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Thread: aileron flutter !!!! help !!!

  1. #21
    Senior Member
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    Default Re: aileron flutter !!!! help !!!

    Mike,

    I'd be concerned about flying it too! And you may also have more than one issue. You purchased this used and haven't provided much history information. Lets start from the beginning. I recall, you bought this about 8 months ago.

    What have you inspected, adjusted, replaced, serviced since you bought it?

    Did it have any issues in your pre-purchase flight/inspection?

    Did the previous owner have any known issues with it?

    Was he/she also the builder?

    How many hours total on the aircraft? How many hours prior to your purchase?

    Was the engine a new install or used from another aircraft?

    Are the log books complete and has all maintenance been performed?

    How long did it sit without being run or flown?

    I do have a point here, but need to know the history to go into detail.

  2. #22

    Default Re: aileron flutter !!!! help !!!

    Hi . Right well . Since owning it . All I did was tweak the wing incidence a bit , as the previous owner/builder flew from the right seat . so it had a turn to the left . Apaft from that it's been fine since I owned it , all I can see is a very slight bit of play in the wing root nylon pieces . That stop the flapperons from flexing . When the stick is fixed . I can manually flex each flapperon maybe 12mm each way . The linkages seem ok . But the gap in nylon (1 bit in turtle deck each side) seems to be the cause of the flex . Any ideas ?

  3. #23

    Default Re: aileron flutter !!!! help !!!

    Just to confirm . The nylon plates ( or whatever the correct name ? ) that sandwich the main control arm of each flapperon at wing root . That is where there should be no play ? There's a tiny bit on each side of mine . Maybe that's enough to cause flutter ? I did cut a small amount away when I first bought the plane , as the flapperons would snag as I folded the wings ! Never had any flutter or violent shuddering though ? Until now !

  4. #24
    Super Moderator Av8r3400's Avatar
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    Default Re: aileron flutter !!!! help !!!

    Those nylon pieces are what I refer to as the "Turtledeck Bearings" and they are super mission critical. I know of several instances where flexing of the flapperons from loose turtleneck bearings on early Kitfoxes (1-3) will induce aileron flutter.

    12mm is nearly 1/2" which in my mind is an extreme amount of flex. These bearings should be snug to the flapperon horns not allowing any flex, while not binding the rotational motion of the horns.

    You definitely need to repair this.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
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  5. #25
    Super Moderator Av8r3400's Avatar
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    Default Re: aileron flutter !!!! help !!!

    The lower half of these bearings is usually mounted on a hinge or is removable in order give clearance to fold the wings.

    The upper half is mounted to the turtledeck and is removed for the folding process.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
    YouTube Videos

  6. #26
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    Default Re: aileron flutter !!!! help !!!

    Mike, I'd love to help, but to be blunt, you've only answered one question of my many. Rather than me spend a lot of time writing a book of "what ifs" it would be more effective if you'd help the cause, so we can narrow it down. You could possibly have more than one issue.

    Besides the other questions, here's a couple more (and I'll probably have a few more):

    Why did the previous owner fly it from the right side?

    Was the Jab 2200 the original engine on this aircraft?

    Greg

  7. #27
    Senior Member Peteohms's Avatar
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    Leander, TX Hangared @ KGTU
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    Default Re: aileron flutter !!!! help !!!

    When I bought my Kitfox 3-912, the "Hatchback bearing's were worn and cracked. They were really not functional. I flew that way for probably 50 hrs with no indication of any problem. Eventually I made new ones. I noticed no difference. I have more than 650 hours flying my Kitfox. I'm not saying don't replace the bearings, just that they made no difference in my plane.
    Pete
    Leander, TX
    Model III SN 1000
    912
    Grove

  8. #28

    Default Re: aileron flutter !!!! help !!!

    Thankyou av8 . Most appreciated . & I'll get onto that asap .
    Danzer . I'm sorry but I only have a mobile phone to use internet & it's not easy to read , remember & reply to lots of questions .
    The previous owner/builder sat on the right as he was used to having a throttle on the left . The only changes I made was tweak the incidence due to a left turn. & move the elevator trim from right side to left . The jab engine was not original . It started with a 582 , the plane has done 350 hours . The jab was zero houred . Dr built & installed & has now done 60 hrs . & runs very well . The plane is 20 years old , I'm 2nd owner . Log book complete & I assume aircraft maintained ? & I hadn't flown it for 4 months but have ran the engine every few weeks .

  9. #29
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    Default Re: aileron flutter !!!! help !!!

    Mike - as I suspected! One more question and then I'll give you my thoughts.

    What propeller is on it? What length? And has it ever been electronically "balanced"? Okay that's 3 questions.

    Greg

  10. #30

    Default Re: aileron flutter !!!! help !!!

    Hi Greg , right well the prop is a 1 off . The previous owner/builder had it made for him . I believe it's fairly fine pitch so he could get out a short strip easier . It's I believe 60" but don't know the pitch . & I balanced it myself recently . Thankyou for your help
    Mike

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