Propeller blade pitch control system

A propeller blade pitch control system comprising:

• a propeller hub for mounting at least one propeller blade;
• a propeller shaft which rotates about an axis to rotationally drive the propeller hub;
• a pitch change yoke located within the propeller hub and configured to change a pitch of the at least one propeller blade in response to hydraulic fluid flow to a pitch change actuator;
• a propeller gearbox including a first, rear end and a second, forward end located between the first, rear end and the pitch change yoke, wherein the propeller gearbox is configured to apply torque to the propeller hub, wherein a portion of the propeller gearbox is radially offset from the axis;
• at least one hydraulic flow controller;
• and
• a hydraulic transfer bearing located between the first, rear end and the second, forward end of the propeller gearbox and operable to selectively permit a flow of hydraulic fluid from the at least one hydraulic flow controller to the pitch change actuator, wherein the hydraulic transfer bearing is located at the first, rear end of an interior of the propeller gearbox, and is accessible from a removable cover on the first, rear end of the propeller gearbox or from the interior of the propeller gearbox.

A propeller blade pitch control system comprising:

• a propeller hub for mounting at least one propeller blade;
• a propeller shaft which rotates about an axis to rotationally drive the propeller hub;
• a pitch change yoke located within the propeller hub and configured to change a pitch of the at least one propeller blade in response to hydraulic fluid flow to a pitch change actuator;
• a propeller gearbox including a first, rear end and a second, forward end located between the first, rear end and the pitch change yoke, wherein the propeller gearbox is configured to apply torque to the propeller hub;
• at least one hydraulic flow controller;
• and
• a hydraulic transfer bearing located between the first, rear end and the second, forward end of the propeller gearbox and operable to selectively permit a flow of hydraulic fluid from the at least one hydraulic flow controller to the pitch change actuator, wherein the hydraulic transfer bearing is located at the second, forward end of an interior of the propeller gearbox.

A propeller blade pitch control system comprising:

• a propeller hub for mounting at least one propeller blade;
• a propeller shaft which rotates about an axis to rotationally drive the propeller hub;
• a pitch change yoke located within the propeller hub and configured to change a pitch of the at least one propeller blade in response to hydraulic fluid flow to a pitch change actuator;
• a propeller gearbox including a first, rear end and a second, forward end located between the first, rear end and the pitch change yoke, wherein the propeller gearbox is configured to apply torque to the propeller hub;
• at least one hydraulic flow controller;
• a hydraulic transfer bearing located between the first, rear end and the second, forward end of the propeller gearbox and operable to selectively permit a flow of hydraulic fluid from the at least one hydraulic flow controller to the pitch change actuator;
• and
• a transfer tube located at least partially within the propeller shaft, and extending along the axis, wherein the hydraulic transfer bearing is fluidly connected with the transfer tube to selectively permit the flow of hydraulic fluid from the at least one hydraulic fluid controller to the pitch change actuator, wherein the transfer tube is concentric with the propeller shaft, and co-rotates with the propeller shaft.

A propeller blade pitch control system comprising:

• a propeller hub for mounting at least one propeller blade;
• a propeller shaft which rotates about an axis to rotationally drive the propeller hub;
• a pitch change yoke located within the propeller hub and configured to change a pitch of the at least one propeller blade in response to hydraulic fluid flow to a pitch change actuator;
• a propeller gearbox including a first, rear end and a second, forward end located between the first, rear end and the pitch change yoke, wherein the propeller gearbox is configured to apply torque to the propeller hub;
• at least one hydraulic flow controller, wherein the at least one hydraulic fluid controller includes a protection unit;
• and
• a hydraulic transfer bearing located between the first, rear end and the second, forward end of the propeller gearbox and operable to selectively permit a flow of hydraulic fluid from the at least one hydraulic flow controller to the pitch change actuator.