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Thread: 51 percent rule?

  1. #11
    Sam Buchanan's Avatar
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    Quote Originally Posted by DennisH View Post
    Thanks for all the replies. My main concern is the repairman certificate. I don't really care about the resale. I figure if someone doesn't want to buy it...well then...don't. I just want to be able to maintain it myself. It did have one of the older airworthiness certificates that had an expiration. I will look into that further.
    Thanks
    Dennis
    Dennis, there aren't any regulatory hurdles that would derail your project. As Ron stated, you can legally do ANY fabrication, modifications, repair and maintenance you wish without the Repairman's Certificate. The Repairman's Certificate is only needed to endorse the logbook following the Condition Inspection. If you can't get the certificate (I don't think you will have any problems getting it....) any A&P (AI not needed) can supervise the Condition Inspection and endorse the logbook. There are many A&P's who will work with you on this once they see you have an excellent knowledge of the aircraft.

    Enjoy!
    Sam Buchanan
    The RV Journal RV-6 build log
    Fokker D.VII semi-replica build log

  2. #12
    Eric Witherspoon's Avatar
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    I would recommend to all - go get AC 20-27G (from the FAA website), and fill in Appendix 8 - Aircraft Fabrication and Assembly Checklist.

    Even using a completely pre-built steel-tube fuselage, the builder could STILL complete >50% of the tasks in just the _Fuselage_. (Fabricate fuselage fuel system components, assemble ffsc, Fabricate fuselage covering or skin, assemble ffcos, Fabricate windshield, assemble ws to fuselage, for a small sample of the fuselage tasks that aren't fabrication/assembly of the airframe structure itself.)

    Tasks in the evaluation form are not proportional to time to accomplish or parts count!

    Even if the builder used pre-built control yokes/sticks, push-pull tubes / cables, brackets & fittings, cables, wire, and lines - there's still THE SAME QUANTITY AGAIN of tasks the builder can take credit for which consist of assembling any of those items _to_ the fuselage.

    Are you starting to see how kit vendors can sell things to the "fast build" levels that they do? Because in evaluating the list, roughly half the tasks are actually "making" the item, with another half of tasks consisting of fitting/assembling/attaching items to the airplane.

    So to Dennis' proposed project, he's got to build the wings, and then there's a task evaluation section for cockpit, landing gear, propulsion - each with dozens of tasks (on the evaluation sheet, hundreds if not thousands of tasks in the real world).

    Then there's _BUNCHES_ of stuff that doesn't count one way or the other - upholstery, paint, avionics wire harnesses, engine rebuild, making the prop, making the wheels, brakes, and instruments, rod ends, bearings, bolts, rivets, bell cranks, etc. ALL of that can be bought ready to bolt/rivet/bond on/in, and it doesn't count one way or the other for or against the "51%" determination. Though if you DO make a prop, you CAN count it, and if you DO build the engine, you CAN count it. But that's only 2 tasks (just for reference, I got a total of 151 tasks in evaluating my airplane, so if you're looking to up your percentage by building the engine, that really doesn't get you very far).

    If anything, Dennis needs to get the checklist and make his own evaluation - because about 1/3 of the tasks are in the tail. A big reason why many kits don't sell a "fast build" tail - they get 1/3 of the way to being a >51% kit by just leaving you with that brief portion of the project!

    The 51% evaluation has NOTHING to do with time OR parts count. If it did, we'd be spending years making our own rivets! (Or composite, fabric-covered welded steel tube, or wood designs would be a LOT more popular...)

    There would be how-to articles about mass-producing your own rivets, your own bolts, your own washers, self-locking nuts - sounds pretty far-out, doesn't it? But it's how the rules are written...
    Murphy's 13th: Every solution breeds new problems...

    http://www.spoonworld.com

  3. #13

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    Eric is right, don't listen to Bill or others and their "opinions" there in no rule stating you can't use previous flying parts, otherwise no Breezy would have ever been built,(certified wing parts usually) you can even use a previous certified fuselage for your build as in a swick t-craft experimental. The FAA in this case is more reasonable than your fellow builders/aviators. AC 20-27G and the associated checklist is your guide. I just went down this road, and alot of builders will tell you straight out crap because they did it some other way and they think you should do the same.... thank God they aren't making the rules! Happy building!

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