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Thread: Boot Cowl Piano Hinge

  1. #1
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    Default Boot Cowl Piano Hinge

    Mitch,

    As discussed earlier today, here’s a progress report on my boot cowl piano hinge installation.

    I am using the same piano hinge that Van uses on RV-4 and RV-7 between the fuselage and the fiberglass cowl ( I know because I’ve built both of these airplanes). The piano hinge is listed in Van’s catalog with the old AN number AN257-P4. The hinge is listed in Wicks and Aircraft Spruce catalogs with the new MS number MS20257P4. These are the rolled hinges, not the extruded ones. I used this hinge because I had enough of it on hand to do the job. You could also use MS20001P4 which is the “closed” extruded version of the same hinge. All of these hinges have an open width of 1.5 inches (that’s a complete hinge with the wire holding the two halves together). Some of these hinges are supplied with aluminum hinge wire. Van recommends replacing the aluminum wire with stainless wire. The diameter of the wire used in these hinges is 0.118” Stainless piano hinge wire is available from the three suppliers previously mentioned.

    A special note about using piano hinges in places where it must follow a curve: It may be necessary to file a bevel on the hinge loops so they will fit together around the curve. Also, if the curve is severe enough, as it was on the RV-4 and the RV-7, you may need to install a smaller diameter wire, 0.089” It helps to grind a beveled point on the tip of the wire so you can push it through the hinge loops without catching on the edge of a loop.

    Attached is a photo of my boot cowl on the fuselage with the piano hinge installed. I used a spacer between the hinge and the boot cowl same Cub Crafters dose when they use a screw plate. You can see where I have used four sections of piano hinge. At the seam on top of the boot cowl there is a space between the two top hinge sections. This is where I intend to put an access opening in the top carbon fiber engine cowl. This access opening will be about 2.5” wide and 1” wide held in place by two screws. With the access plate removed, you will be able to insert or remove the wires that attach the top engine cowl to the boot cowl. At the left and right side of the boot cowl you will see a gap in the piano hinges. This is where the joint between the top and bottom halves of the engine cowl meet the boot cowl. I am not giving you the dimensions of this yet because I think they can refined for a better fit after my installation is completed. Okay, mine will be what it is, but the next one could perhaps be a little better.

    More to follow…..

    When I have it done I’ll write a complete explanation.

    BTW…I did receive the engine cowl without any screw holes, just the way I asked for it.

    Dennis

    Boot Cowl 1.jpg

  2. #2
    Administrator Pete D's Avatar
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    Default Re: Boot Cowl Piano Hinge

    I like it! Really interested to see how it comes out and how hard it is to remove/install the cowling.
    Pete Dougherty
    Customer Support Manager
    Cub Crafters Inc

  3. #3
    Senior Member Dan L's Avatar
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    Default Re: Boot Cowl Piano Hinge

    So Dennis is the idea that you'll pull a couple of flexible pins to remove the engine cowl from the boot cowl rather than the furnished screws?

    I used quarter turn Southco fasteners rather than the screws where the cowl halves attach.
    Flying Carbon Cub EX #11 since 2011

  4. #4
    Senior Member EVRoosevelt's Avatar
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    Default Re: Boot Cowl Piano Hinge

    Dan:
    What size Southco did you use do you remember the part #? I might try that on #3.
    Thanks
    EV

  5. #5
    Senior Member Dan L's Avatar
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    Default Re: Boot Cowl Piano Hinge

    Hi EV,

    The little ones, #82's on the boot cowl. I used the bigger ones, #85's on my extended baggage door. And I used wing head #82's on my oil door. I used the cupped plastic washers under all of them too.
    Flying Carbon Cub EX #11 since 2011

  6. #6
    Senior Member EVRoosevelt's Avatar
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    Default Re: Boot Cowl Piano Hinge

    Did you use the flush or oval ones and do you remember the length?
    Thanks
    EV

  7. #7
    Senior Member Dan L's Avatar
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    Default Re: Boot Cowl Piano Hinge

    Quote Originally Posted by EVRoosevelt View Post
    Did you use the flush or oval ones and do you remember the length?
    Thanks
    EV
    Oval head with the cupped washer under the head. The length varied but I think an average would be about 160's.
    Flying Carbon Cub EX #11 since 2011

  8. #8
    Senior Member stede52's Avatar
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    Default Re: Boot Cowl Piano Hinge

    MilSpec Fasteners also has some very nice flush mount adjustable camlocs that can't be found else where: http://www.milspecproducts.com/index.html#menu. I've used the 2800 series on my Highlander cowlings they also have a heavier duty 4000 series that I'll be looking at for my CC.

    Steve D

  9. #9
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    Default Re: Boot Cowl Piano Hinge

    Quote Originally Posted by Dan L View Post
    So Dennis is the idea that you'll pull a couple of flexible pins to remove the engine cowl from the boot cowl rather than the furnished screws?

    I used quarter turn Southco fasteners rather than the screws where the cowl halves attach.
    The quarter turn Southco fasteners are certainly an improvement over the screws (because there are soooo many screws!). There will be four wires to pull, but there will also be about ten screws. The screws are needed to hold the engine cowl together at the front near the spinner (2), to hold the cover in place where one gets at the two wires holding the top cowl in place (2), screws to hold the covers over the end of the wires that hold the top and bottom helves of the cowl together, at the front of the cowl (4), and probably a screw at each side of the cowl at the intersection between the top, bottom, and boot cowl (2).

  10. #10
    Member gderamel's Avatar
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    Default Re: Boot Cowl Piano Hinge

    Quote Originally Posted by Dan L View Post
    Hi EV,

    The little ones, #82's on the boot cowl. I used the bigger ones, #85's on my extended baggage door. And I used wing head #82's on my oil door. I used the cupped plastic washers under all of them too.
    Dan,

    With the SOUTHCO DZUS® Lion Quarter-Turn Fasteners, which recepticle(s) did you choose?



    the Flat Rivet-On?
    recflatrivetbase.jpg


    or the Vibration Isolating?
    recvibrationiso.jpg

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