Fuel vent relocation to wing

[GAHorn]

And exactly "why" is a checkvalve required for an overboard vent? Answer: to prevent siphoning for vents which exit below the fuel leve such as underwing vents. A gooseneck has no such problem.

A much simpler (and less-costly STC to develop) method to dispense with the gooseneck (if it's truly a bothersome thing for you) would be to install dual vented gas-caps and remove the gooseneck completely, leaving the crossover vent line intact. (Why worry about an overboard path at all?) Of course, that would require a approval. I"ve got a lot of more interesting/useful things to spend money on before I spend a dime getting rid of a gooseneck. I suspect Steve will have wasted a lot of money if he completes that STC (considering how many folks would really buy it.)