Time
to start riveting these things… Only an ounce of proseal this
time. First thing was to rivet the fuel return anti rotation
brackets. I used the squeezer on these. One thing
here… squeezing prosealed rivets can get pretty slippery.
I folded the first one over, so I made it a point after that to wipe
any excess proseal off the rivet prior to squeezing... helped some, but
it still wanted to slide around a bit.
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(18-5 step 4): After the brackets I squeezed the rivets for the drain flanges.
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Now
on to the skin stiffeners. The common thought here is to back
rivet these, but rivets sitting proud seems to be a recurring
issue. Now that there is proseal between the rivet head and the
skin, there is the potential for the rivet to sit proud unless enough
proseal is squeezed out from under the head of the rivet. With
backriveting only the sleeve around the back rivet set is applying
pressure down on the skin and stiffener while the back rivet plate is
pushing up against the rivet. So basically you're relying on the
spring in this sleeve to provide enough force to squeeze out enough
proseal for the rivet to sit flush. I suppose you could apply
additional force to the sleeve, but I've done that before and with the
number of rivets to do, my hands would be killing me! So, our
plan is to install a couple of ribs in the skin so it'll hold its
shape, and then place them in the cradles and rivet with the gun and
bucking bar. So here's Angela applying a dab of proseal to the
rivet hole prior to inserting a rivet. For each hole we simply
used as little proseal as possible while at the same time making sure
it at least touched the entire perimeter of the hole.
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We
knew doing these things one at a time would take FOREVER, so we decided
to do 3 at a time per stiffener. In addition, to minimize tool
cleanup we taped the rivets after inserting to keep the proseal off our
rivet set. This pic makes the squeeze out look like no big deal,
but once you hit it with the rivet gun, theres a lot more proseal to be
seen on the tape... the rivet gun really drives that rivet in the hole
:-) Once we got going we'd pull 3 clecoes, skip 3 clecoes, and
pull 3 more in the same line. We'd do this on both lines, for a
total of 12 rivets at a time. The process was basically pull the
clecoes, pooky the holes, insert rivets, tape the rivets, clean the
back side of the rivets so the bucking bar wouldn't slip, set the
rivets, pull the tape, wipe the proseal off both the tape and skin
(yep, cleaning the tape was quite easy... acetone on a paper towel, and
one quick wipe... the wide rivet tape actually comes in handy here!),
and then repeat. A long process, but hey, it's gotta be
done. And believe it or not, most of the rivets are flush!
I think the ones that aren't are due to our technique.
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Of course, everything seems to take longer than expected, so
we only completely finished one skin tonight. We started the
second one, but quickly realized the remaining proseal started setting
up. Even though we could still squeeze it out of the ziploc, the
rivets weren't sitting flush any longer... yep, time to quit!
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Speaking of rivets not sitting flush (like how I made that
transition ;-) I thought it was appropriate to show a pic of our first
rivet we shot tonight. It had been a while, and I put a tad too
much force on the bucking bar and pushed it out of the hole while
Angela was setting it. Oh well, I'll need to drill this one out.
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