Guide to Maintaining A Homebuilt Aircraft

The following article appeared in the April 1996 EAA Chaptergram, and is an excellent summary of the maintenance responsibilities/priveleges of a homebuilt aircraft builder and/or owner. It is reproduced here by permission.


By Earl Lawrence, EAA Government Programs Office

The EAA Government Programs office has recently received many questions about who can do maintenance and what maintenance is required on an experimental amateur-built aircraft. So I thought this would be a good time to review the regulations.

FAR Part 43.1 (b) specifically excludes experimental aircraft. It states, "This part does not apply to any aircraft for which an experimental airworthiness certificate has been issued, unless a different kind of airworthiness certificate had previously been issued for that aircraft." I stress the word aircraft so that it is not interpreted to include an engine.

What about major repairs and alterations? First, you never have to fill out a form 337 for an experimental aircraft. Repairs, major or minor, can be done by anyone ( remember Part 43.1 (b). However, alterations are different. If you alter the aircraft with a different propeller or engine, for example, then it is not the airplane for which you received an airworthiness certificate. This would also apply to changing pistons or magnetos. It is a new and untested airplane. If you change propellers, you must notify the FAA (not by a 337) of your change.

Your aircraft's operating limitations should have a statement such as the following in regard to major changes: "The FAA cognizant Flight Standards Office must be notified, and their response received in writing, prior to flying this aircraft after incorporating a major change as defined by FAR 21.93."

If you do not have such a statement on your operating limitations, then you can claim you do not have to notify the FAA. However, EAA suggests that you do so even if you do not have this limitation.

The FAA inspector will make a determination as to whether he needs to come out and inspect the change and/or assign a new test-flight period. If the inspector gives you an OK by letter (which is often done), you should note the date, time, name, and change in your aircraft log book. If the inspector wants to inspect the aircraft, it is the same as when you first received your airworthiness certificate. You start all over. It is a new airplane. This information is covered in the FAA ORDER 8130.2C paragraph 142 "Issuance Of Experimental Operating Limitations." Every FAA inspector has a copy of this ORDER.

If the aircraft received its original airworthiness certificate based on the fact that the engine was certified and you alter it in any manner that would render it no longer within certification requirements, then you must notify the FAA of your change and receive an approval.

Look at it this way, you may use any combination of parts you wish to build your aircraft. However, once you receive your airworthiness certificate you cannot alter it without getting the FAA to reinspect the "new" aircraft.

ADs apply to all aircraft, aircraft assemblies and parts the AD is written against, no matter what type of aircraft they are installed in. The key to this statement is, "that the AD is written against." For example, if an AD is written against a particular make, model and serial number propeller, it only applies to that particular make model and serial number. It applies to that particular make model and serial number propeller no matter what aircraft it is installed on. Now this is where I complicate things. You, as an amateur builder, remove the data plate of that propeller, send it to the FAA, the FAA notifies the manufacturer, and you make it a Ross propeller model R1, serial number 001. Now the propeller is no longer the propeller listed in the AD, so it does not apply. The FAA may, however, issue a new AD against the Ross propeller model R1 serial number 001. To date the FAA has never done this, but they can.

If you install an electronic ignition system on a Lycomming engine, you are still responsible for ADs on other accessories on the engine and the engine itself if you have the component listed on the AD on your engine. And, of course, if you haven't changed its designation to the Ross model R1 serial number 001. In general, you can say if your AC received its airworthiness certificate based on the fact it had a certified engine, then the ADs apply. If you received an airworthiness certificate based on the fact that your engine was not certified, then the ADs don't apply.

Isn't this fun?!

Now about who can do work on amateur-built aircraft. Anyone can normally work on an experimental aircraft and sign off the work, including your two-year-old son. Some FAA field inspectors do not believe this. Remember FAR Part 43.1(b) "This part does not apply to any aircraft for which an experimental airworthiness certificate has been issued." The operating limitations that each experimental aircraft must have are what replaces Part 43. Each set of operating limitations is different. However, an FAA inspector has the power to place a requirement in the operating limitations that all work must be done by an FAA certified A&P. So far to EAA's knowledge, this has never happened on an amateur built aircraft. Most operating limitations contain a statement that says an annual "condition" inspection must be performed per the scope and detail of FAR Part 43 Appendix D. It also states that an FAA certificated A&P or repairman must perform this inspection. Note it says, "A&P or Repairman." It does not require an IA.

Let me clarify this. Anyone can work on an experimental aircraft and sign off the work. However, the annual "condition" inspection must be completed by an A&P or a Repairman.

I hope this clarifies some of the confusion that is out there.


Return to Sea and Sky Aviation Page