Fuel leak from wing vents
We have noticed that fuel escapes from at least one wing fuel tank vent/filler unit when that wing is lower than the other when on the ground. It takes very little difference in wing height for this to happen and of course tends to happen when both tanks are reasonably full. It is also a concern that when banking in flight, this could also cause fuel loss. From the construction manual, we are under the impression that the vents have some sort of ball in the tube system that acts as a one way valve and you should be able to shake the vent tubes and hear this rattle. We cannot hear a rattle! Does this mean the vents are faulty, or need maintenance?
Hi, yes it could mean this. One thing you could do is take the cap apart so that you and push a rod up the vent tube. If it goes all the way up to where the holes are, there is no ball. Otherwise the only way to tell if the ball is in, seeing as the other tests failed, is to disassemble the vent.
The leaking of fuel is mainly an issue on the ground as most flight is pretty balanced, even in turns.
Thanks for the reply. I have poked a stiff bit of wire up each vent tube and it ends just where the thicker portion meets the the thinner bit with the breather holes. On this basis, there are no balls? Talking to other owners, it seems that not all vents are of the same design and you may have manufactured some aircraft with a tank venting tube that does not have these plastic ball bearings in the tube. Our kit was purchased in July 2019, an early Gen 4 engine serial 33A. 2841, can you say whether our J430 is likely to have the non-valved vent tubes?? This will help us decide whether to buy them and try to disassemble the tubes somehow!