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Skylight Wing Former Attach

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  • Skylight Wing Former Attach

    Looking at examples I see many builders are bolting their skylight through the top wing formers on the fuselage. This is simple enough, but I'm concerned about water intrusion into that steel tube. I'd rather not give a path into steel structure that is then hidden from view. Has this been a concern for anyone else?
    Dave B.
    Plane Grips Co.
    www.planegrips.com

  • #2
    Bueller...
    Dave B.
    Plane Grips Co.
    www.planegrips.com

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    • #3
      Not exactly the same as I used Piper C channel for mine but.....

      The holes in the Plexi/Lexan need to be drilled oversize to allow some movement. I filled each of these holes with RTV and put the overlying trim strip on and installed the screws while the RTV was still "wet". This should do an OK job of sealing the screws at install.

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      • #4
        Originally posted by BTAZ View Post
        Not exactly the same as I used Piper C channel for mine but.....

        The holes in the Plexi/Lexan need to be drilled oversize to allow some movement. I filled each of these holes with RTV and put the overlying trim strip on and installed the screws while the RTV was still "wet". This should do an OK job of sealing the screws at install.
        I was wondering if it were easier to just do that. Glad to hear someone's already done it. Alternatively I was considering something like the photo I've attached, bolted to the side of the former, weight penalty of course but would ensure the structure is protected. There seems to be enough room.
        You do not have permission to view this gallery.
        This gallery has 2 photos.
        Dave B.
        Plane Grips Co.
        www.planegrips.com

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        • #5
          Well, mine is a C channel so it can't trap water while I expect your concern is trapping water inside the tube. That might be addressed with the RTV on the screws like I used but hard to guarantee for years.

          Perhaps a "Belt and suspenders" approach would be the RTV as discussed plus nylon or rubber washers under the screw heads to provide a second level of sealing.

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          • #6
            Should drill some weep holes in the lowest points at the tube ends to prevent any water build up. If you are in a climate that gets below freezing where water could accumulate then it will freeze to split the tube. Drill some 1/8 " holes at intervals that would allow a person to spray in Corrosion X and apply the Corrosion X after the fuselage has been painted so it will not interfere with the paint process. The tube is more for shape and is not structural but still would be a PIA to fix if it should rust out. Take all the precautions with the fastening to keep water out.
            Last edited by Glenn Patterson; 02-04-2018, 10:27 AM.

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            • #7
              We did not go with the skylight and sometimes wish we had. We drilled the holes & secured the lexan windshield.. Then we took the screws out & drilled the holes oversized on the windshield and installed bushings cut from soft poly tubing to keep the holes centered, The poly keeps the metal from contacting the screws to act as a cushion with some give for expansion and contraction. It is supposed to be one way of protecting the windshield from mounting stresses. Perhaps use the bushings and put sealant under the screws weather. Steel roofing uses screws with rubber washers so perhaps consider getting some of the washers from roofing screws to go under your screws or cut some from some neoprene.

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              • #8
                I think Motorcycles use well nuts to secure the plexiglass wind fairing to its frame.
                Brooks Cone
                Southeast Michigan
                Patrol #303, Kit build

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                • #9
                  Originally posted by Bcone1381 View Post
                  I think Motorcycles use well nuts to secure the plexiglass wind fairing to its frame.
                  https://en.wikipedia.org/wiki/Well_nut
                  I’ve seen these discussed before here: https://bearhawkforums.com/forum/bea...0958#post20958

                  I would tend to agree it’s probably not the best to use them in tension.
                  Dave B.
                  Plane Grips Co.
                  www.planegrips.com

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                  • #10
                    delete...............
                    Last edited by bearhawk2015; 05-24-2019, 04:48 PM.

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                    • #11
                      Originally posted by bearhawk2015 View Post
                      Archer39J, I did mine like your talking about in your pictures. It keeps moisture from going in the tubes but I wish I hadn’t done it that way because it pretty much illuminates being able to get your hand in there from the top, making it more difficult to put the wing bolts in, work on fuel lines, attach flap cable, etc.
                      That’s a good point. I think I’m back to just sealing the holes in the former really well. It shouldn’t be too bad even if I have to disassemble some day.
                      Dave B.
                      Plane Grips Co.
                      www.planegrips.com

                      Comment

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