Ok, I will have to admit that what you are going to read is hearsay. I have been off getting blasted and primed, and have not been witness to any of this.
As I indicated last month, Gregg really did not like the look of the humps, on the fuel bay covers, associated with the electric fuel gauges. One fuel tank was included with the parts I was purchased with. That tank had been modified for the electric transmitter, and as a result had a neck that made it impossible to go back to the original smooth cover geometry.
The answer to this problem is to remove the neck and replace it with flat metal, so the correct cover geometry could be regained. Now we get to the meat of the problem. The initial attempt at removing the hammered dimple was not successful. Piper had originally fabricated the covers with formed ribs, and spot welded the skin to them, forming the cover. The hammering process used to create the dimples in the covers, had gotten excessively close to the welds. This was the issue that would not allow a localized riveted repair.
OK, this forces Gregg into the only option available. He needs to fabricate new fuel bay covers. Now, we go back to regulations, Gregg will be doing this repair with rivets, and the AC 43.13 has specifications for rivet spacing. An interesting point is that the specified rivet spacing and the spot weld spacing are almost identical (Go Figure)! There are four ribs per bay cover, and they need to be riveted on both sides. That is eight rows of rivets per bay, and the spacing gives to total count of 256 for each bay. However, the first problem is to bend the ribs with the break (they are in a modified V shape), and then curve them to the upper shape of the wing.
I am continually amazed at what Gregg can figure out what to do. He has gotten the metal cut for the covers. Not really a big deal, using his shear. Then he has fabricated eight ribs, to the contour of the wing. Then he has drilled and dimpled everything for riveting. Really, Piper had used spot welds to get a flat surface, and the final product also requires a flat surface. I believe that shooting the flush rivets was the most interesting part of the process. In any case, I think the final product looks pretty good.
From here we move on into painting. More about that adventure next time….
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