fuel pump switch

[djpacro]

I have a '79 Decathlon with 150 hp and fixed pitch prop. The Flight Manual does not mention the electric fuel pump in the pre-takeoff checks.

The Pilot's Operating Manual which came with the airplane is from Univair supposedly "a direct copy of the original" from Bellanca. Before takeoff it states turn the fuel pump on. Later in the same manual it states that "Fuel is gravity fed from the tanks to the engine." I was wondering whether it is actually gravity feed to the engine as there is that header tank in the fuselage. If so, then the electric fuel pump is only needed for priming before starting. If not, then I'd expect to turn it on for takeoff.

I believe that the new Flight Manual (for the 180 hp engine & C/S prop) states that the electric pump is required for back-up to the engine-driven pump. Same fuel system as far as I'm aware so it seems that it is not gravity fed?

Any thoughts?

 

[jerrymjr]

Its definately gravity fed.
The Emergency Fuel Pump is just that...a back up to the engine driven pump. So if you are getting low fuel pressure, flip it on.

The Ops (or owners manual) likely has it in there for conservatism. It doesn't hurt to turn it on, its just not doing much when taking off. If the engine driven pump then fails on take off, you should be able to operate normally until you can land. Basically, if your fuel pressure is too low...hit the pump...fly home and see whats wrong.