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, and sensing an axial movement of the transfer tube with the blade angle unit.

A sensor signal produced by a sensor as a feedback device rotates with a propeller about an axis and moves along the axis with adjustment of a blade angle of the propeller is received, the sensor signal indicative of a rotational speed and of the blade angle of the propeller. From the sensor signal, it is determined whether the rotational speed is within a predetermined range of a reference speed and an expected change in the blade angle has occurred in response to a command to adjust the blade angle to maintain the rotational speed at the reference speed. In response to determining that the rotational speed is within the predetermined range of the reference speed and the expected change in the blade angle has failed to occur in response to the command, inoperable movement of the feedback device along the axis is determined and an alert is output.

A sensor signal produced by a sensor as a feedback device rotates with a propeller about an axis and moves along the axis with adjustment of a blade angle of the propeller is received, the sensor signal indicative of a rotational speed and of the blade angle of the propeller. From the sensor signal, it is determined whether the rotational speed is within a predetermined range of a reference speed and an expected change in the blade angle has occurred in response to a command to adjust the blade angle to maintain the rotational speed at the reference speed. In response to determining that the rotational speed is within the predetermined range of the reference speed and the expected change in the blade angle has failed to occur in response to the command, inoperable movement of the feedback device along the axis is determined and an alert is output.

A failure detection method and system for a propeller control unit coupled to a propeller are provided. An actual value of a blade angle and/or a rotational speed of the propeller are obtained. A comparison between the actual value and a threshold is performed. In response to determining, based on the comparison, that the actual value exceeds the threshold, the propeller control unit is caused to adjust the blade angle to bring the blade angle and/or the rotational speed towards the threshold. A subsequent actual value of the blade angle and/or the rotational speed is obtained. From the subsequent value, it is determined whether the blade angle and/or the rotational speed has been brought towards the threshold. In response to determining that the blade angle and/or the rotational speed has failed to be brought towards the threshold, failure of the propeller control unit is detected and an alert is output.

A failure detection method and system for a propeller control unit coupled to a propeller are provided. An actual value of a blade angle and/or a rotational speed of the propeller are obtained. A comparison between the actual value and a threshold is performed. In response to determining, based on the comparison, that the actual value exceeds the threshold, the propeller control unit is caused to adjust the blade angle to bring the blade angle and/or the rotational speed towards the threshold. A subsequent actual value of the blade angle and/or the rotational speed is obtained. From the subsequent value, it is determined whether the blade angle and/or the rotational speed has been brought towards the threshold. In response to determining that the blade angle and/or the rotational speed has failed to be brought towards the threshold, failure of the propeller control unit is detected and an alert is output.

The invention relates to a control apparatus for a hydraulic variable-pitch propeller (12) of an aircraft, land vehicle or water vehicle, comprising: a hydraulic oil feed line (24); a control line (16) which can be connected to the variable-pitch propeller (12); a pressure generating device (73) which is connected to the hydraulic oil feed line (24) and provides hydraulic oil with a basic pressure; a servo valve (78) which is arranged downstream of the pressure generating device (73), the input pressure to which servo valve is the basic pressure and the output pressure from which servo valve during normal operation defines a control pressure in the control line (16) and which servo valve is connected to a controller (28) which delivers a control signal for changing the control pressure; and pressure reducing means which are arranged downstream of the servo valve (78) and upstream of the control line (16), which are mechanically actuated and which, in the event of a failure of the servo valve (78), change the control pressure in the control line (16).

The invention relates to a control apparatus for a hydraulic variable-pitch propeller (12) of an aircraft, land vehicle or water vehicle, comprising: a hydraulic oil feed line (24); a control line (16) which can be connected to the variable-pitch propeller (12); a pressure generating device (73) which is connected to the hydraulic oil feed line (24) and provides hydraulic oil with a basic pressure; a servo valve (78) which is arranged downstream of the pressure generating device (73), the input pressure to which servo valve is the basic pressure and the output pressure from which servo valve during normal operation defines a control pressure in the control line (16) and which servo valve is connected to a controller (28) which delivers a control signal for changing the control pressure; and pressure reducing means which are arranged downstream of the servo valve (78) and upstream of the control line (16), which are mechanically actuated and which, in the event of a failure of the servo valve (78), change the control pressure in the control line (16).

The present invention relates to a control method in case of engine failure of a hybrid helicopter having a power plant connected to at least one lift rotor and to at least one propeller, said lift rotor having a plurality of first blades and said at least one propeller having a plurality of second blades. The method comprises the following steps: (i) measuring a forward speed of the hybrid helicopter, (ii) on condition that said forward speed is greater than a first speed threshold and that each engine has failed, automatically implementing a first emergency piloting mode comprising a step for automatic reduction by an automatic piloting system of a pitch of said second blades toward an objective pitch making said at least one propeller produce a motive power which is transmitted to the lift rotor.

A propeller oil control system for a turboprop engine of an aircraft includes an engine control unit and a propeller oil controller. The engine control unit is operable to determine a flight phase of the aircraft and is configured to supply control commands. The propeller oil controller is coupled to receive a supply of oil and to discharge the oil at a discharge oil pressure. The propeller oil controller includes an electrohydraulic servo valve that receives the control commands moves to a plurality of positions between a first position and a mid-position, and a plurality of positions between the mid-position and a second position. The engine control unit only commands the electrohydraulic servo valve to move out of the first position when the engine control unit determines the aircraft is conducting a take-off roll or the aircraft is in flight.

A propeller oil control system for a turboprop engine of an aircraft includes an engine control unit and a propeller oil controller. The engine control unit is operable to determine a flight phase of the aircraft and is configured to supply control commands. The propeller oil controller is coupled to receive a supply of oil and to discharge the oil at a discharge oil pressure. The propeller oil controller includes an electrohydraulic servo valve that receives the control commands moves to a plurality of positions between a first position and a mid-position, and a plurality of positions between the mid-position and a second position. The engine control unit only commands the electrohydraulic servo valve to move out of the first position when the engine control unit determines the aircraft is conducting a take-off roll or the aircraft is in flight.