There are several
things that you must do differently while
assembling the wing tanks. Let’s
about those differences and some other techniques that will
help you build
The directions talk about
straightening and fluting the ribs
to make them fit. You
will do this just
like you have fluted and straightened all the other parts so far. But a little more
attention is needed on the
front ends of the ribs. Those
flanges on the front of the ribs need to be bent so they don’t drag
skin and scratch through the alclad.
Spend a little extra time here to make sure
The last step in my Vans
"Fitting the Tank Skins to the Ribs and Rear Baffle" talks about
installing the capacitive fuel
unit. This is also
the right time to
make any other mods you are planning.
you are using a constant flow fuel
system and need a fuel
return line to the wing tanks, now is the time to install it. You can run the line
either internally or
externally. If you
run it externally,
you will have to cut a hole somewhere along the T-702 tank baffles,
on how far into the tank you want the fuel to return.
You can easily install an AN833 bulkhead
elbow, and run the line across the back of the T-702s.
All that is left is providing some support
brackets for the line.
you run it internally, you can
drill another hole in the
T-703 root ribs and install the proper bulkhead fitting, either
a straight, 90, or
45 degree elbow. Drill
through the internal ribs, and install plastic bushings to protect and
line. This should
end up looking much
the same as the vent line running through the internal ribs. I like this option better. It keeps all the external
holes on the
inboard rib of the tank, making inspecting and detecting leaks
I have also seen people
add a Fuel
Level Low Sensor to their
wing tanks. This is
from the normal fuel sensors, and normally activates a light and/or
the fuel gets below a set level. Now
the time to install the parts into the tank.
Again, I would recommend installing it on the
rib if there is
room. If you have
to install it in the
T-702 baffle, add a special note to your conditional inspection
ensure you check it for leaks.
Together (Proseal Time)
Proseal is messy,
and will find it’s way onto everything you are using. Wear
clothes you don’t mind getting covered in
I picked a handful of
clecos and made
them the sacrificial
proseal clecos. Now
I reuse the same
clecos over and over whenever I have a proseal job.
I found using two sets of
gloves, one over the other,
was helpful. Then
when the top set got
sticky with sealant, I pulled them off and was able to quickly and
easily put a
new, second set on top of the first.
is tough to pull the plastic gloves over sweaty hands, but it’s a lot
pull them over another set of gloves.
the way, make sure you don’t get the gloves with Talc, it will make a
I bought the tubes of
are pre-measured and only
need mixing. Using the tubes in a gun was much easier than using a tub
trying to ladle the sealant out. You
find the longer working time sealant good for a couple hours. Since you are in no hurry,
this is the best
stuff. Both tanks
took me four tubes—one
for the stiffeners and other parts, two for all the ribs, and one for
I backriveted the
stiffeners to the
skin just like the
directions say, only I put all the rivets in the holes, taped them and
skin against the backriveting plate, then spread the proseal on the
stiffener. Then I
riveted it on.
proseal will get onto both the bucking
bar and the set. Wipe
it off after every
rivet. This is a
little time consuming,
but it will ensure the next rivet bucks properly.
If you leave proseal, you run the chance of
the bar or set slipping while riveting, and ruining the rivet. Then you have to drill it
out with all that
proseal everywhere. Yuck, what a mess.
I had the skin and ribs
in the cradle
while riveting the
ribs. I removed the
clecos from a rib,
slid it out, and buttered the rib flange with proseal.
Then I slid it back into the skin, as
straight down as I could. This
mess to a minimum.
Before you finish this
prosealing, make sure
everything is installed. Did
you run the
vent line? If you
added a return, a fuel
level low sensor, or any other extras into your wing tanks, now is the
time to install and
them. You can bend
the lines and insert
them into the rib holes once the end rib is installed, but it is a lot
to slide them straight in before the end rib is installed.
rivet on the
baffle, take the time to check your proseal job for leaks. After the proseal dried, I
left each wing tank in
the cradle and filled it with water above the top of the last rivet. I checked it the next day
to see if any water
had leaked out. I
would rather find the
leak with the tank still open while it is much easier to apply more
proseal. It’s a lot
harder to seal a leak once the tank
Closing the Wing Tanks
Before installing the
plate, You can again check
for leaks. This
time set the tanks with
the baffle down. Fill
them with water to
the lip of the opening in the end rib.
The next day, you can check for leaks on the
Instead of a dab of
proseal on each
screw, get some thread
sealant from your local auto parts store.
This stuff is made for just this purpose. It will seal the screw
threads, is fuel
and will allow you to remove the screws when you need to.
You can also check each
wing tank for leaks
after you are
completely finished by pressuring up the tank.
Don’t overdo it, you don’t want to blow the
tank up. I’ve seen
calibrated gages both
used to good effect to check the tank for leaks.
You will have to hook up the appropriate
fitting to allow you to pressurize the tank and to monitor that
either the gage or the balloon.
Now it's time to rivet
the wings together!
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