Thanks for the replies guys. So as I read it, if I were to answer the question as asked, reasons for aircraft to be bonded/grounded but not cars would be:
- higher volumes of flow for aircraft refueling causing potentially greater static charges in the refueling line
- possibility of aircraft systems being still powered on in larger aircraft
- and tyres don't effectively ground anything (I must admit I thought this too)
Are we saying then that for an aircraft fuel pump fixed to the ground (self-service style for example), the supplied bonding cable earths the plane once attached, but for a fuel truck (also with non-conducting rubber tyres), the truck would be both bonded to the aircraft and then in some way grounded itself? Or are we saying that as long as they're bonded together somehow then no sparks should leap across the gap anyway.
And also is there anything in the design of the tanks that makes aircraft refueling more susceptible? E.g. a spark at the fuel filling point on a PA28 or C172 could presumably ignite the vapour over the fuel, whereas on a car any spark wouldn't be immediately above the main body of fuel, which is someway down a pipe and inside the tank?
Apologies if I'm over thinking this - my curiosity has gotten the better of me. And that's what we do here, right?
