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51% Rule

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Well-Known Member
Sep 6, 2006
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About the 51% rule. I refer you to the check list FAA form 8000-38 in AC 20-139. AC 20-139 is titled Commercial Assistance during Construction of Amateur Built Aircraft. This check list is on line since the FAA has had the GPO stop printing the book "Amateur Built Aircraft Referance Manual." Much cheeper to have the book down loaded by the user than spend tax payers dollars to print the manual. Cost savings measure. Reading the check list you are going to find much wiggle room. Understand when the you get to the point where the plane in on the gear and covered but not yet painted you have reached the magical 25% mark in the building process. There is still much to be done. The installation of all the system that you desire in you bird. Then paint, engine installation, rigging. Though this part of build can go quickly, more that likly than not, your plane at this point of construction is going to fly by you the builder.
What the Fed's are trying to do is crack down on owners of kits that are very busy in their livelyhood to have a "hired gun" build their plane. The intention of the 51% rule is so you the builder can learn about the process of building. Not to pay someone else to do the learning for you. How equitable is it to you, the one who spent a few thousand hours of time building as to the one who just wrote checks and has the same certifcation under the rules as you do? Hmm...
Anyone who builds from scratch will have no worries about the 51% rule. Take care, Erich

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