Sonex Fuel Tank & Oops Fittings

[BRS]

There are four locations on my tank. One large and three small. Two of them are for a fuel sight tube which I don't use (didn't change them) the third small one is for the fuel level probe (not leaking didn't change). I believe the large engine feed fitting leaks because of so much attached to it trying to wiggle it. Not only is there a valve but often times a fuel cube. These put side loads on the fitting.

Follow up and end of the saga (hopefully). Finally my tank (large fitting) is replaced and the loaned tools are headed back to the owner. I used a small amount of fuel-lube (EZ Turn) where the threads and o-ring meet. The idea was that the plastic ends up with scratches the size of the last grit used and I wanted to have a bit of this to help fill them. Tank was leak free the first try. Here is my before/after pic

[tps8903]

There are four locations on my tank. One large and three small. Two of them are for a fuel sight tube which I don't use (didn't change them) the third small one is for the fuel level probe (not leaking didn't change). I believe the large engine feed fitting leaks because of so much attached to it trying to wiggle it. Not only is there a valve but often times a fuel cube. These put side loads on the fitting.

Follow up and end of the saga (hopefully). Finally my tank (large fitting) is replaced and the loaned tools are headed back to the owner. I used a small amount of fuel-lube (EZ Turn) where the threads and o-ring meet. The idea was that the plastic ends up with scratches the size of the last grit used and I wanted to have a bit of this to help fill them. Tank was leak free the first try. Here is my before/after pic

Guess it's my turn to do this. I was going to take the tank out. But maybe I'll just do the main fitting after all.

[Bryan Cotton]

I did the two small ones and the big one in the sump. I didn't bother with the high one.

[tps8903]

I did the two small ones and the big one in the sump. I didn't bother with the high one.

Did you do it in the plane? Or remove the tank?

[Bryan Cotton]

Did you do it in the plane? Or remove the tank?

I did it proactively before tank installation.

[BRS]

I figured now that the large one is done, if needed, the oops fitting could easily be removed if I have to do the two other small ones. Doing the large one in the plane is no picnic. But it helps once you understand the 'neck' and all. Looking at the neck (more of a mound) on the smaller ones, I believe they will be much easier to do.

[DCASonex]

FWIW: It was one of the small ones on the bottom that first started showing leak on mine but then the larger one also started leaking. Drilling out and the large one first leaves and access hole that, makes it easier to work on the small ones.

David A.

[tps8903]

Thanks guys. I ordered all 3 for the bottom of the tank. I loathe being upside down in the foot well of the plane, so I plan to do it once and hopefully never again. I'm going to incorporate all this into my condition inspection for next month.

[tps8903]

FWIW: It was one of the small ones on the bottom that first started showing leak on mine but then the larger one also started leaking. Drilling out and the large one first leaves and access hole that, makes it easier to work on the small ones.

David A.

Sent you a PM for info on borrowing your tools.

[pfhoeycfi]

Be sure to check the most recent rev of the Sonex oops fitting installation instructions where it says not to use the outside o ring.