EAA is hiring AirVenture and seasonal staff. Attend one of our upcoming hiring events and apply now!

Hands, Mind, and Heart

What started as a handful of passionate enthusiasts has developed into a major force—and a significant component—of the aircraft industry.

The 51% Rule: Frequently Asked Questions

Q: I want to hire someone to finish the wings on my kit. Can I do that?

A: There is no specific prohibition in hiring someone to help with the construction of your aircraft. In fact, that is what you are doing when you purchase a kit; you are hiring someone to help you construct your aircraft. To be eligible for an amateur-built certificate, the “major portion” (at least 51 percent) of the tasks needed to make the aircraft airworthy must be completed by amateurs “solely for their own education or recreation.” So you may hire someone to finish the wings on your kit if you still have 51 percent or more of the tasks remaining to be completed by amateurs solely for their own education or recreation.

To assist builders with assuring that they have accomplished the required number of tasks, the FAA has provided a new checklist that enables builders to fill in an additional column for “commercial assistance” in addition to the kit provider column. This form helps a builder determine if the project would continue to comply with the amateur-built regulations if he or she hired someone to complete additional tasks originally evaluated by the FAA and kit manufacturer to be amateur-builder tasks.

Q: How do I calculate how much of the work was done by the kit manufacturer, how much is left for the amateur builder(s), and how much can be done by commercial assistance providers?

A: The FAA kit evaluation team determines what percentage of a task is assigned to the kit manufacturer when it evaluates a kit for inclusion on the FAA amateur-built kit list. The completed evaluations will be posted on the FAA website so builders can see how close to the limit a kit is when it comes from the kit vendor.

If a builder wants to then hire someone to complete another percentage of a task or tasks, he or she will have to provide the inspector and/or designated airworthiness representative (DAR) called to certificate the project sufficient evidence (pictures, logs, videos, etc.) to show what tasks were performed by the commercial assistance provider and that enough tasks were completed to assure that at least 51 percent of the tasks were completed by amateur(s).

In short it is the applicant’s job to “show” compliance and the FAA’s role to “find” compliance. The burden of proof is on the applicant for the certificate not the FAA inspector or DAR.

Q: Am I correct that I can hire tasks to be done by commercial assistance providers, but that work won’t count toward my total, and I have to be careful not to do that too often or my total won’t be high enough?

A: You are correct. Regardless of the task hired out, the applicant for an amateur-built certificate must provide evidence that the major portion (51 percent or more) of the tasks were completed by an amateur(s). The FAA inspector or DAR will reference the task list, when the aircraft is one that is on the FAA list, and the applicant will need to “show” that the hired-out tasks did not result in a project having more than 49 percent of the required tasks completed by the kit company and/or commercial assistance.

Q: I want to farm out some of the more critical parts of the kit. What is the procedure that will let me know ahead of time whether I’ll be hiring too much done and won’t be able to certificate the finished airplane?

A: If you want to hire out additional tasks after a kit has been evaluated by the FAA, the burden to prove compliance will be solely on you, the applicant, for the certificate. The FAA will not provide an official evaluation of the effect of such additional commercial assistance prior to undertaking the additional work. However, AC 20-27G suggests that you contact your local FAA office to discuss the use of commercial assistance before proceeding. It would be advisable to get input from the FAA when making the decision to use commercial assistance.

A kit manufacturer will sometimes provide an option to complete some additional tasks not provided in the basic kit. The kit manufacturer can call upon the FAA to provide another kit evaluation that includes the evaluation of the additional optional tasks being completed commercially. These kits are commonly called the “fast build” option by kit companies.

If a builder wants to have additional tasks completed commercially and wants assurance that the project will still comply with the amateur-built regulations, the builder should look to the FAA-evaluated “fast build” options kit manufacturers are providing.

Q: Is it a correct statement that if a kit is approved by the FAA and comes up to 49 percent, then the only things left that I can hire done commercially are tasks not specifically mentioned on the checklist, such as paint, upholstery, etc?

A: This is correct. Even if an amateur must complete all the remaining tasks, he or she still can hire out projects that are not tasks on the FAA checklist. The premise is that the tasks on the form are what is required to construct an airworthy aircraft, but there are always additional tasks not required for airworthiness that can he hired out, such as painting.

Q: In the fabrication and assembly checklist, item C10, wiring, is mentioned as “…fabricate electrical wiring, controls and switches.” Does this include avionics or airframe electrical systems only.

A: There is a separate task listed in the fuselage section that will cover most airframe wiring. The key consideration here is what is required for the basic aircraft to be airworthy. There may be a judgment call to be made by the individual who issues the certificate. Depending on the aircraft, the amount of wiring necessary could be different.

Q: If I use a pre-fabricated wiring harness for my avionics, and avionics is considered “wiring,” how do I know how much of that pre-fabricated component deducts from my building total?

A: You do not know. The safe thing to do is to consider that 100 percent of the task has been completed commercially. That said, one could provide “evidence” sufficient to convince the “administrator” (inspector/DAR) that you, the builder, completed at least 10 percent of the task. The FAA instructions for evaluating tasks state that tasks may be broken down in increments of 10 percent but not less.

Q: I bought a partially completed project. How does the FAA handle the work already done by the previous owner (none of it commercial), and will that affect my ability to get the repairman authorization or have it certificated?

A: If you are purchasing a kit from another amateur-builder, you need to obtain evidence—logs, pictures, etc.—from the previous builder sufficient to show that the major portion of the aircraft was completed by amateurs. The FAA does count the previous amateur-builder work as amateur-completed tasks. The total of all tasks completed by all amateur builders (yourself and any before or after you) must be the major portion (that is, more than 51 percent) of the total tasks. As long as this is the case, the aircraft is eligible for an amateur-built airworthiness certificate.

Eligibility for a repairman certificate is not based on percentage of work accomplished on an amateur-built project. The eligibility for the certificate requires that the applicant was one of the builders and “show to the satisfaction of the Administrator that the individual has the requisite skill to determine whether the aircraft is in a condition for safe operations.” The FAA is not required to issue a repairman certificate to any builder regardless of the percentage of work he or she may have done on a project unless it can determine the individual has the skills necessary to determine the aircraft in question is in a condition for safe operation.

Q: If the kit is 90 percent finished by a previous owner, so I don’t do most of the work, can I still certificate it?

A: Yes, again the requirement is that the major portion is constructed by amateur(s) for their own education or recreation. However the burden to prove that the previous 90 percent of the work was done by an amateur solely for his or her own education or recreation is on the applicant. So one needs to be ready to show evidence in the forms of logs, pictures, videos, and affidavits that the previous builder was an amateur.

Q: If the former owner of a kit project hired too much of the kit done commercially to allow it to be certificated as a homebuilt, how do I know that prior to buying the project?

A: There is no way to know for sure. If you are interested in purchasing a kit from another builder, insist on extensive documentation that clearly shows what work was accomplished by amateur(s) and what was not. If the aircraft is being constructed from an evaluated kit, you can reference the FAA kit checklist (to be available soon on the FAA website) for the aircraft in question. Review the tasks required to construct the kit and assure yourself that you have sufficient evidence to prove to the FAA that the major portion of the aircraft will be constructed by amateurs. If you cannot obtain such evidence, then EAA suggests you do not purchase the project. Remember the burden of proof is on the applicant, not the FAA.

Q: I bought a set of approved kit wings that were finished by an amateur who ran out of money, and I want to use them on my kit of the same make. How is that handled, and what effects will it have on my completion percentage?

A: This is handled the same as purchasing a kit that was started by another amateur. The work done by the previous amateur is counted as tasks done by an amateur as long as sufficient evidence can be provided to the FAA to show that the work was done by an amateur and not hired out.

Q: I bought a scratchbuilt project that’s about three-quarters completed, depending on how you figure the percentage. Who evaluates what I have or haven’t done to finish it, and what kinds of problems will there be. The work wasn’t done commercially, but I didn’t do it either.

A: The FAA is not concerned about the number of amateurs who built an aircraft. It is just looking to be presented with sufficient evidence that the “major portion” of the aircraft was completed by amateurs. If the project is a scratchbuilt project, then there would be very little reason for an FAA representative to be concerned about eligibility. Again the burden of proof would be on the applicant to show, through the use of builder logs, photos etc., that the major portion of the aircraft was amateur-built.

Q: Paint and upholstery aren’t mentioned on the kit evaluation form. Does that mean I can farm that out and it won’t detract from my percentage of the tasks completed?

A: One can farm out any tasks not listed on the kit evaluation form. Again the intent is to only evaluate the tasks that are required to build an airworthy aircraft. There are many aircraft flying without paint; therefore, paint is not normally considered a required task. But at the same time some “paint” may be required, for example, with a fabric-covered aircraft if it is a part of the covering process.

Q: What are acceptable methods to prove to the FAA that I have performed at least 51 percent of the tasks/work involved in my aircraft?

A: The Advisory Circular 20-27G provides guidance regarding proper documentation. Just remember the burden of proof is always on the applicant not the FAA. The FAA will not issue a certificate until “sufficient evidence has been presented to the Administrator.” Typically this would include pictures and construction records (usually referred to as a “builder’s log”) and the ability to show intimate knowledge about the construction of the aircraft to the inspector/DAR.

Q: I purchased an aircraft kit that was not on the 51 percent approved list prior to the policy’s implementation. How do the rules affect this project?

A: When a kit has not been evaluated by the FAA, the burden to prove the aircraft kit complies with the regulations is solely that of the applicant for the certificate. If the kit was purchased prior to September 30, 2009, and no commercial assistance was used, the aircraft will be certificated under the prior policy. If the kit was purchased after September 30, 2009, or if any commercial assistance was used, the new policy will be used to certificate the aircraft.

Q: I began building a Pitts S-1S 10 years ago. I bought a fuselage, gear, and tail complete with the control system from Steen and had it build the wings. I assembled the airframe but then had someone cover it for me after I put in the systems, instruments, electrical, etc. On the new list it appears I have roughly 40 items against 55 for the manufacturer/commercial vendor. What do I do?

A: From your description of the work hired out, it would appear that insufficient work was done by amateurs for the aircraft to be eligible for an amateur-built certificate. If that is the case, you may be eligible for an experimental exhibition certificate. The exhibition category has a specific grouping for performance competition aircraft such as the Pitts. Many aircraft used in air shows and aerobatic competitions are certificated as experimental exhibition.

However, this may not work in all cases. Since the purpose of an experimental exhibition airworthiness certificate is to “exhibit” the aircraft, there must be a legitimate reason to exhibit it. Aerobatic competitions, air show work, air racing, sailplane competitions, and historical aircraft such as warbirds all have legitimate reasons for an exhibition certificate. Aircraft that do not have some legitimate reason for an exhibition certificate will not have this option available.

Q: I want to use Tri-Pacer wings in which I had to replace the spars and build new ribs, on a Wag-Aero Cub fuselage. Since the wings were certified wings, and the parts I used to rebuild them were certified parts, does any of that work apply to my “major portion?” Also, most of the fuselage tasks were done. According to the checklists, this could be a difficult thing to do, and I’d have to follow the checklists very carefully. Is that correct?

A: None of the work on the salvaged parts is credited toward the amateur’s major portion. So you would get zero credit for the wings, no matter how much work/repair you may have done. In order to qualify this project for an amateur-built airworthiness certificate you would have to be able to show that there were enough other fabrication and assembly tasks performed by amateur builders so that the amateur portion still is 51 percent or more of the total tasks. This may be difficult if enough prefabricated or salvaged components are used.

Q: Recognizing that an area operation restriction would apply, can I take an approved kit, have the majority of it done commercially, and certificate it in the experimental exhibition category? Can this be done with any homebuilt that fails the “major portion” rule?

A: There are clear requirements to be eligible for an experimental exhibition certificate that the aircraft would have to meet. It is not automatic that an aircraft would be eligible for an exhibition certificate. According to the FAA, valid exhibition purposes include organized air shows, organized air races, organized fly-in activities, organized exhibitions, youth education events, shopping mall/school/similar static displays, organized aerobatic competition, sailplane fly-ins or competitive races or meets, and movie or television productions. If the aircraft is not to be used for these types of exhibitions, it would not be eligible for an experimental exhibition airworthiness certificate.

To provide a better user experience, EAA uses cookies. To review EAA's data privacy policy or adjust your privacy settings please visit: Data and Privacy Policy.