Abstract: 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.

Abstract: 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.

Abstract: A propeller pitch control system for a turboprop engine of an aircraft includes a negative torque sensor, a full feather control valve assembly, and a feather valve assembly. The feather valve assembly is responsive to fluid pressures from the negative torque sensor and the control valve assembly to move between a plurality of positions. An engine control unit or a manual user interface can also be used to control the position of the feather.

Abstract: A propeller pitch control system for a turboprop engine of an aircraft includes a negative torque sensor, a full feather control valve assembly, and a feather valve assembly. The feather valve assembly is responsive to fluid pressures from the negative torque sensor and the control valve assembly to move between a plurality of positions. An engine control unit or a manual user interface can also be used to control the position of the feather.

Abstract: 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.

Abstract: 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.

Abstract: A propeller pitch control actuation system includes a relatively lightweight, relatively inexpensive means for selectively preventing the propeller pitch control actuator from commanding reverse pitch positions.

Abstract: A propeller pitch control actuation system includes a relatively lightweight, relatively inexpensive means for selectively preventing the propeller pitch control actuator from commanding reverse pitch positions.

Abstract: A fuel control system (100) for supplying metered fuel flow to a gas turbine engine is disclosed that includes a variable delivery fuel pump (116) for outputting a fuel flow that includes a burn fuel flow for the gas turbine engine and a surplus fuel flow recirculated back to an inlet (124) of the variable delivery fuel pump (116) and a pump control (148, 158, 122) for controlling the output of the variable delivery fuel pump to maintain the surplus fuel flow at a substantially constant rate. A method of controlling a fuel system (100) is also disclosed.

Abstract: A system and method provide dual level pressurization control of a fuel supply system based on whether fuel is being supplied to one or more secondary fuel loads. Fuel pump discharge backpressure is maintained above either a first minimum pressure value or a lower second minimum pressure value by determining whether fuel is being supplied to one or more secondary fuel loads. The fuel pump discharge pressure is maintained above the first minimum pressure value if it is determined that fuel is being supplied to the one or more secondary loads. The fuel pump discharge backpressure is maintained above the lower second minimum pressure value if it is determined that fuel is not being supplied to the one or more secondary loads.

Abstract: A flow prioritizing system includes a regulating valve and a flow prioritizing valve. The regulating valve receives a first portion of the fluid supplied from a fuel supply pump, and is responsive to a control pressure to selectively allow or prohibit flow to secondary loads. The flow prioritizing control valve is responsive to fluid pressure representative of delivery pump discharge pressure to control the control pressure to which the regulating valve is responsive.

Abstract: A system allows a user to manually manipulate fuel flow to a gas turbine engine during a loss of power to the fuel supply system fuel metering unit. The fuel metering unit includes a fuel metering valve, a metering valve actuator, a fail-fixed valve, a flow increase valve, and a flow decrease valve. The fuel metering unit is configured such that, upon electrical power interruption to the metering valve actuator, the fail-fixed valve shifts and provides a hydraulic lock on the fuel metering valve, to thereby maintain its position. The flow increase and flow decrease valves are powered from a power source that is independent of that used to power the fuel metering unit and, when appropriately energized will allow movement of the fuel metering valve.

Abstract: A system and method provide dual level pressurization control of a fuel supply system based on whether fuel is being supplied to one or more secondary fuel loads. Fuel pump discharge backpressure is maintained above either a first minimum pressure value or a lower second minimum pressure value by determining whether fuel is being supplied to one or more secondary fuel loads. The fuel pump discharge pressure is maintained above the first minimum pressure value if it is determined that fuel is being supplied to the one or more secondary loads. The fuel pump discharge backpressure is maintained above the lower second minimum pressure value if it is determined that fuel is not being supplied to the one or more secondary loads.

Abstract: A thermal recirculation throttle valve (1) for an aircraft fuel system includes a housing (11) having a throttling valve chamber; a cover (5) operatively engaging a first side of the housing (11); a power piston (6) within a power piston sleeve (7), the power piston (6) having a first (21) and second face (22) for control pressure to act upon, the power piston (6) and power piston sleeve (7) operatively engaged with the housing (11) within the throttling valve chamber; a Linear Variable Differential Transformer (15) for measuring a linear position of the power piston (6) within the housing (11); a throttling valve (8) within a throttling valve sleeve (9), the throttling valve (8) operatively engaged with the power piston (60) to transfer the linear movement of the piston (6) between a fully extended and a fully retracted operating position; and a flow deflector (10) engaged with the throttling valve (8) for protecting the housing (11) from flow erosion from fuel exiting flow windows (37).

Abstract: A fuel control system for a gas turbine engine includes a metering valve for metering a flow of fuel, a throttling valve for maintaining a pressure drop across the metering valve, the throttling valve being shiftable between an open state and a shutoff state blocking an outlet of the metering valve, a primary control pressure supply for supplying a primary control pressure to the metering valve for controlling the position of the metering valve, a backup control pressure supply, a transfer valve shiftable between a first position connecting the primary control pressure to supply to the metering valve and a second position connecting the backup control pressure to the metering valve, and an electrohydraulic servovalve (EHSV) operably connected to the throttling valve and the transfer valve and controlling the state of the transfer valve and the position of the throttling valve. Also a method for controlling a transfer valve and a throttling valve.

Abstract: A fuel control system (10) for a gas turbine engine includes a main fuel inlet line (18), an auxiliary fuel inlet line (20) and an engine fuel outlet line (16). A first flow path extends from the main fuel inlet line (18) to the engine fuel outlet line (16) and a second flow path extends from the auxiliary fuel inlet line (20) to the engine fuel outlet line (16). A check valve (22) in the first flow path allows fuel flow through the first flow path in a direction from the main fuel inlet line (18) to the engine fuel outlet line (16) and substantially prevents fuel flow through the first flow path in a direction from the engine fuel outlet line (16) to the main fuel inlet line (18). The check valve (22) is shiftable between a first position connecting the auxiliary fuel inlet (20) to the engine fuel outlet (16) and a second position blocking the second flow path. Also a method of controlling fuel flow in a fuel control system of a gas turbine engine.

Abstract: A flow prioritizing system includes a regulating valve and a flow prioritizing valve. The regulating valve receives a first portion of the fluid supplied from a fuel supply pump, and is responsive to a control pressure to selectively allow or prohibit flow to secondary loads. The flow prioritizing control valve is responsive to fluid pressure representative of delivery pump discharge pressure to control the control pressure to which the regulating valve is responsive.

Abstract: The present invention provides a relatively simple way to automatically turn on and off the fuel to a starter/generator cooling system during engine start. The present invention takes advantage of a fuel pressure rise provided by an engine fuel boost pump during the period from engine start to engine idle conditions. This pressure rise is used to stroke a shutoff valve in a fuel return to tank valve (FRTTV), which shuts off the starter generator cooling fuel flow. This shutoff occurs automatically with no other external input from, for example, an engine controller. A check valve is also included that prevents back flow through the FRTTV in the event of an engine start with no aircraft pumps running.

Abstract: A system allows a user to manually manipulate fuel flow to a gas turbine engine during a loss of power to the fuel supply system fuel metering unit. The fuel metering unit includes a fuel metering valve, a metering valve actuator, a fail-fixed valve, a flow increase valve, and a flow decrease valve. The fuel metering unit is configured such that, upon electrical power interruption to the metering valve actuator, the fail-fixed valve shifts and provides a hydraulic lock on the fuel metering valve, to thereby maintain its position. The flow increase and flow decrease valves are powered from a power source that is independent of that used to power the fuel metering unit and, when appropriately energized will allow movement of the fuel metering valve.

Abstract: An electro-hydraulic servovalve (EHSV) (10) that includes a nozzle (16), a motor (12) operably connected to the nozzle (16) for controlling the position of the nozzle (16) based on current provided to the motor (12), a spool (18) having first and second ends (22,26) slidably mounted in a sleeve (34) having first and second ends (31,33) and a first land (21) near the first end (22), a first passage (40) extending from near the nozzle (16) to the first end (31) of the sleeve (34), a second passage (42) extending from near the nozzle (16) to the second end (33) of the sleeve (34), the spool (18) shifting to a first fail-safe position when the current is below a first predetermined level and latching in a second fail-safe position different than the first fail-safe position when the current exceeds a second predetermined level greater than the first predetermined level.