Thread: Fuel leaks in the wing.

I am interested to know if anyone else has had the problem I found during a recent 100 hourly.
When the underwing inspection plates were removed it became evident that a leakage of fuel had been occurring from the "T" in the breather or tank vent system. This "T" in the vent system connects two metal pipes with a plastic pipe.
The plastic pipe is "flared" and attached to the "T"... only problem is that this "T" is an aluminium AN fitting and should never be used on plastic pipe. The "flare" in the plastic pipe had been sheared off by tightening of the nut and this allowed the plastic pipe to partially withdraw from the fitting resulting in a leak. Obviously the problem has only occurred when operating with full tanks.
The fix was easy, but shouldn't be necessary. A short piece of 5/16" diam tube was flared and fitted to the AN "T" piece. A piece of 5/16" ID fuel hose was then used as a joiner between the short metal tube and the plastic pipe using hose clamps. Both wings had the same problem.

Were you getting any smell in the cabin on the ground or in flight?

We thought we could smell fumes very occasionally in flight, but only early in the flight. This makes sense because as the fuel level drops the chance of it getting into the vent system and leaking via the sheared pipe also drops. The fumes could enter the cabin through the wing rib holes etc. Visual evidence of the leak was a coating developing over the clear under wing cover plate.
I don't want to make this out as a big problem, just so others are aware that it can happen.
If it does happen the cure is simple and takes only a very short time to correct. We have also experienced fuel leaking from the winglet vent (aircraft was level at the time) on the same side as the sheared vent pipe, but again this could be associated with the tanks being extremely full.
Will be doing a flight next week with full tanks so it will be interesting to see the results of our fix.

We have experienced similar events. Since we started 'toping off' at the 16.5gal level we appear to of solved the 'leak and smell' situation... That leads me to believe that there is some type of seeping when very full and sitting in very warm hangar.