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Thread: Wing and tail mounting hardware questions

  1. #1
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    Default Wing and tail mounting hardware questions

    My A&P friend noticed surface corrosion on the wing and tail mounting hardware on his first quick walkaround when I first bought my Mod IV. So I've got hardware to change! As I'm not the original builder I have none of the original plans or parts list. I'm assuming the wing strut bolts, top and bottom, are close tolerance. And at a casual glance, the upper strut bolt and nut look impossible to change as they are half hidden in the wing covering. And then I start wondering about the proper torque. And then that leads me to wonder about the mounting hardware at the leading edge. It came with castle nuts and safety pins. Is that normal?
    Thanks,
    Jay

  2. #2
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    Default Re: Wing and tail mounting hardware questions

    I used self locking nuts, but the bolts are loaded in double shear, so the joints do not need alot of clamping force.

  3. #3
    Senior Member HighWing's Avatar
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    Default Re: Wing and tail mounting hardware questions

    Agree with mr bill. Bolts are AN bolts. I routinely purchase from Aircraft Spruce. On the wing struts with one end of the bolt buried in fabric, I took a wrench and ground it down so it could be pushed under the fabric to minimize pressure on the fabric. A "T" made of 2X2s to support the wing during replacement.
    Lowell Fitt
    Goodyear, AZ


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  4. #4
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    Default Re: Wing and tail mounting hardware questions

    Quote Originally Posted by mr bill View Post
    I used self locking nuts, but the bolts are loaded in double shear, so the joints do not need alot of clamping force.
    Are you referring to the leading edge bolts?
    jay

  5. #5
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    Default Re: Wing and tail mounting hardware questions

    Quote Originally Posted by HighWing View Post
    Agree with mr bill. Bolts are AN bolts. I routinely purchase from Aircraft Spruce. On the wing struts with one end of the bolt buried in fabric, I took a wrench and ground it down so it could be pushed under the fabric to minimize pressure on the fabric. A "T" made of 2X2s to support the wing during replacement.
    Any idea what torque they call for?
    thx,
    jay

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Wing and tail mounting hardware questions

    All this is in the assembly manual.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7
    Senior Member jiott's Avatar
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    Default Re: Wing and tail mounting hardware questions

    As just a general friendly piece of advice, I would strongly encourage anyone who buys a project Kitfox, whether its major or minor repairs, to immediately buy the appropriate assembly manual from Kitfox. Spend the $50 or whatever to get the authentic information; after all you are going to be spending probably thousands of dollars to get it running. Are you going to trust some yahoo like me to give you a torque value or a hardware spec on an item that your life may very well depend on? I have seen much bogus information go out on this forum over the years; 99.5% of it is good info but get the proper bible to be sure.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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    Default Re: Wing and tail mounting hardware questions

    It really is a good investment.

  9. #9
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    Default Re: Wing and tail mounting hardware questions

    Of course you are correct Jim. I pulled the build manual out and started thumbing through the pages. It's not a very easy read to find the info, but I did find some of the info I was looking for. I did find the upper wing strut attaching hardware, but no info on how to torque a half hidden nut. Hmm. I'll keep looking but I don't have and extended crows foot. I did find the tail info in the fuselage section, one page, and it looks like the hiem joint on the V strut support is a female thread. Laying under the tail I thought it was male. Hmm, may need new V struts. Yikes! Wife is going to be upset!

    P.S. Have they improved the manual from 25 years ago?

  10. #10
    Senior Member jiott's Avatar
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    Default Re: Wing and tail mounting hardware questions

    Yes, I hear that the manual keeps improving over the years. I can only speak to the SS7 manual which in my opinion is excellent. A torque value for nearly every bolt is given; however, for the few that are not individually called out, the manual says to use the standard torque tables given, I believe, in the "Builder's Tips" section. Its good that you are trying to find the correct info. I know a guy who was just winging it and actually broke a bolt from overtorque in a critical area. Its a good thing the bolt actually broke so he could replace it, rather than an invisible overstress that would break later.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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