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Thread: stabilizer tail brace rod ends lash

  1. #1

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    Default stabilizer tail brace rod ends lash

    On my Kitfox 5 vixen, I have changed the rod end and nuts/bolts on both stabilizer tail brace because they where old and they do have some lash even after the bolts were checked.

    All was ok on ground but after 20' of flight, there is some lash again with bolts checked.

    Is it normal?
    On the wings, rod ends do not have this lash.


    I have seen since I bought this plane that during initial climb, the stabilizer leading edge is vibrating. Is it a "normal" happening?

    I have send an email to John, but he is not at work until june 20th.

  2. #2
    Senior Member Dave S's Avatar
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    Default Re: stabilizer tail brace rod ends lash

    I have a series 7 - fuselage is the same as the 5 but with a different trim mechanism - I believe yours would have the electric trimmable horizontal stabilizer - ours has a fixed horizontal stabilizer with trim tabs on the elevator. I think the horizontal stabilizer side struts and rod ends are the same for both the 5 & 7.

    Have you checked to see if there is any play in the horizontal stabilizer trim mechanism which may be responsible for the vibration?

    In any case, I cannot see where the vibration you are describing is normal - all of my rod ends are tight - no slop.

    Sincerely,

    Dave S
    KF7 Trigear
    912ULS/Warp drive

  3. #3
    Senior Member Dave S's Avatar
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    Default Re: stabilizer tail brace rod ends lash

    another thing you can check on which I didn't mention earlier - make sure the bolts going through the rod ends are not bottoming out on the threads and leaving the rod ends a little loose- in other words - make sure the bolts are the right length.

  4. #4
    Senior Member Dorsal's Avatar
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    Default Re: stabilizer tail brace rod ends lash

    can you give a better description of the lash, how much play at the end of the stabilizer? how would you describe the vibration, can you feel it? what does it look like?
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  5. #5
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    Default Re: stabilizer tail brace rod ends lash

    Make sure the slider blocks that slide on the square tube at the leading edge of the horizontal stab are snug against the tube .

  6. #6

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    Default

    Thanks for your answers.

    It is an electrim trim.

    I will check for the length of the bolts, but it seems that there is no lash on the bolts but on the rod end itself. The fact is that they are new!

    The stab is vibrating just during initial climb and decrease rapidly when in cruse. I can feel it, but very light. I can see it looking at the turtledeck. It is only on the left side, not realy on the right side.

    Ther is around 1/4 to 1/2 inch play at the end of the stab, but only on the left one, just 1/4 on the right.

    I will check if the slider blocks that slide on the square tube at the leading edge of the horizontal stab are snug against the tube.

    I saw this :

    http://www.teamkitfox.com/Forums/showthread.php?p=1025


    what was the solution for those who had the same problem?

  7. #7
    Senior Member
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    Default Re: stabilizer tail brace rod ends lash

    I did two things to firm up the any play in the horizontal stab. As I mentioned in a previous post, make sure your slider blocks are firm against the square post that they travel on and 2) I replaced my rod ends for the struts. I found with my plane they only last for about 100 hrs of flying before the play returns so they will be replaced at each annual. The play is exhibited when I grab the end of the horizontal stab and wiggle it during preflight. A slight amount of play is detected. Bruce

  8. #8
    wadeg's Avatar
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    Default Re: stabilizer tail brace rod ends lash

    I too have chronic last on my left stab strut rod end bearing. Not much but perhaps 1/8"-1/4" vertical play on the left side. Wondering if the mystery has been solved and if the higher end rod end bearings fit and resolve it.

  9. #9
    Senior Member jtpitkin06's Avatar
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    Default Re: stabilizer tail brace rod ends lash

    Perhaps a bit of preload would help here. There is normally a down force on the tail so preloading the braces with a slight upload might take out the vibration. Back the rod ends out enough to make the stab nice and tight without putting too much up bend in the spar.

    A slight up bend in the spar is probably OK because it will balance out in flight to near zero.

    By preloading the stab you add a level of stiffness and may be able to eliminate the shakes.



    John Pitkin
    Greenville, TX

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