Actuating mechanism for a variable pitch fan or propeller

Claim 1

An engine comprising: a bladed rotor having variable pitch fan blades, means for rotating the fan blades about their longitudinal axes to vary their pitch, an actuating mechanism for varying the pitch of said fan blades, said mechanism comprising in combination, a casing, means connecting the casing to the bladed rotor for rotation therewith about the axis of the engine, a hydraulic actuator, a pump, a hydraulic fluid tank for supplying hydraulic fluid to the pump, and a valve supplied with fluid from the pump and selectively operable to supply the fluid to the hydraulic actuator, said actuator, pump, tank and valve all being contained within and rotatable with said casing, means for sealing the casing against egress of said fluid therefrom, means including a splined connection for connecting the actuator to the blade rotating means, means for driving the pump for supplying pressurised fluid to the actuator during normal operation of the engine, auxiliary drive means for selectively providing a second drive to the pump, said auxiliary drive means being disposed externally of the casing of the mechanism and being connected to drive the pump by means of a gear, and said actuating mechanism being a complete module which can be assembled and removed as a unit through disconnection of the splined connection.