There is described herein methods and systems for testing a propeller feathering function. The method comprises monitoring a rotational speed over time of propeller blades of an aircraft, commanding an angle change of the propeller blades, comparing a post-angle change rotational speed of the propeller blades to an expected rotational speed without the commanded angle change and obtaining, by the processor, a rotational speed difference, and issuing a test passed signal when the rotational speed difference exceeds a threshold and a test failed signal when the rotational speed difference does not exceed the threshold.

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).

A method and system for operating a gas turbine engine coupled to an aircraft propeller are described herein. The method comprises detecting a command for unfeathering the propeller, inhibiting shaft shear detection logic in response to detecting the command for unfeathering the propeller, detecting completion of the unfeathering of the propeller, and enabling the shaft shear detection logic in response to detecting the completion of the propeller unfeathering.

The invention relates to a fan module with variable-pitch blades for a turbomachine, comprising a rotor (2) carrying blades (3), a stationary housing (7), a mechanism (11, 12, 13, 14, 20) for regulating the pitch of the blades (3), which is connected to the rotor, and a control means (16, 17) mounted on the stationary housing (7) and comprising a control part (18) that can be moved in translation according to an axis (X) of rotation of the rotor (2), and a bearing (19) for load transfer between the control part (18) and said mechanism, characterised in that it also comprises a stationary track (23) supporting the elastic restoring means (26, 27) which are arranged so as to exert an axial restoring force on the control part (18) towards a determined position, preferably corresponding to the blade (3) feathering.

A system for controlling the pitch of fan blades of a turbine engine propeller, the system including an actuator secured to a casing of the turbine engine, having a movable portion that is movable in translation relative to the casing, the movable portion being mechanically coupled to a load transfer bearing having an outer ring that is coupled to fan blade pivots so that a movement in translation of the movable portion of the actuator leads to a change in the pitch angle of the fan blades, and at least one locking peg secured to the casing of the turbine engine and suitable, in the event of the actuator malfunctioning, for mechanically locking the load transfer bearing in a position wherein the fan blades are feathered.

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 system is provided. The system includes a dual piston actuator and valves. The dual piston actuator includes a primary actuator and a protection actuator. The primary and protection actuators move to increase and decrease a pitch of propellers of an aircraft with respect to a supply of first and second mediums. The valves include a first check valve, a second check valve, and a third valve. The third valve operates between a first mode and a protection mode. The second medium is directed to the primary and protection actuators through the first and second check valves by the third valve when the third valve is operating in a protection mode.

A propeller control unit (PCU) has: a pitch angle actuator; a valve operable to selectively fluidly connect the pitch angle actuator with a source of oil for controlling pitch angles of blades of a propeller and with a drain line for draining oil out of the pitch angle actuator for feathering the blades; and a bypass line having an inlet hydraulically between the valve and an inlet of the drain line, the bypass line having an outlet hydraulically between the inlet of the drain line and an outlet of the drain line.

An exemplary spring-loaded link for an aircraft including a spring interposed between a first and a second rod, the spring, when compressed, urging the first rod and the second rod away from each other.

A counterweight for use in a variable-pitch propeller system (includes a weighted element having walls forming a sealed chamber). The sealed chamber contains a weighting material, and an arm. The counterweight is configured to be coupled to a propeller blade the walls of the weighted element and the arm comprise a single piece, and are an additively manufactured single piece. The weighting material may comprise a powder element. The sealed chamber may have been sealed during the additive manufacturing process, or after the additive manufacturing process has been completed.