The Murphy Builders Site

Jean,
Yes, this is can be a difficult problem. I assume that you have plenty of
room
for the skin to fit under the LE skin, but it is the fuel tank skin area
that is
having trouble and preventing everything else from working. The answer is
two-fold.
1.) Remove excess proseal that has squeezed to the outside of the tank
area
(underneath the tank skin). I used a scrap piece of aluminum to cut and
scrape the soft proseal and my fingers to rub it away, and feel that it is
clear. I also ran that piece of scrap aluminum between the ribs and tank
skin, and between the stringers and tank skin to clear out any excess
proseal. Take care not to push too far in and ruin the proseal that is
needed
between tank skin and rib or stringer! I had also used Mike Betti's
suggestion
to use dummy waxed strips of aluminum as spacers when I riveted the tank
skin down -- at least on my second wing. :) This helped, but the job is
still
doable if you hadn't done this.

2. This is related to the first part... MAM calls for at least 1/4" edge
distance
for the rivet holes on the main skin where it underlaps the tank skin.
Make
sure whatever you have meets that spec and is not way over (e.g. 3/8"),
bumping into the tank bulkheads. The hardest part is squeezing the main
skin
under the tank skin at ribs 1,2, and maybe 3 or 4. On mine, a tank skin
to rib
rivet happens to be 1/16" aft of the rest in that row, so I also rounded
a
1/16" divit into the main skin edge to allow the skin to get close enf to
that
rivet. (hard to visualize but even at this divit, I still have at least
1/4"
distance to the next hole because the hole spacing is set by the ribs
instead
of the row behind the bulkheads)

Both of these helped enf to finally get the skin in. Difficult, but
do-able
instead of frustrating and impossible before the above. I can't remember
off
the top of my head, but I had also made my tank skins and overlap rivet
holes go a tiny bit further aft (1/16"?) to allow for more room between
the
overlap hole distances where it picks up the main skin, i.e., I should
have
been able to keep > 5/16" edge distance for my main skin edges if I
wanted,
but on fitting the skin in there, I shaved off to barely over 1/4".

Hope this helps. Let me know if unclear, which wouldn't surprise me!
-Ben/ 496R





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