I'm in Phase I on my -9A so this is the first I've had much fuel in the tanks. It appears I have a leak around the fuel sump from the staining on the ground and near the flange. I'm confident it isn't the sump drain itself as the staining goes beyond and onto the flange t. I'm suspicious the VA-112 Drain Flange is where the leak is occurring. I haven't determined if it is a single rivet or the flange to skin seal that is leaking. I am guessing the Pro Seal has a failure point. Is there any way to repair this without removing the tank? A 1/4 in hole is pretty small to get something in there to do any good. Input from the Brain Trust? TIA
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Fuel Leak at Sample Drain
- Thread starter kthom_441
- Start date
Might be worth replacing the O ring just to check. It’s cheap and easy to do. Just wear gloves, unscrew the drain and quickly screw in a 1/8” plug while you replace the O ring.
If that’s not it, you might have to go in through the fuel gauge hole and put some more pro seal around it.
If that’s not it, you might have to go in through the fuel gauge hole and put some more pro seal around it.
I was thinking about doing that as a first step. I’ve done it before on Cessnas. Not sure the gloves help much as the fuel drains into my armpits but I get the thought. I don’t thing there is enough access to the fuel sender hole without pulling the tank.
Roadjunkie1
Well Known Member
If it appears to be a small leak, go fly and run the fuel down in that tank. THEN, while outside, pull the quick drain out and funnel the rest into a fuel can. Most hold 5 gallons so have two available and use a funnel. Then you won't have to worry about getting fuel all over yourself. I mean some people are attracted to the smell of 100LL but.....
Fuel is strange stuff. The leak can be the drain fitting and the fuel will snake around and look like it's coming from somewhere else. If you are in Phase 1 the drain is fairly new (I assume) and the "O"ring might be OK but this will give you a chance to look at it and replace it if it will make you feel better. Just make sure you get the proper "O" ring. I believe ACS has them: Part# MS29513-006 MFR Model# MS29513-006 if I recall.....
What did you seal your quick drain threads with? My favorite are the Loctite 565 or 567. Those threads have been a source of leaks I have found in the past and have had none since using these.
Hopefully one of these will keep you from having to go into the tank.............
dmattmul
Well Known Member
After you use the quick drain rotate the stem 180 degrees, seems to help.If it appears to be a small leak, go fly and run the fuel down in that tank. THEN, while outside, pull the quick drain out and funnel the rest into a fuel can. Most hold 5 gallons so have two available and use a funnel. Then you won't have to worry about getting fuel all over yourself. I mean some people are attracted to the smell of 100LL but.....
Fuel is strange stuff. The leak can be the drain fitting and the fuel will snake around and look like it's coming from somewhere else. If you are in Phase 1 the drain is fairly new (I assume) and the "O"ring might be OK but this will give you a chance to look at it and replace it if it will make you feel better. Just make sure you get the proper "O" ring. I believe ACS has them: Part# MS29513-006 MFR Model# MS29513-006 if I recall.....
What did you seal your quick drain threads with? My favorite are the Loctite 565 or 567. Those threads have been a source of leaks I have found in the past and have had none since using these.
Hopefully one of these will keep you from having to go into the tank.............
Sam Buchanan
been here awhile
Stand beside the leading edge, reach under the wing to the drain and fuel won’t run down your arm.
Maybe just replace the quick drain with a pipe plug with thread sealant for a couple of 'hangar sitting' days and see if it changes the characteristics. It can be done quickly over a catch pan and spoil very little fuel.
squeakersc063
Well Known Member
Funny enough those drain assemblies are something that I did and then thought about after doing them and removed them. When I did the initial install I had sealed the rivet areas using minimal sealant but after thinking about how it works decided I probably needed to have sealed the whole thing because it's not just the rivet areas that fuel is trying to get to. Perhaps that's what whoever built your tanks did without the afterthought. For examples, here is my log from that day. https://eaabuilderslog.org/?blprojentry&proj=7meNUQnN4&e=82O4RAvbv&listcat=&sid=
Without taking the tank off, you can get to the drain flange through the access plate with tank sender unit. We did this for the same reason a couple weeks ago. It is a bit tight with the float. My initial access plate install was with a cork gasket, so it was relatively easy to get off and clean up for re-installation. Some mirror, light, tongue and mouth positioning (within normal aircraft maintenance standards) is required to get the sealant on the rivets.
PilotjohnS
Well Known Member
There seem to have been a quality issue with some of the drain valves Vans supplied a few years ago: The valve part that includes the part you screw in to the plane's fitting has a hole through it. The sealing O-ring sits on the inside surface of this hole. On mine, this part has a nice burr, so the O-ring sits on the burr. Most of the time, the O-ring will still seal, occasionally not. I bought a replacement valve from Vans for one side and there is no burr, works great. When my burr'd valve starts leaking gain, I will drain the tank and remove the burr, and install a new O-ring. For those who haven't put fuel in the tanks, one might want to check these valves for a good sealing surface for the O-ring.
