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Maintenance & Technical (105)

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

Steve Ells

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.

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”

Q&A: Emergency landing gear extension, troubleshooting water in the fuel and checking the idle mixture

Q&A: Emergency landing gear extension, troubleshooting water in the fuel and checking the idle mixture

May 2015-
Q: Hi Steve,
I watched a gear-up landing at my local airport a week ago. Nobody in the Piper Arrow was hurt, so it was a good landing. But after all the facts were known, it appears as if the cause was the pilot didn’t know how to, or got emotionally seized up, when he attempted to do an emergency gear extension.

As I pondered this I wondered if I would be able to get the gear down in my Arrow II if something went wrong. I’ve read the book on the emergency gear-down procedure, but I’ve never actually done it.
I decided to survey the other pilots here that fly retractable landing gear airplanes and found that only one or two out of 14 had ever completed an emergency gear-down procedure while flying.

I know I can re-read through the manual, and sit in the cockpit and coach myself through the steps when I’m on the ground. I believe I understand the landing gear system, but wonder if I should insist that my instructor let me perform an actual emergency gear extension.
What do you think?

—Landing Gear Gary

A: Dear Gary,
I’m impressed with the fact you’re striving to learn all you can about the landing gear system in your Arrow II. An intimate knowledge of systems increases confidence and makes flying safer.

The landing gear (LG) system in your PA-28R-200 is pretty simple. During the gear-up cycle, the LG is retracted using hydraulic pressure generated by a pump/reservoir/valve assembly located aft of the baggage compartment on the pilot’s side of the centerline.

Once the gear is up and the actuating cylinders have reached the limit of up travel, the hydraulic pressure builds to approximately 1,400 psi. At that point a pressure sensing switch turns off the pump. A one-way check valve seals the up pressure line and the LG legs are held up by the captured hydraulic fluid.

If there’s a small leak past the check valve or past a piston in one of the actuators, pressure will bleed off. At approximately 1,100 psi the pressure sensing switch will turn the pump motor back on until the pressure again builds to approximately 1,400 psi.
An emergency landing gear extension is quite simple: pushing the emergency gear extension lever on the pilot’s side of the console between the front seats opens up the gear-up fluid lines.
Without pressure, the gear will fall out of the gear wells and lock itself down. Built-in restrictions, called snubbers, in the fluid lines prevent the LG from slamming down into position. Extension of the nosegear is assisted by springs.

As you know, there is an in-flight emergency gear-down test procedure in the service manual of your Arrow. Get together with your flight instructor, review the procedures and then go out and practice.
Gaining this kind of experience with the steps involved in extending the LG in an emergency will go a long way in easing your concerns.

Happy flying.

Q: Hi Steve,
Our 1967 Arrow will experience very rough—but quite intermittent—engine operation in very cold weather. I’ve noticed this hiccup occurs shortly after departure and also on taxiing after landing. The coughing eventually stops, but it is somewhat unnerving, especially on departure.

The engine-driven fuel pump was replaced in 2014 and seemed to resolve the problem. However, the quirkiness reared its ugly head again last winter. The airplane is kept in a heated hangar, and temperatures during flight are ranging from 20 degrees to -20 degrees F.
Speculation suggests that frost on plugs and/or injectors turns to water and gets ingested into the fuel, or a possible air intake blockage.

Additional information:
1) The phenomenon only occurs in cold weather, and did not occur before we had a heated hangar.
2) The coughing primarily occurs when the Arrow is in a nose-up pitch attitude. Is a vent getting blocked?
3) There is a delay of at least 30 to 60 minutes after leaving the hangar before it happens. Evidently the issue is dependent on outside temperature? When it occurred for the first time last winter, it took about 45 minutes and we were departing Duluth, Minn. (KDLH), nose up.
Perhaps water is condensing because of temperature decrease from hangar to outside, somewhere in the fuel system—probably on the right side—and then freezing, creating ice crystals and causing a partial restriction of fuel flow?
Any suggestions would be most welcome!

—Arrow Angst

A: Dear Arrow,
It sounds like you’re getting little bits of water in the fuel. Not enough to cause a real emergency or loss of power, but enough to cause a tighter grip on the yoke.
The most common causes are a leaky fuel cap or condensation. Since you’re moving your airplane from a heated hangar I’d bet that your problems are condensation-based.

Try to shake the wings by putting one hand on top of the wing and one hand on the bottom of the wing at the wing spar, and do your best to move the wing up and down. The idea is to dislodge any water globules and get them flowing to the fuel sump drain.
Then drain a lot of fuel—at least a quart—out of the right tank. (Might as well do the left tank, too, since you’ll be warmed up!) Keep draining until you no longer see any evidence of water.

The next thing to do is add isopropyl alcohol to the fuel tank. The alcohol absorbs water and prevents water in the fuel from freezing. Don’t use rubbing alcohol even though it does contain isopropyl alcohol; it’s diluted.
I’ve included a fuel additive chart for you to refer to (page 23). One example adds five cups of alcohol to 30 gallons of fuel. If you’re having a hard time rounding up isopropyl alcohol, you can order Prist Hi-Flash Lo-Flo anti-icing fuel additive from Aircraft Spruce and Specialty.

After pondering your write-up, it appears that in addition to the water from condensation you have an idle mixture problem. It’s important to reset the idle mixture and idle speed with seasonal changes. If that wasn’t done it may explain the spark plug fouling and hard starting problems.
A simple test to determine if the idle mixture is set correctly is to slowly pull the mixture control knob aft at idle rpm after a flight. (It’s important that the engine is at operating temperature for this test.) Some maintenance texts suggest doing this test at 600 rpm; some at 1,000 rpm.

A properly set idle mixture will cause a slight (25 to 50 rpm) rise prior to engine cutoff. If you have an analog tachometer it may not show this slight change, but you’ll be able to hear the rise if it’s there.
If the increase is greater than 50 rpm, the mixture is set too rich; if there’s no rise, the mixture is too lean.
Please let me know if these tips work.

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 Paso Robles, Calif. with his wife Audrey. Send questions and
comments to .


Prist Hi-Flash Lo-Flo
Anti-Icing Fuel Additive


Piper Mandatory Service Bulletin 1245A

Existing Instructions for Continued Airworthiness (i.e., the appropriate Piper Maintenance Manual and associated Service Publications) include an inspection of all flight control pulleys, cables, fittings and turnbuckles on a recurring basis. However, service history suggests that over time, the turnbuckles used in the stabilator flight control cable system may develop cracks or corrosion which may not be detected during these inspections. This Service Bulletin provides specific instructions for the recurring inspection of the stabilator flight control system.

Click the link below to download PDF


AD 2013-02-13

We are adopting a new airworthiness directive (AD) for certain Piper Aircraft, Inc. (type certificate previously held by The New Piper Aircraft Inc.) PA-28, PA-32, PA-34, and PA-44 airplanes. This AD was prompted by reports of control cable assembly failures that may lead to failure of the horizontal stabilator control system and could result in loss of pitch control. This AD requires inspections of the stabilator control system and replacement of parts as necessary. We are
issuing this AD to correct the unsafe condition on these products.

Click the link below to download PDF

Restoration on a Budget: A New/Used Autopilot

Restoration on a Budget: A New/Used Autopilot

I recently managed to take care of one of the items on my wish list, and I did so at a significant discount.

April 2015-

Back in the day, all I wanted was a new Nav/Com, a wing leveler and an engine that didn’t leak too much oil.
Times changed, and my wish list got more expensive. Now it includes a new GPS-based flight management system (FMS), a new autopilot with all kinds of GPS-enabled capabilities—and an engine that doesn’t leak too much oil. (Along with a new paint job!)

I’ve recently managed to take care of one of the items on my wish list: the replacement of a 37-year-old autopilot with something modern. I’d been using a Century III autopilot with altitude hold and Nav/GPS/localizer tracking—no glideslope coupler, no altitude preselect, no beep when the autopilot kicked offline. (On the other hand, when the Century III worked, it was amazing.)
After flying with Century III and Century 41 autopilots for over 40 years, I had grown accustomed to this quiet, invisible and completely reliable equipment flying the plane for long hours at a time.

The need for a reliable autopilot
For those of you that have never flown a Seneca, here’s my one-sentence summary of its flying attributes. It is highly stable, but it can be a bear to fly.

That is, it’ll fly for long periods of time on-heading and on-altitude with the autopilot offline, my hands in my lap and my feet flat on the floor. After a while it will slowly drift left or right, up or down. The drift is so slow that if I’m not careful, I’ll bust my altitude and have to account for my poor flying habits. Every few minutes you have to roll left or right a bit, or pitch up or down a bit.

Q&A: Stabilator Tip and Wingtip Replacement Options, Control Cable Assembly Inspection and Replacement

Q&A: Stabilator Tip and Wingtip Replacement Options, Control Cable Assembly Inspection and Replacement

April 2015-

Q: Hi Steve,
I fly a Piper Cherokee 180 and want to install new stabilator tips and wingtips. Mine are original, and they are in pretty sorry shape.

My mechanic said he could remove them and use off-the-shelf fiberglass products to fix them up, but I don’t think that’s what I want.

I’ve seen other Cherokees with tips that are much better looking than the originals. What are my options for new tips?

—Bad Tip Terry

A: Dear Terry,
A long time ago Piper manufactured wingtips out of aluminum, but later changed to using ABS plastic because it was lightweight, easy to manufacture and economical. And as long as it was well protected by good paint, ABS was pretty durable.

However, I wouldn’t recommend attempting a repair of your original ABS plastic wingtips or stabilizer tips with fiberglass. ABS plastic is a much more flexible product; although fiberglass can be repaired, in this case you’d be mixing a rigid product (fiberglass) with a flexible product (ABS). It’s better to use ABS repair products on ABS tips, and ABS repair components are available from various vendors.

Restoration on a Budget: Door Handle Replacement

Restoration on a Budget: Door Handle Replacement

Door Handle Replacement

Cost: Two-door Piper: less than $100
One-door Piper: Less than $50
Complexity: Simple
Time Required: 15 minutes
Applicable Airplanes: PA-28, -32, -34

Before I take my Seneca in for painting, the exterior needs to be in great condition.

This quick and inexpensive project was a piece of cake to accomplish.

March 2015-

I’m always restoring something on my Seneca II and talking about my experiences on the member forum at PiperFlyer.org. I just celebrated my 10th anniversary of owning this airplane and I’m slowly moving toward getting the airplane painted... but I’m rapidly running out of things to replace!
With the high cost of painting an aircraft I find myself doing all of these little projects first, but I’m finding that fewer people want to fly with me because—unfortunately and incorrectly—they equate airworthiness with paint condition. (Even more unfortunately, paint is about $15,000!) At least some of the other parts of my Seneca are new and shiny.
I did visit a paint shop once, where I received some sound advice. Before I take my PA-34 in for painting, I was reminded that the exterior of the plane better be as good as it can be. If the exterior isn’t in great condition, paint isn’t going to help it much. It would be like putting lipstick on a pig, as the saying goes.

Q&A: Spare Key Blanks, Cabin and Baggage Door Lock Replacement, Maintaining a High Performance Single and Solutions for Hard Starting

Q&A: Spare Key Blanks, Cabin and Baggage Door Lock Replacement, Maintaining a High Performance Single and Solutions for Hard Starting

March 2015-

Q: Hi Steve,
I want to make another set of keys for my Piper PA-30 Twin Comanche. I’ve decided to let my son buy a half share in the airplane and he needs keys.
My experience is that buying anything from Piper is expensive—and besides, this airplane is 48 years old. Do you think Piper still stocks key blanks for my airplane?
What do you recommend?

—Keyless Ken

Not Just a Bunch of Hot Air: Exhaust system inspection tips

Not Just a Bunch of Hot Air: Exhaust system inspection tips

Three defects can show up on exhaust systems; read on to find out exactly what they are and how to find them.

February 2015-

Light airplane exhaust systems don’t garner as much attention as a carburetor or induction air filter, yet these systems must be maintained as attentively as any other engine accessory, if not more so. That prosaic exhaust system is the only fire control system under your cowling.
Exhaust systems rarely rate a second thought. Why? Because unless your airplane is turbocharged or turbo-normalized, the exhaust system doesn’t have any moving parts—it just sits there.
Light aircraft exhaust systems are designed to collect hot exhaust gases from each cylinder and route these gases safely out of the engine compartment. Systems in single-engine airplanes also flow the gases through rudimentary metal heat exchangers that radiate heat to outside air that’s used to provide cabin and carburetor heat.
It’s common to mistakenly believe that these heat exchangers are mufflers because they look like an automobile muffler. Some heat exchangers include internal baffles designed to slow the exhaust gases in order to increase the amount of heat transfer. Twin-engine Pipers don’t have these heat exchangers; they utilize Avgas fuel combustion heaters for cabin heat. (For an in-depth look at combustion heaters, refer to the November 2014 issue of Piper Flyer. —Ed.)

Q&A: All about Comanches and wing stall strips on a pre-1989 Archer II

Q&A: All about Comanches and wing stall strips on a pre-1989 Archer II

February 2015-

Q: Hi Steve,
I just bought a sweet little Piper Comanche. I can’t believe how much the prices have fallen in the last five years. This one is a 1964 Comanche 250. I am planning to upgrade the avionics and get a new paint job and figured that all into my budget when I penciled out the numbers. So far I couldn’t be happier.
Since I’ve just entered the Comanche world, I need some guidance on how to keep my airplane alive and healthy. What are the big maintenance items? What parts do I need to buy now and stockpile for the day the parts pipeline dries up? Where can I learn all there is to learn?

—Comanche Newbie

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