Patent ID: 8651425

Claim:
For use with a helicopter including a rotor system having a main rotor with an adjustable pitch that is controlled at least in part by a pilot using a collective control, an apparatus comprising: an actuator arrangement that is configured to change the adjustable pitch by exerting an actuation force from a motor such that the pilot is able to overcome said actuation force using the collective control but which otherwise biases the adjustable pitch into a minimum collective pitch position; and a control arrangement that is configured to receive a signal that is indicative of a low rotor RPM condition and to respond to said signal by activating the actuator arrangement to exert the actuation force; wherein said motor includes a motor shaft and said motor shaft supports an actuator shaft assembly which includes a clutch disk that co-rotates with the motor shaft and a clutch assembly supported by the clutch disk and configured (i) to co-rotate with the actuator shaft assembly in the given direction to serve in transferring the actuation force to reduce the adjustable pitch and (ii) to slip relative to the actuator shaft assembly responsive to an application of a counterforce applied by the pilot to the collective control such that the counterforce overcomes the actuation force to thereby at least maintain a current setting of the adjustable pitch.