Booster pump

An electrically driven centrifugal pump mounted in the bottom of the fuel tanks in large aircraft. Boost pumps are used to provide a positive flow of fuel under pressure to the engine for starting and to serve as an emergency backup in the event the engine-driven pump should fail. They are also used to transfer fuel from one tank to another and to pump fuel overboard when it is being dumped. Boost pumps maintain pressure on the fuel in the line to the engine-driven pump to prevent a vapor lock forming in these lines. Centrifugal boost pumps have a small agitator propeller on top of the pump impeller. This agitator causes the vapors in the fuel to be released before the fuel leaves the tank.