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Thread: 51%

  1. #1

    Join Date
    Jul 2011
    Location
    Hillsboro, Oregon / USA
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    64

    51%

    How deep does the 51% rule apply?

    The issue is sub-assemblies? When is a buildable assembly a component? Is there a bright line the FAA uses? We make brake systems. We build ribs. We install radios and instruments. Yet we're not expected to raise our own trees, extrude aluminum, or make semiconductors. We are expected to use those materials intelligently.

    Instrumentation and avionics traditionally have been seen as components. But they don't need to be. If I wanted to provide a kit that enabled builders to make an (experimental) aneroid altimeter, would the 51% rule require the builder to construct the bellows? Would the labor involved add to or detract from the builder's "larger" 51% responsibility for the whole aircraft?

    How about software? When the rule was created software didn't really exist, at least not in its current form. If I wanted to make software available to builder-pilots for their experimental avionics, would they need to write 51% of the code?
    Richard Johnson, EAA #395588

  2. #2

    Join Date
    Aug 2011
    Location
    Rochester Hills, MI
    Posts
    2
    The 51% rule applies to TASKS, not EFFORT. If one of the tasks is drill a hole, and you drill one hole and others drill the rest, you still get 'credit' for doing that task. You need to get a copy of the latest 51% rule (recently revised). I'm sure it is explained somewhere on the EAA site (at least one would hope so :-)

  3. #3

    Join Date
    Jul 2011
    Location
    Tustin, CA
    Posts
    66

    51% Rule

    You need to get a copy of FAA Advisory Circular 20-27G and read it. There it describes the process of determining "51% rule" compliance, in other words whether of not a project is majority amateur built. I am sure the EAA has it somewhere or you can get it from the FAA web site.

    Items that do not have to be counted towards majority amateur built include paint, interior and avionics. For example if you buy a pre-wired instrument panel, you do not have to count that as commercial assistance, which would otherwise subtract from the amount of the plane that was amateur built.

    The easiest thing to do is get a kit that has been evaluated and approved by the NKET (National Kit Evaluation Team). Another fairly foolproof way to go is to build from plans with no or minimal commercial assistance. After that you need to look at each project on an individual basis.

    Dave Prizio

  4. #4

    Join Date
    Jul 2011
    Location
    Hillsboro, Oregon / USA
    Posts
    64
    Thanks! It's here: http://www.faa.gov/documentLibrary/m...C%2020-27G.pdf

    Is NKET part of the EAA?

    What I'm considering (very early idea stage at this point) is a glass-panel kit (including sensors, electronics hardware, wiring, etc.) for homebuilders. With open source hardware and software, and minimal purchases, a custom and very classy panel should be installable for a few thousand, as opposed to a few tens of thousands. Whether the idea takes off depends in part on what that circular says.

    Now, to RTFM ...
    Richard Johnson, EAA #395588

  5. #5

    Join Date
    Jul 2011
    Location
    Tustin, CA
    Posts
    66

    Nket

    The NKET National Kit Evaluation Team was set up by the FAA to evaluate amateur built aircraft kits. For more info you can use this link: http://www.faa.gov/documentLibrary/m...er/8130.35.pdf

    I am sure the EAA had input into the process, but this is a government organization.

    Dave Prizio

  6. #6

    Join Date
    Jul 2011
    Location
    Hillsboro, Oregon / USA
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    64
    Thanks again Dave. The circular is pretty clear. The rule is built around the key concept of "safe airframe." Seems very reasonable to me (for various definitions of how a federal agency can be reasonable.) Avionics and instruments are usually treated as necessary components. If the owner/builder constructs them, that has little (direct) bearing on the safety of the airframe--so long as they too are designed and built according to some documentable and documented "current best practice", with some proof that they won't go poof in the air (or if they do, how the fall-back position works.)

    Now to spend the next many, many years figuring it out, building a working system, finding people who want to play in the same sandbox, etc.
    Richard Johnson, EAA #395588

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