A method of operating a variable pitch propeller system for an aircraft. The method includes: receiving aircraft flight information; performing a virtual pitch calculation to determine a virtual propeller pitch or virtual blade angle from the aircraft flight information; and performing a pitch protection process in response to low virtual propeller pitch or virtual blade angle being determined.

A hydraulic system for controlling orientation of fan blades in a turbine engine including at least one set of adjustable pitch fan blades actuated by actuators that are connected to a hydraulic pump, and a small pitch protection valve controlled by an associated solenoid valve to make it possible on the ground, when the orientation of the blades is substantially perpendicular to the axis of the turbine engine, to pass from a first operating zone in which a speed of pitch variation of the blades is low to a second operating zone in which a speed of pitch variation is considerably higher, wherein operating pressure of the hydraulic pump is controlled by the solenoid valve controlling the small pitch protection valve to define two outlet levels corresponding to the two operating zones.

A system includes a first mast torque transfer system, a second mast torque transfer system coupled to the first mast torque transfer system, and a torque limiting system. The torque limiting system includes a first sensor configured to determine a torque of the first mast torque transfer system, a second sensor configured to determine a torque of the second mast torque transfer system, and a processor configured to determine a differential torque between the torque of the first mast torque transfer system and the torque of the second mast torque transfer system and configured to control at least one of a torque input and a torque output to at least one of the first and second mast torque transfer systems as a function of the determined differential torque.

A propeller controller for a variable-pitch propeller of an aircraft is provided. The controller is configured to determine a requested oil flow for delivery to a hydraulic actuator of the variable-pitch propeller based on a speed error between an actual rotational speed of the variable-pitch propeller and a set point rotational speed for the variable-pitch propeller, determine a requested oil flow for delivery to the hydraulic actuator based on the speed error, determine a trimmed oil leakage rate out of the hydraulic actuator by multiplying an estimated oil leakage rate out of the hydraulic actuator by a leakage trim multiplier based on the speed error, and combine the trimmed oil leakage rate with the requested oil flow to generate a commanded oil flow. The commanded oil flow is delivered to the hydraulic actuator to adjust the pitch of the variable-pitch propeller.

Systems and methods for controlling a variable-pitch propeller of an aircraft are provided. A method for controlling the variable-pitch propeller includes using a feedback controller, operating the variable-pitch propeller at a current operating condition including a current rotational speed, determining a speed error between the current rotational speed of the variable-pitch propeller and a set point rotational speed for the variable-pitch propeller, determining a gain for the feedback controller based on a power coefficient and an advance ratio of the variable-pitch propeller. Using the feedback controller, a propeller pitch command is determined based on the speed error and using the gain. The pitch of the variable-pitch propeller is adjusted according to the propeller pitch command to reduce the speed error.

A propeller propulsion system includes: a prime mover having at least one spool, a propeller arranged to be driven by the spool, a pitch adjustment subsystem comprising an electronic control unit and an electronic protection unit, a prime mover speed sensor arranged to detect a rotation speed of the spool; and an additional speed sensor arranged to detect the rotation speed of the spool or arranged to detect a rotation speed of the propeller. A first of the electronic control unit and the electronic protection unit is arranged to use an output from the prime mover speed sensor to determine the rotation speed of the propeller; and a second of the electronic control unit and the electronic protection unit is arranged to use an output from the additional speed sensor to determine the rotation speed of the propeller.

Systems and methods for controlling a variable-pitch propeller of an aircraft are provided. A method for controlling the variable-pitch propeller includes using a feedback controller, operating the variable-pitch propeller at a current operating condition including a current rotational speed, determining a speed error between the current rotational speed of the variable-pitch propeller and a set point rotational speed for the variable-pitch propeller, determining a gain for the feedback controller based on a power coefficient and an advance ratio of the variable-pitch propeller. Using the feedback controller, a propeller pitch command is determined based on the speed error and using the gain. The pitch of the variable-pitch propeller is adjusted according to the propeller pitch command to reduce the speed error.

A method of operating a variable pitch propeller system for an aircraft. The method includes: receiving aircraft flight information; performing a virtual pitch calculation to determine a virtual propeller pitch or virtual blade angle from the aircraft flight information; and performing a pitch protection process in response to low virtual propeller pitch or virtual blade angle being determined.