1 Fuel Tank Leak – How To Fix ?

[brndiar]

Hi.

I have fuel in the right wheel well (co-pilot site, picture below), but only when right tank is completely full. There is no leak "symptom", when I refuel right tank approx. 1,5-2 inches less.

From pictures it is clear, that right tank has already been repaired.

Where should I start? How "acute" is the problem?

Thanks in advance for your opinion/experiences

lg,m.

 

Edited May 23, 2020 by brndiar

[ArtVandelay]

I would try to patch it. Emptied the tank and have your AP inspect the fuel tank and if the existing sealant looks good then just patch it if it looks bad then I would do a full reseal. I would also clean up your wheel wells, prime and paint it. It desperately needs it.

[67 m20F chump]

Don Maxwell has a good write up on how to put plexiglass over the inspection hole and use soap and water to find the leak.  I can’t tell from that picture but it looks like they didn’t run he proseal wide enough in one spot.  Follow the Maxwell article and hope for the best.

[67 m20F chump]

If you look in the Mooney maintenance manual and read the service bulletin it says how wide the boarders should be.  I think it looks thin to me but I’m only an owner.  I tried to circle an area of interest but it is a thin line.

Edited May 23, 2020 by 67 m20F chump

[brndiar]

Thanks, I found this:

http://donmaxwell.com/fuel-tank-repairs-how-we-fix-them/

what should I use to prime wheel wells after cleaning?

m

[EricJ]

Another way to localize a leak, per the SMM, is to spray soapy water (or soapless bubble fluid if you prefer), in the wheel well where you think it is leaking.   Put the fuel selector in the OFF position, and a hose on the vent tube and blow gently in the hose.   Spray the bubble fluid where you think it might be leaking.   If there's a leak there it'll be fairly obvious (at least it was when I did this).     This tells you generally where the fuel is coming out, but it may have travelled under some sealant to get there, i.e., the patch inside may need to cover more area.

FWIW, my leak is along the top of the outer rib.   It doesn't leak if I leave that tank about three gallons low, so that's what I do. 

Note:  If you use soapy water to find the leak, rinse it thoroughly with clean water afterward.   Otherwise you can mix a soapless bubble fluid using the instructions in the SMM or buy some from Aircraft Spruce.

Edited May 23, 2020 by EricJ

[carusoam]

Heat from the sun is often the source of damaged sealant...

Fuel stains can be left over from prior to the last fix...

It may help to clean things up prior to looking for the new leak...

It may help to not fill the tank all the way while trying to determine where the leak actually is...

Get some pics from inside the tank...

Some sealant projects are best determined from stuff falling off from the inside....

Some sealant years were worse than others...

+1 on all the methodology offered by DMax in the posts above....

My plane went to DMax to solve some leak issues early on... the plane had lived in the SW for a few years.... The top access panels and Seams got some attention....

Hopefully, this is finding the leaky rivets kind of thing... but, you want to know if the problem is larger or involves the whole tank....

If it’s 60s original sealant.... it’s gone a long way so far...  

PP thoughts only, not a mechanic....

Best regards,

-a-