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: Additively-manufactured flow restrictors are provided, as are methods for producing additively-manufactured flow restrictors. In various embodiments, the additively-manufactured flow restrictor includes a flowbody through which a flow path extends, a restricted orifice located in the flowbody and providing a predetermined resistance to fluid flowing along the flow path in a first flow direction, and a first internal perforated screen positioned in the flow path upstream of the restricted orifice taken in the first flow direction. The flowbody and the first internal perforated screen integrally formed as a single additively-manufactured piece utilizing, for example, Direct Metal Laser Sintering (DMLS) or another additive manufacturing process. In certain embodiments, the first internal perforated screen may include an endwall and a peripheral sidewall, which is integrally formed with the endwall and spaced from an inner circumferential surface of the flowbody by an annular clearance.

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: Additively-manufactured flow restrictors are provided, as are methods for producing additively-manufactured flow restrictors. In various embodiments, the additively-manufactured flow restrictor includes a flowbody through which a flow path extends, a restricted orifice located in the flowbody and providing a predetermined resistance to fluid flowing along the flow path in a first flow direction, and a first internal perforated screen positioned in the flow path upstream of the restricted orifice taken in the first flow direction. The flowbody and the first internal perforated screen integrally formed as a single additively-manufactured piece utilizing, for example, Direct Metal Laser Sintering (DMLS) or another additive manufacturing process. In certain embodiments, the first internal perforated screen may include an endwall and a peripheral sidewall, which is integrally formed with the endwall and spaced from an inner circumferential surface of the flowbody by an annular clearance.

Abstract: Flow restrictor assemblies including a monolithic flow restrictor and methods for manufacturing the same are provided. The monolithic flow restrictor is configured for disposing in a fluid passage of a housing body. The monolithic flow restrictor comprises a first end and a second end, a first screen at the first end and a second screen at the second end, and a series of cross-sectional portions between the first screen and the second screen. Each cross-sectional portion has a plurality of slots formed in a radially outer surface thereof for connecting a series of restricting orifices formed in the monolithic flow restrictor for tortuously conducting a fluid through the series of cross-sectional portions.

Abstract: A pumping apparatus includes a gear pump in fluid communication with a boost pump. The gear pump includes a pump housing, a first gear, and a second gear. The first and second gear have gear teeth and trunnions on opposite sides thereof, and are disposed in the pump housing. The gear teeth of the first and second gear are meshed in a mesh region. An inlet cavity is defined adjacent to the first and second gear, on one side of the mesh region. A pump outlet is defined on an opposite side of the mesh region from the inlet cavity. A bearing is configured to support at least one trunnion of the first gear and/or the second gear. A bearing interface is defined between the bearing and the at least one trunnion. A flow path is defined between the bearing interface and the inlet cavity.

Abstract: Flow restrictor assemblies including a monolithic flow restrictor and methods for manufacturing the same are provided. The monolithic flow restrictor is configured for disposing in a fluid passage of a housing body. The monolithic flow restrictor comprises a first end and a second end, a first screen at the first end and a second screen at the second end, and a series of cross-sectional portions between the first screen and the second screen. Each cross-sectional portion has a plurality of slots formed in a radially outer surface thereof for connecting a series of restricting orifices formed in the monolithic flow restrictor for tortuously conducting a fluid through the series of cross-sectional portions.

Abstract: A fuel return valve and system includes a flow-level select and shut-off valve and a servo control valve. The flow-level select and shut-off valve includes a first fuel inlet, a second fuel inlet, a return-to-tank fuel outlet, and a valve element movable between a shut-off position, a mid-flow position, and a max-flow position. The servo control valve is coupled to the flow-level select and shut-off valve and is configured to control relative fluid pressures therein to selectively move the valve element to the shut-off position, the mid-flow position, and the max-flow position.

Abstract: An impeller, a centrifugal pump, and an aircraft fuel system are provided. The impeller includes a central hub disposed along a rotational axis of the impeller and that defines an axial bore extending through at least a portion of the central hub along the rotational axis. The central hub further defines an opening to the axial bore at a leading end of the central hub. The impeller further includes an impeller section spaced from the leading end and that includes at least one impeller vane fixed to the central hub. The impeller further includes an inducer section that is disposed between the leading end of the central hub and the impeller section and that includes at least one inducer vane extending along an outer surface of the central hub. The central hub defines at least one radial aperture in the inducer section in fluid communication with the axial bore.

Abstract: A pumping apparatus includes a gear pump in fluid communication with a boost pump. The gear pump includes a pump housing, a first gear, and a second gear. The first and second gear have gear teeth and trunnions on opposite sides thereof, and are disposed in the pump housing. The gear teeth of the first and second gear are meshed in a mesh region. An inlet cavity is defined adjacent to the first and second gear, on one side of the mesh region. A pump outlet is defined on an opposite side of the mesh region from the inlet cavity. A bearing is configured to support at least one trunnion of the first gear and/or the second gear. A bearing interface is defined between the bearing and the at least one trunnion. A flow path is defined between the bearing interface and the inlet cavity.

Abstract: A fuel return valve and system includes a flow-level select and shut-off valve and a servo control valve. The flow-level select and shut-off valve includes a first fuel inlet, a second fuel inlet, a return-to-tank fuel outlet, and a valve element movable between a shut-off position, a mid-flow position, and a max-flow position. The servo control valve is coupled to the flow-level select and shut-off valve and is configured to control relative fluid pressures therein to selectively move the valve element to the shut-off position, the mid-flow position, and the max-flow position.

Abstract: A seal assembly is provided for sealing a gap with a high pressure side and a low pressure side between a first component and a second component. The seal assembly can include a primary seal configured to be arranged on the first component and spanning the gap on the high pressure side between the first and second component; and a backup ring configured to be arranged on the first component adjacent the primary seal on the low pressure side. The backup ring includes an inner diameter and a scarf cut slit at an angle that is a function of the inner diameter of the backup ring.

Abstract: A seal assembly is provided for sealing a gap with a high pressure side and a low pressure side between a first component and a second component. The seal assembly can include a primary seal configured to be arranged on the first component and spanning the gap on the high pressure side between the first and second component; and a backup ring configured to be arranged on the first component adjacent the primary seal on the low pressure side. The backup ring includes an inner diameter and a scarf cut slit at an angle that is a function of the inner diameter of the backup ring.