ORIGINAL: siclick33
So would I!!. The 2 reasons for the manual valve, as far as I can see, is that you prevent the engine being flooded when refuelling and so that you have the means to shut off the engine following some form of ECU failure that leaves the pump running. It is a last resort shutoff only if the TX shutoff doesn't work.
Agreed. The pressure generated in the fuel system when refueling the plane certainly is great enough to push fuel past the fuel pump. Come to think of it though, between the fuel pump and the engine is the solonoid shut off valve and that would stop the engine from being flooded.
Assuming that the solonoid valve doesn't leak through, that would leave only one reason for the manual shutoff, it is the last resort.
Correct me if I'm wrong here, but I think the AMA requirement for a shutoff valve is met by the solonoid valve and there is no requirement to ALSO have a manual valve. Either way, I always install one (just in case) and it is ALWAYS closed when I refuel.