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Thread: Mystery Clamp?

  1. #1

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    Mystery Clamp?

    Given that the active builder community for my particular aircraft, an Acey Deucy, is basically ... just me, I will take the opportunity to use the larger EAA homebuilder community to ask the occasional question.

    I am compiling a list of parts for the aircraft. My focus now is on the wings. There is one part mentioned in the plans that draws no relevant results via web searches. I suspect it is a clamp: AN-520-836.
    (See accompanying image).

    Does that part number ring a bell with any of you more experienced builders?

    The need is for the securing of the aileron cable fairlead brackets, once they are positioned on the compression strut.

    Thank you,
    Mark Conover


  2. #2
    DaleB's Avatar
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    I think it's calling out AN520 screws to attach the split 4130 tubing base of the fairlead to the compression strut. The diagram seems to show the holes for the screws, with a centerline through each pair.
    Measure twice, cut once...
    scratch head, shrug, shim to fit.

  3. #3
    Sam Buchanan's Avatar
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    Yep, those 'clamps' are to be fabricated by the builder using tube stock and the drawing specifies the tube sizes.. The AN callout is for hardware to secure the clamps to the structure.
    Sam Buchanan
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  4. #4

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    Thank you, Dale.

  5. #5

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    I would think that, once the fairlead bracket assembly is positioned correctly on the compression strut, it could simply be welded in place.
    Any reason to think that, over time, the location of the bracket might need to change? I doubt that. But, I also have no experience with this type of airplane (only spam cans).

  6. #6
    Sam Buchanan's Avatar
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    That was my first thought but I wasn't sure if the compression strut was 4130 or aluminum. If steel the tube retaining the fairlead could be directly welded to the strut without the "clamp" tube. That was how the fairleads on my Legal Eagle were attached.
    Sam Buchanan
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  7. #7

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    Quote Originally Posted by Sam Buchanan View Post
    That was my first thought but I wasn't sure if the compression strut was 4130 or aluminum. If steel the tube retaining the fairlead could be directly welded to the strut without the "clamp" tube. That was how the fairleads on my Legal Eagle were attached.
    That particular compression strut is 4130. So, I do foresee just welding it in place.

    Thanks, Sam.

  8. #8
    Sam Buchanan's Avatar
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    Just make sure there isn't an assembly/disassembly sequence that would be complicated by having the fairleads attached permanently to the strut. If the strut has to be inserted through the hole in the spar that may be why the fairleads were designed to be removable.
    Last edited by Sam Buchanan; 04-23-2018 at 09:51 AM.
    Sam Buchanan
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  9. #9
    DaleB's Avatar
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    I don't know if there is any situation where you would want to remove the compression strut without disconnecting the cables. Also, if the cables have thimbles or swaged fittings on the end they're not coming back out through those fairleads without cutting the ends off and replacing the cables. If you weld it all up, something's not going to be reusable if it ever has to come apart again.
    Measure twice, cut once...
    scratch head, shrug, shim to fit.

  10. #10
    Sam Buchanan's Avatar
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    Quote Originally Posted by DaleB View Post
    I don't know if there is any situation where you would want to remove the compression strut without disconnecting the cables. Also, if the cables have thimbles or swaged fittings on the end they're not coming back out through those fairleads without cutting the ends off and replacing the cables. If you weld it all up, something's not going to be reusable if it ever has to come apart again.
    No, the fairleads are sized so that when they are removed from the tube in which they fit a cable fitting can be pulled through the tube. This makes it possible to remove or install an assembled cable after the fact. A smart person figured all this out many decades ago......
    Sam Buchanan
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