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Nother Leaking Fuel Tank

raabs

Well Known Member
New -10, pressure testing the fuel tanks. Balloon stayed inflated on first tank for 4 days. Second tank just a day. I was hoping it was a crummy balloon. Second balloon test was same. On the third test, the leak(s) finally showed. Two small leaks in the top baffle seam, one in the outboard bay 3-4 inches inside the filler, and the second, one bay inward. Pic attached.

Not QB. What is the best way to fix this?
Try cleaning and sealing the outside?
Cut a hatch on the baffle and add more Proseal on the inside seam?

Can I add new proseal over cured proseal along the inside seam (cured for > year).?

Overall, a camera inspection shows good seal inside but a little light in these two spots. I'll add fuel to tanks and test further after solving this issue.
 

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You might try getting some Type A tank sealant from skygeek.com or another vendor. It's the consistence of honey. Then topcoat the existing sealant on the seams and rivets per these pictures.

Dave
 

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Cut a hatch on the baffle and add more Proseal on the inside seam?

Can I add new proseal over cured proseal along the inside seam (cured for > year).?

I think cutting a hatch (van's makes access plates to facilitate this) is your best long term option. Fix it right and don't worry about it for 30 years.

Proseal sticks to proseal, so I'd use the Type A sealant over the old sealant (on the inside) as has already been suggested. This is a PITA, but you'll forget all about it once you start the cabin top and doors. It wouldn't hurt to apply type A proseal on the outside of the seams as long as you don't get it anywhere it hinders tank attachment.
 
This is a PITA, but you'll forget all about it once you start the cabin top and doors.

LOL. Cabin and doors are finished. I'm trying to forget about that by doing this!:) Tanks have been done for a while but just being tested.

As painful as it is, I think the hatch may be the solution. I don't want to have to deal with this after paint or chase it for 10 years.
 
Open up the rear baffle and fix it that way. The tank has not yet been installed or painted so the repair is relatively painless. You would not be happy to have the tank start leaking again after the the plane has been painted.
 
LOL. Cabin and doors are finished. I'm trying to forget about that by doing this!:) Tanks have been done for a while but just being tested.

As painful as it is, I think the hatch may be the solution. I don't want to have to deal with this after paint or chase it for 10 years.

If you want to tackle this from the outside I think it's worth a try. Removing the tank after installation is not an issue if you use a stubby ratchet. I've had my left tank off twice in the last year. First to fix an inboard rib leak and then to fix the flare on the vent line when it cracked because the builder didn't put a sleeve on it.
 
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