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Thread: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

  1. #1
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    Default Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    The last revision of the EX2 construction manual predates this SB.

    It is unfortunate that there is no mention anywhere that the SB is available on the website.
    Without Ricks wise advice, Id pass by.

    My question: Do we need to replace all these AN470 rivets by Cherry Max from the construction stage, or are the 470 acceptable ?

    Y.

  2. #2
    Senior Member TroyBranch's Avatar
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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Curious on what others say but my opinion is the solid rivets are fine. It is just a matter of continually checking for security of the bracket. If the bracket is loose you will need to replace with cherry rivets as you could not buck through the hole. My guess is this is a forever inspection and the new rivets could get loose as well over time? Solid rivets are better than cherry IMO.


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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Thank you Troy !

    If the solid rivets are better than Cherry Max than you are fully right.

    How can I objectively argue that the solids are better?
    Do you know any comparative document?

    Yves

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    Senior Member TroyBranch's Avatar
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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Did some research and Cherry's are better. So I would think we need to continually inspect and change if we see an issue? If you are building, I would use Cherry's. Hopefully someone can confirm. Cherry have a smaller bulge on the end so I still think a solid is better in tension in thin material. This situation is not "thin" material though.

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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    There was a lot of discussion on this over on SuperCub.org.(New SB out (supercub.org) Someone had ground looped a CC and tore the jury strut off. But the SB came up. Doesn't provide a definitive answer just a little more information.

    I vaguely recall installing the brackets on my EX-2, I believe I didn't like the length of rivet called out and went with a longer solid AN470 (SB was not out yet). I had built a RV-7 so pretty familiar with riveting.

    Now if I was building I can't say which rivet I would use. Cherry's are stronger in shear, but each has it's application. They obviously went with a pull rivet on the SB for ease of installation.

    Rumor has it that some of the planes, which I believe is a small population were always moved around using the struts. This put fore and aft loads on the struts. Just FYI: plane in SuperCub thread was a FX factory built (yes I know, builder assist).

    After 200hrs my struts are solid.
    Last edited by aeroaddict; 04-30-2021 at 08:15 AM.
    Dan Arnold
    KEUL

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    Senior Member ceslaw's Avatar
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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Two observations

    1. If cherry max was better, wouldn't CC be using them in the original build?

    2. Would it be advisable to add another rivet or two while during the initial build?

    I am at a point building an EX2 where it would be easy to make for foregoing mods, if warranted.

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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    My opinion to your suggestion is that CC does use modern engineering modeling and stress analysis for design. And develops their manufacturing processes to meet those requirements.

    Now CC cannot foresee what or how a customer might use their product. If my statement above is true; moving the plane around with the struts as a habit, then I could see the jury struts coming loose over time.

    I personally would not drill another hole in the spar.
    Dan Arnold
    KEUL

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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    I forward the question to "support".
    I'll tell you !

    Y.

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    Senior Member Andy's Avatar
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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Quote Originally Posted by aeroaddict View Post
    Now CC cannot foresee what or how a customer might use their product. If my statement above is true; moving the plane around with the struts as a habit, then I could see the jury struts coming loose over time.
    What do you mean by "moving the plane around with the struts"?. CubCrafters approves using the forward lift strut but does not mention the aft lift strut or the jury struts. I always pull my FX-3 out of the hangar by the lift struts but never, ever, pull on the jury struts.

    What can or cannot be used to handle various airplanes seems to vary a bit. When I was towing gliders it was common to handle Super Cubs and Pawnees by the upper attach points of the tail braces. CubCrafters prohibits that but I have watched their mechanics do it.

    AFM extract -

    AFM handling.PNG
    Last edited by Andy; 04-30-2021 at 12:33 PM.

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    Default Re: Application of Service Bulletin SK-SB007 _ Jury strut braket rivets

    Rumor/speculation not fact.
    Dan Arnold
    KEUL

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