Leaky fuel tank

[Timothy Percarpio]

I recently noticed that my right fuel tank will leak if it’s topped off. If it’s down a little, say about 26 gallons, it doesn’t leak. Any advice will be appreciated. Do I need total reseal, repair or maybe switch to bladders? I’m based t CXY, Harrisburg, PA, so I would prefer somewhere in the Northeast or at least the East coast. 

[Shadrach]

16 minutes ago, Timothy Percarpio said:

I recently noticed that my right fuel tank will leak if it’s topped off. If it’s down a little, say about 26 gallons, it doesn’t leak. Any advice will be appreciated. Do I need total reseal, repair or maybe switch to bladders? I’m based t CXY, Harrisburg, PA, so I would prefer somewhere in the Northeast or at least the East coast. 

The only way to tell is to open the tank. Is there visible fuel staining on the wing?  It could also be a sending unit gasket.

[Timothy Percarpio]

Thanks, I think I’ll have Henry Weber Aircraft check it out. 

[Shadrach]

They certainly have the expertise. It's good practice to try to make the first turn off (Bravo) when landing 31 at KLNS.  It's just under 1000' and puts you right on Weber's ramp.

[Jsno]

The sealant is probably deteriorated from heat on a high seam.  Should be easy to find and fix.

[Yetti]

What kind of leak and where?  If the screws on the plates that can be fixed with some Permetex 3.    Just don't leave it topped off would be the best solution.

[PT20J]

Where is the leak? If it is at the outboard end of the tank, I would first check the fuel sender. 

[Timothy Percarpio]

I normally don’t leave it topped off. The other day I flew to KIDI for lunch and topped off both tanks. After lunch we noticed the right main wheel was in a small puddle of fuel. I could see a drip right over the tire. I’m going to take it to Weber Aircraft to have them take a look at it. Thanks for all the suggestions. 

[N201MKTurbo]

I don't think heat is the culprit. If it was all the Mooneys in Arizona would be leaking. My old M20F lived outside for years here and it never leaked. The temperature of the skin of a dark painted wing here can easily top 200F in the summer. 

I did a search and finally found an academic paper on the subject. It is a good read. It suggests that the major mechanism for degradation of tank sealants is microorganisms. They were just looking at Jet fuel tanks, but it think it applies here too.

 

10.11648.j.ijmsa.20221105.11.pdf

[ArtVandelay]

17 minutes ago, N201MKTurbo said:

I don't think heat is the culprit. If it was all the Mooneys in Arizona would be leaking. My old M20F lived outside for years here and it never leaked. The temperature of the skin of a dark painted wing here can easily top 200F in the summer. 

I did a search and finally found an academic paper on the subject. It is a good read. It suggests that the major mechanism for degradation of tank sealants is microorganisms. They were just looking at Jet fuel tanks, but it think it applies here too.

 

10.11648.j.ijmsa.20221105.11.pdf 1 MB · 2 downloads

They call out jet fuel (kerosene) is more suited to microorganisms than gasoline, because of chemistry.

Arizona may be so hot that it kills the microbes.

[N201MKTurbo]

4 minutes ago, ArtVandelay said:

They call out jet fuel (kerosene) is more suited to microorganisms than gasoline, because of chemistry.

Arizona may be so hot that it kills the microbes.

That's what I was thinking too.

They also mention peroxides formed from oxidizing fuel. I would think this would happen faster in the presence of moisture. There may be some correlation between fuel age and peroxide formation. My old M20F never set. I flew it enough that it usually got a new tank of fuel every week. It never had any fuel tank issues.