although I did have to make larger tank skins to do it comfortably. I'd
do this again for at least the top wing skin for access all around the tank.
I also cut one inspection hole in the bottom of the tank so I could
paint all the joints, rivets, and stringer exits on the top of the tank
with brusheable proseal. I riveted the baffles to the ribs after
applying the brusheable proseal. Seemed like a small thing to do
compared to potentially cleaning and repairing a leak later.
Ken
Tim Hickey wrote:
Since there seems to be a few folks who are still needing to do the wings, I
will post what I did here for your evaluation.
I can't say that what I did was much of an improvement over what the manual
calls out, but you can be the judge.
The manual seems to want the builder to rivet the stringers to the bottom
wing skin, and then proceed with the prosealing of the bottom tank
bulkheads, stringer, and lower tank skin. I guess what this does for you is
to lock into position the lower stringer that goes through the tank.
I didn't want to do that, because I wanted to be able to remove the bottom
skin so I would have access to the top of the tank when I was prosealing the
top. With the bottom skin removed, you have a much better chance to slop
proseal around the three tank rib penetrations where the stringers pass
through.
So I clecoed the lower skin in place, prosealed and installed the tank
bottom.
Placed the rivets into the tank bottom.
Flipped the wing, and then reached inside the tank so I could dab proseal on
each and every rivet, and to make sure that the lower joints were well
covered with proseal.
Caution here: When you apply the proseal, tank care to not get proseal on to
the lower wing skin itself. Because if you do, it will make subsequent
removal of the lower skin much more difficult. ( I slopped a 1/4" spot on
the lower skin, and it was a bit of a bear to remove the lower skin the next
day, but I did manage to get it off)
Be with the proseal on the stinger. Get plenty on the intersection between
the tank skin and the stringer, but keep it from where the wing skin slides
under the lower tank skin and stringer.
The next day after prosealing the bottom tank skin, I flipped the wing and
then removed the bottom skin. And then replaced it . I did that just to make
sure that I could. I did find a spot of proseal on the lower wing skin that
I removed (the spot above), but that was about it.
Next it was time to do the top of the tank. This is a little more difficult,
in that there are three stringers going through the tank, and the warped
condition of the tank bulkheads makes this job tougher.
I started out trying to make a jig that would hold the stringers in the
proper position with the inboard bulkhead. That looked good on paper, but
did not work so well when it came time to proseal. What I did was to make a
mental note of the relationship of a hole in the stringer with the bulkhead.
Then when we prosealed the stringers, we put them into the approximate
position, and prosealed the sealing plates and stringers together. We put
extra proseal 3/4 of an inch each way from the bulkhead, figuring that the
stringer was going to move a little when the tank skin went on. I don't
think that the stringers moved much more that 3/16" during the fit up.
We used cut up coat hangers to guide the tank top onto the warped bulkheads
(we put a cleco in each corner of the tank skin and into the main spar)
pulling things into shape as we lowered the tank top to the top of the
bulkheads.
We then clecoed the tank top to the bulkheads. And then we installed the top
rear skin. We chose to put the top skin under the top tank skin. I see that
Simon Smith did that on his Rebel, and it looks nice to me. We had to slide
the skin under the top tank skin, under the front wing skin, and above the
stringers. We installed a few clecos to hold things in position, and the
riveted the tank skin on. At this point it pays to keep track of where the
tank starts and ends, because we did not want to put any rivets into a hole
that also served to hold the rear skin.
We then flipped the wing, pulled the lower skin off, prosealed the visible
rivets, and buttered up the seams. Again the caution of keeping the proseal
off of the wing skin if you have any plan of removing it the next day.
You have to put rivets into the leading edge skin on both the top and bottom
of the wing where the tank is, but that seems pretty plan.
So, what did we gain? I can now pull the lower or upper skin off the wing if
I need to. I have not riveted the upper or lower skin to the wing. I have
the wing skins positioned under the tank skins, and I think that it looks
better when finished.
One think I have lost popped up in a note here the other day, where some one
suggested drilling out some rivets so you could peel the top skin back and
have access to the back and side of the fuel tank. Since my tank skins are
under the wing skins, I can't do that.
I guess the main thing gained was the opportunity to have good access to the
joints between the tank top and the tank sides.
One other thing that I might suggest is that we conducted a rehearsal of the
procedure before we stated. It seemed to help. When you are elbow deep in
proseal is not the time to have to back track and do something over.
We have to yet pressure test the tank, as I want to let that proseal "cook"
before I put any stress on it. We did fill the tank with 6 gallons of water
before the top went on, and let it set overnight. There were no leaks on the
bottom joints.
Tim Hickey
2658 300th St
Montrose, Iowa 52639
Home 319 463-7047
Cell 319 795-2684
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