Fuel tank leaks revisited

[Dan]

Is it accurate to say.. Its a matter of time before Mooney tanks need to be stripped and resealed?  Is there some percentage that escape this or do ALL vintage Mooneys need this eventually? A few of the planes I have been seeing  tell me the tanks do not leak and have not been stripped. I think they will need it eventually?

Thanks

Dan

[MB_M20F]

My F model will be 40 years old in May and will hit 5,000 hours AFTT this year. It still has original fuel tanks in very good shape. So, I'm living in the hope...

[Piloto]

A properly sealed tank can last over 30 years without a leak. The main culprit for tank leaks is heat. The sealant, like any other rubber based material deteriorates quickly when exposed to heat. You can see this on the seats and glareshield of cars when exposed to the sun for long periods. When the plane is left in the sun inside wing temperatures can raise over 150F in less than an hour. The heat causes some of the bonding molecules of the sealant to evaporate. This results in a sealant with less elasticity that with time will shrink and crack causing gaps thus leaks. Best way to avoid sealant deterioration is to keep the plane in a hangar. If this is not possible keep the tanks at least half or more full. Fuel helps on lowering the temperature thus sealant deterioration. Most leaks start on the upper surface of the tanks where it gets hotter. You will also notice that leaks are most noticeable during winter but not in the summer. This is because during summer fuell running along spar caps and ribs evaporates before reaching and outside exit point. Later sealant products have better resistance to heat and will last longer. Fuel tank leaks problems is not unique to Mooneys but to airplanes in general having rubber based tanks (bladders or sealant).       

José

[HRM]

Quote: Dan

Is it accurate to say.. Its a matter of time before Mooney tanks need to be stripped and resealed?  Is there some percentage that escape this or do ALL vintage Mooneys need this eventually? A few of the planes I have been seeing  tell me the tanks do not leak and have not been stripped. I think they will need it eventually?

Thanks

Dan

[N6843N]

Mine have never been resealed and are in great shape. Its all in how they are cared for. I do not agree with heat being a factor while I have owned my plane it lived in the desert most of the time with summer temps going up to 110+ degree F. I have never parked my plane with out filling the tanks, and I think that is the secret. being full of fuel keeps the sealant temps very stable or at least does not subject them to rapid change which = expansion and contraction. Thats my story and I'm stickin to it.

[231Pilot]

Keeping the tanks full is one big help in dodging the leaking wet wing...avoiding hard landings is another.

[ErickR]

I just did a reseal on my new (to me) m20b left wing... I never want to to that again