Abstract: A hybrid-electric propulsion (HEP) system for powering an aircraft is provided that includes a gearbox, a gas turbine engine, and an accessory device. The gearbox includes an input shaft, an output shaft, a drive gear, a layshaft assembly, an accessory device pad, and a planetary gear arrangement. The gas turbine engine is in drive communication with the input shaft of the gearbox. The accessory device is engaged with the accessory device pad. The layshaft assembly includes a layshaft, a first layshaft gear, and a second layshaft gear. The first and second layshaft gears are attached to the layshaft. The first layshaft gear is engaged with the input shaft and the second layshaft gear is engaged with the drive gear. The planetary gear arrangement is engaged with the drive gear. The accessory device is mounted to the accessory device pad and is engaged with the planetary gear arrangement.

Abstract: A method of lubricating a subset of components of an engine of a multi-engine aircraft, the subset of the components being prone to windmilling-induced rotation, the method comprises: when the aircraft is powered on, supplying lubricant to the components from a lubricant tank with a main pump and scavenging the lubricant from the components back to the lubricant tank with a scavenge pump; and when the aircraft engine is shut down during flight: supplying the lubricant to the subset of the components from a lubricant source with a secondary pump; scavenging the lubricant from the subset of the components back to the lubricant source; and preventing the lubricant from flowing through a remainder of the components from the lubricant source.

Abstract: A motorized gear system of a gas turbine engine, having: a reduction gear including: an input shaft, driven by an engine output shaft; a first branch having a first shaft and a first gearset, driven by the input shaft; a second branch having a second shaft and a second gearset, driven by the input shaft; an output shaft, driven by the first branch and the second branch; and wherein the motorized gear system includes a first motor, coupled to the first branch.

Abstract: A rotating seal assembly of a gas turbine engine includes a rotating seal element and a rotationally stationary seal support positioned radially outboard of the rotating seal element. The rotating seal element and the seal support are configured to define a seal interface therebetween. The seal element includes an axial pump portion defined by one or more axially and circumferentially extending grooves to urge an airflow therethrough. The airflow is configured to prevent a fluid from entering the seal interface.

Abstract: A hybrid-electric propulsion (HEP) system for powering an aircraft is provided. The HEP system includes an inlet case, an engine output shaft, a gearbox, a gas turbine engine, an electric motor, and a gear system. The inlet case forms a cavity of the HEP system. The engine output shaft is disposed within the cavity and extends axially along a first rotational axis. The gearbox is in drive communication with the engine output shaft, and the gas turbine engine in drive communication with the engine output shaft. The electric motor is in drive communication with the engine output shaft. At least a portion of the electric motor is disposed within the cavity. The gear system is configured to rotatably engage the electric motor with the engine output shaft.

Abstract: An aircraft engine, has: a low-pressure assembly having first components having first inlets and first scavenge outlets; a high-pressure spool having second components having second inlets and second scavenge outlets; a lubricant system for lubricating the first components and the second components, the lubricant system having: a lubricant tank containing a volume of lubricant; a main pump fluidly connected to the lubricant tank and to the components; and a scavenge pump fluidly connected to the scavenge outlets and to the lubricant tank; and an electric motor drivingly engageable to the main pump, the lubricant system having: a standard configuration in which the electric motor is powered off and in which the main pump is drivingly engaged by a shaft of the aircraft engine; and a windmilling configuration in which the main pump is drivingly engaged by the electric motor.

Abstract: An aircraft engine, has: a low-pressure assembly having first components having first inlets and first scavenge outlets, one of the first components having a lubricant-receiving volume; a high-pressure spool having second components having second inlets and second scavenge outlets; a lubricant system having: a lubricant tank; a main pump and a scavenge pump driving drive a flow of the lubricant; a secondary pump connectable to the volume and an outlet connectable to the first components; valves; the lubricant system having: a standard configuration in which the valves define a standard flow path extending from the lubricant tank to the first inlets and the second inlets via the main pump; and a windmilling configuration in which the valve define a windmilling flow path extending from the lubricant-receiving volume to the first inlets via the secondary pump while bypassing the main pump, and from the first scavenge outlets to the lubricant-receiving volume.

Abstract: A propulsion system includes an engine, a drivetrain, and a propulsor. The engine includes an engine output shaft. The drivetrain is coupled with the engine output shaft. The drivetrain includes a propulsor output shaft, a gear assembly, and an electric motor assembly. The gear assembly includes a propulsor output gear mounted on the propulsor output shaft. The electric motor assembly includes a bevel gear assembly and an electric motor. The bevel gear assembly is rotatable about a second rotational axis. The bevel gear assembly is engaged with the propulsor output gear. The electric motor includes a rotor rotatable about a third rotational axis. The third rotational axis is oriented at an oblique angle relative to the second rotational axis. The rotor is engaged with the bevel gear assembly. The propulsor is interconnected with the propulsor output gear.

Abstract: A hybrid-electric propulsion (HEP) system for powering an aircraft is provided. The system includes a gearbox, a gas turbine engine, and an electric motor. The gearbox includes an input shaft, an output shaft, a drive gear, a first layshaft assembly, a second layshaft assembly, and a first gearbox accessory mount. The gas turbine engine is in drive communication with the input shaft of the gearbox. The electric motor is engaged with the first gearbox accessory mount. The first layshaft (FL) assembly includes a first layshaft, a first FL gear, and a second FL gear. The first and second FL gears are attached to the first layshaft. The first FL gear is engaged with the input shaft and the second FL gear is engaged with the drive gear. The first gearbox accessory mount is in geared communication with the drive gear independent of the first layshaft assembly.

Abstract: The hybrid aircraft power plant can have a load, a thermal engine coupled to drive the load via a clutch, and coupled to drive a first lubricant pump, an electric motor coupled to drive the load and a second lubricant pump. In a first mode, the clutch is in an engaged configuration, and the thermal engine drives the load via the clutch and drives the first lubricant pump. In a second mode, in which the clutch is in the disengaged configuration and in which the thermal engine may be inoperative, the electric motor is operated to drive the load and the second lubricant pump.

Abstract: An aircraft engine has: a low-pressure assembly having first components having first inlets and first scavenge outlets; a high-pressure spool having second components having second inlets and second scavenge outlets; a lubricant system having: a lubricant tank; a main pump and a scavenge pump operable to drive a flow of the lubricant; a secondary pump; and valves; the lubricant system having: a standard configuration in which the valves define a standard flow path extending from the lubricant tank to the first inlets and the second inlets via the main pump; and a windmilling configuration in which the valves define a windmilling flow path extending from the lubricant source to the first inlets via the secondary pump while bypassing the main pump, and from the first scavenge outlets to the lubricant source while bypassing the scavenge pump.

Abstract: A hybrid-electric propulsion system for an aircraft is provided that includes a thermal engine, an electric motor, a propulsion unit, a gearbox, and an electric motor disconnect system. The gearbox has a housing and is configured to receive a first rotational drive input from the thermal engine and a second rotational drive input from the electric motor. The gearbox is also configured to transfer an output rotational drive to the propulsion unit. The electric motor disconnect system is disposed within the housing of the gearbox. The electric motor disconnect system is disposable in a connected state wherein the electric motor is engaged with the gearbox to provide the second rotational drive input to the gearbox, and disposable in a disconnected state wherein the electric motor is disengaged from providing the second rotational drive input to the gearbox.

Abstract: A turboshaft engine transmission with a torque measurement system is provided. The turboshaft engine transmission includes a front housing, a rear housing, a mating flange axially interposed between the front and rear housings, the mating flange defining a sensing bolt hole, assembly bolts disposed to assemble the front and rear housings to the mating flange with a preload sufficient to maintain assembly during engine operational conditions and a sensing bolt installed in the sensing bolt hole to measure forces exerted on the mating flange by the front and rear housings.

Abstract: An aircraft motor assembly is provided and includes a high-power gear, a rear housing from which the high-power gear is exposed, a gear train, which is disposable in multiple orientations relative to the high-power gear, and which includes a first end configured to register with the high-power gear with the gear train disposed in one of the multiple orientations and a second end and a front housing configured to be installed about the high-power gear and the first end of the gear train and to accommodate the second end protruding outwardly from the front housing in a direction that corresponds to the one of the multiple orientations in which the gear train is disposed.

Abstract: A reduction gearbox of an aircraft propulsion system includes an input shaft configured to input rotational energy into the reduction gearbox, an output shaft configured to output rotational energy from the reduction gearbox to a propulsor of the aircraft propulsion system, and an epicyclic gear arrangement mechanically coupling the output shaft to the input shaft. A transfer gear is positioned at a component of the epicyclic gear arrangement and is configured to mechanically couple an accessory component to the reduction gearbox.

Abstract: The hybrid aircraft power plant can have a load, a thermal engine coupled to drive the load via a clutch, and coupled to drive a first lubricant pump, an electric motor coupled to drive the load and a second lubricant pump. In a first mode, the clutch is in an engaged configuration, and the thermal engine drives the load via the clutch and drives the first lubricant pump. In a second mode, in which the clutch is in the disengaged configuration and in which the thermal engine may be inoperative, the electric motor is operated to drive the load and the second lubricant pump.

Abstract: A reduction gearbox of an aircraft propulsion system includes an input shaft configured to input rotational energy into the reduction gearbox, an output shaft configured to output rotational energy from the reduction gearbox to a propulsor of the aircraft propulsion system, and an epicyclic gear arrangement mechanically coupling the output shaft to the input shaft. A transfer gear is positioned at a component of the epicyclic gear arrangement and is configured to mechanically couple an accessory component to the reduction gearbox.

Abstract: The power plant can have a structure; an output shaft connectable to a load, the output shaft rotatable about an axis relative the structure; a thermal engine secured to the structure, the thermal engine having a thermal engine shaft; an electric motor having a stator and a rotor shaft, the stator secured to the structure; an epicyclic gearing having a sun gear coaxial to a ring gear, a plurality of planet gears meshed between the sun gear and the ring gear, and a carrier coaxial to the sun gear and to the ring gear, the sun gear, carrier, and ring gear being rotatable relative the casing structure, the output shaft and the rotor shaft both coupled to the carrier, and the thermal engine shaft coupled to sun gear and the carrier; and an overrunning clutch operable to prevent the rotation of the ring gear in one angular direction.

Abstract: An aircraft motor assembly is provided and includes a high-power gear, a rear housing from which the high-power gear is exposed, a gear train, which is disposable in multiple orientations relative to the high-power gear, and which includes a first end configured to register with the high-power gear with the gear train disposed in one of the multiple orientations and a second end and a front housing configured to be installed about the high-power gear and the first end of the gear train and to accommodate the second end protruding outwardly from the front housing in a direction that corresponds to the one of the multiple orientations in which the gear train is disposed.

Abstract: A spline coupling comprises a male spline member having male spline teeth and a female spline member having female spline teeth complementary to and engaged with the male spline teeth. One or more of the female spline teeth has a tooth height lesser than a tooth height of another one or more of the female spline teeth. The tooth height of the one or more of the female spline teeth is defined by a top land surface of the one or more of the female spline teeth. The tooth height of the other one or more of the female spline teeth is defined by a top land surface of the other one or more of the female spline teeth. A drainage hole in the top land surface of the one or more of the female spline teeth passes through the one or more of the female spline teeth.