A variable pitch propeller assembly operatively coupled with an engine and methods for controlling the pitch of a plurality of propeller blades thereof is provided. In one example aspect, the variable pitch propeller assembly includes features for combining overspeed, feathering, and reverse functionality in a single secondary control valve. The secondary control valve is operable to selectively allow a controlled amount of hydraulic fluid to flow to or from a pitch actuation assembly such that the pitch of the propeller blades can be adjusted to operate the variable pitch propeller assembly in one of a constant speed mode, a feather mode, and a reverse mode.

A propeller blade angle control circuit for a turboprop engine includes a propeller control unit controlling a supply of oil to modify an angle of propeller blades, a pump located upstream of the propeller control unit and providing the supply of oil from an engine oil return system to the propeller control unit, and a flow regulator between the pump and the propeller control unit, the flow regulator modulating a supply of oil to the propeller control unit. A bypass, downstream of the pump in the propeller blade angle control circuit, has an inlet fluidly coupled to the pump. The bypass is operable between a closed position and an open position in which a portion of the oil supplied to the propeller control unit is diverted away from the propeller blade angle control circuit. The open position is engaged when an oil pressure reaches a predetermined threshold.

A rotor blade control system includes a main control valve having an inlet for receiving liquid and an outlet for issuing liquid to a rotor pitch change actuator. The main control valve is configured to control flow of liquid from the inlet to the outlet to modify pitch angle of rotor blades. A feathering system has a first conduit in fluid communication with the outlet of the main control valve, a second conduit in fluid communication with the rotor pitch change actuator, and a drain conduit in fluid communication with a liquid return system. The feathering system has a normal operation mode for supplying liquid from the main control valve to the rotor pitch change actuator, and a feathering mode for allowing drainage from the rotor pitch change actuator to the drain conduit across a range of flow rates.

An actuation system is provided for varying the pitch of the blades of a variable pitch fan or propeller. The actuation system includes a first actuator and a second actuator. The actuation system further includes a first linkage which operably connects the first actuator to the blades such that operation of the first actuator varies the pitch of the blades via the first linkage. The actuation system further includes a second linkage which operably connects the second actuator to the first actuator such that operation of the second actuator varies the pitch of the blades by series connection of the second linkage to the first linkage.

A system and method for controlling an aircraft propeller are provided. In anticipation of a condition in which a parameter related to an angle of a plurality of blades of the propeller reaches a value beyond a predetermined threshold, a first control signal is output comprising instructions to actuate a feather valve operatively coupled to an actuator configured to adjust the angle in response to hydraulic pressure, thereby causing the feather valve to provide the hydraulic pressure to the actuator and the angle to be adjusted for bringing the parameter towards the threshold. When the parameter reaches the predetermined threshold, a second control signal is output comprising instructions to hold the feather valve at a position in which the hydraulic pressure is withheld from the actuator, thereby causing the angle to remain unchanged.

A pitch control assembly for adjusting the pitch of a propeller blade, including a pitch control unit comprising a housing, with a plurality of control valves and corresponding hydraulic lines located within the housing, a blade angle unit, a transfer bearing mounted to the housing and having a plurality of hydraulic lines fluidly coupled to the hydraulic lines of the pitch control unit, a transfer tube axially receiving and axially moveable relative to at least a portion of the transfer bearing, a magnetic core sleeve carried by the transfer tube and located within the blade angle unit.

A propeller control unit (PCU) for controlling pitch angles of blades of a propeller, has: a pitch angle actuator; a servo valve hydraulically connected to the pitch angle actuator and to a first hydraulic fluid source; and a feather valve having a body movable within a cavity, the feather valve having a first actuation port and a second actuation port both in fluid communication with the cavity, the body between the first actuation port and the second actuation port, the body being movable to selectively hydraulically connect the pitch angle actuator to the servo valve through the feather valve or to hydraulically connect the pitch angle actuator to a drain line through the feather valve, the first actuation port and the second actuation port hydraulically connected to a second hydraulic fluid source independent from the first hydraulic fluid source.

The invention concerns a hydraulic adjusting device (1, 35) having at least two leakage paths (24, 25) which are connected by a transition channel (27), a sealing arrangement (18) which leads back to a working chamber (10) being provided in one of the leakage paths (24, 25) in delimiting manner relative to the working chamber (10) of the adjusting device (35).

The rotor control system includes a main control valve having an inlet for receiving liquid and an outlet for issuing liquid to a rotor pitch change actuator. The rotor control unit is configured to control flow of liquid from the inlet to the outlet to modify pitch angle of rotor blades. A feathering system with a first conduit connected in fluid communication with the outlet of the main control valve, a second conduit for fluid communication with the rotor pitch change actuator, and a drain conduit. The feathering system has a normal operation mode for supplying liquid from the main control valve to the rotor pitch change actuator by allowing flow through the feathering system from the first conduit to the second conduit. The feathering system has a feathering mode for controlling drainage from the rotor pitch change actuator to the drain conduit.

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).