A system and method for feathering an aircraft propeller are provided. A first feather solenoid and a second feather solenoid each comprising at least one solenoid coil and a solenoid valve coupled to the actuator and to the at least one solenoid coil are provided. At least one controller is configured to selectively energize and de-energize the at least one solenoid coil. The solenoid valve of the first feather solenoid is configured to be activated when the at least one solenoid coil of the first feather solenoid is energized and the solenoid valve of the second feather solenoid is configured to be activated when the at least one solenoid coil of the second feather solenoid is de-energized. The solenoid valve is configured to, when activated, modulate the supply of hydraulic fluid to an actuator for adjusting a blade pitch of the propeller towards a feather position.

A system and method for feathering an aircraft propeller are provided. A first feather solenoid and a second feather solenoid each comprising at least one solenoid coil and a solenoid valve coupled to the actuator and to the at least one solenoid coil are provided. At least one controller is configured to selectively energize and de-energize the at least one solenoid coil. The solenoid valve of the first feather solenoid is configured to be activated when the at least one solenoid coil of the first feather solenoid is energized and the solenoid valve of the second feather solenoid is configured to be activated when the at least one solenoid coil of the second feather solenoid is de-energized. The solenoid valve is configured to, when activated, modulate the supply of hydraulic fluid to an actuator for adjusting a blade pitch of the propeller towards a feather position.

A system and method for feathering an aircraft propeller are provided. The aircraft propeller is coupled to an actuator for setting a blade pitch of the propeller. The blade pitch is controlled by modulating a supply of hydraulic fluid to the actuator. At least one feather solenoid is provided that comprises a first solenoid coil, a second solenoid coil, and a solenoid valve coupled to the actuator and to the first and the second solenoid coil. At least one controller is configured to selectively energize and de-energize the first and the second solenoid coil. The solenoid valve is configured to be activated when the first solenoid coil and the second solenoid coil are de-energized and to, when activated, modulate the supply of hydraulic fluid to the actuator for adjusting the blade pitch of the propeller towards a feather position.

A system and method for feathering an aircraft propeller are provided. The aircraft propeller is coupled to an actuator for setting a blade pitch of the propeller. The blade pitch is controlled by modulating a supply of hydraulic fluid to the actuator. At least one feather solenoid is provided that comprises a first solenoid coil, a second solenoid coil, and a solenoid valve coupled to the actuator and to the first and the second solenoid coil. At least one controller is configured to selectively energize and de-energize the first and the second solenoid coil. The solenoid valve is configured to be activated when the first solenoid coil and the second solenoid coil are de-energized and to, when activated, modulate the supply of hydraulic fluid to the actuator for adjusting the blade pitch of the propeller towards a feather position.

A method for controlling an aircraft propeller is provided that comprises obtaining a measurement of a speed of the propeller, comparing the propeller speed to a first threshold, responsive to determining that the propeller speed exceeds the speed threshold, outputting a valve control signal for opening a two-position solenoid valve coupled to the propeller, the two-position solenoid valve configured for controlling fluid flow to and from the propeller to control propeller blade angle, computing a rate of change of the propeller speed, comparing the rate of change of the propeller speed to a second threshold, and responsive to determining that the rate of change of the propeller speed is below the second threshold, outputting the valve control signal for closing the two-position solenoid valve. A system for controlling an aircraft propeller and an aircraft propeller control assembly are also provided.

A propeller pitch control system for a turboprop engine of an aircraft includes a negative torque sensor, a full feather control valve assembly, and a feather valve assembly. The feather valve assembly is responsive to fluid pressures from the negative torque sensor and the control valve assembly to move between a plurality of positions. An engine control unit or a manual user interface can also be used to control the position of the feather.

A control circuit for changing the angle of propeller blades includes a propeller pitch change mechanism, and a fixed-displacement pump providing the supply of oil from an engine oil return system. A valve has an outlet port to direct oil from a cavity of the valve, and a pitch port in fluid communication with the pitch change mechanism. A spool of the valve is operable between a first position and a second position to respectively open and close the outlet port, and direct oil flow away from or to the pitch change mechanism.

A control circuit for changing the angle of propeller blades includes a propeller pitch change mechanism, and a fixed-displacement pump providing the supply of oil from an engine oil return system. A valve has an outlet port to direct oil from a cavity of the valve, and a pitch port in fluid communication with the pitch change mechanism. A spool of the valve is operable between a first position and a second position to respectively open and close the outlet port, and direct oil flow away from or to the pitch change mechanism.

A propeller pitch control system for a turboprop engine of an aircraft includes a negative torque sensor, a full feather control valve assembly, and a feather valve assembly. The feather valve assembly is responsive to fluid pressures from the negative torque sensor and the control valve assembly to move between a plurality of positions. An engine control unit or a manual user interface can also be used to control the position of the feather.

A central-positioned pitch control device used in a coaxial helicopter includes an upper propeller hub; a lower propeller hub; a first blade mounted on the outside of the upper propeller hub; a second blade mounted on the outside of the lower propeller hub; and a central-positioned pitch control device placed between the upper propeller hub and the lower propeller hub.