Aircraft Maintenance: Owner-produced parts

FAR 21.9 (a)(5) provides the legal basis for owner-produced parts, and AC 20-62E lists parts produced by aircraft owners or operators among those acceptable for installation in type certificated aircraft. The key word in the regulation is “produced; As the owner of the aircraft, you are responsible for the part’s “production,” not necessarily for its “manufacture.” In other words, you must (at a minimum) be the manager of the production process, defining the requirements, design, and conformity of the part. This is an important distinction, as it opens up the world of owner-produced parts far beyond those folks with a machine shop in their basement. If you can’t find a part and are willing to do the legwork, chances are that you can find a solution that fits your abilities.

The part must be properly designed

An owner-produced part is a replacement for an FAA-approved part; it is not an alteration. Therefore, you need to have design data to ensure that you are producing a part that is equivalent to the original. The simplest solution would be to get access to the manufacturer’s original drawings, although most aircraft manufacturers will not release this data. If, however, the manufacturer of your aircraft is either out of business or no longer supporting the aircraft, you can petition the FAA Aircraft Certification Directorate for the data on how the part was made under the Freedom of Information Act. In some cases, you can contact the supplier that made the part for the original manufacturer and ask them to produce an equivalent part for you. You still need the design data, so if you decide to take that route the supplier would have to give you the specs for the original part .

If you have no access to design data and you need to make a part from scratch, you may need help with the design. This is where a professional such as a Designated Engineering Representative can help. They can validate or create a design that will conform to the regulations as a suitable replacement in lieu of original design data.

Alternatively, you can take the most common approach: reverse engineering the part you are replacing. In some cases, such as control cables, exhaust parts, or simple airframe components, this can be relatively straightforward. However, the devil is in the details. Even if a part looks simple, you still need to know exactly what material it is made from and any special processes that may have been applied to it (such as heat treating, coatings, or other modifications). If you cannot do the work yourself, you would give your old part to a supplier or repair facility and ask them to evaluate and reproduce it. If you use an FAA-approved facility, you’ll have the added benefit of getting a jump-start on the next step: conformity.

The produced part must conform to the design

Once you have the approved design data in hand, you now need to produce the new part and prove its conformity to the original. This includes the materials used, manufacturing processes, assembly, and testing.  Using an FAA-approved facility means that you’ll have easy traceability for all of this. Otherwise, it’s up to you to document conformity.

The produced part must have proper documentation

If a part is produced without the documentation showing its equivalency to the original part, its design, and how the final part conforms to the design, it is not a legal part in the eyes of the FAA. Being the manufacturer of the part places the same documentation and traceability requirements on you as it would on any aircraft parts manufacturer. You will need to keep records of the design and manufacturing documentation related to the new part. These records might include receipts and traceability information for the materials that you purchased and a careful explanation of your testing procedures and test results.

The produced part must be properly maintained

Although it may seem obvious, this clause ensures that the new part gets the same ongoing maintenance as the original one did. In most cases, nothing needs to be done to comply with this guideline. However, if your new part is different from the original in some meaningful way, you may need to develop new maintenance documentation and append it to the aircraft documentation as additional “Instructions for Continued Airworthiness” (ICA).

As noted earlier, you do not have to manufacture the part yourself, but you do need to be the “producer” of it. The FAA requires that the aircraft owner participate in the manufacture of the part in one of five ways:

• The owner provides the manufacturer of the part with the design or performance data.
• The owner provides the manufacturer of the part with the materials.
• The owner provides the manufacturer with fabrication processes or assembly methods.
• The owner provides the manufacturer of the part with quality control procedures.
• The owner personally supervises the manufacture of the new part.

Owner-produced parts can be the salvation of an aging GA fleet and get owners out of a tough bind when parts are difficult to come by. By participating in the production of the part and following the documentation requirements for all legal aircraft parts, you can preserve both your aircraft and your wallet. Be sure to work closely with your mechanic throughout the process. You, the aircraft owner, can produce the part. However, in most cases it’s your mechanic who installs it and attests to its airworthiness. You each have a role to play in the process and the paperwork. So, work together as a team to solve parts problems and keep your airplane flying for years to come. Until next time, I hope you and your families remain safe and healthy, and I wish you blue skies.