Emergency control system for gas turbine engine variable compressor vanes

Claim 1

In a gas turbine engine, a control for varying the position of the rear compressor vanes comprising fluid controlled actuator means connected with said compressor vanes and adapted to vary the position thereof, a source of pressurized fluid, a first fluid path connecting said fluid source with said actuator means, a second fluid path connecting said fluid source with said actuator means, a first slide valve connected in both said first and second fluid paths, said first slide valve having a first position which permits passage therethrough of the fluid in said first fluid path only, and having a second position which permits passage therethrough of the fluid in said second fluid path only, said first slide valve normally being in said first position, means responsive to selected engine operating conditions for generating a first control signal indicative of desired compressor vane position, servo valve means connected in said first fluid path and responsive to said first control signal for regulating the flow of fluid in said first fluid path to thereby vary the position of said compressor vanes when said first slide valve is in said first position, means for generating a second control signal indicative of desired compressor vane position, and means for connecting said second control signal to said actuator means, said second control signal being adapted to actuate said actuator means and regulate the position of said compressor vanes and regulate the position of said compressor vanes when said first slide valve is moved to said second position.