<November 13, 2006>
Reworked Left Tank/LE Seam
A few weeks ago, when I installed the tanks on the wings for what I hoped was for good, I noticed a small amount of pillowing or puckering of the tank skin between the first and second most forward screws where the tank meets the leading edge (LE). While this was perfect prior to riveting, the riveting process has a tendency to allow things to shift around somewhat. My understanding is that this is a fairly common issue, but I couldn't find a solution so I posted the question to VAF. Rick Gilati came forward and suggested a small shim between the rib and splice plate, which would force the LE skin out a bit more hopefully more closely matching the curve of the tank skin. Ironically, I had used the shim idea elsewhere (see October 27), but I it hadn't occurred to me to try it here. I am happy to report that the shim was easy to install and it worked great.
I forgot to take pictures during the operation, but the process went something like this; remove tank, drill out rivets (4), fabricate shim, re-rivet with shim in place, reinstall tank. Its as easy at that.
Here is what it looked like prior. You can see a small gap (pillow) between screws #1 and #2. I attempted to coerce the pillow away by hand, and while I was able to improve it somewhat, but it never completely went away.
Once the shim was installed, the contour of the tank and LE matched each other exactly. Problem solved.