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Rules For Owner-Performed Maintenance

Rules For Owner-Performed Maintenance

As an aircraft owner and pilot, you can legally perform some maintenance tasks, but you must adhere to strict guidelines when doing so. STEVE ELLS walks us through packing wheel bearings, while highlighting what’s important to stay legal.

As most readers of Piper Flyer know by now, all aircraft maintenance tasks must be overseen or performed by an appropriately-rated person. For maintenance tasks, this means an A&P mechanic—or a technician, as some like to be called these days—is frequently both performing and signing off on the work. This mechanic must (by regulation) have up-to-date versions of the appropriate manuals, bulletins, tools and equipment necessary to complete the tasks. 

However, there are also a number of maintenance tasks that owners may legally perform. These are termed preventive maintenance (PM) tasks. There’s a long list of them in Appendix A of FAR 43. 

What is considered preventive maintenance?

Appendix A is titled, “Major Alterations, Major Repairs and Preventive Maintenance.” Paragraph (c) lists preventive maintenance tasks. Type “Appendix A of Part 43” into your favorite search engine (or find the link in Resources on Page 33. —Ed.).

There is a surprisingly long list of tasks allowed. For instance, owners are permitted to remove and replace batteries, replace bulbs, reflectors and lenses of position and landing lights, and replace prefabricated fuel lines. 

They can also remove and replace panel-mounted communications and navigations receivers and update databases in panel-mounted avionics such as GPS navigators. 

Great news, right? It is, especially if a pilot has the time and a place to do these tasks. The potential for saving money exists, but much more important is the satisfaction to be gleaned from learning how to take care of your own airplane. (For further reading, see the sidebar on Page 32. —Ed.)

Are you permitted to perform preventive maintenance tasks?

FAR 43.3 paragraph (g) says that “…the holder of a pilot certificate issued under Part 61 may perform PM on any aircraft owned and operated by that pilot which is not used under Part 121, 129 or 135 of this chapter.” 

So, according to this section, if the owner and pilot is not using his airplane for hire, whether on a scheduled service, an on-demand service or as a foreign carrier operating for hire in the U.S., he/she can perform PM. 

But there’s a catch. It’s in 43.13. It’s titled “Performance Rules (General).”
43.13 Performance Rules (General)

The following three points—from paragraphs (a) and (b) of the performance rules—have been abbreviated to simplify the important points the maintenance performance rules for owners. 

1. Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer’s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques and practices acceptable to the Administrator.

2. He [or she] shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. 

3. Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).

In other words, if you’re going to do PM, you must follow the procedures in the manuals. It’s as simple as that. 

It’s important at the outset to understand that airplane maintenance, while seeming to be like automobile or other gas engine maintenance in that it must be done right, is different in a very important way. In airplane maintenance, there is a published protocol for every operation, even the tightening of a nut or bolt. 

Another peculiar-to-aircraft trait is this: the strength versus weight equation must always be kept at the forefront of every operation and decision. In other words, if you believe that more is better, whether it be the size of a bolt or the amount of torque, you’re going to do more harm than good. 

Gathering the manuals and bulletins to meet the requirements of the FARs is much easier and less expensive than it used to be. The secret is the internet. Manufacturers have come to realize that making their manuals and bulletins available at no cost or consolidating a double-shelf full of manuals onto a CD is a sound idea, simply because access to manuals makes it much easier for maintenance shops (especially smaller shops) to access the precise methods and techniques the manufacturer has developed for maintaining its product. 

So, step one for owners that want to start working on their airplanes is to have or have access to manuals, and either have the tools or be able to manufacture the tools required to properly perform each maintenance task. 

Let’s look at an example of why manuals are important.

Greasing wheel bearings: a “simple” preventive maintenance task

Greasing the wheel bearings on an airplane may seem simple. At its most basic, it can be described in the following steps: First, jack up the airplane or axle enough to get the tire off the ground, then remove the axle nut and pull the wheel/tire assembly off the axle. Next, remove each bearing, clean it and the bearing race, inspect for damage or corrosion, replace if necessary, pack with grease and reinstall. Finally, reinstall the tire/wheel assembly, tighten the axle nut and lower the tire to the ground. 

Not so fast. There’s more to it. In fact, there’s quite a bit more.

To remove the tire/wheel assembly (TWA), the brake assembly must be partially disassembled. This disassembly requires the removal of two or four bolts to release what’s called the brake back plate(s). The TWA can be removed only after the back plate(s) have been removed.

Assuming the airplane has been jacked up far enough to lift the TWA, a large cotter pin must be removed prior to removing the axle nut. Then, the TWA can be pulled from the axle.

There is an inner and an outer bearing. Does a Piper parts book refer to these bearings? No. Piper parts books don’t show an exploded view of the wheels. Piper parts manuals only provide the Cleveland part number for the wheels on its single-engine airplanes.

That means you also need a Cleveland manual for dimensions, wear limits and bolt torque specs when greasing the wheel bearings on your Piper single. 

Here’s another thing to know that is hard to find in any manual: Bearings and races are matched pairs. Don’t take the bearing assembly you removed from the race on the valve stem side of the TWA and install it in the race in the non-valve stem side of the TWA.

What grease to use?

The 2009 Piper Lance service manual suggests the use of Aeroshell 22 grease and Mobil EP 2 grease (also marketed at Mobilux™ EP 2), which is a lithium-based grease. 

Cleveland, the manufacturer of brakes and wheels used on Piper singles, suggests the use of Mobil SHC™ 100 grease. 

Bearing removal, cleaning and greasing

After the TWA has been removed, the bearings are removed. This usually requires the removal of a snap ring, a washer, a felt grease seal and another washer. 

Bearings are then cleaned with Stoddard solvent, applied by either an air-powered solvent sprayer or a brush. Air can be used to blow the grease out, but never spin a bearing by directing compressed air perpendicular to the rollers. 

Directing a stream of air across—not between—the rollers in roller bearings is dangerous because the bearing cage is designed only to maintain the spacing between the rollers. It’s not strong enough to contain the rollers when they rotate at a high rate of speed; in other words, directing air across when bearings can result in fast-moving projectiles.

After the bearing is clean and dry, look for corrosion and/or pitting. If found, replace the bearing and matching race.

Bearings are repacked by putting a gob of clean grease in the palm of either hand and forcing the grease up into the bearing. Press the bearing down into the grease until the bearing comes into contact with your palm. Repeat this procedure until grease appears at the top of the bearing cage.

You can also buy a bearing packer and use it to pack the bearing. Look up “wheel bearing packing tool” on your favorite search engine. YouTube also has wheel bearing packing videos. (See Resources for an additional article that discusses wheel bearing service. —Ed.)

The last step is to look at the grease seals. For decades, Cleveland, the manufacturer of most GA wheels and brakes, has used felt pads to seal against sand and fine dirt. These seals are inexpensive and work well. 

Recently, Cleveland has replaced the felt pads with molded rubber grease seals. These may be used in place of the felt seals.

Putting it all back together

The newly-greased bearings are reinstalled in the side of the wheel which they came from. Slide the TWA onto the axle. If it doesn’t slide all the way on, you’ve got the large steel washers on each side of the felt seal in wrong. Swap the washers around until the TWA slides all the way onto the axle.

Thread the axle nut onto the axle. 

How tight should it be? I couldn’t find definitive information on how tight the axle nut should be. Field experience suggests to tighten the nut up well to seat the bearings, then loosen it until you can feel a slight movement of the wheel in and out on the axle, then snug it back down until the TWA spins without resistance and no in-out movement is felt.

Now, to reassemble the brake. Two or four bolts were removed so the back plate could be removed to free the brake disc from the inner and outer brake pads. 

Whenever I have a TWA off the axle, I clean up the brake guide pins with a Scotch-Brite pad. I also clean the guide pin holes in the torque plate. These guide pins must slide in and out to allow the brake to self-adjust as the brake pads wear. 

The devil is in the details

The last step is often missed as it’s not in the Piper manual. It’s found in the Cleveland Wheels and Brakes Component Maintenance Manual, Appendix A titled, “Wear Limits and Torque Values.” This manual, and all of the Cleveland wheel and brake manuals, are available for free on the Cleveland website. Start by downloading the Technician’s Service Guide. (See link in Resources. —Ed.)

Piper parts books don’t have all of the information needed to service a tire and wheel assembly. The Technician’s Service Guide from Cleveland Wheels & Brakes can be an essential companion for owner-performed maintenance.
Oftentimes, similar-looking parts call for different torque values. It is crucial to use the correct value for your part. 

This critical step in reassembly is applying the proper torque to the two or four back plate tie bolts. Overtorqueing the bolts can deform the brake housing. 

The proper torque on almost every Piper single engine brake is 75 to 90 inch-pounds (6.25 to 8.5 foot-pounds). That ain’t much. It doesn’t need to be much since these bolts aren’t in a compression application. They are loaded in shear, and as long as these bolts are snugged down to the proper torque, that’s sufficient. 

Sign off your work

The good news is that owners can legally do a lot of work on their airplanes. However, as mentioned, there are catches. Catch No. 1 is that you must own or have access to the manuals. Catch No. 2 is that you must enter the work you performed in the aircraft records in a manner that’s acceptable to the Administrator. That’s FAA talk for the head of the agency. 

The requirements for these entries are listed in FAR 43.9. It says if you perform PM, you shall make an entry in the maintenance records containing the following information:

1. A description of the work performed.

2. The date the work was completed.

3. The name of the person performing the work.

4. If the work was performed satisfactorily, the name, certificate number and signature of the person performing the work. The signature constitutes an approval for return to service only for the work performed. 

(This is a summary of FAR 43.9. Please refer to Resources for a link to the complete text. —Ed.)

Notice that the regulations do not require the entry to include the aircraft total time or tach time, but it’s extremely helpful to include that information. 

An example1 of an entry for the work described above would read:

Month/day/year. “Greased left and right main landing gear wheels in accordance with information in the Piper (model number) service manual and the Cleveland Wheel and Brake Component Maintenance Manual, Appendix A, paragraph A3.”

Signed: Joe Pilot Cert # 1245654

The point of this article is to make sure owners understand the freedom and the limitations that are part of owner-performed PM. Go ahead and do it, but make sure you do it right; by the book. 

1For more about complete and detailed logbook entries, see “Deciphering Logbooks: Pre-purchase Maintenance Record Review” by Kristin Winter in the December 2017 issue. 

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 .

RESOURCES >>>>>

FURTHER READING

Part 43.3, Part 43.9, Part 43.13, Appendix A to Part 43

Electronic Code of Federal Regulations

Technician’s Service Guide AWBTSG0001-1

Cleveland Wheels & Brakes– PFA supporter

Component Maintenance Manual AWBCMM0001-12

Cleveland Wheels & Brakes– PFA supporter
“Wheel Bearing Service: Why and How” by Jacqueline Shipe 
Piper Flyer, July 2016 

 

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Wheel Bearing Service: Why & How

Wheel Bearing Service: Why & How

A&P Jacqueline Shipe describes how to service wheel bearings in this article, the second in a DIY series for pilots who wish to take on preventive maintenance of their aircraft.

FAR 43 Appendix A lists the preventive maintenance items owners may legally perform on their planes. This list is fairly long—and some of the items are a little involved for a person to perform the first time by themselves, while other tasks on the list are pretty straightforward. 

There are several preventive maintenance tasks pertaining to the landing gear, including tire changes, strut servicing and servicing the wheel bearings. (Last month, Shipe discussed the steps involved in changing an aircraft tire. See the June 2016 issue for more information. —Ed.) 

Bearings: small but mighty

While cleaning and greasing wheel bearings doesn’t seem like too difficult a task, there are some guidelines that need to be followed. The failure of a wheel bearing can cause major damage to the wheel and can even allow the wheel assembly to slide off the axle.

Wheel bearings are relatively small, but are incredibly strong. They have to support the weight of the plane while allowing the wheel to spin freely in all types of temperatures and conditions. In addition, wheel bearings and races on airplane wheel assemblies also have to be capable of withstanding hard landings and both vertical and horizontal loads without failing. 

Types of bearings

The bearings on most airplane wheel assemblies are the tapered roller-type. The outer part of the bearing is larger than the inner part, and the rollers are installed at an angle. 

The bearing itself rides in a metal cup called a race. The race has a “pressed in” fit in the wheel half, and is tapered on the inside to match the bearing. The biggest advantage of tapered bearings is the high load capacity that they can withstand. 

Automotive wheel bearings, on the other hand, usually use spherical rollers (i.e., balls). Ball bearings can withstand prolonged high speeds without building up too much heat, but cannot take high impact loads. 

Tapered bearings will bear up under the not-so-good landings that occur from time to time with an aircraft. In addition, proper servicing of these bearings will keep the wheels spinning freely and will last for a long time. 

Removing the clips

Once a wheel assembly is removed from the axle, the wheel bearings are easily removed by taking out the metal retaining clips that secure the bearings and grease felts. 

There is an indention in the outer part of one end of the clip to allow a screwdriver to be used to pry it out. The clips don’t have a lot of tension on them and can be easily removed. 

Once the clip is off, the bearing, metal rings and grease felts can all be lifted out together. 

Be sure to keep all the rings and clips organized so they can be reinstalled into the same wheel half and in the same place. The metal rings that retain the bearing are sometimes slightly smaller on the outer half than the double rings used on the inner half, and can be easily mixed up. 

Cleaning the parts

A small bucket with 100LL Avgas works well to clean the bearings. Swishing the bearing around and spinning it by hand while it is submerged will clean all of the old grease and gunk out. 

The metal rings and clips should also be cleaned, but the felt material needs to be set aside; it should not be submersed in anything. There is really no way to clean the felt, anyway—as long as it is still in one piece, it’s good to go. Any grease felt that is torn or missing a section needs to be replaced. 

Once all the parts are cleaned, they should be blown out with compressed air (if available) or laid out on paper towels to dry. The parts need to be thoroughly clean and dry before fresh grease is applied. Inspecting the parts

After the bearings, metal rings and clips are clean and dry, the bearing and race should be inspected for pitting or damage. If the race is smooth and has no corrosion, the bearing is generally corrosion-free as well. 

Races that have light surface corrosion can sometimes be smoothed out with a piece of light grit sandpaper (800 to start and 1200 to finish). Deep pits in a race mean replacement is needed. 

Discoloration on the bearing or race, such as a rainbow or gold color, can be a sign that these parts have generated excessive amounts of heat, in which case they should be replaced.

Preventing corrosion

Wheel bearings typically fail for two reasons: corrosion or overheating. 

The greatest threat to airplane wheel bearings is usually corrosion. Almost all bearings and races will eventually require replacement due to water getting past the grease seals and accumulating in the bearing cavity, causing rust and pitting. 

When cleaning a plane, strong degreasers should not be used on wheel assemblies and wheels should never be sprayed with a water hose. The pressurized water will get past the grease seals and ruin the bearings. 

Folks that want their wheels clean can wipe them out with a rag that is lightly moistened with a little Gojo original white cream hand cleaner (the non-pumice kind). Then the wheels can be wiped clean with a dry rag. 

 

Replacing the races

Wheel bearing replacement is easy, but replacement of the races is a little tough to do without the proper tools. 

Because the race has a pressed-in fit in the wheel half, it has to be driven out. This can be accomplished by using either a hammer and punch or a bearing driver tool. 

Occasionally a person encounters a wheel assembly with a race that has broken loose and is spinning in the wheel half itself. In this case, the wheel assembly has to be replaced; there is no permanent way to hold the race in place if the wheel assembly has lost enough metal that the race is no longer fitting tightly. 

The wheel is made of cast aluminum. When reinstalling the steel race, it is very important that it be driven in straight. If it gets cocked—even a little—the much softer aluminum will be gouged and damaged. 

The best tool for the job is a bearing driver, as it allows each blow of the hammer to be applied equally around the circumference of the race. 

Once the race is almost near the bottom of its recess, very light blows should be used to seat it in the wheel half. Many mechanics have driven the race in too far and cracked the fairly thin aluminum ring that retains the race. 

The wheel should always be thoroughly inspected for any sign of cracking on the front and back sides, whether or not a race is replaced.

 

Packing the bearings and reinstalling

Once all of the races are installed and the wheel halves are inspected, the bearings are ready to be packed and installed. A high-quality wheel bearing grease that has good water resistance should be used. 

The grease has to be pushed up through the bearing until it comes out the top between each roller. If it doesn’t squeeze through each opening, the inside of the bearing will have gaps and inadequate lubrication. 

It takes a little while to pack a bearing by hand. There are bearing packers sold in almost any automotive store that make the job a little faster and a little less messy. 

Once the bearing is packed, apply a layer of grease to the entire surface of the race to ensure it is covered as well. 

The bearing can then be reinstalled along with the correct order of retaining rings and grease felts. 

Lastly, reinstall the clip. It is a good idea to make sure the clip is pressed into place all the way around by pushing it outward with a screwdriver. 

After all the clips are in, the wheel bearing service is complete.

 

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 .

 

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