shortfielder wrote:I can get 40 gals. in mine on top of the unuseable fuel.
Anyone who believes that all aircraft fuel tanks are identical is apt to wind up with false E/W.
I've seen fairly significant differences in tank capacity in several aircraft types.
BUT, Gary, bear in mind that "Useable Fuel" implies that fuel which the airplane can use in "normal flight". In fact, the new rules require quite a bit more fuel than the old rules, due to requirements to feed fuel in a variety of "flight attitudes". Just because you can drain it out while the plane is sitting in a hangar doesn't necessarily imply that the engine can access that fuel in flight, as in a descent for example.
An example of the new cert rule is the CC Top Cub, which has SIX gallons unuseable fuel, according to CC and their POH.
Nevertheless, after seeing similar airplanes with very different tank capacities, I would always insist on weighing with fuel drained.
MTV