Ask the DAR

Service bulletin compliance, buying an aircraft with uncompleted flight testing.


Recently there has been what seems like a rash of service bulletins within the Experimental/Amateur-Built aircraft community. The forums and vendor sites have been buzzing. There are questions asking, “Do I really have to comply exactly as the kit manufacturer specifies?”

“Can there be an alternate method of compliance?”

“Do I even have to comply at all?”

Well, the bottom line answer is no! Service bulletins are not mandatory, even in the Part 91 certified world. The only thing that is truly mandatory is an airworthiness directive. And an airworthiness directive cannot be issued against an amateur-built aircraft.

Now, before you jump up and start sending emails on the “ADs can’t be directed to amateur-built aircraft” subject, keep this in mind: ADs may be directed to certain components of amateur-built aircraft, just not the aircraft itself. Remember, amateur-builders are pretty much left to themselves as far as design and construction. But that’s another article.

Here we are talking about service bulletins. Just because you don’t have to comply doesn’t mean you shouldn’t. Service bulletins are issued because of a problem in the field. For example, if the main spar of your horizontal stabilizer is cracked, it needs to be repaired. Period! Under normal circumstances, the kit manufacturer has investigated the problem and has come up with a reasonable solution. The service bulletin will reflect that solution. Can you come up with your own solution? Of course. But keep in mind that the designer of the aircraft, usually associated with the kit manufacturer, probably knows more about the design characteristics of the aircraft than you do. If you think you have a better method of compliance, it might be worthwhile to submit your solution to the kit manufacturer. He will then either approve of your method, tell you why it is not acceptable, or tell you, “It’s up to you, but we have tested our solution and think it is better.” The latter is more likely to happen.

Now, one more thing to consider. When you, or whoever does your annual condition inspection, make that logbook entry stating that, “I find this aircraft to be in a condition for safe operation,” do you feel comfortable making that statement if there is an outstanding service bulletin? In other words, in case of an accident, would you be comfortable explaining to a judge why you knew better than the aircraft designer?

Regardless, the final decision is yours. Make sure you are comfortable with it!

Question: I want to purchase a completed aircraft that already has its airworthiness certificate. The builder began, but did not complete, the flight test program, and the airplane has sat for several years. Will I need another complete inspection by a local DAR if I restart a test program? There have been no major or structural changes to the airplane since the initial airworthiness issuance.

Answer: There should be no reason to need a DAR inspection on this aircraft. You can simply continue the phase I test program started by the original owner. If you have moved the aircraft from the original location, you will need to have the operating limitations amended to show the new location for phase I flight testing. Other than that, you should be good to go.

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

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Mel Asberry
Mel Asberry is an experienced Designated Airworthiness Representative specializing in Experimental/Amateur-Built aircraft. He and his wife, Ann, have built seven amateur-built airplanes including two ultralight types, a Moni Motorglider, a Dragonfly Mk2, two RV-6s and a Zenair CH 601HDS. They are currently building a scratch-built biplane.


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