Abstract: A fuel pump assembly for supplying fuel to a gas turbine engine has a centrifugal pump, including an impeller, that furnishes the necessary pressure for engine operation at high engine speeds. A vane pump, attached to the back side of the impeller of the centrifugal pump, supplies fuel to the engine for starting and acceleration to idle. The vane pump is of the type having a stationary centrally disposed cam and an annular rotor with radially inwardly directed vanes which ride over the surface of the cam. Before idle speed is attained, the vanes which are substantially hydraulically balanced and made of a light plastic material are adapted to lift off the surface of the cam without the need of pressure relief behind the vanes.

Abstract: A fuel pump assembly for a gas turbine engine incorporates an impeller pump and a vane pump which are driven by a common drive shaft. A centrifugally operated clutch functions to disengage the vane pump from the drive shaft at a predetermined angular velocity. The vane pump is designed to fulfill dry lift, starting flow and pressure requirements for the engine. The impeller pump, alone, provides fuel to the engine near idle speed and above after the vane pump has been disengaged from the drive shaft.