The present disclosure is directed to a turbine engine (10) defining an axial direction, a radial direction, a circumferential direction, a first end (99) and a second end (98) opposite of the first end (99) along the axial direction. The turbine engine includes a propeller assembly (14) proximate to the first end including a plurality of blades (42) arranged in the circumferential direction disposed around an axial centerline (12), and a feathering mechanism (60) including a hollow piston rod (19). The feathering mechanism rotates the plurality of blades about a pitch axis (13) extended in the radial direction from the axial centerline. The turbine engine further includes a housing (45) proximate to the second end disposed in adjacent arrangement with the propeller assembly in the axial direction. The axial centerline is defined through the propeller assembly and the housing. The turbine engine further includes a beta tube assembly (100) extended through the hollow piston rod and at least partially through the housing in coaxial alignment with the axial centerline. The beta tube assembly defines an at least partially hollow walled pipe (101) extended along the axial direction. The beta tube assembly further defines a plurality of grooves (111, 112) extended along the axial direction proximate to the housing. A first groove (111) extends at least partially in the circumferential direction and along the axial direction to at least partially define a helix (114) corresponding to a rotatable range of the plurality of blades about the pitch axis, and a second groove (112) extends in the axial direction.

An actuator is disclosed comprising: a moveable member; a first hydraulic chamber in contact with a first surface of the moveable member; a second hydraulic chamber in contact with a second, opposing surface of the moveable member; a movable locking mechanism coupled to a moveable wall of the second hydraulic chamber; and a resilient biasing member acting on the moveable wall of the second hydraulic chamber so as to bias the moveable wall and locking mechanism. The actuator is configured to selectively vary the pressure in the second hydraulic chamber so that the resilient biasing member is able to bias the moveable wall to move, thereby moving the locking mechanism to engage the moveable member so as to prevent the movement of the moveable member towards at least one of the first and second hydraulic chambers.

An actuator is disclosed comprising: a moveable member; a first hydraulic chamber in contact with a first surface of the moveable member; a second hydraulic chamber in contact with a second, opposing surface of the moveable member; a movable locking mechanism coupled to a moveable wall of the second hydraulic chamber; and a resilient biasing member acting on the moveable wall of the second hydraulic chamber so as to bias the moveable wall and locking mechanism. The actuator is configured to selectively vary the pressure in the second hydraulic chamber so that the resilient biasing member is able to bias the moveable wall to move, thereby moving the locking mechanism to engage the moveable member so as to prevent the movement of the moveable member towards at least one of the first and second hydraulic chambers.

A propeller pitch control system for a turboprop engine of an aircraft includes an engine control unit and a pitch control unit. The engine control unit is operable to determine a phase of flight of the aircraft and is configured to supply control commands. The pitch control unit is coupled to receive the control commands from the engine control unit and includes a housing, a beta piston, a position sensor, a beta tube, and an electrohydraulic valve. The engine control unit only commands the electrohydraulic valve to move the beta piston from the fully retracted position when the engine control unit determines the aircraft is conducting pre-takeoff roll taxiing operations or is conducting post landing touchdown operations.

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 device for locking the pitch and for feathering adjustable-pitch fan blades of a turbine engine propeller, the device including an actuator having at least one movable portion designed to be coupled to pivots of the fan blades of the propeller in order to modify their pitch angle when it slides, a movable part having first mechanical device suitable for co-operating with the actuator when in a fan blade pitch-unlocking position in order to enable the actuator movable portion to slide over an extended actuator stroke; and second mechanical device suitable for co-operating with the actuator when in a fan blade pitch-locking position in order to enable the actuator movable portion to slide over an actuator stroke that is shorter than the extended actuator stroke, and an actuator.

A system for controlling a propeller having a plurality of blades having a primary control system and a backup control system. The primary control system including a sensor responsive to a propeller state, and a controller connected to the sensor and to an electrohydraulic control actuator. The electrohydraulic control actuator connected via a bypass valve to a hydraulic actuator that controls at least a blade angle of a blade of the propeller. The controller generating commands to the electrohydraulic control actuator based on at least the propeller state. The backup control system including a second controller, an electrohydraulic solenoid operably connected to the bypass valve. The backup control system operable to hydraulically disable the primary control system via the bypass valve upon the occurrence of a selected condition, the second controller modulates the operation of the electrohydraulic solenoid to control the bypass actuator based on the propeller state.

A system for changing the pitch of blades of at least one turbomachine rotor is provided. The system generally includes a control means acting on a connecting mechanism connected to the blades of the rotor and having a body mobile in translation along a longitudinal axis with respect to a fixed body, load-transfer bearing mounted on the mobile body cooperating with the connecting mechanism, and means for lubricating the bearing having a lubricant duct and extending radially above the fixed and mobile bodies. The duct generally includes first and second telescopic tubular parts that slide coaxially with respect to one another, the first part connected to the fixed body and the second part connected to the mobile body, and means for spraying lubricant into the bearing mounted on the mobile body and lubricant supply conduit mounted on the mobile body to connect the duct to the spraying means.

A system for changing the pitch of blades of at least one turbomachine rotor is provided. The system generally includes a control means acting on a connecting mechanism connected to the blades of the rotor and having a body mobile in translation along a longitudinal axis with respect to a fixed body, load-transfer bearing mounted on the mobile body cooperating with the connecting mechanism, and means for lubricating the bearing having a lubricant duct and extending radially above the fixed and mobile bodies. The duct generally includes first and second telescopic tubular parts that slide coaxially with respect to one another, the first part connected to the fixed body and the second part connected to the mobile body, and means for spraying lubricant into the bearing mounted on the mobile body and lubricant supply conduit mounted on the mobile body to connect the duct to the spraying means.

An aircraft comprising a fuselage and propelled by a turbine engine having two coaxial and contrarotating fans, the turbine engine comprising a power turbine having two contrarotating rotors, one of which drives a fan upstream from the turbine, the other a fan downstream from the turbine, each fan comprising a ring of blades, and the assembly of the fans and the power turbine being incorporated at the rear of the fuselage, in the extension of same. The aircraft comprises, for at least one of the fans, a device for blocking the rotation of the fan and a device configured to modify the pitch of the blades of the fan in such a way as to make it operate as a flow straightener with respect to the other fan.