The Ailerons recieve a counter-weight tube to balance them around the hinge. 3/4" holes are drilled or cut in the very forward edge of the nose ribs to receive the counter-weight tube (a 3/4" aluminum tube which is filled with lead).
When the holes were made in the nose ribs, I didn't get the edge of the hole right up against the rib flange. Therefore, the tube does not lay against the rib flange and small gap is created. I'm afraid that when the pull rivet is squeezed down, the skin will be puckered and create an ugly dent at each rivet location. To fix this, I made a small shim out of .063 aluminum that's about 2" long and 5/8" wide and inserted it between the rib flange and the tube to fill the gap:
In the picture above you can see the hole is a little oblong. This is because I attempted, at first, to open the hole a little but since I had already drilled the rivet hole front edge, the tube was held up away from the bottom by the clecos, so I decided to just shim it. You can see the shim laying between the bottom of the tube and the rib flange. I made the shims long enough to be caught by the rivet aft of the tube as well as the rivet that goes through the tube itself. Of course these shims were also primed. This worked fine and the skins lay nice and flat after riveting:
