Patent ID: 6059528
Filing Date: 2000-05-09
Classification: B64C

Abstract:
A system for controlling the blade angle of a plurality of blades of a propeller, said system comprising:an actuator for adjusting the blade angle of the plurality of blades in response to hydraulic pressure;a servo valve disposed in selective fluid communication with said actuator, said servo valve providing hydraulic pressure to said actuator in response to a control signal;an electronic control providing the control signal to actuate said servo valve in response to a plurality of input signals;a protection valve disposed in fluid communication with and intermediate said servo valve and said actuator, said protection valve selectively providing fluid communication between said servo valve and said actuator in response to a protect pressure; anda backup device in fluid communication with said protection valve, said backup device providing a protect pressure to actuate said protection valve in response to a predetermined condition;wherein said backup device includes a low pitch retardation system having a solenoid for releasing a feather latch in response to a retract signal provided by said electronic control.