Abstract: The main control servo valve responsive to electrical input signals modulates a power piston to position a throttle valve that varies the flow of fluid during normal operation. A transfer servo valve responsive to the pressure in the servo system moves hard over upon sensing a low pressure signal that is normally lower than the system's pressure to cause the power piston to position the throttle valve closed. In the preferred embodiment the system throttles compressor air of a gas turbine engine to provide an anti-icing function and activates the transfer servo valve upon a hard over malfunction.

Abstract: A fuel metering and actuation system includes a main centrifugal pump 16 supplying fuel to the combustor 18. Gear pump 50 takes suction from the main pump discharge and supplies actuators 42, 44, 45, 46 at high pressure. Variable set point pressure relief valve 56 operates to decrease the gear pump pressure level when high pressure is not required. Selection valve 21 directs discharge from the gear pump 50 to the combustor 18 when the main pump 16 supplied insufficient pressure for the fuel nozzles. Bypass line 30 around the selector valve with check valve 82 permits main pump 16 discharge fuel to be used for the actuator if the gear pump 50 becomes inoperative.

Abstract: An optical sensor (40) located in the manifold area (20) of an augmentor senses the presence of liquid. The engine control provides a high fuel flow rate from remotely located augmentor fuel control (58) until liquid is sensed. Flow is then reduced to the desired metered rate.