HYDRAULIC ACTUATION SYSTEMS

An hydraulic actuation control module is provided for installation in a pitch change actuator of a propeller assembly. The module comprises a flow metering valve arranged to supply hydraulic fluid flow and pressure to an actuator and an electronic control unit arranged to control the flow metering valve. The flow metering valve is arranged to meter hydraulic fluid flow and pressure to increase and decrease pitch chambers of the pitch change actuator, in accordance with the control of the electronic control unit. The flow metering valve is arranged to receive an hydraulic fluid supply from an entity relative to which the propeller assembly rotates such as an engine driving the propeller assembly or aircraft on which the propeller assembly is installed. A propeller assembly comprising the hydraulic actuation control module is also disclosed, together with a method of installing the module within a propeller assembly.