Abstract: A self-contained apparatus for moving the portions of a cowl covering the gas-generator portion of a turbofan jet engine includes a motor-driven pump for pumping hydraulic fluid from a reservoir mounted on the engine through a control circuit which selectively channels the fluid to actuators associated with each of the cowl portions to move the cowl portions to their desired positions. The hydraulic control circuit preferably includes solenoid-actuated valves associated with each of the actuators and operable to selectively permit flow of fluid into and out of the actuators as is desired to open and close the cowl portions. Another solenoid valve is provided to control passage of the fluid from the actuators back to the reservoir during the closing of the cowl portions. The speed of closure of the cowl portions is regulated by one-way flow restrictors in the outlet ports of the actuators that control the rate of flow of fluid out of the actuator.