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Thread: Pa-12, adding left structural support tube for floats

  1. #1

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    Pa-12, adding left structural support tube for floats

    Pa-12, modification,
    Does anyone have information about a structural support tube that can be welded in for additional strength between front landing gear attachment and the forward wing attachment point?
    Thanks
    Nolan



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  2. #2
    www.SkupTech.com mike mcs repair's Avatar
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    https://goo.gl/photos/PuiR5ha2aBDbkUBS8

    https://goo.gl/photos/GRXyyNHPoUik2V44A

    You may need to move throttle handle some. And mod rod between handles


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  3. #3
    TurboBeaver's Avatar
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    The original mod from Edo requires two tubes that simply bolt in. No welding involved......... If you are pre cover with bare fuselarge then go ahead and weld in the vertical tube.
    If not just add the 2 tubes as per Pipers drawings to convert for floats.
    By the way IF you are welding its not a bad idea to replace the vertical tubes from rear fittings up to rear wing attachment to next size larger; ALOT of 12s have compressed that tube when they have been landed in real rough water. We often find them bent
    about 4" down from the wing fitting.
    Good Luck.
    E

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  4. #4

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    Pa12 structural tube

    Thanks, I’m trying to attach a photo

    Quote Originally Posted by TurboBeaver View Post
    The original mod from Edo requires two tubes that simply bolt in. No welding involved......... If you are pre cover with bare fuselarge then go ahead and weld in the vertical tube.
    If not just add the 2 tubes as per Pipers drawings to convert for floats.
    By the way IF you are welding its not a bad idea to replace the vertical tubes from rear fittings up to rear wing attachment to next size larger; ALOT of 12s have compressed that tube when they have been landed in real rough water. We often find them bent
    about 4" down from the wing fitting.
    Good Luck.
    E

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    KJC's Avatar
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    Click image for larger version. 

Name:	54B37B77-3EE0-470C-948F-29AD20956757.jpeg 
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ID:	44438Here is another shot. Damn near a must on rebuild. I have an original factory seaplane brace if you interested.
    PA-12 N418BS

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    Quote Originally Posted by KJC View Post
    Click image for larger version. 

Name:	54B37B77-3EE0-470C-948F-29AD20956757.jpeg 
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ID:	44438Here is another shot. Damn near a must on rebuild. I have an original factory seaplane brace if you interested.

    PM sent

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    Quote Originally Posted by nbills77 View Post
    PM sent
    Do you have any photos of your throttle linkage?
    my vertical tube is welded in the same as yours

  8. #8
    KJC's Avatar
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    In the vertical tube, you have to remove about an inch and a half “c” chunk out of the tube and weld in a new piece so the integrity of the tube isn’t compromised. This is so the throttle linkage doesn’t rub on the new tube. Either that or maybe put a joggle in the linkage......? No pics handy. I’d have to go to the hanger and remover the linkage cover.
    PA-12 N418BS

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    Click image for larger version. 

Name:	B80D80BD-C310-44BE-AC14-48BDB892E5B5.jpeg 
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ID:	44454Original float plane brace tubes and drawings for PA-12.
    PA-12 N418BS
    Thanks nbills77 thanked for this post

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    skywagon8a's Avatar
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    I'm confused. Is this first picture supposed to be showing the seaplane tube installation? The tube which is supposed to be reinforced is not.

    Quote Originally Posted by Nolan View Post
    Thanks, I’m trying to attach a photo
    This is what is called out on the Type Certificate A-780: Airplane Serial Nos. 12-1 through 12-3011,and 12-3901 through 12-3966, except 12-3943, 12-3945, 12-3947, 12-3949 and 12-3965, must haveadditional fuselage brace tubes (Parts Nos. 11026 and 11027 in accordance with Piper Dwg. 11031)

    KJC's drawing and parts are the correct ones. They have no resemblance to Nolan's photo.


    Quote Originally Posted by KJC View Post
    Click image for larger version. 

Name:	B80D80BD-C310-44BE-AC14-48BDB892E5B5.jpeg 
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ID:	44454Original float plane brace tubes and drawings for PA-12.
    N1PA

  11. #11
    TurboBeaver's Avatar
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    Interesting side note: I have a buddy that has two old PA 12 fuselarge's. Both of them have that diagonal tube
    bent from rough landings in "exactly" that position the original factory seaplane brace gets placed (12 3/4")
    Neither of these ever had a brace but one had been on floats before?
    So the engineers were very aware of
    exactly where it would bend.......
    Both of these bent forward bowed towards the engine, so the forward brace tube would correct that, however the side brace tube that connects over to the seat truss must have also been nessasary to keep it from moving inwards or outwards.
    Actuall its kinda silly to go to all the trouble to weld in the front vertical tube, then leave the rear ones, that are known to compress below the rear wing attach fittings; original ???? Which is exactly were your going to bend it; as soon as you fix the front..........
    If anyone is in deep enough to be welding the front mod in, they should keep right on going, and replace the rear vertical tubes as well.imho.
    E


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    Quote Originally Posted by skywagon8a View Post
    I'm confused. Is this first picture supposed to be showing the seaplane tube installation? The tube which is supposed to be reinforced is not.



    This is what is called out on the Type Certificate A-780: Airplane Serial Nos. 12-1 through 12-3011,and 12-3901 through 12-3966, except 12-3943, 12-3945, 12-3947, 12-3949 and 12-3965, must haveadditional fuselage brace tubes (Parts Nos. 11026 and 11027 in accordance with Piper Dwg. 11031)

    KJC's drawing and parts are the correct ones. They have no resemblance to Nolan's photo.

    Ok, so KJC’s drawing’s is a correct fix for a original 12 with the Trust still inside, that requires no welding.
    But you also can look at KJC’s photos of the welded fix he did where he is also changing out the seat to a pa-18 seat, his welded in tube matches mine

    Thanks

  13. #13

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    Quote Originally Posted by nbills77 View Post
    PM sent
    KJC
    what STC did you use for your extended baggage?
    Looks Great!

  14. #14
    skywagon8a's Avatar
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    Quote Originally Posted by Nolan View Post
    Ok, so KJC’s drawing’s is a correct fix for a original 12 with the Trust still inside, that requires no welding.
    But you also can look at KJC’s photos of the welded fix he did where he is also changing out the seat to a pa-18 seat, his welded in tube matches mine

    Thanks
    Yes Nolan, I see that. Your original question specifically mentions a structural support tube for floats. The tube which you have reinforced, while it may need reinforcing is not the tube which is called for on the TC to be modified for a float installation. If you are planning a float installation that other diagonal must be reinforced regardless of whether you have removed the original landing gear shock truss or not. Piper's support for that tube requires support in two different directions. WHY?, I can't answer except that the TC requires it, unless you can come up with an alternative approval.
    N1PA

  15. #15
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Nolan View Post
    Ok, so KJC’s drawing’s is a correct fix for a original 12 with the Trust still inside, that requires no welding.
    But you also can look at KJC’s photos of the welded fix he did where he is also changing out the seat to a pa-18 seat, his welded in tube matches mine

    Thanks
    this is also the only way I have seen it done.... never seen that one bolt into the truss.....

  16. #16
    KJC's Avatar
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    Unfortunately the left front side landing gear attach point is the weak spot on the -12. If you have it’s apart, just weld in the tubes from the fwd wing attach down to the gear leg. Don’t think too much just do it. You’ll be happier. Make it look like the right side. You’ll be fine!! The seaplane brace shown in the above drawings and called for on the type certificate is nothing but a band aid. It might help some but better to do it correctly.
    PA-12 N418BS
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  17. #17
    skywagon8a's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    this is also the only way I have seen it done.... never seen that one bolt into the truss.....
    mike, During your repairing of PA-12 float planes have you ever seen that diagonal which is called for reinforcement on the TC bent or otherwise damaged?
    Perhaps someone long ago determined that the new long tube between the gear fitting and the front wing attach fitting was a better method and just didn't get an approval? Perhaps it is on a pre 1955 337? Just because that is the way "we have always done it", doesn't make it legal even though it may be better.

    Makes no difference to me as I'm not likely to be working on -12s on floats again. But for those of you who do, you may want to make sure that you are legal.
    N1PA

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