simple flushing. Oftentimes, new oil coolers are fairly inexpensive, and it is easier and cheaper to simply replace them rather than overhaul them. 

All hoses should be replaced at overhaul. Hoses deteriorate with age and exposure to heat, and should be replaced periodically. New hose installations also help prevent contaminating the freshly overhauled engine with any sludge or debris remaining in the hose. 

It’s also a good idea to replace all the SCAT hoses. Most of the tubing (like the aluminum oil return lines) is cleaned, inspected and reused.


Choosing an overhaul facility

Engine overhauls are extremely expensive. When it’s time to overhaul an engine, choosing a high-quality facility to do the job is important. The best way to choose where to send an engine is usually by personal referral. Ask other owners what shop(s) they have used and what the long-term results have been. Owners or operators that have put three to five hundred hours on an engine usually know by that time whether the overhaul was a good one. Low cylinder compressions, oil leaks or other problems are signs that the overhaul may not have been the best. 

Most Part 91 owners only have to face an engine overhaul once. The process can be stressful to go through. Owners who do lots of research ahead of time, understand the process and ask lots of questions can help to avoid major problems down the road. 



Jacqueline Shipe grew up in an aviation home; her dad was a flight instructor. She soloed at age 16 and went on to get her CFII and ATP certificate. Shipe also attended Kentucky Tech and obtained an airframe and powerplant license. She has worked as a mechanic for the airlines and on a variety of General Aviation planes. She’s also logged over 5,000 hours of flight instruction time. Send question or comments to


Airmark Overhaul

Granite Air Center

Poplar Grove Airmotive

RAM Aircraft

Triad Aviation

Aircraft Specialties Services

Crankcase Services, Inc.

DivCo, Inc.

Avstar Fuel Systems, Inc.

Aircraft Accessories of Oklahoma

NPRM FAA-2017-1059 – Checking for Main Wing Spar Corrosion in Cherokees 

NPRM FAA-2017-1059 – Checking for Main Wing Spar Corrosion in Cherokees 


Over 10,000 Piper PA-28 and PA-32 series aircraft will be affected by a proposed Airworthiness Directive requiring inspection of the main wing spar for corrosion. Associate editor SCOTT KINNEY decides to act now to inspect his Cherokee and secure his peace of mind.


One of the benefits of hanging around type-specific flying forums on the internet is that you’ll often get wind of FAA Airworthiness Directives (ADs) before they’re made public. I’d chanced across just such a post on Nov. 6, 2017.

The poster claimed that Piper Service Bulletin (SB) No. 1304 was about to become an AD, affecting thousands of aircraft. SB 1304 mandates a “thorough one-time inspection of the wing root area for corrosion” and lays out steps to be taken if corrosion is found. To perform the inspection, an access panel must be installed in each wing if one does not already exist.

Sure enough, the next morning, my email inbox contained a confirmation of the rumor: the FAA was moving to adopt SB 1304 as an AD after a 45-day comment period. (See page 60 of this issue. —Ed.) The Notice of Proposed Rulemaking (NPRM) states that compliance will be required within the next 100 hours or 12 months’ time in service from the date of the AD.

Summary: 11,476 PA-28 aircraft owners will soon be getting potentially expensive news.

I’m one of them.

My 1963 Piper PA-28-180 Cherokee 180, N7294W, has served me well for the past few years. As with many older birds, she has a few negatives in the logs. Four Whiskey lived her first several years near the beach in Southern California. I’d guess she was parked outside too, as the logbooks show a few corrosion repairs in the mid-1970s. Since then, she’s been primarily a high desert airplane.

Why not wait?

I decided to move forward with the inspection right away. I suppose I could’ve held off until my July annual and/or until the AD wording was finalized. It may be that the final AD has other accepted methods for inspection (borescope?) that don’t require cutting large access panels in the lower wing skins.

However, I had never seen the spars on N7294W with my own eyes. I am not sure I would’ve been happy flying the airplane for many more hours knowing the potential consequences of wing spar corrosion. November is also a good time of year to get work done on an aircraft in Oregon—it’s not flying season.

And I kept coming back to the reasons behind the proposed AD. A failed main spar means that your wings may fall off. In my book, that’s a very bad day.

Checking for access panels

The first step was to check for existing access panels. I thought that perhaps the panels could have been installed as part of some of the previous repair work. Since I was at home and had the aircraft logs on hand, I checked for any mention of SB 1304, SB 1244B or SB 789A (the latter two Service Bulletins also recommend addition of the access panel kit). Nothing.

The previous owner did pull the fuel tanks about seven years ago to check for spar corrosion (Piper SB 1006), but that’s further outboard on the wing. I went to the airport and crawled under the wing. Maybe the work hadn’t been logged and the panels were already in place.

No joy. I fired up Google and went parts shopping.

Finding parts

The NPRM estimates the cost of Piper’s 765-106V kit “that contains provisions to install inspections access panels on both wings” at $175. I lucked out and found a new old stock kit for a little less than that.

Since the announcement on Nov. 7, 2017, these kits have gotten increasingly difficult to find. Many vendors sold out of 765-106V in the first two days after the announcement, though they have since restocked.

Current street price for P/N 765-106V is between $200 and $250; slightly higher than the $175 estimated in the NPRM. As of early December 2017, PFA supporter AirWard shows a dozen kits in stock at a price of $229; a Google search for “Piper 765-106V” will give the most current situation. I would expect these kits to become increasingly rare or backordered immediately after the final AD is announced.

Installing the access panels

I contacted PFA member Tony Hann at Infinite Air Center in Albany, Oregon to schedule the work. Tony and his lead A&P/IA, Robert Lind, operate several PA-28s out of Albany Municipal Airport (S12). Robert has been working with Piper aircraft for more than 30 years and their shop is just a short hop from my home base.

Once I had my parts in hand, I braved the stormy mid-November weather and flew Four Whiskey up to Albany in what I’ll generously call “imperfect VFR conditions.”

Nuts ‘n bolts

Robert, Tony and I unpacked the kit’s contents onto the wing of the aircraft.

They’d ordered a few kits from Aviall to service their PA-28s. We compared the Aviall kits with my kit from Piper. My kit—dated 1987—matched up parts-wise, meaning Piper hasn’t changed the kit contents in 30 years.

The kit consists of two reinforcing doubler plates and two inspection covers. There are also 40 AN426AD4-4 rivets, used to affix the plates to the lower wing skin and 16 MS24693-S48 machine screws for attachment of the inspection covers to the doubler plates.

The Piper instructions are skimpy, to say the least, and leave some room for imagination (or improvisation?):

1. Skin cutout to be located midway between ribs and midway between the main spar and stringer as shown in
Figure 1 (Sheet 4).

2. Locate and install doubler 38571-02 as shown and attach to skin using [P/N] 420 722 rivets. Dimple for C/S rivets.

3. Cover 38572-02 can be installed/removed as required, using [P/N] 414 761 fasteners.

Other vendors have been kind enough to include more detailed instructions and a tool list. I’ve seen the documentation AirWard supplies with its kit, and it’s a very helpful supplement.

Positioning the inspection panels

The Piper instructions that came with my kit, those in the new Aviall kits and the drawings in SB 1304 all specify slightly different placements of the access panel in relation to the main spar, ribs and stringers.

After some deliberation over the instructions, Robert, Tony and I positioned the cover and used it as a template to define the cutout area.

We marked the hole as specified in the new Piper instructions and SB 1304—approximately 2 inches aft of the main spar rivet line and 3 inches outboard of the rib at WS 24.240. The long and short of it is that you want to leave sufficient space on every side of the access hole to be able to rivet the doubler in place without getting too close to the spar or ribs.

It’s also important to understand that this is a recessed access plate; it’s different from those further out on the wing. Those are attached to the outside of the lower wing skin. When finished, the new inboard inspection cover will be flush with the wing skin.

Cutting access holes

Out came the power tools. I closed my eyes and turned the other way as Robert began the surgery. He drilled a 1-inch pilot hole with a step drill to provide a starting point.

For the primary cut in the skin, Robert chose a Dremel-like rotary tool with a fine tungsten carbide cutting bit. Smart choice. It allowed him to make a smooth radius cut in the thin aluminum skin.

It was helpful to have two sets of hands to finish the cuts—Robert on the Dremel and me holding the cutout piece in place to ensure it wouldn’t prematurely depart the wing. Wear eye/face protection and appropriate clothing when working with the Dremel as the hot aluminum shards fall straight down.

I cleaned up the edges with a half-round file while Robert moved on to the other wing and repeated the process. I held off from peeking inside until we were done cutting the panels.

The inspection

With the holes cut, it was time for the moment of truth. Robert asked, “Do you want to do the honors?” I meekly replied, “Uhh, I guess.” If the spars showed significant corrosion, it likely meant a repair bill of several thousand dollars.

I grabbed a flashlight and inspection mirror and rolled back under the right wing on a mechanic’s creeper. I poked the mirror up into the hole.

Oh, thank God. My wings will not fall off.

The main spar looked pristine. The aft spar was excellent as well. The WS 24.240 (inboard of the access panel) and 36.920 rib (outboard of the panel) showed some oxidation and very minor surface corrosion. Four Whiskey’s main spars had been treated with chromate at the factory, but the ribs hadn’t, so the corrosion on the ribs was no surprise.

Robert took a look and confirmed my initial thoughts. “That’s real clean. Great news!” The left wing looked the same.

It wasn’t all sunshine and rainbows, though. The inspection panel in the right wing allowed me to see the underside of the wing walk skin. A few minor cracks had developed in the reinforcing louvers—a common problem with PA-28s. I have felt a slight bit of oil-canning in the wing walk in the past, so I wasn’t shocked by the finding. Such is life with an old aircraft; one more thing to fix.

Cleaning and priming

Robert and I cleaned the interior of the inspection area with a degreaser spray per Part I, Step 3 of SB 1304. After 50 years, the wings had an impressive collection of dead bugs and grime. We reinspected the spar after cleaning and found no corrosion.

SB 1304 states that if corrosion is found in the main spar area, it must first be removed per FAA Advisory Circular AC 43.13-1B, Chapter 6. The affected areas then must be measured for minimum thickness. It is not possible to directly measure all dimensions, so nondestructive methods (ultrasound, eddy current, etc.) may need to be used.

If the thickness of the parts is greater than the limits specified in SB 1304 Part I, Step 5, the areas can be epoxy primed and the aircraft returned to service. The SB contains a list of approved epoxy primers.

If the thickness is below minimums, an FAA-approved structural repair must be performed. This is likely to be an expensive proposition.

We chose to clean and apply epoxy primer to the ribs to ensure no further corrosion on these surfaces. Though this action is not required by SB 1304, it made sense to do with the aircraft already opened up.

Affixing doublers and buttoning up

After the inspection and corrosion mediation steps were complete, Robert went to work on affixing the doublers. Riveting isn’t my strong suit, so I played the role of gofer.

Each doubler plate required 20 countersunk rivets. The rivets are equally spaced around the doubler plate, approximately 5/16 of an inch outside the cutout. Robert used a drawing compass, a slide rule and some mechanic’s magic to get the spacing right. The AirWard instructions contain an error here. They give a layout scheme for 24 rivets per plate, not the 20 per plate that is specified in the Piper documents. They are otherwise really helpful.

Drilling the holes for the rivets is a six-step process. First, Robert clamped the doubler in place. Next, he drilled 1/16-inch holes through the skin and doubler. He then enlarged the holes to 1/8 inch.

Once the holes were drilled, he removed the doubler and deburred the holes. The fifth step was to dimple the holes with a rivet squeezer and appropriate die. Finally, he used Clecos to hold everything in place while he set the rivets into the skin and doubler with the squeezer. The right tools made this job go quickly.

When he finished riveting, Robert made an entry in the logs noting compliance with SB 1304. All that was left was to install each cover with the eight machine screws. I managed this on my own. Four Whiskey needs a bit of paint touch-up in other spots, so I plan to paint the covers and rivet heads later on this winter as a part of that project.

Final thoughts

It took about eight hours of work for Robert to install the panels, clean the interior of the wing and perform the inspection. The NPRM estimates six hours’ labor for the panel installation and two hours for the inspection. For obvious reasons, the NPRM does not estimate labor time or parts costs for corrective actions, as these may range from a small area of sanding/priming all the way up to spar replacement. Nor does it account for cosmetics. Paint touch-up may take additional time.

I’d encourage those owners whose aircraft are affected to consider complying sooner rather than later. It may be that your aircraft already has the access panels, in which case it’s a quick inspection. Even if your aircraft doesn’t have the panels, the installation and subsequent inspection is time-consuming, but isn’t particularly complicated.

Installation of the panels can facilitate later inspections required by this or other ADs or SBs. Additionally, you’ll have better access to the inboard areas of the wing for future upgrades (pulling wires) or repairs (the wing walk comes to mind).

Now that I’ve seen the clean spar with my own eyes, I’m 100 percent confident that I have structurally sound wings holding me up in the air. It’s hard to put a price on that feeling of security.

Scott Kinney is a self-described aviation geek (#avgeek), private pilot and instructor (CFI-Sport, AGI). He is associate editor for Piper Flyer. Scott and his partner Julia are based in Eugene, Oregon. They are often found buzzing around the West in their Cherokee 180. Send questions or comments to .



Infinite Air Center



Piper Service Bulletin No. 1304
“Main Wing Spar Inspection,”
published Aug. 23, 2017


Piper Service Bulletin No. 1244B

“Aft Wing Attach Fitting Inspection Requirements,” published Oct. 29, 2015



Piper Service Bulletin No. 789A

“Aft Inboard Wing Access Panel Retrofit and Aft Wing Spar Modification”

published May 7, 1985

Notice of Proposed Rulemaking (NPRM)

Docket No. FAA-2017-1059; Product Identifier 2017-CE-035-AD

https://www.federalregister.gov/documents/2017/11/07/2017-24083/airworthiness-directives-piper-aircraft-inc-airplanes (See page 60 of this issue. Comments closed Dec. 22, 2017. —Ed)

P/N 765-106V – VENDORS

AirWard, Inc.
– PFA supporter






Chaparral Parts







Airplane Maintenance for the DIYer: First Steps

Airplane Maintenance for the DIYer: First Steps

Owning an airplane is usually the result of years of hard work and planning. For many, it is a fun and rewarding experience—the fulfillment of a lifelong dream. 

Although airplane ownership is a big source of joy, it can also be an expensive and responsibility-filled endeavor. In fact, cost is the number-one concern that most pilots have when it comes to owning a plane. 

The initial purchase price of a plane is only one part of the equation. Insurance, fuel, storage, maintenance, avionics upgrades and any updates to the paint or interior can add up to be far more than the initial purchase price over a period of time.  

One way to lower the operating costs is to be actively involved in your plane’s maintenance. In addition to cleaning the plane, there is a surprisingly long list of maintenance actions that an owner may legally perform on his or her aircraft, provided it is not operated under FAR Parts 121, 129 or 135. 

The benefits of DIY maintenance

There are several benefits for owners who decide to do a lot of their own maintenance. Long-term, it does save on labor costs, although initially there are some expenses for tools and supplies. 

In addition to the cost savings, working on a plane gives a person the opportunity to get a better understanding of how different systems operate and how things on their aircraft are put together. This translates into a better understanding of the readings on the gauges in the cockpit and may allow the pilot to detect potential problems more quickly. 

Owner-performed maintenance also helps a pilot know how to operate the plane in a prudent manner that is easy on mechanical items. 

Owners also typically aren’t as pressed for time as mechanics working in a shop. This means that they can take the time to address cosmetic issues as well as maintenance issues. Little things like repainting removed items, fixing cracks in plastic or fiberglass trim pieces, or replacing rusted panel screws with stainless ones not only makes a plane look better, it adds to the resale value.

Preventive maintenance 

FAR 43 Appendix A, section (c) lists the maintenance tasks that an owner with a private pilot certificate is allowed to do and legally sign off. These all fall under the category of preventive maintenance, and the list is pretty extensive. 

A few of the items listed include tire changes, landing gear strut servicing, greasing wheel bearings, oil changes, fuel strainer cleaning, replacing or servicing the battery, and (with the exception of the control surfaces) even repainting a plane. 

Although these tasks are legal to perform, some of them are a little complicated, and the consequences if a mistake is made are high. Specialized tools and maintenance manuals are required for a number of the procedures. 

It is best for owners who decide to tackle some of these maintenance tasks themselves to pay a mechanic to show them the ropes for the first time. It is also a good idea for any owner to buy the latest revision of the parts and service manual for the specific make and year model of the plane he or she owns. 

Even folks that aren’t interested in maintaining their planes themselves can still benefit from a parts and service manual so they may look up part numbers, compare parts prices and have the information available in case the mechanic they work with doesn’t have it. (Mechanics have extensive libraries, but it is nice to supply them with complete paper copies that are easy to access.)


The necessary tools

In addition to the manuals, there are a few tools that are required for preventive maintenance. Most folks already have a general tool set for home use. The same items needed for tinkering on a car are needed for a plane: socket and wrench sets, screwdrivers, etc. 

A good ratcheting screwdriver that has separate bits works well for removing panels. The DeWalt brand Phillips drywall bits are great for removing stuck screws because the end is rounded so that more of the bit sinks into the screw head, making it easier to break the screw loose and less likely to round out the head. 

Screw guns really speed things up, but aren’t a necessity. A 7/8-inch socket made just for aviation spark plugs is nice to have also, and can be purchased from almost any aircraft parts distributor. 

Safety wire pliers and a can of .032 inch safety wire are handy to keep around. The oil filters and most of the bolts that require safety wire utilize this size. The pliers vary in price—from over $200 for high-quality ones, to around 20 bucks for a cheaper set. 

The better quality pliers are designed so that the teeth won’t gouge into the wire and weaken it as the pliers are clamped down. Safety wire can be twisted by hand; it’s just a little more difficult to do if you’re working in a tight place. 


Jacks and a tail weight

The biggest equipment investment that an owner who is really serious about maintaining his or her plane might want to consider investing in is a set of jacks. 

Low-wing planes and planes with retractable landing gear all need to be completely raised on jacks periodically for gear servicing or tire changes. Jacks can range in price from around $300 to a couple thousand dollars per jack, depending on the style and quality. 

The better ones have a long metal tube that slides over the hydraulic piston. This tube has holes drilled in slight increments along the length to allow a safety pin to be installed to prevent the jack from accidentally lowering if it loses hydraulic pressure. This type of jack is the safest, but it is a little more expensive than others. 

In addition to two jacks, a tail weight will be needed. These are fairly easy to make with some steel tubing and an old galvanized tub filled with concrete. The jack manufacturers also sell tail weight kits that are easy to assemble and fairly inexpensive; one just has to be sure the weight is heavy enough to counterbalance the heavy nose as the plane is lifted. 

Any time a plane is jacked, use caution to ensure it is being raised evenly on both sides. If the work is being done outside, make sure the wind is not forecast to get too high. Significant damage can occur to a plane if it falls off a jack.

Logbook entries

After purchasing the proper tools and manuals, and with a little guidance, a person is well on his or her way to performing a variety of preventive maintenance items. 

Once a particular task has been completed, a logbook endorsement should be made stating the date, tachometer time, a description of what was done and the reference material that was used for completing the task. It is good to also include the part numbers for installed items. 

For example: “September 15, 2014; 2245 tach time; removed and replaced landing light bulb part number GE4554 in accordance with Piper Cherokee service manual; operational check good.” The signature and the pilot certificate number of the person completing the work is what returns the airplane to service. 

Once a pilot gets started working on their plane, he or she may find it almost as rewarding an experience as flying it. The benefits for owners that learn to do a lot of their own maintenance can be well worth the initial investment in tools and materials.

Note: In future issues of Piper Flyer, Jacqueline Shipe will be discussing specific preventive maintenance items step-by-step. 

Jacqueline Shipe grew up in an aviation home; her dad was a flight instructor. She soloed at age 16 and went on to get her CFII and ATP certificate. Shipe also attended Kentucky Tech and obtained an airframe and powerplant license. She has worked as a mechanic for the airlines and on a variety of General Aviation planes. She’s logged over 5,000 hours of flight instruction time. Send question or comments to .

One Part of the Whole: New Surplus & Used Aircraft Parts

One Part of the Whole: New Surplus & Used Aircraft Parts

Piper Flyer recently talked to Dodson International, Preferred Airparts and Wentworth Aircraft to find out what you need to know about airplane parts.

For many pilots, the availability—and the affordability—of replacement parts is a deciding factor in which aircraft they choose to own. 

For others, availability isn’t an issue—until they find their plane is down for an unusually long time due to a simple part that’s difficult to locate, or perhaps worse, a common part that’s difficult to locate at a reasonable price. 

Define your terms

When an owner-pilot has a need for a part for their airplane, navigating the landscape of parts suppliers and parts classifications can be confusing.

First of all, a yellow tag is somehow better than a green tag when it comes to airplane parts. Also, the term “new old stock” isn’t an oxymoron, it’s an accepted way to describe a manufacturer’s surplus. 

What’s more, sellers sometimes use different terms to refer to the same thing, which can make reading a description of an airplane part feel more like an SAT test question to the uninitiated. 

In order to help you understand what’s what, our editors have compiled a list of working definitions for the various categories of aircraft parts, which you can find on page 22.

The triumverate 

Several companies around the United States have made it their business to evaluate, purchase, inventory, store and distribute surplus and used Piper aircraft parts. Piper Flyer set out to talk to various companies to get some insight about GA airplane parts in today’s market. 

Piper Flyer reached out to several companies to provide information for this story; not all were able to respond by our deadline. The three that did, however, are diverse enough to give readers and members a serviceable—if I may—representation of the parts market. 

All joking aside, these three companies do have one thing in common: they dismantle an astonishing variety of aircraft that result in a huge number of saleable parts. 

Dodson International

“We sell everything you could find on an aircraft, and part just about any make and model,” explained J.R. Dodson, owner of Dodson International Parts, Inc. “This means any part on the aircraft: avionics, engines, props, interiors.”  

Dodson International, located in Rantoul, Kan., has over five million in-stock aircraft parts, and in the company’s 32 years of operation it has torn down more than 3,000 aircraft—an average of one plane every four days, for over three decades. New Surplus (NS), Overhauled (OHC) and As Removed (AR) parts are available from Dodson International. 

Preferred Airparts

Preferred Airparts has made New Surplus parts its specialty, with over 14 million new parts in stock at its Kidron, Ohio location. “We stock new surplus OEM parts for many aircraft, engines, props and accessories,” explained Dale Miller, marketing manager for Preferred. 

The company was founded in 1982 and also stocks used parts, including many yellow-tagged and overhauled parts with 8130s. 

Wentworth Aircraft

Wentworth Aircraft in Crystal, Minn. is the largest volume buyer of aviation insurance company salvage airplanes in the world, reports company co-founder and CEO Steve Wentworth. “The majority of our parts are used,” Wentworth explained, “and we buy 150 to 175 aircraft every year.” 

Wentworth Aircraft has purchased over 4,600 airplanes and is entering its 30th year in the aircraft salvage business. At this rate, by the time you read this story, an average of another dozen aircraft will have been delivered to the warehouse.

Storage facilities

Speaking of warehouses, all three of these companies utilize them—so please, cast away your visions of mouldering parts in a field in the middle of nowhere (it’s more like a field of roofs in the middle of nowhere).

“All of our parts are stored under roof at Preferred Airparts—everything including fuselages,” explained Miller. “Parts are cleaned and stored in a climate-controlled warehouse as needed.”

Dodson stores its parts in warehouses as well, and the avionics inventory is kept in an anti-corrosive, anti-static, climate-controlled environment. They utilize plugs and desiccant when appropriate.

Parts are kept in hangars at Wentworth Aircraft, too, so there’s zero exposure to Minnesota weather. “Even our stock of over 450 wings are all inside,” Wentworth explained. Smaller parts—instruments and switches, avionics and landing gear—are kept in climate-controlled buildings.

In whole, or in part?

Dodson, Preferred and Wentworth get their aircraft parts in a variety of ways, but each relies on some major sources. 

For example, Dodson buys from aviation companies worldwide. “These companies have parts available for a myriad of reasons, including new surplus, closeouts, liquidation and incident-related. Non-incident aircraft sometimes fly in to be parted,” said Dodson. 

Preferred Airparts mainly gets parts from people who have overstock, companies going out of business and insurance companies, according to Dale Miller. 

Wentworth Aircraft almost exclusively buys whole airplanes from insurance companies. “Most of the airplanes we part out are in current calendar annual, or just out of annual, so the undamaged components are airworthy and have recently been
flying,” Wentworth explained.

The Mark I eyeball

A thorough visual inspection and the inspector’s experience are key for evaluating used parts, and Dodson, Preferred and Wentworth all perform these checks in-house before a used part is placed in inventory. 

“The two best inspection tools are the eyes of an experienced inspector,” Steve Wentworth told me. This method works well for items like a gear leg, but the company also has a magneto test stand and other specialized equipment.

Dodson employs A&P mechanics, IAs, commercial pilots and other FAA licensed personnel to advise and support its customers. Preferred Airparts’ staff includes 10 A&Ps by my count of the directory included on the company website. 

All three companies work with outside repair stations for any used parts that may be tagged, like avionics and accessories. 

Staying organized

Storing so many millions of parts requires a good organization system. “All parts are properly identified by part number, trace and condition before they are put on the shelf,” Dodson explained. “Before a part is shipped, it is checked by the parts picker, salesmen and shipping for part number, serial number and condition.” 

Preferred Airparts also exercises meticulous inventory control, and because the company sells out of its own stock, customers deal direct rather than going through a parts broker. More than 90 percent of the time, a part in-stock at Preferred can be shipped the same day.

Wentworth Aircraft’s inventory system groups parts by similar types, while identifying each part by the aircraft it was removed from. “With so many parts to choose from, this allows our parts pullers to seek out the very best of several available parts,” Wentworth explained.  

But what about my plane?

Let’s assume you’re in the market for something for your Piper. If you were asking my advice, I’d tell you that all of these companies are definitely worth a try. 

If you’re looking for a new surplus part for your Piper, Preferred Airparts stocks more than 20,000 part numbers, according to its website. Several acquisitions have expanded the scope of parts to include Piper Mirage/Malibu.

For the Cherokee line, Wentworth can be a great place to check for used parts. “We are a leader in Piper Cherokee parts, from 140 through Arrow and Archer, to the Six and Lance,” Wentworth said. “We have most anything for these airplanes, including parts the factory can’t or won’t sell you. We also regularly part out Senecas, both single and Twin Comanches, and the occasional Tri-Pacer as well.”

Dodson, too, has a large inventory of Piper parts. “We part everything from Tomahawk to Cheyenne, and have parts from 1953 aircraft on up,” Dodson told me. “Piper aircraft as new as 2014 have been parted.” A check of the online inventory of Piper aircraft yielded results for parts from 285 discrete planes at Dodson International.

What if it’s wrong? 

Yes, you can send it back. “Sometimes a part doesn’t fit, or is not what the customer expected. We offer a 30-day, money-back guarantee for those circumstances,” Wentworth said.

Parts from Dodson are guaranteed for 30 days, and Preferred will replace any defective or mismarked part with an acceptable part if notified within 30 days of sale. (For further detail on return policies, circumstances and any exceptions, check with company representatives. —Ed.)

Rejected parts

For Preferred Airparts, rejecting new surplus parts isn’t a common occurrence. 

But when you’re dealing mainly with used parts, it’s a must to ensure the integrity of your inventory. “Any rejected parts are mutilated and scrapped,” Dodson explained.

Wentworth added, “We recycle bad or damaged parts at the rate of two or three trailer loads a week—so you may be drinking your soda out of a can made of a damaged Cherokee wing!”

Online inventory, RFQs… or just contact PFA!

If you are looking for a specific part, contact these companies directly to inquire about availability and receive a quote.

You can also contact us at the Piper Flyer Association to make use of the parts locating service. This convenient benefit is included with your membership, will definitely save you time and may even save you a little money, too.


Dodson International Parts, Inc.



Preferred Airparts, LLC



Wentworth Aircraft, Inc.





Q & A: A Patch Repair on a Straight-Tail Lance & the Pros & Cons of the Arrow III OEM Turbocharger

Q: Hi Steve,

I have a PA-32-300R straight-tail Lance (1976). I just noticed a three-inch by three-inch skin repair on both sides of the trailing edge of the rudder. 

I cannot find a 337 or logbook entry—
it was done before I bought the plane. 

My mechanic advises that this type of repair is taboo on the control surface and the rudder needs to be re-skinned. Is this correct? 

If repairs are okay, where do I confirm and show to my mechanic? Any help is appreciated.


A: Dear Pete,

Damage along the lower trailing edge of Piper PA-28 and PA-32 rudders is a common occurrence, according to Roy S. Williams at Airframe Components, a well-known control surface repair facility in Kendallville, Ind. 

“It’s usually caused by overzealous pilots moving the rudder back and forth during a preflight,” Williams told me. 
The material is only .016 inch thick and 
is easily deformed.

Williams stated that it’s a common misconception that patch repairs are not allowed on moveable control surfaces. This, he said, is a holdover from the Piper PA-24/30/39 Comanche service manuals that had specific statements in the Structures section, including, “…repairs to moveable control surfaces is strictly prohibited. Any repair beyond changing hinges or fasteners will require replacement of the entire component…”.

I was surprised to learn that the 
PA-32 service manual does not specifically prohibit patch repairs on moveable control surfaces. “The Structures section of the PA-32 series service manual only states that ‘…all repairs must be made 
in accordance with AC-43.13…’” 
Williams explained. 

“If your mechanic feels that the repair meets the criteria, he or she would need to create a Form 337 that would describe the repair that has been made. You would also need to perform and document a static balance check of the control surface.

“However, that being said,” Williams continued, “Murphy’s Law would probably go into effect. You would probably be on a cross-country trip when you’re approached by an inspector who believes that patch repairs are prohibited on moveable control surfaces of PA-32 aircraft. 

“You would have to produce the Form 337 that documents the repair and spend time trying to prove that the repair is legal. Worst-case scenario, the airplane would get ‘red-tagged’ and you’d have to come back and retrieve it at a later date with a perfect rudder in hand.

“The effort and expense that you expend repairing or replacing the rudder now might be less than the effort 
and expense required to prove that you have a legal rudder at a later date,” Williams reasoned.

The rudder that is installed on your aircraft is PN 65342-002, said Williams. “This same rudder is used on all straight-tail PA-28 and PA-32 series aircraft from the mid-1970s and following,” he explained. “This rudder is used on current production PA-28 aircraft even today. There should be a plentiful supply of perfect rudders available from various salvage yards.”

You can buy a used serviceable rudder from Dodson, Preferred Airparts and Wentworth Aircraft; all three of these companies are Piper Flyer Association supporters. (PFA can help you find a rudder or any other part; this service is included in your membership benefits. —Ed.)

Or, Williams said, you could also have a new skin installed on your existing rudder structure. “If you choose to re-skin your rudder, be sure to send it to a facility that has proper jigging fixtures to insure that the rudder does not get twisted during the rebuilding process,” he said. All of the skins are still available from Piper.

Happy flying.


Q: Hi Steve,

I fly a Turbo Arrow III and have some questions about the turbocharger system. 

In a nutshell, how does the system work? I’ve heard guys at the airport talk about wastegates and other terms, but I’m not getting it. 

Can you provide a turbocharger briefing for the system on my T-Arrow?

—Turbo Ted


A: Hi Ted,

Good question. The normally aspirated (non-turbocharged) Arrow III uses a 200 hp four-cylinder, parallel valve Lycoming engine. Your T-Arrow uses a 200 hp Continental TSIO-360F or -FB six-cylinder engine with a fixed wastegate turbocharging system. The turbocharger system, if adjusted correctly, provides sea level power (200 hp) up to 12,000 feet pressure altitude. 

One benefit of turbocharging (and turbo-normalizing) is an increased safety margin when operating in and out of high altitude airports. Another benefit is higher cruise speeds, since 65 or 75 percent power is available up into the mid-teens in altitude where atmospheric drag is lower. 

Finally, cruising at altitudes that are too high for normally aspirated airplanes and too low for turboprops—typically between 10,000 and 17,000 feet—is ideal, since this block of airspace is less populated by other aircraft. This often increases the chances of receiving GPS direct routings. 

The illustration above shows how the system in your Arrow works. The turbine (hot) wheel and the compressor (cold) wheel are mounted on opposite ends of a common shaft through a bearing in the center housing. The bearing is lubricated by pressure oil from the engine. 

Rotational speeds of the wheels are dependent on the pressure and volume of the exhaust gases directed onto the turbine (hot) wheel. The engine exhaust gases are routed either onto the turbine wheel or around the turbine wheel through an adjustable orifice in the bypass tubing. 

This type of system is termed a “fixed” (or “ground-adjustable”) wastegate system. It’s a simple system but since there is no boost control system, the pilot must be very careful when managing the throttle. 

If the throttle is advanced too quickly during takeoff, the manifold pressure will shoot past redline. When the pressure is too high, the overboost safety valve will unseat, thereby opening a hole in compressor discharge tubing to relieve the high pressure and protect the engine. 

The other disadvantage of this type of system is that the wastegate is fixed; the pilot can’t control it to increase the exhaust gas flow to the turbine wheel when air density decreases in the climb. 

Turbocharging (and turbo-normalizing) systems with adjustable wastegates are more efficient at higher altitudes since closing the wastegate is the best way to compensate for the decreased air density at altitude. 

The other drawback to a fixed wastegate system is that the turbocharger is always online and since the system is always bypassing some of the exhaust, the system works harder to maintain the desired manifold pressures. This results in higher compressor discharge temperatures (CDT) and, in turn, higher cylinder head temperatures (CHT). 

There are a couple of modifications that have been developed with the goal of reducing the heat-related stress of the fixed wastegate turbocharging system in your Arrow.

The first is the installation of an intercooler in the air path between the compressor outlet and the engine inlet. An intercooler is an air-to-air radiator. Cool ram air is ducted across the intercooler as the compressor discharge air flows through the cooler. 

According to Turboplus, its $5,500 mod drops CDT by up to 160 degrees. The intercooler mod cools the induction airflow so much that manifold pressures have to be adjusted down from the Piper power charts to compensate for the increased power resulting from the denser inlet air. 

Benefits of installing the Turboplus mod are better fuel economy (lower manifold pressures to get equivalent power), increased detonation margins and lowered risk of heat-related cylinder problems. 

The second mod is the installation of an automatically-controlled moveable wastegate in place of the fixed wastegate. Merlyn Products’ Black Magic was developed 27 years ago and retails today for $3,290. 

The Black Magic system is simple and results in greater turbocharger efficiency since the total compressor output is available to maintain manifold pressures. This results in lower compressor speeds required to maintain desired boost. Lower compressor speeds result in cooler CDT, which in turn result in lower CHT. 

This system is so much more efficient than the original system that the critical altitude is increased from 12,000 feet to 18,000 feet pressure altitude. (Critical altitude is defined as the altitude where the turbocharger system is no longer able to maintain sea level pressure.) 

Black Magic is not a totally automatic system, so the pilot still has to be vigilant when adjusting the throttle to set manifold pressures, but it’s a big improvement over the OEM fixed wastegate system.

Occasionally, a pilot may decide to crank in a “performance increase” by adjusting the wastegate adjustment bolt to increase the critical altitude. This is counterproductive since it ratchets up the CDT throughout the entire operating envelope. 

Two adjustments are required to ensure engine health. The first is adjustment of the altitude compensating fuel pump in accordance with the chart and instructions in the service manual. These adjustments provide the correct fuel flow at high power operations (and thus throughout the engine operating range). 

The other adjustment is at the wastegate. A flight to 12,000 feet pressure altitude is needed to determine if the wastegate is set to provide the recommended critical altitude performance. If your manifold pressure drops off at a lower altitude—or doesn’t begin to drop off at 12,000 feet—the wastegate will need adjustment. 

This adjustment can only be done on the ground. It consists of loosening a lock nut and turning a large bolt either counterclockwise or clockwise; then tightening the locknut. The adjustment will then need to be checked by a test flight. 

Both the Turboplus and Black Magic mods address the main shortcoming of the fixed wastegate system and are well worth looking into. Suzanne Evans, owner of Merlyn Products, suggests that the Black Magic system should be installed first since it improves engine performance at all altitudes, but went on to say that the Turboplus intercooler works very well in combination with the Black Magic system, especially for pilots that consistently fly at higher altitudes. 

Remember that in a fixed wastegate turbocharging system the throttle is the direct controller of manifold pressure boost, especially at lower altitudes. Pilots that are experienced with this type of system never firewall the throttle on takeoff; instead they slowly advance the throttle to obtain approximately 30 inches manifold absolute pressure (MAP), then wait a few seconds for the turbocharger to get up to speed before gradually advancing the throttle to takeoff power redline. 

Happy flying.


Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to 



Used rudders – PFAsupporters

Dodson International Parts, Inc.



Preferred Airparts, LLC



Wentworth Aircraft, Inc.



Control surface repair

Airframe Components by Williams, Inc.



Fixed wastegate turbocharging system mods

Merlyn Products, Inc.





The Care and Feeding of Diesel-Fueled Aircraft Engines

The Care and Feeding of Diesel-Fueled Aircraft Engines

Three diesel engine experts explain what's required to keep a diesel engine running well.

No spark plugs, no plug wires, no magnetos; no wonder diesel engines require less service than an Avgas engine.  

In spite of the fact that these engines have a lot of advantages over an Avgas-fueled engine, today in the United States only one OEM—Piper—sells a diesel-powered airplane. (Piper’s new Archer DX utilizes a CD-155 engine by Continental. For more information about the DX, see page 38 in this issue. —Ed.)  

Diesels are more fuel efficient, require less maintenance and are more dependable since there are far fewer moving parts. And because Jet-A fuel is a lubricant rather than solvent, internal engine rust is eliminated.  

I interviewed John Weber, the diesel engine service expert on the 155 hp liquid-cooled CD-155 at Continental Motors; Thierry Saint Loup, chief of North American support for the SMA 230 hp SR305-230 oil- and air-cooled engine; and Dennis Webb, president and CEO at DeltaHawk Engines to learn what it takes to keep a diesel engine running well.  

They all said essentially the same things. Critical maintenance items include observing the best clean-room techniques possible when dealing with diesel fuel systems and keeping the induction filter clean. 

Saint Loup mentioned that maintenance procedures on an SMA diesel are more akin to servicing a turbine powerplant, and that as long as the fuel system and inlet air filter are kept operating-room clean, “a diesel engine will run a long, long time.” 

Saint Loup also told me that SMA estimates that maintenance man-hour costs are 50 percent less than the costs to maintain an Avgas-fueled engine. 

Data logging 

The CD-155 and the SR305-230 diesels are equipped with data logging (a request for this information from DeltaHawk wasn’t received by press time); the CD-155 sports a cluster of data sensors that gather information to monitor and control systems such as the turbocharging, fuel injection, fuel pressure, propeller rpm and others. 

The SR305 records engine hours and fault modes. At each inspection these engines are connected to a laptop computer and an engine operations text file is downloaded. This data can be applied to MS Excel to compare engine performance with earlier downloads. The files can also be sent to service centers when troubleshooting help is needed. 

Service intervals for the  SMA SR305-230

Every 100 hours (100/200/300/400, etc.):

Change engine oil and filter; check magnetic sump plug for metal; run up engine and download data. Conduct a thorough visual inspection for condition and external corrosion. Clean inlet air filter. Estimated labor man-hours: three.


Every 200 hours (200/400/600/800, etc.): 

Conduct 100-hour maintenance listed above. Replace spin-on fuel filter and remove and clean turbocharger oil return check valve. Estimated labor man-hours: four.

Every 600 hours (600/1,200/1,800, etc.): 

Conduct 100- and 200-hour maintenance above. Perform cylinder compression test; remove and replace fuel injectors (exchange); check and adjust as necessary setting on fuel injection pump; replace pin in turbocharger if axial play of main shaft exceeds limits.

Every 1,200 hours: 

Conduct 100-, 200-, and 600-hour maintenance. Replace turbocharger and remove and replace electronic control unit (ECU). Estimated labor man-
hours: 10.5.

At 2,400 hours: 

Exchange engine for new or rebuilt engine.

Service Intervals for Continental Motors (formerly Thielert and Superior Air Parts) CD-155: 

At first 100 hours and every 100 hours thereafter:  

Change engine oil and filter and gearbox oil.

At first 200 hours and every 200 hours thereafter: 

Conduct 100-hour maintenance, plus change engine air filter.

At first 600 hours and every 600 hours thereafter: 

Major inspection. Conduct 100- and 200-hour maintenance plus exchange gearbox; inspect dual mass flywheel (DMF); exchange electric pressure fuel pump; exchange common rail fuel 
control valve; exchange alternator.

Every 900 hours:  

Conduct appropriate hour interval maintenance, plus change camshaft timing chain.

Every 1,200 hours: 

Conduct appropriate 100-, 200- and 600-hour maintenance. Change V-rib belt; exchange fuel feeder pump.

Every 1,500 hours: 

Exchange engine and install new motor mounts. 


At this point, all aircraft diesel engines are serviced with Aeroshell Diesel Ultra fully synthetic multi-grade oil. Shell recommends 100-hour oil change intervals.

Cost is about $10 a liter versus $7 a quart for Aeroshell 15W-50 multi-grade Avgas engine oil. (One liter equals 1.056 U.S. quarts. An equivalent price in quarts for the diesel oil is $9.46.  —Ed.)

Service intervals on DeltaHawk’s V4 engine 

According to a service interval document supplied by Webb, DeltaHawk’s plan for the V4 is very similar to the other two engines except a few of the intervals are shorter, including 50-hour oil changes—and in addition to the engine oil change, oil is also changed on the fuel pump and supercharger. 

Diesel engines haven’t been widely used, but interest in the technology—due in part to recent auto-industry improvements that offer higher power-to-weight ratios more suitable for an aircraft application—is growing. 

Diesel’s significant benefits, including increased fuel efficiency, decreased maintenance and more dependability are being welcomed by many in the General Aviation industry. 

In addition to the three companies highlighted here, many other manufacturers have diesel engines in development.


Steve Ells has been an A&P/IA for 43 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to .



CD-155 engine (155 hp)

Continental Motors Group 



SR305-230 engine (230 hp) 




V4 multi-fuel engine (160 to 200 hp) 

DeltaHawk Engines, Inc.




Q & A: Replacing an old starter contractor, and proper antenna installation for a 406 MHz ELT

Q: Hi Steve,

I think I should replace the starter contactor on my 1978 Cherokee Six 300. As far as I can tell, the contactor is working fine, but it looks like it’s almost 40 years old. I haven’t found an entry in the aircraft maintenance records that indicate it’s ever been changed. 

I am a firm believer in paying it forward on maintenance. I fly my Six into mountain strips all over the Western United States and would hate to have to figure out how to get my engine started if the contactor ever fails out in the bush.

What’s your opinion?

—Contactor Charlie

A: Dear Charlie,

I am in the same boat. As far as I can tell from logbook research and general appearance, the starter contactor on my Comanche is also the original unit. That makes it 55 years old. 

Like yours, mine also seems to be working fine. But as an A&P who has cut apart a few contactors to inspect the internal components, I know that arcing and time will reduce the current-carrying capacity. 

I know of two approaches to replacing an older contactor. 

Piper Service Letter (SL) 1093A, published on May 8, 2015, provides information on starter contactor replacement parts and installation procedures for Piper-supplied contactors. SL 1093A is applicable for PA-18 through PA-46 aircraft, supersedes SL 1093 and expands the serial numbers affected. (“Aircraft that have previously complied with SL 1093 are in compliance with SL 1093A,” according to the publication. —Ed.) Piper Engineering Order (EO) 88371, Revision E is part of  SL 1093A. 

These documents supply a list of replacement part numbers for starter contactors that are identical to the original configuration, and descriptions of (and differences between) the original and newer replacement contactors. In addition, they provide instructions on how to install the original grounded-case style of contactors and how to install the newer insulated-case style of contactors. 

Grounded-case contactors are easy to identify: there’s only one small lug and two large lugs. 

Insulated-case contactors have two small and two large lugs. In addition, insulated-case contactors have a black plastic insulator on each mounting tab. 

One thing that may confuse installers and owners is the fact that the contactor—part number 487-149—installed on my Comanche, and the contactor on your Cherokee Six—part number 487-169—are specified as six volt intermittent contactors. 

Since my Comanche and your Cherokee Six have 12 VDC electrical systems, this flummoxed me. I wrote to Piper, and within hours, Piper wrote back to say that six volt contactors are used in the starter circuit to insure that the contactor stays closed—thereby energizing the starter—even when battery voltage drops below the level where a 12 volt contactor would stay closed. 

The part number for new starter contactors from Piper for your Cherokee Six is 602-847 (99130-003). Internet prices range from $120 to $160; I did find one in original Piper packaging on eBay for $79.

Changing a grounded case contactor is a simple remove-and-replace job. 

Changing from a grounded case to an insulated case contactor requires the installation of a jumper wire from one of the small lugs to one of the mounting bolts or screws that secures the contactor to the firewall. The Piper part number of the jumper wire is 84580-044; cost is around $20.

The second approach you can take to replace your old contactor is a replacement solution from Sky-Tec in Granbury, Tex. 

Sky-Tec offers a complete line of 12 and 24 volt FAA-PMA approved original configuration grounded-case starter contactors. 

Replacement contactors for 12 volt systems—part number STS-S12—sell for $69, while 24 volt contactors—part number STS-S24—sell for $79. 

Sky-Tec contactors are sold by most aviation supply houses. The Instructions for Continued Airworthiness (ICA) for the Sky-Tec contactors require replacement after 30 years of service. 

Remember to always hold the nut nearest the body of each contactor with a wrench to prevent turning while applying torque to the terminal securing nuts.

Happy flying.

Q: Hi Steve,

I’m getting ready to install a 406 MHz ELT. I like the ELT 345 from Artex. (PFA supporter Emergency Beacon Corp. manufactures the EBC 406ap and EBC 406af for use in GA aircraft as well. —Ed.) 

One the guys at the airport is telling me that I have to keep my 121.5 MHz antenna from my existing ELT and install a new antenna that’s included with the Artex ELT. He says it’s because the 406 ELT sends out signals on both 121.5 MHz and 406 MHz. 

That doesn’t sound right. Will you check this for me?

—Antenna Art

A: Dear Art,

Your airport guy is wrong on this one; only one antenna is needed. 

During the installation of a 406 MHz ELT, most installers remove the 121.5 MHz antenna. After making sure the mounting location meets the installation requirements of the 406 MHz antenna (or after reinforcing it so it will comply), use the same hole to install the 406 MHz antenna. 

According to the data plate of the ACR Artex ELT 345, an activated unit will send out a five watt 406 MHz signal for 24 hours and a 100 milliwatt (mW) 121.5 MHz signal for 48 hours. The 121.5 signal is homed in on by low altitude search and rescue aircraft. The 100 mW signal is strong enough for close-by searchers to detect. 

This antenna, while not ideally tuned for the 121.5 MHz signal, is sufficient for the purpose intended. I installed a 406 MHz ELT in my Comanche and am glad I did. 

Happy flying.


Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 43 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to


Piper Maintenance Alert Service Letter 1093A



FAA-PMA grounded-case starter contactors Sky-Tec Partners Ltd.



Artex ELT 345 ACR Electronics, Inc.


An Archer intermittent front-end shake, and the proper technique for replacing pipe thread fittings

An Archer intermittent front-end shake, and the proper technique for replacing pipe thread fittings

Q: Hi,

I’m new to flying and bought a 1976 Archer II in February. It’s a great airplane, but I have an issue that my mechanics can’t figure out. 

The front end shakes badly, but only occasionally. It happens only when braking—and then, only one time in seven or eight. If I get off the brakes and back on, it’s usually okay. 

We’ve tightened everything we know to tighten, and recently put in a new scissor kit, which oddly enough, actually made it worse. Please help! Thanks in advance. 


P.S. I really love your magazine!

A: Hi Steve,

Here’s what I want you and your mechanic to do: remove the nose tire wheel assembly and balance it. Then reinstall it and see if your problem disappears.

Here’s my line of thinking. I suspect the tire/wheel is quite far out of balance and that it is tending to shimmy—but not quite far enough out to shimmy all the time. 

Every one out of seven times, it hits a discontinuity in the runway; or, when you apply the brakes unevenly that exacerbates the out-of-balance condition and it starts shimmying. 

When you tightened up the linkages it didn’t stop the incipient shimmying, it just better transferred that slight motion to the rudder pedals/airframe.

If your mechanic already has a wheel balancer, that’s great. If your mechanic doesn’t have one, I bought a slick little toolbox-sized one from McFarlane Aviation that I use to balance all my tires/wheels.

Tire Balancer

If he is reluctant to spend $200 on the tool, you can balance the tire using this “bush mechanic” method:

Remove tire/wheel/axle from the airplane. Clean all the grease off the bearings and bearing races. Clean!

Reinstall the bearings in the races and install the wheel assembly on the airplane. 

Spin the tire/wheel by hand. Let it spin down until it stops on its own; the heavy point will be down. 

By trial and error, place tire weights (get them at an auto parts store) on the wheel until the “down” spot of the tire/wheel assembly is random. When you reach this point, your tire/wheel assembly will be balanced. 

Finalize the weight placement, grease the bearings and re-mount the tire.

These actions will very likely solve your shimmy problem. Let me know.




Q: Hi Steve,

I need to replace the AN fittings indicated in the photo (see page 19). 

My [problem] is that new parts get tight before reaching the required angles. Should I apply enough torque to get the alignment, or use thread seal (i.e., Teflon) tape?

Thanks for help, as always.



A: Hi Roberto,

I had to search to find information describing the techniques to install pipe fittings. 

The first place I always look for information on general maintenance subjects is AC 43.13-1B, “Acceptable Methods, Techniques and Practices – Aircraft Inspection and Repair.”  You can download the complete 646-page circular from the internet. (The link is provided under Resources. —Ed.) 

However, after a cursory search, I concluded that there is nothing in this circular related to torqueing pipe fittings.

I next searched the Aviation Mechanic Handbook by Dale Crane. It’s an ASA toolbox reference book. Nothing.

I also looked in a Cessna service manual, a Columbia service manual and a Mooney service manual. In fairness, I don’t have copies of the very latest Cessna manuals.

I finally found the information you—and now, we—are looking for in Parker Catalog 4300, under Section S, “Assembly/Installation.” The Parker manual says:

The full thread profile contact of NPT threads is designed to give the tapered threads self-sealing ability without thread sealant. However, variations in condition of mating threads, fitting and port materials, assembly procedures and operating conditions make self-sealing highly improbable. Some type of thread sealant is, therefore, required to achieve proper seal and, in some cases, additional lubricity to prevent galling. 

Types of Sealant/Lubricant Sealant/Lubricants

Lubricants assist in sealing and provide lubrication during assembly, reducing the potential for galling. Pipe thread sealants are available in various forms such as dry pre-applied, tape, paste and anaerobic liquid.

PTFE (commonly referred to as Teflon) tape, if not applied properly, can contribute to system contamination during assembly and installation. In addition, because of PTFE’s high lubricity, fittings can be more easily overtightened; and it does not offer much resistance to loosening due to vibration. 

Paste sealants can also contribute to system contamination, if not applied properly. They are also messy to work with; and some types require a cure period after component installation, prior to system start up.

For proper performance, sealants and Teflon tape need to be applied to clean and dry components, carefully following the manufacturer’s directions.

Brakes PA 28

Tapered Thread Port Assembly 

The proper method of assembling tapered threaded connectors is to assemble them finger-tight and then wrench tighten further to the specified number of turns from finger tight (TFFT).

The following assembly procedure is recommended to minimize the risk of leakage and/or damage to components.

  1. Inspect components to ensure that male and female port threads and sealing surfaces are free of burrs, nicks and scratches, or any foreign material. 
  2. Apply sealant/lubricant to male pipe threads if not pre-applied. For stainless steel fittings, the use of Parker Threadmate sealant/lubricant is strongly recommended. (Pre-applied dry sealants are preferred over other sealants). With any sealant, the first one to two threads should be left uncovered to avoid system contamination. If PTFE tape is used, it should be wrapped one-and-a-half to two turns in clockwise direction when viewed from the pipe thread end. Caution: More than two turns of tape may cause distortion or cracking of the port. 
  3. Screw the connector (fitting) into the port to the finger-tight position. 
  4. Wrench tighten the connector to the appropriate TFFT values referred to below, making sure that the tube end of a shaped connector is aligned to receive the incoming tube or hose assembly. Never back off (loosen) pipe threaded connectors to achieve alignment. 
  5. If leakage persists after following the above steps, check for damaged threads and total number of threads engaged. If threads on the fitting are badly nicked or galled, replace the fitting. If port threads are damaged, re-tap, if possible; or replace the component. If the port is cracked, replace the component. 

Normally, the total number of tapered threads engaged should be between three-and-a-half and six. Any number outside of this range may indicate either under- or overtightening of the joint or out of tolerance threads. If the joint is undertightened, tighten it further, but no more than one full turn. If it is overtightened, check both threads, and replace the part which has out-of-tolerance threads. As a rule, pipe fittings with tapered threads should not be assembled to a specific torque because the torque required for a reliable joint varies with thread quality, port and fitting materials, sealant used, and other factors. 

The TFFT value for the most common NPT sizes are two to three for a 1/8-27 fitting; two to three for a ¼-18 fitting and two to three turns for a 3/8-18 fitting.

I’ve edited the exact text to better answer your question. 

The only pipe thread fitting installation I’ve seen that prohibits the use of Teflon tape is where a fitting is screwed into a vacuum power artificial horizon or direction gyro instrument.

Happy flying.

Know your FAR/AIM and check with your mechanic before starting any work.


Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to



TOOL108 wheel balancer 

McFarlane Aviation, Inc. 



Further reading

AC 43.13-1B

“Acceptable Methods, Techniques and Practices – Aircraft Inspection and Repair”


(search “AC 43.13-1B” under Advisory Circulars)


“Aviation Mechanic Handbook, 6th Ed.” by Dale Crane

Aviation Supplies & Academics, Inc. Newcastle, Wash. 



Catalog 4300

“Industrial Tube Fittings, Adapters and Equipment”




Pre-purchase Particulars: What you should know

Pre-purchase Particulars: What you should know

By Kristin Winter


A&P/IA Kristin Winter explains where to look for a competent pre-purchase inspector, why a pre-buy is different than an annual inspection, and how to get peace of mind with a used aircraft purchase. 

you ever seen a forlorn and lonely airplane sitting on the ramp with flat tires and moss growing on the wings and wondered what happens to these planes? 

Some are doubtless scrapped but many are cleaned up and sold to overexuberant first-time buyers. Often for too much money. 

For some reason, many hopeful new owners often seem to think they know how to judge a good plane. Usually it is the avionics that seduces them. Throw an older GPS Nav/Com and a used PFD in the panel of a maintenance nightmare and watch it fly away. 

Buying for the gizmos in the panel or the pretty paint job is a little like playing Russian Roulette with your wallet. 

I only learn about the sad stories after the fact when a deflated new owner seeks some help. If only they had called me before they bought.

A few fundamental truths

There are some fundamental truths to the process of buying an aircraft that can help avoid walleticide. 

The first thing to know is that if you have never bought a plane or been involved in the care and feeding of one, you may well not know what you don’t know. The more complex and the more unique or rare the aircraft, the more there is not to know.

The second thing to know is that an annual inspection is not a guarantee of airworthiness, even at the time of its completion. 

Apart from the fact that things break on the first flight, the quality of annual inspection is controlled by the diligence of the inspector (“IA”), the willingness of the owner to spend money on the maintenance, and the knowledge of the IA about that particular type. 

A cheap owner will only authorize the minimum required repairs but then may whine enough about the cost that it affects the IA’s judgment. Cheap-Charlie owners also are experts at finding the least expensive IAs, often meaning the ones with the lowest standards. 

Annual inspections completed with the anticipation of selling the plane are also notoriously sketchy.

The differences between annual and pre-purchase inspections

The biggest mistake that most new buyers make—and even some experienced buyers—is to believe that any A&P can do a pre-purchase inspection competently. In truth, few can. It is not a skill that is taught, and there is no FAA standard. 

Most mechanics do not have any experience as an owner/pilot, so they don’t understand what the buyer needs to know. 

Instead, they often try to sell the hopeful new owner on an annual inspection, as they know how to do that. They will tell you that the annual is more thorough—which in a way is true, but misses the point. 

The annual inspection is for a different purpose. The annual inspection is to determine if the aircraft is minimally airworthy. Most buyers do not want to buy an aircraft that is just minimally airworthy, especially when the annual inspection does not check the avionics or test the aircraft in flight. 

A good pre-purchase inspection looks at the known issues for the type of aircraft and can give the buyer an assessment of what needs immediate attention and what is likely to need attention in the first year or two of ownership. 

It is that kind of economic information that is needed for the prospective owner to determine if the airplane is a good buy.

Finding a competent pre-purchase inspector

The need for a pre-purchase inspection increases with the complexity and expense of the aircraft. If the aircraft is somewhat rare as well as complex, the importance of a competent pre-purchase inspection increases dramatically. 

Comanches, Aztecs, and most other long-out-of-production twin engine aircraft and high performance singles require a professional who is well versed in the particular type. 

Ideally the person would have both substantial maintenance experience and flight experience in the type. Type clubs can often be a good resource to find someone qualified to take a prospective buyer through the process.

Because there is no industry standard as to what a pre-purchase inspection should consist of, the scope and detail is open to negotiation, but the buyer should have a good understanding of what will be accomplished and what will not be done. 

As each aircraft is different, the scope of inspection is likely to change from one to another. For example, an aircraft which has recently had a factory remanufactured engine installed and was then flown regularly will need less attention to the engine than one that has mid-time engine with a spotty usage history.

Logbook inspection

An excellent starting point is a logbook review. Any serious seller of an aircraft should have photographed the logbooks, the 337s, the AD compliance sheet, the weight and balance, and any documentation supporting the last engine overhaul such as work orders, 8130-3 forms, yellow tags, etc.

The logbook photos should be the entire airframe, engine (back to, and including the last overhaul), and the propeller (back to, and including the last overhaul). 

It takes 15 to 20 minutes to photograph 50 years’ worth of records if the seller just snaps a photo of two open pages together, turns the page, snaps the next two, etc. As long as they are done is a sequential order, they are easy to read. I normally convert the photos to PDF files, which takes only a few minutes.

The written report of the logbook review should tell the buyer where the plane has lived, what type of flying it has likely been doing, the usage pattern, recorded damage history, status of repetitive ADs and significant Service Bulletins, modifications, and the status of parts with a practical life limit. 

The review serves several purposes. One is to weed out aircraft which pose an unacceptable financial risk for the price being asked. The most common example of that is a little-used aircraft with a poorly documented engine overhaul, yet is reasonably low-time—and priced accordingly. 

The logbook review also helps establish the parameters for what needs the most attention on a physical inspection. The goal in the physical inspection is to confirm the story the logbooks are telling and to look at the known problem areas and components that might need expensive repairs. 

While doing an annual inspection, A&Ps look at all the little pulleys, electrical wiring details, etc.; these things rarely implicate expensive repairs. 

It makes little sense to pay your pre-buy professional $50 to find a pulley that needs a squirt of lubricant or to replace a 20-cent nut. The focus needs to be on the condition of the expensive systems such as engine, retractable landing gear, leaking fuel bladders, avionics, autopilots, etc. The logs should be the guide as to what items are more likely to need maintenance in the near term.

Lastly, the logbook review, along with the physical inspection, should give the new owner a blueprint for what work needs to be done immediately (and possibly negotiated in the transaction), as well as an understanding of what areas to focus on in the first year or two of operation.

A logbook review can run anywhere from four hours on up, depending on volume and complexity. Obviously, a 15-year-old Archer will take much less time for both logbook review and physical inspection than will a 1984 pressurized Mojave. Most run around five to six hours for the log review and four to eight hours for the physical inspection, depending on whether a flight test is involved. 

Physical inspection

As avionics are a large portion of the value of many used aircraft, a test flight and assessment of the condition and functionality of the avionics can be an important part of the physical inspection.

The physical inspection can consist of a flight test to include function-checking the avionics, a thorough inspection of the engine and an inspection of the troublesome areas in the airframe. 

For a retractable gear aircraft, jacking the aircraft and cycling the landing gear and inspecting all the linkages is a necessity. Retractable landing gear is often one of the most overlooked systems on an aircraft. 

Control surfaces, trim systems, stabilator components and fuel systems are also areas for close attention.

The engine, being one of the most expensive components of the aircraft, generally merits considerable attention (save for those examples of aircraft with a new engine from an unimpeachable source). A compression check, cutting the filter open and borescoping the cylinders are all common techniques to assess the condition of the engine. 

One thing that is difficult to check is internal corrosion. On Lycoming engines, the only way is to pull a cylinder or two and check. There are some easier options with the Continentals, which are less prone to cam and cam follower corrosion. The usage history and the aircraft’s location are key components in determining whether there is a significant risk of corrosion.

Hidden damage, unexpected expenses

There is an understandable temptation—particularly when on a budget—to skip the pre-purchase inspection process and rely on the last annual inspection. In rare cases where the aircraft is simple and the buyer knows the seller and the history of the aircraft, skipping this expense can be warranted. 

I have seen many instances where the aircraft was owned by an A&P, yet was still in terrible condition.

It is more common than it should be that a new owner is faced with a first annual inspection and repairs that equal 50 percent of the amount paid for the aircraft. A landing gear system that needs to be rebuilt can cost several thousand dollars, or more. 

Unairworthy skin patches can take many hours of labor to correct (see photo 01, page 22).

Photo # 1

Unapproved and undocumented repairs of control surfaces are also common. (See photo 02, page 24.)

Photo # 2

Hidden damage that is common to the type, but often missed on annual inspections—let alone a pre-purchase inspection by a mechanic who does not know where to look for problems, can also be very expensive to repair and should be the responsibility of the seller, either as a condition of sale or as an adjustment of price. (See photos 03 and 04, right.) 

Photo # 3

Photo # 4

The worst-case scenario is undetected corrosion that can render the new pride and joy unairworthy and not economically repairable. 

Valuable peace of mind

The best money that a prospective owner can spend is the several hundred dollars needed to reveal that the aircraft is not one he/she wanted to own. 

Nothing is a bigger buzzkill on a purchase than to have it in the shop for most of the first year of ownership and spending all of the avionics upgrade budget fixing things that could have been found by a competent pre-purchase inspector. 

The confidence of knowing exactly what you bought—what may need attention in the future, and what should be solid—is also valuable peace of mind, particularly if the seller was forced to be responsible for some of the issues discovered. 

Buying one’s first airplane is an excitement like no other, and it doesn’t even lose much of its enjoyment on subsequent purchases. A first bad experience can mean little joy, and no subsequent experiences. 

While it is not fun for the pre-purchase inspector to have to burst a few balloons, the joy of a new buyer getting a good plane makes up for being the occasional bearer of bad news about the shiny plane with cool avionics and, unfortunately, a risky engine.

Kristin Winter has been an airport rat for almost four decades. She holds an ATP-SE/ME rating and is a CFIAIM, AGI, IGI. In addition, Winter is an A&P/IA. She has over 8,000 hours, of which about 1,000 are in the Twin Comanche and another 1,000 in the Navajo series. She owns and operates a 1969 C model Twinkie affectionately known as Maggie. She uses Maggie in furtherance of her aviation legal and consulting practice; she also assists would-be Comanche, Twin Comanche, and other Piper owners with training and pre-purchase consulting. Send questions or comments to .


December 2016

Modern Stopping Power for Classic Aircraft

Modern Stopping Power for Classic Aircraft

by Dennis Johnson


Upgrade your Cub with a disc brake conversion kit

I’d been thinking about that old aviation adage, “you don’t have to go up, but you do have to come down.” I thought it might be equally true that, “you don’t have to start, but you do have to stop… somehow or the other.” And it’s also probably best if that stop doesn’t come suddenly off the end of a runway, or involve tree branches. 

With these cheery thoughts in mind, it wasn’t a difficult decision to update the drum brakes on my 1952 Super Cub to modern disc brakes when it underwent a complete restoration in 2014.

A Super Cub Special restoration, with improvements

Bob Hunt, the ragwing aircraft restoration expert I chose to transform a pile of dusty and rusty parts into a shiny new airplane, showed me the original drum brake parts at his shop. As he pulled them from a tattered cardboard box I remarked, “These are off a go-kart, right?”

“Nope,” he said. “So I guess there’s no need for me to explain to you why I recommend this disc brake conversion kit?” 

For this historic aircraft restoration Bob wanted to keep everything as authentic to the time period as possible. Our project was not a typical civilian airplane, but a minor warbird, and we were determined to return it to its original appearance. 

Although the aircraft never saw any fighting, it did help train the military pilots who did. These 1952-1953 PA-18-105 Super Cub “Specials” were specially built for the Air Force during the Korean War and are fairly rare. Only 242 were built, and mine—N105T—was the fifth one off the line, rolling out on Nov. 12, 1952. 

In Roger Peperell’s book, “Piper Aircraft – The development and history of Piper designs,” the author describes what set these planes apart from other Super Cubs:

“1952 saw the start of a special version for the Civil Air Patrol (CAP), the PA-18-105 Special. This was used for training purposes by the CAP, U.S. Army and Air Force flying clubs as well as for some actual military pilot training, and was referred to as the PA-18T. It had the Lycoming O-235-C1 of 108 hp and provision for seat parachutes; no flaps, but it had horn balanced elevators.”

Because the N-number of all these Specials end with a “T,” they are often known as “Tango Cubs.”

While keeping historic accuracy in mind, Hunt also wanted to update my Tango Cub with modern safety improvements.

Hunt recommended the new disc brakes, an updated fuel system, a GPS ELT, strobe lights, a Mode S transponder and new radios to improve the safety of flying a 64-year-old plane. (See “Dump the Tanks” in the March 2016 issue of this magazine for details on how the fuel system was simplified. —Ed.)


Modern brakes offer multiple benefits

Of all the modifications, the disc brakes are the only items that alter my Tango Cub’s original appearance. (But still, you have to look closely to notice these 21st century brakes on the 1950s plane.) Hunt selected an FAA-STC approved disc brake conversion kit made by Grove Aircraft Landing Gear Systems for the project. 

The new disc brakes offer multiple benefits. Along with the obvious one—that they will actually brake the plane when needed—with improved braking comes easier ground handling. 

For tailwheel airplanes, a good application of the brakes on one side will allow a taxi turn in almost the length of the plane. That’s very handy for parking at a jaunty angle on the grass at your favorite airport restaurant. It’s also handy after back-taxiing on a narrow grass strip to face into the wind for takeoff. 

Besides working better, the disc system is more reliable and needs far less maintenance. Also, many parts for older brake systems are becoming increasingly hard to find, so installing this new upgrade means parts can be readily ordered from Grove. That’s especially helpful if you have a problem while away from your home base and need a part quickly.

 Caliper 2

 Caliper 2

Cub Kit

Cub Kit

Cub Kit

The conversion process

Anyone with a bit of mechanical experience and know-how can perform this simple conversion. However, the FAA requires that work on certificated aircraft is done under the supervision of an FAA licensed mechanic, and he or she will need to sign off on the project. 

All of the parts and a few special tools are included in the kit from Grove Aircraft. Installation only requires standard hand tools and a rivet gun—and there’s no need to change any wheels, tires or other brake system parts (such as the master cylinder and brake lines), so that keeps the cost fairly reasonable. 

No modifications are needed to any part of the landing gear strut or any other part of the aircraft, except for the wheel assembly. 

This is not a step-by-step guide; you’ll follow the instructions that come with the kit. But essentially, the process goes like this:

  1. Jack up and support the landing gear. Remove the hubcap to expose the wheel hub. Pull the cotter pins, nuts and washers to remove the wheel.
  2. Disconnect the brake lines and drain the fluid.
  3. Remove the existing brake frame and inspect the gear leg and axle for damage; repair if needed. Bolt on the new torque plate.
  4. Take the wheel to your workbench. Deflate the tire and remove it from the wheel.
  5. This next part requires some care. The brake drum, which is riveted to the wheel, needs to be removed. If you have a good drill press, the rivets can be drilled out, but do this only if you’re sure you won’t enlarge the holes in the aluminum wheel. Grove Aircraft recommends grinding off the back of the rivet and then punching it out.
  6. Clean and inspect (and repair, if needed) the wheel. Then, new holes must be carefully drilled in the wheel and the new disc brake rotor riveted on. 
  7. Reinstall the tire on the wheel and inflate it.
  8. Reinstall the wheel onto the axle, with fresh grease. The nut should be tightened until the wheel won’t turn 
  9. and then eased off until the wheel just turns freely. 
  10. Insert the cotter pin. Install the hubcap.
  11. Install the brake caliper according to the instructions—which you are following, right? It bolts into the existing holes.
  12. This next step may require some advice from a mechanic, as the brake lines on many planes have been changed over the years and may not use the same connectors. You are only instructed to hook up the brake lines using the appropriate connectors. You may have to make your own flexible line with hose material and fittings.
  13. Refill the brake system with aviation-grade brake fluid, and make sure the brakes are purged of air. The detailed instructions included with the kit tell you how to do this. If you have a soft brake pedal, this is an indication of air in the system or that adjustments need to be made. The instructions will guide you through troubleshooting.
  14. Complete the paperwork. (Yes, this is a real step listed in the installation manual!)
  15. Clean all the greasy fingerprints off your beautiful plane, take a selfie with your new brakes, and try them out on the ramp.

Now, go out and fly, remembering to always land in a manner such that you never have to put these highly effective brakes to the test.

Dennis K. Johnson is a writer and a New York City-based travel photographer, shooting primarily for Getty Images and select clients. He spends months each year traveling, flies sailplanes whenever possible and is the owner of N105T, a restored Piper Super Cub Special. Send questions or comments to .


Further reading

Piper Aircraft: The development and history of Piper designs,” by Roger Peperell. Air-Britain, 1996.


December 2016



Electronic ignition promises enhanced fuel economy, less maintenance, and safer operation when compared to traditional magneto ignition. Steve Ells takes the plunge and upgrades his 1960 Comanche with an Electroair electronic ignition system (EIS).

Modern Electronic Ignition For a Vintage Comanche

Electronic ignition promises enhanced fuel economy, less maintenance, and safer operation when compared to traditional magneto ignition. Steve Ells takes the plunge and upgrades his 1960 Comanche with an Electroair electronic ignition system (EIS).

June 2017-

This past winter, as my traveling season slowed down into my “work on the airplane” months, I started listing airplane maintenance tasks only to realize that my 1960 Piper PA-24-180 Comanche 180, Eight-Five-Papa, is finally up to snuff.

I flew Papa from my home on the California coast to AirVenture in Oshkosh a couple of years ago and he never missed a beat. I am confident that, given enough Avgas, Papa is safe to fly anywhere.

I’ve been refurbishing Papa since 2004. I bought the airplane from a friend who was selling it for a friend. They were having a hard time finding a buyer because the aircraft’s maintenance logs only went back a few years. Missing maintenance logbooks can easily take 15 to 20 percent off the value of a good airplane.

The original logs turned up about 10 years after I bought Papa—a shop owner from a couple of stops back contacted me saying he had found them as he was cleaning out his hangar. He was willing to send them to me for cash. I considered them to very valuable, and after some easy negotiations, I sent him a couple of Benjamin. I now have complete records.

In addition to tracking down the logs, I’ve done quite a bit of work on Papa over the past decade. I reconfigured the instrument panel, rebuilt the engine, overhauled the prop and prop governor, sent the landing gear motor and transmission to Matt Kurke (the Comanche gear expert) for overhaul, completed the critical 1,000-hour landing gear AD (77-13-01) and installed shoulder harnesses.

I was finally caught up on deferred maintenance. It was time for an upgrade!

I had been wanting to install an Electroair electronic ignition system (EIS) for a long time. I’ve written about the advantages of the system and after speaking to longtime users, I’ve come to believe that the system does deliver an increase in fuel economy and smoother engine operations while also reducing ignition system maintenance chores.

Over the winter, I ordered and installed the Electroair EIS-41000 system on my four-cylinder 180 hp Lycoming O-360-A1A.


Why Electroair?

Why did I choose the Electroair system? First, I want Papa to operate as well as possible. I believe that the Electroair system provides measurable operational advantages including an increase in safety, performance and economy over my dual-magneto system.

Secondly, I have come to know Mike Kobylik and Peter Burgher at Electroair over the past decade. After watching Electroair grow and stand up for its customers, I have confidence in the company.

Just last year at AirVenture, Electroair introduced an electronic ignition system that is designed to replace the Bendix D-2000 and D-3000 dual magneto, something no other company offers. Electroair is not a “here today, gone tomorrow” company.

Finally, Electroair is the only aftermarket bolt-on electronic ignition system that is FAA-approved for installation in my certified airplane.

The Electroair system is approved for installation on almost all piston-powered certified and experimental airplanes. Buyers can elect to replace either the left or right magneto with either a magneto timing housing (MTH) on four-cylinder engines, or a crankshaft trigger wheel on six-cylinder engines. According to Kobylik, replacing a single magneto yields approximately 80 percent of the benefits of a fully-electronic ignition system.

Electroair does not provide the option of replacing both magnetos due to the cost and time needed to create the wide range of backup battery solutions to fit the many airframe configurations in the General Aviation fleet. Electroair believes that a combination electronic/magneto system is the best cost/benefit option.


Left or right?

I decided to replace the right (non-impulse-coupled) magneto with the Electroair system and kept the left impulse-coupled magneto. It could be argued that I should have replaced the left magneto, since impulse coupling failures can wreak serious havoc within an engine.

While there is always the remote possibility of a serious impulse coupling problem, there hasn’t been a new coupling-related AD for nearly 30 years. Additionally, I lessen the odds of failure by always complying with 500-hour magneto inspections. I send my magnetos to Clifton “Cliff” Orcutt at Aircraft Magneto Service (in Missoula, Mont.) I’ve known Cliff for over four decades and I’m confident in his shop since Cliff and his son Don don’t do anything but magnetos.

Ease of starting also factored into my decision to keep the impulse-coupled magneto. The impulse coupling on the left magneto retards the spark timing at starter-driven rotational speeds to make starting easier. Once the engine starts, the impulse coupling is no longer a factor and the timing reverts to the normal advance. If I had replaced the impulse-coupled left magneto, I would lose the ability to easily start the engine in the case of an electrical system issue.

Since I chose to retain the magneto with the impulse coupling, I will always be able to get my engine started by hand-propping even if the battery voltage is too low to fire the EIS system.


Redundancy, redundancy

Long ago, I learned that redundancy is at the heart of airworthiness. It seems to me that the only drawback of an Electroair EIS is that it needs battery power to operate and continue to fire. The system requires at least eight volts when installed in a 12-volt airplane, or 16 volts in a 24-volt installation.

My thinking is that in the remote chance that I lose my alternator in flight or some other electrical system failure occurs that causes the electrical system voltage to drop below the Electroair system trigger voltage, the remaining standard magneto will deliver ignition for continued reduced-power flight.

As I mentioned earlier, in the case that I’m already on the ground and need to get started, by leaving the impulse-coupled left magneto in place and hand-propping the engine, I have given myself options.

Once the engine is started, there should be enough voltage in the battery to excite the alternator to get it back online. If the electrical problem is limited to a low charge on the battery, after the alternator has provided bus system power for a few minutes, the electrical system voltage will be high enough to fire the EIS. If this sounds like a doomsday scenario—hand propping, taking off behind an ignition system that is dependent on electric power when the battery is not fully charged, depending on an alternator to maintain voltage during the full-power takeoff—it is. My thinking is based on the years I spent in Alaska where “How can I make this work?” is a way of life.

If the alternator comes online, if there isn’t a major fault in the electrical system that has completely drained the battery, and if I can get the EIS system working long enough for a full-power takeoff, then I will most likely get Papa home on the working magneto if I can fly my route at 50 to 60 percent power which the engine will safely produce with one ignition source. That is a bunch of ifs—but assuming they line up, it would be possible to get home in a pinch.



The Electroair system arrived in a large box that contained a controller, a magneto timing housing (MTH), a manifold air pressure (MAP) sensor, a coil pack, a wiring harness, four REM37BY spark plugs, and automotive style spark plug ignition harness leads that I would need to cut to length for my engine.

From my experience and my discussion with installation centers, it seems that it takes about one workday for an experienced shop to install an EIS on a simple airplane with a four-cylinder engine. Six-cylinder engines and more complex installations will take longer.

The installation instructions specified that the MAP sensor and the controller needed to be installed aft of the firewall and that the coil pack should be installed on the firewall or at another location forward of the firewall.

The lion’s share of the installation time revolved around planning. Where was I going to install the components? Would I need to cut a hole in the firewall to run the wiring? Where would I tap into the manifold pressure supply line to feed the manifold pressure sensor?

Since there’s not a great deal of space between the aft side of the firewall and the forward side of the instrument panel in my Comanche, I built a wooden controller box and a wooden MAP sensor box so I could mock up different choices as I explored mounting options.

When Kobylik told me he had seen the MAP sensor piggy-backed on top of the controller, I realized I could do this too as I had room above the controller. I removed the metal cover of the controller and mounted the MAP sensor on that cover.

Years ago, I had installed a steel glove box on the right side of my instrument panel. This proved to be the perfect location to mount the piggy-backed controller and MAP sensor. I installed both on the top of the glove box.

I did have to check with Electronics International to see if their CGR-30P engine monitor would accept the 12-volt square wave tachometer signal from the EIS controller. It would. I made the tach connection, and found that the two systems play well together.

Electroair’s instructions recommend installing the coil pack on the firewall. However, I looked for a different solution since the coil pack weighs nearly three pounds and I wasn’t sure the thin firewall on my Comanche could support it. Instead, I opted to use high temperature Adel-style clamps to secure the coil pack to the steel tubing on the engine mount between the firewall and the cylinder baffling.

I removed the right magneto to make space for the new EIS magneto timing housing. I had to remove the drive gear off the magneto before installing it on the shaft of the MTH. I tightened the nut to the torques specified in the Slick magneto manual. I slowly rotated the drive end of the MTH until a small locating pin dropped into position. It was now ready for installation.

I positioned the engine to top dead center (TDC) position on the number-one cylinder and installed the MTH on the now-vacant right magneto mounting pad. During one of my previous improvement projects, I had plugged an existing one-inch diameter hole in the firewall. The wiring harness plug to the MTH fit easily through this hole; I didn’t need to cut another.

After some discussion with Mike Kobylik and installation centers familiar with the Electroair, I also chose to replace the ancient magneto key switch with one of Electroair’s newest products—the FAA-approved 1300M switch panel.

This small panel has one toggle switch for the EIS and one for the magneto, and a push button to engage the starter. It can be mounted vertically or horizontally. ACS magneto key switches that were installed on a large number of Cessna single-engine airplanes are subject to recurrent ADs, and the installation of an Electroair 1300M replacement will terminate these switch ADs.

The 1300M switch panel eliminates the possibility of an ignition miss that does occur when a standard key switch is cycled during the pre-takeoff runup. Depending on when (in the engine rotational cycle) the switch is moved from ‘both,’ there often is a one- or two-rotation ignition miss of the EIS since the controller box must see a pulse from the MTH or trigger wheel to fire the coils. The standard magneto still fires the plugs so there’s no dead zone in engine operation; it’s just different than the mag check with two magnetos.

I found that the engine rpm drop during the pre-takeoff ignition system check is around 30 rpm when testing the EIS, and around 90 rpm when testing the magneto. This is a result of a long-duration hot spark. I’ll explain how that works (and the benefits it offers) next.


Long-duration hot sparks

The EIS system delivers a white-hot dose of spark energy, especially compared to the output of a well-maintained magneto. On average, a standard magneto delivers 12,000 volts over a five-degree rotation of the crankshaft when running, and around 6,000 to 8,000 volts during the starting cycle.

In comparison, the EIS system delivers around 70,000 volts across 20 degrees of crankshaft rotation at all rpms. A much hotter spark over a much longer period eliminates hot starting problems that are common on fuel injected engines, and makes cold weather starting much more reliable.

Each EIS-powered spark plug fires every time the piston comes up in the cylinder. One pair of the two paired coils in the coil pack fires at the same time. One is firing on the compression stroke while the other in the coil pair is firing on the exhaust stroke. This “wasted spark” system is different from a standard magneto which incorporates an internal distributor to deliver the high-energy spark only on the compression stroke.

Unlike a magneto, the EIS doesn’t deliver spark energy only on the compression stroke; each spark plug fires every time the piston comes up in the cylinder. One pair of the two paired coils in the coil pack fires at the same time; one is firing on the compression stroke while the other in the coil pair is firing on the exhaust stroke. This is termed a “wasted spark” system. It simplifies the EIS since it eliminates the need to time the ignition event to the compression stroke, and is common on electronic ignition systems.


Fuel economy

Electroair suggests widening the spark plug electrode gap by a factor of nearly two—from .016 inch or .018 inch for the magneto-fired plugs to .036 inch for plugs fired by the EIS. A much hotter spark for a longer period over a wider gap produces a more complete fuel burn, and thus better fuel economy.

The other fuel economy enhancing component of the EIS is the manifold pressure sensor. Standard magnetos deliver energy at a fixed point in the crankshaft’s rotation. For instance, the left and right magnetos on my Lycoming engine are designed to fire at 25 degrees before top dead center (BTDC) on the compression stroke. That point is static—it doesn’t matter if the engine is turning 2,700 rpm during takeoff or idling at 600 rpm.

The spark timing also doesn’t change based on altitude and air pressure. It’s the same timing if the aircraft is at 0 feet msl or 10,000 feet msl.

The MAP sensor signals the EIS controller to adjust ignition timing based on atmospheric conditions to enhance fuel economy. The Electroair’s MAP sensor is connected to the controller by a three-wire harness. The controller automatically advances the timing of the spark event in a linear fashion from the fixed timing point of 25 degrees BTDC on my Lycoming to a maximum of 40 degrees (15 degrees advance) BTDC when the engine manifold pressure drops to 17 inches.

As airplanes ascend, the air becomes “thinner” which means the prop doesn’t have as much air to grip and the wing doesn’t generate as much lift. An EIS can’t change the physical properties of air, but it can advance the spark as manifold pressure decreases. An advanced spark moves the peak pressure generated by the less dense, weaker fuel/air mixture to a more advantageous point than if it were maintained at 25 degrees BTDC.

The standard atmospheric pressure lapse rate is one inch per 1,000 feet. I do most of my cross-country flying at between 6,500 and 8,500 feet msl. My wide open throttle (WOT) at 6,500 feet would be around 24 inches of manifold pressure; the point where the advance starts.

At 8,500 feet the advance would be four degrees for a spark timing of 29 degrees BTDC. When I need to climb to maintain clearance over terrain or choose to go higher than usual to take advantage of a tailwind, the automatic spark advance will continue to adjust to provide the spark advance needed to achieve optimum spark timing for my higher-altitude flying.

The author replaced the old key-type magneto switch with a new EA-13000 that included ignition test switches and a starter button. Ells mounted his as shown; it can also be mounted in a vertical orientation.
The author replaced the old key-type magneto switch with a new EA-13000 that included ignition test switches and a starter button. Ells mounted his as shown; it can also be mounted in a vertical orientation.
The EIS-41000 preassembled wiring harness.
The EIS-41000 preassembled wiring harness.
The business end of the spark plug shows the 0.036 inch gap—twice as wide as the gap specified for magneto-fired spark plugs.
The EIS-41000 preassembled wiring harness.
The author secured the coil pack to tubes of the engine mount. This shortened the plug wire runs. The magneto timing housing (MTH) is installed on the right magneto mounting pad.
The author secured the coil pack to tubes of the engine mount. This shortened the plug wire runs. The magneto timing housing (MTH) is installed on the right magneto mounting pad.

Ongoing maintenance

Standard magnetos require periodic maintenance. A 500-hour magneto service includes removal, cracking open the magneto housing and inspecting for wear, applying lubrication and installing new wear components. After reassembly, each unit must be tested to ensure it meets performance specifications. Both Slick and Continental Motors (formerly Bendix) recommend that these off-airplane magneto inspections be carried out every 500 hours.

Aircraft Magneto Service will do a 500-hour inspection on my Slick 4373 magneto for $365, or $765 if I need a new impulse coupling. That is the average parts and labor cost. The 500-hour inspection on a Continental (Bendix) four-cylinder magneto will average around $475, again including parts and labor.

Using the inspection rates cited above and factoring in the labor costs (from the Cessna flat rate manual) of an average time of two hours to remove, install and time the mag to the engine, it’s easy to spend at least $1,500 for maintenance of each magneto over a 2,000-hour TBO period.

Not so with the Electroair. One of the things I like best about the Electroair system is the almost complete lack of ongoing maintenance requirements. Oil leak inspections are required at every annual. The spark plug wires need to be replaced every 1,000 hours and at engine overhaul. In the event of a prop strike, the MTH must be exchanged for a replacement. That’s the entire list of items on the Instructions for Continued Airworthiness (ICA).

Adding up the benefits

According to Kobylik, an informal FAA study showed that safety was improved by two orders of magnitude when the Electroair system was used with a conventional magneto over a traditional dual magneto ignition system. I believe anything that improves safety is a good investment.

Most aircraft owners are also interested in the dollars-and-cents return. A certified EIS for a four-cylinder engine costs around $3,600 plus installation. The cost for a six-cylinder EIS is between $4,800 and $5,500 plus installation. Except for replacing the automotive-type ignition wires at 1,000 hours and checking for oil leaks at every annual, the ongoing maintenance costs are very small. My Comanche’s owner’s manual shows 75 percent power fuel burn at between 10 and 11.5 gph. Plugging in $5 a gallon Avgas and assuming that my 180 horsepower Lycoming will always consume 10 gph, I will burn approximately $5,000 of gas for every 100 hours I fly with standard magnetos. Installation of an EIS—which is advertised to provide a 10 to 15 percent reduction in fuel burn rates—will save me $500 every 100 hours. Over the 2,000-hour life of my engine, I’m way ahead by installing the EIS.


Flight test

One of the things I noticed after I lit off the system for the first time was a more eager idle. I had to lean the idle mixture and back off the low rpm stop. Not only did the engine feel more eager at idle, it didn’t feel “lumpy” at 600 rpm. I believe the more vigorous ignition event contributed to the need to tweak the idle speed and mixture.

I was eager to see how the EIS performed so I did a full power climb up to 10,500 feet msl. Papa went right on up there with what seemed like a fresh eagerness and hasn’t missed a beat since. He starts right up which is rarely a problem with my carbureted engine but Kobylik says the long-duration hot spark eliminates heat-soaked fuel-injected engine starting headaches. I believe the EIS is a great upgrade to my Comanche. I haven’t yet flown enough to gather enough flight data to determine the economy gains from installing the EIS, but will in the future.

Any upgrade that promises improved safety, lessenes maintenance and lowers operating expenses is very tempting to aircraft owners. Based on my experience with the Electroair EIS so far, I’m glad I went for it.

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and lives in Templeton, Calif. with his wife Audrey. Send questions and comments to .



Aircraft Magneto Service LLC
The first place that corrosion was found was on the vertical stabilizer between the stabilizer and the rudder.

Aging Gracefully: Addressing Corrosion

September 2015

In the March 2015 issue of Piper Flyer is a column authored by my hero Lyn Freeman about getting older. Of course I can’t speak for Lyn; only he can. And if he says he’s getting older, than he must be getting older.

As for myself, I’ve been flying 47 years and am on airplane number seven. I’m pretty sure that I’m not getting any older—but I know my airplane is.

As many of you know, I have been writing articles about the restoration of my Seneca II. Most of the major restoration was done over the course of the last decade and I’ve been getting the airplane ready to be painted for the last couple of years. That’s pretty much all that’s left to do before the restoration is complete… and then I’ll have to start over again!


Three projects at once
A year ago when it froze over in Wisconsin I couldn’t get my hangar door open for two months. The following summer I conspired with my A&P to do all of my work in January and February when I could keep my airplane in their heated hangar for two months.

Unfortunately this results in losing one month on my annual every year—the 13th month is free if your A&P signs off on your annual inspection on the first of a month—but the trade-off for being able to access my plane over the winter months is well worth it to me.

Last winter I was able to do three projects at once. First, I replaced my center stack of avionics, which I’ve written about in this magazine. (See “In with the New: An Avidyne IFD540 Plug-and-Play Conversion” in the June and July 2015 issues, “A New/Used Autopilot” in the April 2015 issue, and stay tuned for future articles. —Ed.)

Second, I was able to complete the installation of auxiliary fuel tanks that I bought used about five years ago and never installed. (Be on the lookout for this story in a future issue of Piper Flyer, too. —Ed.)

Third, I had my annual inspection about two months early. I hadn’t intended on doing my inspection two months early, but my lead mechanic Erich—whose advice and judgment I covet every time I am in his presence—recommended that I do so while I was installing my auxiliary fuel tanks.

As he said, “Why take apart and reassemble the airplane twice? Save yourself some money, Scott!”
Point—and advice—taken.

The good news from the annual was that my airplane is mostly in excellent shape. The bad news was that I had two small areas that showed some corrosion that needed to be addressed. Right now.


That scary “c” word
Hearing the word “corrosion” from your A&P could be likened to hearing the word “cancer” from your physician; they’re both scary.

With all of the restoration projects over the last 10 years, I consider myself fortunate that corrosion was really the only thing that needed addressing in early 2015. I got the plane in questionable condition in 2004, but it was as close to free as any 3,000-hour twin could be.

At that time I gutted the interior and addressed a little bit of corrosion around and under the windows. I overhauled the engines, so everything firewall-forward and behind was addressed. I replaced all of the glass so that there were no leaks going forward, and the landing gear was overhauled and treated.

Most importantly, my technicians sprayed ACF-50 into the wings to arrest any corrosion that may have been there. While ACF-50 weeped from the wings for several years and was quite annoying, it certainly was the right thing to do. I highly recommend this treatment for any aging airplane.


AC 43-4A
My other mechanic, Nathan, showed me a publication on corrosion from the FAA. I promptly went home and downloaded Advisory Circular 43-4A, “Corrosion Control for Aircraft,” from the FAA website.
I wholeheartedly recommend that every airplane owner and pilot read this publication. It’s free, contains a complete description on airframe corrosion, and details the many types that can potentially be found on an airplane.

I was surprised to discover there are seven forms of corrosion that occur on airframes. Seven! As depressing as that sounds, I took comfort in the fact that my airplane only had two small areas containing two forms of corrosion.

Without further ado, here are the seven types:
A. Uniform Etch Corrosion
B. Pitting Corrosion
C. Galvanic Corrosion
D. Concentration Cell Corrosion
E. Intergranular Corrosion
F. Exfoliation Corrosion
G. Filiform Corrosion

Rather than try and quote the FAA publication’s description each type, I recommend you download the document and look on page 14. (See Resources for a link to the PDF through PiperFlyer.org. —Ed.) The descriptions are accompanied by photographs, and the document also includes details on how to remove and repair corrosion.


Picture 01

Trouble spot number one
The first place that corrosion was found on my aircraft was on the vertical stabilizer between the stabilizer and the rudder. (See picture 1) Once the rudder was removed, Nathan removed the rudder attach hinges—and lo and behold, underneath the hinges was pitting corrosion. Picture 2 gives you a closeup of one of two of these areas.

Picture 2

Picture 03

 Picture 04

At first glance you see that it is shiny and clean. Well, it is shiny and clean, as Nathan had cleaned it up, but you’ll notice that above the large hole is a round area that looks slightly bumpy and not as shiny as the other cleaned-up area.

I thought that Nathan would just clean this area, too—perhaps treat it with an anti-corrosion treatment, like chromate primer—put the hinge back on, reattach the rudder and move on to the next project. Unfortunately it never seems to work out that way.

Instead, Nathan used a caliper to measure the thickness of the good area versus the area with the pitting corrosion. What he discovered was that more than 10 percent of the thickness of the aluminum plate had been eroded. Nathan explained to me that it was not a safe practice to just treat the area and reassemble it when more than 10 percent of the aluminum was gone.

Of course, I’m thinking dollars and Nathan is thinking safety. I’m also thinking I can impress him with my 47 years of airplane ownership and give him the answer. Feeling quite proud of myself, I said,

“Throw on a doubler!”

Nathan slowly shook his head no. To safely address this corrosion, we had to order a new plate, drill out all of the rivets, prime, paint and install the new plate and only then could we put the rudder back. Well, it’s only money, I thought. I told him to proceed.

Picture 6 is the new rudder vertical spar after replacement. Nice and green and new. And safe! Picture 7 is a closeup of that spar.


Trouble spot number two
A couple of days later I was back to see the progress on my plane when I got called over to the cabin area. My mechanic had been searching the entire plane for corrosion and not to be denied, he found some. He had removed the back two seats and the carpeting underneath them to check on the control cables and pulleys.

If you look at picture 3 you’ll see a steel angle bracket riveted to two pieces of aluminum. Even after you ignore the green chromate and the glue (that was holding some insulation and carpet down), it’s obvious that the steel plate has a significant amount of rust. Six inches away is another bracket holding another two pieces of aluminum together and that bracket is very rusted, too.
I figured that Nathan would clean it up with an abrasive cleaning pad, re-chromate it, and move on. Instead, Nathan drilled out the rivets and removed both brackets. You can see what he found on Picture 4.

Picture 05

You’ll see on Picture 5 that underneath the brackets the aluminum had turned to dust. Nathan caught this issue in time to prevent the deterioration from spreading to other areas. All we had to do was to order new brackets and the appropriate aluminum parts. And of course, pay for it. (Oh well, it’s just money! I didn’t want to leave any to my kids anyway!)

As for the interior, apparently a water leak occurred a long time ago. That water had pooled under the rear seat and started the corrosion—which had festered for at least a decade—and was missed by all of my prior mechanics.

 Picture 06

Picture 07

No shortcuts—this is structural
Pictures 8, 9 and 10 show corroded parts after they were removed from the airplane. I urge you to have your mechanic dig very deeply into your plane when he or she is doing the next annual. No shortcuts to save a few bucks. Picture 11 shows the area cleaned up with the old parts removed.
When I next visited the heated hangar, I found two signs on my airplane. One was taped near the front door and the other was by rear door.

Picture 08

Picture 09

Picture 10

I asked my corrosion expert, John, about them. He said, “Scott, the parts removed were structural. If someone gets in the plane while these parts are removed, you could bend the fuselage.”
You can add up 2+2 yourself. The corroded parts were structural. Unfortunately all of this corrosion is costing me a couple of months in the shop and some money. But it could have progressed to something unthinkable that would have cost me and my family much more. I don’t even want to go there.

Picture 11 

Picture 12

Remedies and ruminations
Looking at Picture 12, you can see several things. First, you’ll see that the entire floor was cleaned and coated with two coats of primer. John had removed many more aluminum pieces from the area, inspected, cleaned, primed and reinstalled them.

Second, you can also see the two new aluminum spars and steel brackets are installed.
Third, this photo shows you the floor. I mean, the real floor—the only piece of metal between me and a great view of the ground below. There isn’t a second layer anywhere to be found. (Structural integrity becomes even more incontestable when you think about it in these terms.)

Fourth, there are actually several tiny drain holes in the aluminum skin. Any pooled water in this area should drain out, but obviously it didn’t. Why? The carpet throughout the airplane had been glued down with adhesive.

None of the mechanics assigned to the aircraft in the previous 10 years were able to inspect the area without damaging the carpeting, so they didn’t. My mechanic was troubled by this fact.

As I had personally installed the plane’s Airtex upholstery kit, I began to wonder if I didn’t do it correctly. Airtex offers high quality, custom kits that you can install yourself to save on labor costs, and that’s just what I did. (Longtime Piper Flyer Association supporter SCS Interiors offers pre-cut carpet and vinyl floor kits as well. See Resources for the link. —Ed.)

Unfortunately, my Airtex kit didn’t come with any instructions whatsoever. The company’s customer support is excellent; they will answer any installation question you may have. However, nowhere that I found does it say not to install the carpeting with adhesive.

In my case, it was a matter of “you don’t know what you don’t know”—and I didn’t know to ask! I’ve now done four airplanes with Airtex interiors and had glued all of the carpeting down. So what are other people doing?

I asked my mechanic, and he showed me the interior of a twin turboprop. He recommended that next time I do what the expensive business aircraft do: use a fabric fastener (i.e., Velcro) or snaps. That way a mechanic can remove and reinstall carpeting in just a few moments; any water will find its way to the drain holes, and mechanics (and owners) can check for corrosion themselves at any time. Epiphany! Thanks, John.

I’ve ordered new carpeting from Airtex for the backseat of my airplane and it will be here this week. I should be able to get my plane back together and get back in the air next week.

Next winter when I’ve got nothing to do, I’ll order replacement carpeting for the remainder of the airplane, tear up the old stuff and reinstall with snaps and Velcro.


Grateful to have the best
At the end of the day, this was the extent of the corrosion damage on my airplane. With a couple of down months and a few dollars comes peace of mind. I have a safe, reliable airplane that’s aging gracefully and safely.

It pays to have a quality team taking care of your airplane, and I feel like I have the best. I hope you do, too.

If you have questions about your airplane or feel like your mechanic isn’t digging deep enough during inspection, it’s time for the two of you to have a serious talk. You have an expectation of quality and safety in your flying machine, and if you’re concerned about something, don’t ignore it. It’s your life!
Piper Flyer Association member Scott Sherer is a multi-engine and instrument rated private pilot. He’s logged over 2,600 hours and is the owner of a 1977 PA-34-200T based at Burlington Municipal (KBUU) in Burlington, Wis. Sherer anxiously awaits the day when N344TB finally gets new paint. Send questions or comments to .

Electric Fuel Pump

Q&A: The electric fuel pump in my Piper PA-24-180 started oozing

September 2015

Q: Hi Steve,

The electric fuel pump in my Piper PA-24-180 started oozing yellow goop out of the place where the electrical lead enters the body of the pump.

I started looking around for one and was told the Piper list price for one of these (Part No. 481 666) is $630.60. Somebody has got to be kidding! This pump looks exactly like a clicker-type electric fuel pump that I can buy at the local auto parts store for less than $50.

When I asked my mechanic is I could put one of the auto parts store’s pumps on my Comanche, he told me that he had to have paperwork to legally install it.

Is there anything I can do to get the price down where it’s reasonable?

—Fuel-less Fred


A: Dear Fred,

Many an aircraft owner has asked the same thing—and I’d suspect that there is more than one facet fuel pump from an auto parts store installed on a certified airplane like yours—but it’s not legal to do so.

Fortunately there is a solution to reduce the cost of one of these pumps and still comply with the regulations. It won’t get the price down to auto parts store prices, but it will cut it almost in half.

McFarlane Aviation in Baldwin City, Kan. sells replacement electric fuel pumps that are approved for installation on your airplane by STC. The cost of the replacement pump (Part No. CA35328-800E) is $245—and that includes free shipping.

You will have to go to the McFarlane website to download the STC paperwork and the Instructions for Continued Airworthiness (ICA) that are needed to complete the installation.

These pumps have a one-year warranty from McFarlane.

I guess you can be grateful you don’t fly a later PA-24-250; it has two of these pumps.

Happy flying.


Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 43 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to .

Pulse Oximeter

Q&A: Do you think I should get a small portable oxygen setup?

September 2015

Q: Hi Steve,

I’m a 56-year-old man. I had a good job and retired a couple of years ago. I was approached by a fella at my local airport who wanted to sell me his Piper PA-22 Tri-Pacer.

I didn’t know much about Tri-Pacers so I asked my flight instructor what he thought, and I got a mechanic to check it out.

My instructor described the Tri-Pacer as a good, if somewhat unusual airplane. He said it performs as well as a Cessna 172 and sells for a lot less.

Well, I bought it and have been flying it around Oklahoma and Texas for the last six months.

Now I’m considering a flight from my home in Oklahoma to southern Oregon next month. I’ve been taking my PA-22 to a local airport on hot days (90 degrees F or hotter) with a real long runway and making takeoffs with 60 and 70 percent power to get a feel for the loss of performance I’ll experience when flying in the mountains. It’s pretty dramatic.

I’ve read lots of magazine articles with lists such as “Top 10 Mountain Flying Tips,” and “Density Altitude for Dummies,” so I have a pretty good idea about how altitude and temperature will affect my flight.

My plan is to fly early in the day and give myself plenty of time.

My question, though, is about oxygen. Do you think I should get a small portable oxygen setup?
—Tri-Pacer Tom


A; Dear Tom,

The Tri-Pacer won’t quite provide the same performance (or carry as much, or go as far when the fuel tanks are full) as pre-1967 Cessna 172s, but it’s not far behind. But a PA-22 is much less expensive.

 There’s no denying Tri-Pacers are quirky: manual flaps; smallish fuel capacity (36 gallons); typical Piper overhead trim handle; bungee-cushioned main landing gear; a brake handle that applies braking to both mains simultaneously; and last but not least, a master switch that’s located under the pilot’s seat.

In spite of these quirks, most Tri-Pacer owners smile smugly when they hear others bad-mouth their airplanes.

If you take what’s called the Southern Route from Oklahoma (El Paso, Tex.– Phoenix–Twentynine Palms, Calif.–Apple Valley, Calif.–Palmdale, Calif.) into the California Central Valley, you’ll never have to fly higher than 7,500 feet.

I recommend that most pilots keep a small oxygen setup in their airplane just to be on the safe side. This is especially true if you aren’t physically active or are over age 50.

It will never hurt to take a few hits of oxygen if you spend more than a couple of hours flying above 6,000 to 7000 feet MSL or if you are flying at night. The restorative effects of oxygen will amaze you.

 It’s a rule of thumb that blood oxygen levels should be kept above 90 percent during day flights and above 95 percent during night flights.

The only way to measure your blood saturation levels is by using a pulse oximeter. All you do is stick the end of one finger in an oximeter, and in a few seconds the unit displays your percent of blood oxygen saturation and pulse rate. Good units are available at many pilot supply stores.

Piper Flyer Association supporter MH Oxygen Systems provides a wide range of supplemental oxygen systems. One of the simplest is its Co-pilot System. This $215 system consists of three non-refillable bottles full of oxygen, a mask and a regulator that is adjusted to deliver flow rates of 33 percent, 66 percent and 100 percent.

At first glance it’s hard to imagine that these small bottles (they are approximately the size of a can of shaving gel) are capable of providing much protection—especially after reading on the MH website that one bottle provides a 100 percent oxygen flow (two liters/minute at sea level) for only nine to 10 minutes.

However, according to MH most users choose to extend the useful oxygen delivery time by taking regular “hits” of oxygen. One example cited was taking three breaths during a 10-second period every 15 minutes at the 100 percent setting. (The regulator is turned off between hits.) At this rate, the bottle/mask combination will last 12 hours.

The advantages of the Co-pilot include portability, light weight and affordability. And once you have the system, replacement bottles only cost $25. The duration can be extended substantially by using a $29 Oxymizer nasal cannula instead of the mask. Another advantage is that the bottles never have to be re-tested in accordance with Department of Transportation (DOT) regulations.

Larger kits from MH Oxygen Systems can be categorized as constant flow or pulsed flow systems. All constant flow systems include a storage bottle in a wide range of capacities, a regulator with up to six stations, and an adjustable flow meter and a normal cannula for each station. Each system is housed in a tough carry bag that’s fitted with straps and buckles intended to secure it to the back of the copilot’s seat.

Portable pulsed demand systems use MH Electronic Delivery System (EDS) O2 D1 or O2 D2 modules to monitor the users’ breathing cycles to deliver oxygen at the most beneficial period in each inhalation cycle.

According to MH, this innovation increases available oxygen per fill by up to 30 percent over constant flow systems. This means that the bottle size and weight needed is much smaller than the bottles used with constant flow systems to deliver the same blood oxygen saturation levels.

To put this in some kind of perspective, an individual pilot tapping oxygen from an AL-113—the smallest bottle MH sells—would be get 1.6 hours of oxygen when using what MH calls its MH4 adjustable flow meter and a normal cannula. He would get 4.7 hours of oxygen when using a MH3 flowmeter and an Oxymizer cannula and 6.9 hours of oxygen when equipped with an EDS O2D1 and an Oxymizer cannula.

I think I would start with the purchase of a pulse oximeter. If your saturation level goes below 90 percent at 7,000 feet MSL, I’d get the supplemental oxygen system and equipment that best fits your needs.

Happy flying.


Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 43 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to .

Restoration Rules of Thumb

Restoration Rules of Thumb

Have a DIY project in mind? Read these eight simple tips before you start.

June 2015-

As pilots, we have a responsibility to know our aircraft as well as we can, and one great way to learn about our airplanes is to complete a restoration project. Things like replacing bulbs, installing new seatbelts and new seats, repairing upholstery and decorative furnishings; as well as simple repairs and adjustments—and many other service actions which don’t involve disassembly of the primary structure—are all permitted under the preventive maintenance section of FAR part 43, Appendix A. (We’ve recently added a link to the U.S. Government Publishing Office on PiperFlyer.org. Look for “Browse e-CFR Data” under the Knowledge Base tab. There you can review FAR part 43, Appendix A and other regulations. —Ed.)

Here are some general tips to keep in mind if you’re contemplating a DIY project.

01 Define the scope of your project, and be realistic about your restoration skills and budget.

If this is your first restoration project, you’ll want to keep your project small and inexpensive.
When you’re planning, keep in mind that if you run into trouble you could have your plane down for weeks (or longer) while you get help. Talk to your A&P before you start any work, and if you have difficulty after you begin your project, get your mechanic’s advice. You can also reach out to your fellow members through the PFA forums by logging in to PiperFlyer.org.


Q&A: Blue smoke coming from the right engine of a Seneca II, a dropped de-ice plate and maintenance limits for pneumatic boots

June 2015-

Q: Dear Steve,
I fly a Seneca II and so far it’s been a very dependable airplane. But I’m seeing something that I haven’t seen before and wonder if you can give me some information to understand what’s happening.

One of my crew told me that he has seen some blue smoke coming out of the exhaust of the right engine when I first start up. When I asked him to tell me about it, he said the blue smoke was visible for about 10 seconds, then it disappeared. (He didn’t see any blue smoke when I started the left engine.)

He’s been working for me for five years, and is almost always the guy that takes me to the airplane when I have to fly to one of our remote locations. He’s a smart guy, and when he told me that he didn’t remember ever seeing the blue smoke before, I thought I better get some help.

—Seneca Sam

A: Dear Sam,
It sounds like oil is leaking into the hot side of your turbocharger and then being burnt as the turbocharger heats up after starting the engine.
On the outside, aircraft turbochargers look like nothing more than two scroll-like housings joined to a steel center section. There’s a scroll-like housing on the turbine (the exhaust, or “hot”) side of the assembly; and a scroll-like housing on the compressor (the air inlet, or “cold” side) of the assembly.

The turbine wheel and the compressor wheel are mounted on a common shaft that is supported by bearings in the cast-iron center section. The shaft is cooled and lubricated by pressure oil pumped from the engine. Labyrinth seals prevent the lubricating oil from leaking out of the center section.

The turbocharging system that’s installed in your Seneca II is what’s known as pressure relief valve control system. This type of system is used on Seneca IIs, Seneca IIIs and turbocharged versions of the Arrow and Dakota.
This simple system routes all the exhaust gas pressure developed by the engine to two parallel paths: the first path goes to the exhaust turbine, the second path is a bypass path. A restriction in the bypass path is adjusted on the ground by mechanics to produce the proper full throttle critical altitude. This restriction is a fixed wastegate used to control the turbine rpm.

In the case of your Seneca, a properly adjusted system should be capable of producing 39.5 to 40 inches of manifold pressure (at 2,575 rpm and full rich mixture) up to an altitude between 11,500 and 12,500 feet MSL.
This type of turbocharger system is extremely simple but requires constant pilot attention since any throttle movement directly affects boost, and because the inlet air to the engine is always warmed by passage through the turbocharger.
Finally, although the turbocharger itself has the capacity to provide additional boost above the critical altitude, this boost can’t be utilized since the wastegate can’t be adjusted during flight to “get” that boost.

Fortunately, Merlyn Products of Spokane, Wash. has developed Merlyn Black Magic, a wastegate control system that lowers engine temperatures, greatly increases the critical altitude and relieves the angst that revolves around the possibility of overboosting the engine due to accidental or inadvertent throttle mismanagement.
A couple of things can cause smoke upon startup. The easiest (and therefore, the first) thing to check is bearing wear. You can do this by removing the ducting from the inlet-air side of the turbocharger and trying to manually move the shaft.

The shaft must rotate smoothly, but there shouldn’t be any in-and-out or up-and-down movement. Spin the shaft; feel for ease of rotation and wear. Listen for any rubbing sounds.
If the shaft drags, it’s a sign of heavy coking or sludge in the oil cavity. This may have been caused by not changing the oil often enough; not delaying engine shutdown until the turbocharger has cooled down; or a restriction in the oil delivery line. Restricted oil flow will cause overheating in the center section.

While you have the inlet air ducting off, take a good look in the scroll for oil. There shouldn’t be any on the cold side. While you’re at it, get a mirror and a flashlight and inspect the turbine (hot) side for evidence of burned oil.

A weak oil scavenge pump can also cause smoking and leaking check valves in the oil delivery and oil return lines. When the engine isn’t running, these check valves close to prevent oil from flowing under gravity to the center section. If one of these valves isn’t seating fully, oil will creep past the shaft labyrinth seals.
Three Piper Flyer Association supporters—Approved Turbo Components (ATC) Hartzell Engine Technologies (HET) and Main Turbo Inc.—all offer great information about turbocharger systems and troubleshooting on their company websites. (See Resources for the URLs. —Ed.)

ATC’s Knowledge Center includes FAQs, troubleshooting, torque tables and more available as downloadable PDFs.
HET’s Troubleshooting page is in a Q&A format and can give you important details with just a few clicks. Service Information (Service Bulletins, ADs, Service Letters) are also accessible.
Main Turbo’s troubleshooting information is organized by symptom, offering possible causes of trouble and actions for each. The company also offers a maintenance tips newsletter by email subscription.

Happy flying.

Q: Hi Steve,
I too fly a Seneca II, and am probably okay since summer is finally here, but I need a new windshield ice plate. My five-year-old dropped it when I wasn’t looking and the glass shattered.
I install the shield as soon as the snow starts to fly in the fall and leave it on until spring. I don’t often have to turn it on, but since I fly all around the Northeast and sometimes into Chicago and Cleveland, I have to be ready for an ice encounter.

What are the options for getting this one repaired? I’ve heard that new ones are hideously expensive. If I have to bite the new-part bullet, I will—but I’d like to know if there are other options.
I also need some guidance on how many times I can patch my wing boots. Every few years we find another hole or two. I know I have to budget for de-icing boot replacement—but I want to know the repair limits, just so I can gauge if it’ll be sooner, or later. Can you help me?

—Busted Bob
A: Dear Bob,
It’s too bad your son dropped the plate. You have a couple of options.
The Piper part number for your plate is 78148-00. I checked with a Piper parts dealer and these plates are available, but the dealer told me she would have to check with Piper for a lead time. One online site cited a six- to nine-month delivery delay. List price is $5,501.
PFA supporter B/E Aerospace sells windshields for Piper Saratogas, but in talking with Joe Evans, marketing specialist at B/E, if you or any Seneca owners need help securing a replacement plate before winter, the company would be happy to help.

Evans mentioned that you can also get a quote from one of B/E’s installation centers. The link is in Resources at the end of this article.
I found plenty of used plates by typing that part number into an internet search engine, and the majority of the ones I found were listed as “used-serviceable.” Most used parts houses provide a short-term return-if-not-satisfied window; I’d ask before sending your money.
As far as boot replacement, B/E Aerospace has a pneumatic de-icer maintenance manual that provides guidance on evaluating boot condition. (See Resources for the link. —Ed.)

The tests for condition include a time-to-inflate test, a leak test and a time-to-deflate test. Any variation from prescribed times (six seconds to full inflation at regulated pressure; no more than 3 psi pressure loss after 60 seconds with inlet pressure sealed, and no more than 22 seconds to leak down (no vacuum)) indicates a less-than-healthy boot.

The following is from the B/E manual regarding total patch areas:
Recommended limits for application of patches for maximum operating efficiency of a pneumatic de-icer.
Three (3) small patches (1 ¼” x 2 ½”) per any 12-inch square area.
Two (2) medium patches (2 ½” x 5”)
per any 12-inch square area.
One (1) large patch (5” x 10”) per any 12-inch square area.

Additional information about evaluating your boots is listed on the
“10 Reasons to Replace Your Wing Boots” published on the Ice Shield website.
This information should provide some guidance for determining the state of your de-icing boots.

Happy flying.

Know your FAR/AIM and check with your mechanic before starting any work.

Steve Ells has been an A&P/IA for 43 years and is a commercial pilot with instrument and multi-engine ratings. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960
Piper Comanche. Send questions and
comments to .


Turbo systems and service
– PFA supporters
Approved Turbo Components, Inc.

Hartzell Engine Technologies

Main Turbo Systems, Inc.

Wastegate control system
Merlyn Products, Inc.

B/E Aerospace, Inc. – PFA supporter
Ice Shield installers

Ice Shield Pneumatic De-Icer,
B/E Report #97-33-047

“10 Reasons to Replace
Your Wing Boots”

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