OSH curse strikes again. RV-6 Fuel Tank Leak

Last year my alternator died on the day before OSH, and today I was getting the plane all cleaned up for a second attempt at OSH and I noticed blue stains around the fuel sump on the left tank.

Can someone explain the fuel tank construction at the inboard part of the wing? The area of the leak is at the bottom of a large circle/oval area that surrounds the fuel line out and fuel sender. The fuel sender has a small circle area 1.5" and this is ok. Both areas are covered in proseal and i am not able to see how this end cap is fastened? Screws with gasket? Is this area supposed to be covered in proseal? The leak is in the six o'clock position and the proseal is very soft.

Suggestions on how to fix this problem?

The leak is very slow with a drip every ten minutes or more. Suggestions on flying, or keep it grounded and manually drain the tanks? Of course they are both full.

Chad

The access plate is secured with screws. There is either a cork gasket sealing the plate to the tank or maybe they just used proseal. Some use both. You can fix this in a day (plus a couple more days for proseal to cure) if you have time to empty the tank, pull the access plate, clean the surfaces, and re-seal with proseal. Access is tight but it is doable - there was a service bulletin a decade or so ago and all of us had to remove both tank access covers.

If it is only dripping once every 10 minutes, I'd be tempted to fly the airplane to the show and deal with the leak later. I'm sure there are different opinions too.

Leaky tank

You may try tightening the screw a little where it looks to be leaking, may fix your problem. If it is a very small leak, you should be fine.

You should really wait around 4 days to see gas if you decide to fix it. Full cure is over 100 hours.

Good luck.

You're in Madison? You don't need much fuel to get to OSH. If you are concerned about the leak and don't have time to fix it, you could drain and don't use that tank.

Counting drips

We used to have to count the number of drips per hour when I worked for one of the major airlines. Can't remember how many was acceptable, but it was more than most folks realize. I'm with Kyle on this one.

When you do fix it, replace the screws with 8-32 cap screws. I use stainless steel ones from www.mcmastercarr.com. They are much easier to install and remove in such a tight place. You can order a small cup of sealant from Van's for a reasonable price.

Mine is leaking too.

Mine has had a very small leak for a while and has recently gotten a bit worse. Drip every 15-20 mins...I am geussing. I dont consider it a big safety issue. It is sliding off the back of the wing by the flaps. I am going to fly mine like it is and fix it when I get back.

The last flight I had I ran that tank down (right side) down to probably 2-3 gallons, then it sat in my hanger for 2-3 weeks and did not fly it. The other tank had 12-13 gallons in it. I went to fly it around the patch by myself and during takeoff as soon as I left the ground I had to give it almost full aileron due to the slow speed and uneven weight distribution. I would not recommend doing that especially with an empty tank on right and full tank of left. I drove to the airport and picked up 10 gallons of 100LL so I could even it back out before I flew again.

forensic analysis may be required....

I had a similar seepage, but looking REALLY closely, taking photos, then wiping everything clean, then inspecting later...etc.
..turns out the leak was THROUGH the screws! I have just the cork gaskets, not sure if there's permatex or other sealant as well, but no proseal.

I pulled each screw separately, gooped with SEAL-ALL, and threaded back in, even with gas weeping out, it fixed the 'seep'.

Working in my case, just another consideration.

Update

I placed a piece of cardboard under the troubled area for 24 hours, and I did not have one drop leave the plane. I was able to see a small blue line of barely visible gas on the trailing edge of the tank seam, but not enough to form a drip.

I will make the trip the OSH, pickup some tank sealant, and reseal it when I get home.

Thanks for all the help and suggestions.

Chad

flyboy1963 said:

I had a similar seepage, but looking REALLY closely, taking photos, then wiping everything clean, then inspecting later...etc.
..turns out the leak was THROUGH the screws! I have just the cork gaskets, not sure if there's permatex or other sealant as well, but no proseal.

I pulled each screw separately, gooped with SEAL-ALL, and threaded back in, even with gas weeping out, it fixed the 'seep'.

Working in my case, just another consideration.

Click to expand...

Are you talking about this stuff?
http://www.eclecticproducts.com/sealall.htm

If so, it's pretty impressive stuff. I'm not saying to build a/c fuel tanks with it, but it really is amazing. I bought some 'garage sale' plastic gas cans a while back, & one was pretty heavily sun-damaged. First time I filled it, it had a pretty bad leak through a roughly 1" long crack. I had a tube of the stuff, so I grabbed some old 50 grit sandpaper, roughed up the crack & about 1/2" around it, and spread a wide bead of Seal-All over the crack. No leaks for months now, with mogas in the can.

I also used it to seal the seams on an aluminum intake manifold plenum I built, but can't testify yet on how well it will work (engine's not running yet).

Charlie