F-01411 bulkhead flanges

I assembled the F-01411 bulkhead a while back and had tweeked the flanges to pretty well fit the F-01479 aft bottom skin (they still need just a little more). Today, I have been working on shaping the cutout in the aft bottom skin for the U-00018 tail dragger spring mount. In the process, I clecoed the F-01411 bulkhead in place to help position the spring mount. What I found was that the rivet holes in the two sets of flanges are farther apart than the matching holes in the aft bottom skin. I'm sure that I need to tighten the radius at the base of the flanges but need a suggestion for a good way to do that. I did try gently compressing the tips of the flanges with a clamp but didn't want to take that very far as it seemed fraught with peril.

Any ideas?

Flanges

Those flanges will need to be fluted. A special pair of pliers is required for this. There is a section in the instructions that talks about fluting.

I used fluting pliers to get them close to shape for the curve of the skin and still need to do a little more. Problem is that the fluting pliers aren't going to move the rivet holes back in line.

Tighten the radius on both bulkhead flanges. Put the bulkheads together and measure the hole spread required and adjust. You will see where the issue is.

SabreFlyr said:

I assembled the F-01411 bulkhead a while back and had tweeked the flanges to pretty well fit the F-01479 aft bottom skin (they still need just a little more). Today, I have been working on shaping the cutout in the aft bottom skin for the U-00018 tail dragger spring mount. In the process, I clecoed the F-01411 bulkhead in place to help position the spring mount. What I found was that the rivet holes in the two sets of flanges are farther apart than the matching holes in the aft bottom skin. I'm sure that I need to tighten the radius at the base of the flanges but need a suggestion for a good way to do that. I did try gently compressing the tips of the flanges with a clamp but didn't want to take that very far as it seemed fraught with peril.

Any ideas?

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These part usually don't statically lay with the holes aligned.
Can you get clecos in the holes? If so, then don't worry about the misalignment.
If not, then other measures may be required. Usually this is caused by not fully adjusting the shape via fluting and deburing (removing the puckers at the flange notches as detailed in Section 5). Then when you put the two bulkheads back to back, they don't lay tight against each other as designed.

I can get clecoes in but three or four go in at a significant angle with a little difficulty. A mechanic in our company hangar suggested that I alternate my clecoes side to side and "average out the discrepancies." (I had put all the clecoes in one side, as you can see in the pic, putting all the the disparity on the other side.) That helped. With the misalignment, I was figuring that I wouldn't get good rivets.

Thanks!