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Thread: vortex generators and the FAA

  1. #1

    Join Date
    Nov 2014
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    Gainesville, tx
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    Default vortex generators and the FAA

    Asked over on the avid site as well. I have an avid flyer and I put vortex generators on. My ops limits state that any major change I need to notify the cognizant FAA office and get their response in writing prior to flight. Well I contacted the FAA and have been less than reasurred. I have gotten anywhere from "its experimental so do what you want just be careful" or call such and such and he would never answer his phone. I called a DAR that was recomended by an faa guy and he said any inspector could help me. Well the inspector I called today in his 3 yrs with the faa he had never heard of something like this. He did say he would find out, but after saying I would have to have it evaluated and all kinds of math to figure out the possible effects on flight all while saying he has no idea who to have that done. So any ideas on what I need to tell the FAA? I am trying to get legal prior to my condition inspection. Or am I being overly concerned by this? I would suspect a a+p would see vgs and go hmm if there is no mention in log books, but I have never had a plane inspected. Thanks Mark Whiddon

  2. #2
    Senior Member
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    Default Re: vortex generators and the FAA

    "Do what you want" is the correct answer. VG's are not a major change, like changing from a 6.00 tire to an 8.50. No big deal. A major change would be something like changing engine types or changing to a different wing type, where you're supposed to contact a DAR and you'd probable be required to fly off a certain amount of hours in test phase. My opinion, it's always best to not ask questions from the FAA. The less, the better. You probably won't get the same answer twice. It's like when I asked my airport FBO manager about landing on the grass. Her answer, "better not ask, just do it and if anyone complains, deal with it then." So far, no complaints. James Thomas

  3. #3

    Join Date
    Nov 2014
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    Gainesville, tx
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    Default Re: vortex generators and the FAA

    Well ordinarily I would agree because the only other time I have called the FAA I got similar results. I have just never had a plane go through a condition inspection. Have I screwed up? will the a+p call the faa if I just don't mention it and bring the plane in for inspection with nothing in the books?
    Mark

  4. #4
    Senior Member rv9ralph's Avatar
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    Aug 2014
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    Greenleaf, ID
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    Default Re: vortex generators and the FAA

    My operating limitations on my KF3, issued in 1993, state: "Any major change to this aircraft, as defined by FAR 21.93, invalidates the Special Airworthiness Certificate issued for this aircraft."

    So, the definition of "Major Change" is defined as a negative in the wording below, as in if it isn't a minor change as we define here, it must be a major change.
    You be the judge as to how your changes fit.

    § 21.93 Classification of changes in type design.
    (a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” (except as provided in paragraph (b) of this section).

    Ralph

  5. #5
    N981MS's Avatar
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    Dec 2012
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    Default Re: vortex generators and the FAA

    RV9RALPH I think is on the right page. Major vs minor is up to interpretation. Unfortunately, the only interpretation that will matter is upon an unlikely future FAA or NTSB investigation. As you have determined some of the "authorities" are not on the same or correct page.

    I believe VGs are a major change in that they change the flight characteristics. Otherwise why use them. But it does not matter what I think. I am not the FAA.

    Here is what I would do. Call the FSDO tell them what you did and you plan to put the plane back in phase I for x number of hours within 25 miles of your home base. You will test at fore and aft cg and document in the log book any findings. If you have a reasonable plan and sound like you know what you are doing they will likely take your name and N number and say go ahead and have a nice day. It worked for me.
    Maxwell Duke

    Kitfox S6 IO-240 Built it (Flying since 2003)
    Maule M7-235C Sold it (liked it though)
    RV-10 IO-540 Bought it
    Zenith CH-750 Built with 7 friends (DAR Vic Syracuse)

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