Abstract: A method of performing health monitoring for an aircraft having a variable pitch propeller system. 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; receiving a measured propeller pitch or blade angle from at least one physical sensor associated with the propeller; and using the virtual propeller pitch or virtual blade angle and the measured propeller pitch or blade angle to perform a health monitoring process to determine a health condition of at least one component of the aircraft, wherein the at least one component is distinct from the blades.

Abstract: 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.

Abstract: 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.

Abstract: A method of operating a propeller system for an aircraft. The method includes: receiving propeller speed information, the propeller speed information indicating propeller speed; receiving a target propeller speed; performing a propeller speed threshold adjustment process, the propeller speed threshold adjustment process comprising adjusting a propeller speed threshold as a function of the target propeller speed; comparing the propeller speed to the propeller speed threshold; and in response to propeller speed exceeding the propeller speed threshold, performing an overspeed protection process.

Abstract: 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.

Abstract: A method of performing health monitoring for an aircraft having a variable pitch propeller system. 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; receiving a measured propeller pitch or blade angle from at least one physical sensor associated with the propeller; and using the virtual propeller pitch or virtual blade angle and the measured propeller pitch or blade angle to perform a health monitoring process to determine a health condition of at least one component of the aircraft, wherein the at least one component is distinct from the blades.

Abstract: A method of operating a propeller system for an aircraft. The method includes: receiving propeller speed information, the propeller speed information indicating propeller speed; receiving a target propeller speed; performing a propeller speed threshold adjustment process, the propeller speed threshold adjustment process comprising adjusting a propeller speed threshold as a function of the target propeller speed; comparing the propeller speed to the propeller speed threshold; and in response to propeller speed exceeding the propeller speed threshold, performing an overspeed protection process.