Ask the DAR

The 51% rule, data plates and rebuilding.


Question: My question is probably one to which you cannot provide a definitive answer, but since the designer and kit providers didn’t respond, I would like your opinion. My interest in a CX-4 was initiated when I first saw one at Sun ‘n Fun. Recent magazine coverage and the Internet indicate there are kits available, but they are available from different people and, apparently, not representative of an FAA-approved 51% kit.

Some years ago there were T-18 builders who took advantage of different commercially available components from various providers to complete their projects. When it came time to get FAA approval, it was reportedly denied because the builder had not completed the necessary percentage of the construction. I am concerned that building a CX-4 and taking advantage of the advertised kits may put me in the same difficulty—that the sum of the purchased parts may exceed the limit allowed by the FAA.

Answer: Thank you for your question. The answer is really quite simple. A kit aircraft does not have to be listed as approved by the FAA to qualify under the 51% rule.

If it is not on the list, however, it will be your responsibility to show that the “major portion” rule is met. You will need to gather the information from the various “partial kit” suppliers and evaluate the amount of fabrication and assembly provided.

This is accomplished by filling out the AMATEUR-BUILT AIRCRAFT FABRICATION AND ASSEMBLY CHECKLIST (2009) (FIXED WING), which can be found in AC 20-27G, Appendix 8.

Fill out the checklist according to the instructions found on pages 8-10 to 8-11. The result will tell you if your aircraft meets the major portion rule.

You are to be commended for researching this issue ahead of time. There are many people who do not do this kind of investigation and find themselves painted into a corner with no way out.

Question: The EAA Certification Guide says the builder should be on the data plate and must match the registration, but an online post [] says to list Van’s Aircraft, Inc. on my RV-9.

Answer: Vans Aircraft, Inc. only goes on the RV-12 if it’s certificated as an ELSA. All aircraft certified as EAB must have the builder listed. This also applies to the aircraft registration.

Question: I have an Experimental aircraft that has not yet flown off the test hours, but was damaged in a landing accident. I am interested in selling it as rebuildable salvage. Could a new owner continue to fly off the hours? Who would have to sign off the flight-test hours? I think that if the new owner did the rebuild, they might qualify under the 51% rule and re-register in their name. Would this be the DAR’s call?

Answer: Anyone can rebuild, and anyone qualified to fly the aircraft may do the flight testing. The new owner would not be qualified for the Repairman Certificate; only the original builder would. Rebuilding doesn’t count toward the construction and assembly. The aircraft could be re-registered by a new owner, but the “builder” will remain the same. That can never change.

Please send your questions for DAR Asberry to [email protected] with “Ask the DAR” in the subject line.


  1. Vic, Another issue with selling an E-A/B after being issued an AWC but still in Phase 1 is the Ops Limits geographic flight test area. If new owner wants to complete the Phase 1 outside the area listed on the original Op Limits, then another Op Limit document will need to be issued. Naturally this will lead to another set of questions.


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