Tank Leak

I have a leak in my right tank. It?s at the outer rear bottom juncture of the tank?s skin, outboard rib, and rear baffle. Picture shows just where it is.

I have fairly easy access through the filler cap to the corner and could probably seal it from inside with a flashlight, small mirror and a new grease gun with an extension. I found a post where someone had done it sucessfully and I think I could, too.

Sure looks like I could just ProSeal it on the outside, though. I'd be careful to avoid interference with the W423 Joint Plate, naturally.

Anyone have experience with an outside fix like this?

Thanks.

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Lot's if proseal on the outside corner.

I don't see how you will put proseal on the inside through the filler cap. Maybe using a long syringe, but even then it won't be all that easy. I would try first applying extra sealing on the outside.

Another option is to cut a hole in the tank baffle at the last bay and reach in and cover it up later with an additional T-407 reinforcement ring and tank access plate if you want to remove it later, or just a tank access plate with pop rivets if you don't. But it's a lot of work for a small leak that can probably be closed from the outside.

The only correct way to seal a leaking tank is from the inside.

Walt said:

The only correct way to seal a leaking tank is from the inside.

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I agree.

This is a common leak and the fix from Vans is -

COVER AND RIVETS
FUEL TANK REPAIR KIT

$8.10

I had similar leaks last winter on my left tank. There were actually several different locations on my tank I had to fix but there was one on the top outboard corner near the filler neck. It is difficult to get pro-seal up into that corner but it is possible. A mirror, a small application stick of some sort bent to allow reaching back into that corner and some good hand eye coordination while looking in the mirror were required. I had to practice a bit on moving the end of the stick while looking at it in the mirror. You kind of have to train your brain to think differently. It will be messy inside the tank and you may end up with more pro-seal inside than you hoped for. Some of it may end up elsewhere than on the leak but it can be done.

Appreciate the replies.

I finally got around to snapping a picture of the inside leaking corner through the filler cap as shown in the attached photo. It's easy to see that access for sealing it wasn't difficult. You can see the original little dab of ProSeal in the corner that squeezed out during construction and it's clearly not enough. Lesson is don't be stingy with the ProSeal during construction.

I'm fortunate this is my only leak and that it's so accessible. I wondered about the other corners, but my left tank has been full to the filler cap for 12 days with no signs at all of leaking.

Dabbing ProSeal into the corner was easy to reach but not easy to control with my chosen tool - a 3/8" wooden dowel. Not a pretty job, but it's the inside of the tank so only I will know that it's not a perfectly faired fillet.

Thanks to all.

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But now we all know. And, we're tellin'.
Van's (I think it was Van's) also has a short video on fixing small leaks like that with Loctite, from the outside. It wicks into the hole and seals it up.

Here is my experience fixing some leaking tanks. I purchased a partially finished RV-6. I finished it in Oct 11. The tanks were at least 12 years old and had never had fuel in them and they were primed. I did a pressure test and had about 5 leaks, four were rivets and one was the inboard bulkhead seam. I applied Loctite from the outside to all the leaks and let it sit for 48 hours. I did another leak test with low pressure air and did not find any more leaks. A few weeks later I flew the aircraft for the first time and noticed 4 rivets were weeping fuel. I drained the fuel and reapplied Loctite. I flew another 4 or 5 hours in the aircraft and these 4 rivets were still leaking. I drained the fuel again and cleaned around the rivets. I took some Proseal and using my finger pressed it all around the outside of the rivet. I then immediately wiped down the rivet and skin with mineral spirits. I now have 160 hours on the aircraft and there are no leaks. The aircraft was painted in April 12.

Corner leaks

I had one corner that leaked when I checked my tanks. Fortunately it was in the cell where the fuel filler cap was. I took a really long soda straw and put a generous amount of proseal in it...then extended the straw into the corner and blew the proseal out just like blowing bubbles in your milk. Angled the tank so this was the low corner the cell...once the stuff set up, no more leak.