| 摘要 |
A pitch change actuation system is disclosed for adjusting the pitch of a variable pitch propeller blades (120) operatively connected for pitch change to a pitch change actuator piston (140). A pitch change control system (10) is operatively connected to the pitch change actuator piston (140) for selectively pressuring the pitch change actuator piston to effectuate a desired change in the pitch of the propeller blades (120). The pitch change control system (10) comprises a primary electrohydraulic valve (30), a protection valve (60), an electronic controller (20) and a protection solenoid (50). During normal operation, the primary electrohydraulic valve (30) is modulated under control of the electronic controller (20) to effect pitch change. In the event of failure of the electronic controller (20), the protection solenoid (50) is operative to activate the protection valve (60) to assume pitch change authority over the primary electrohydraulic valve (30) thereby providing emergency feathering capability, overspeed protection, low pitch stop limit protection, and in place pitchlock despite failure of the electronic controller.
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