• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Pa-12, adding left structural support tube for floats

Nolan

MEMBER
River Falls, WI
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



Sent from my iPhone using SuperCub.Org mobile app
 
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

Sent from my LM-X210 using SuperCub.Org mobile app
 
Pa12 structural tube

Thanks, I’m trying to attach a photo

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

Sent from my LM-X210 using SuperCub.Org mobile app
 

Attachments

  • 809944B4-1506-4387-8B06-4462F9131B55.jpg
    809944B4-1506-4387-8B06-4462F9131B55.jpg
    79.1 KB · Views: 325
54B37B77-3EE0-470C-948F-29AD20956757.jpegHere is another shot. Damn near a must on rebuild. I have an original factory seaplane brace if you interested.
 

Attachments

  • 54B37B77-3EE0-470C-948F-29AD20956757.jpeg
    54B37B77-3EE0-470C-948F-29AD20956757.jpeg
    300 KB · Views: 324
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.
 
B80D80BD-C310-44BE-AC14-48BDB892E5B5.jpegOriginal float plane brace tubes and drawings for PA-12.
 

Attachments

  • B80D80BD-C310-44BE-AC14-48BDB892E5B5.jpeg
    B80D80BD-C310-44BE-AC14-48BDB892E5B5.jpeg
    135.7 KB · Views: 315
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.

Thanks, I’m trying to attach a photo
attachment.php

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.


View attachment 44454Original float plane brace tubes and drawings for PA-12.
 
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


Sent from my LM-X210 using SuperCub.Org mobile app
 
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
 
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.
 
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.....
 
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.
 
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.
 
Back
Top