[Paul B]

What is the best way to rivet the 3 platenuts for the inboard tank attach brackets to the spar? The platenuts go on the aft side of the spar and take AN426 (flush-head) rivets. I counter-sunk the forward side of the spar so the tank attach bracket will sit flush on the spar (I hope that was the right thing to do). I can't squeeze the rivets and some of the rivet heads are too close to the spar flange bars for my mushroom set to be used. I have some ideas but I thought I would ask those who have been there. Any advice is appreciated!!

 

[apkp777]

Paul,

I am pretty sure that I was able to get in there with a "mushroom" header. You may have to rock the header a bit to get the header on the rivet just right, but I think that's the only way to get it. You could also try back riveting (driving the tail, with a bar on the head).

 

[Andrew M]

Old fashion way

Get a helper on the flush head with a bar and set the shop head with a hammer and punch. Don't know if you have room for that, but it is very precise and easy to go slow.
Andrew
-9 preview

 

[Rick6a]

Get a helper on the flush head with a bar and set the shop head with a hammer and punch. Don't know if you have room for that, but it is very precise and easy to go slow.
Andrew
-9 preview

This is a good old school technique. A variation of back riveting, you really do not need a helper to assist you if you can lay the spar down flat and the spar is supported along its length in such a way that the spar flange does not come into contact with the work surface. Insert the nutplate rivets. Use tape to hold the rivets in place if you have to. Then carefully place a flat bucking bar down on the work surface between the rivet manufactured heads and the work surface. Make certain everything is fully supported. Now you should be looking down on the work. Insert a nutplate, then use a hammer with a good flat pin punch to set the shop heads of the rivets. At first, do not set the first rivet shop head fully....merely swell the head just enough to make sure the nutplate is seated properly. Set the second rivet fully. Finally, go back to the first rivet and finish setting it. All done.

 

[Paul B]

Job done!

Thanks everyone for your suggestions. The wing was already on the stand with the ribs riveted and top skins clecoed on. With a helper holding a heavy bar on the flush head, I was able to swing a hammer up between the wing-walk ribs and hit a punch on the shop head of the 2 most trouble-some rivets. About 8-10 moderately hard taps did the job. I padded the top skin in case of poor aim. The remaining rivets were easily done with a helper and rivet gun in the usual manner. On to the next task!