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.

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 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.

The present disclosure is directed to a system 100 for feathering a propeller assembly 14, wherein the system is disposed within a housing 47 of the propeller assembly. The system 100 includes a sleeve 110 defining an outer wall 111 and one or more sleeve tabs 115 extended outward in a radial direction along at least a circumferential portion of the sleeve, wherein the one or more sleeve tabs is separated from the outer wall in an axial direction. The system 100 further includes a retainer 120 defining one or more retainer tabs 125 extended inward in the radial direction, wherein the one or more retainer tabs is disposed between the outer wall 111 and the one or more sleeve tabs 115 of the sleeve 110 along the axial direction. Still further, the system includes a beta tube assembly 130 extended through the sleeve along the axial direction, wherein the beta tube assembly defines one or more internal walls 131, wherein the one or more internal walls defines a hydraulic fluid transfer cavity 132 in fluid communication with one or more hydraulic fluid transfer orifices 133.

A gas turbine engine including: a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order; a fan defining a fan axis and comprising a plurality of fan blades rotatable about the fan axis; and a pitch change mechanism operable with the plurality of fan blades, the pitch change mechanism including a plurality of linkages, the plurality of linkages including a first linkage coupled to a first fan blade of the plurality of fan blades and a second linkage coupled to a second fan blade of the plurality of fan blades; and a non-uniform blade actuator system operable with one or more of the plurality of linkages to control a pitch of the first fan blade relative to a pitch of the second fan blade.

A method of controlling a propeller assembly, having a blade, piston end cap, and piston, with a pitch control unit, having a transfer bearing and a blade angle unit, the method comprising: axially moving a transfer tube relative to and circumscribing the transfer bearing, sensing an axial movement of the transfer tube with the blade angle unit.

A method of controlling a propeller assembly, having a blade, piston end cap, and piston, with a pitch control unit, having a transfer bearing and a blade angle unit, the method comprising: axially moving a transfer tube relative to and circumscribing the transfer bearing, sensing an axial movement of the transfer tube with the blade angle unit.

A control system for an engine operatively coupled with a propeller and methods for controlling an engine operatively coupled with a propeller are provided. In one example aspect, the control system includes a controller and an electric propeller governor. The electric propeller governor includes a motor operatively coupled with a flyweight governor spring. The motor is communicatively coupled with the controller. The controller is operable to receive data indicative of the speed of the propeller, determine if the measured speed exceeds a propeller speed threshold, and if the threshold is exceeded, the controller is configured to change a propeller speed set point. Particularly, the controller can cause the motor to change the preload on the flyweight governor spring, which in turn causes adjustment of the propeller speed set point. In this way, propeller speed overshoot is prevented during fast acceleration of the engine.