Abstract: An aircraft includes first and second engines, one or more aircraft rotors associated with the first and second engines, a first epicyclic gearbox having: a) an output operatively connected at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the first epicyclic gearbox; and a second epicyclic gearbox having: a) an output operatively connected to at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the second epicyclic gearbox. Output of the first epicyclic gearbox is defined by the carrier. Output of the second epicyclic gearbox is defined by its ring gear. A multi-engine aircraft and a method of operating a multi-engine aircraft are also described.

Abstract: A gear assembly for a gas turbine engine has an input gear adapted to be secured to a turbine shaft. An output gear is adapted to be secured to a compressor shaft, the input gear and the output gear having the same number of teeth. A pair of idler gear shafts is provided, each said idler gear shaft having a first stage gear meshed with the input gear to be driven by the turbine shaft at a first stage of speed change. A second stage gear is axially spaced from the first stage gear and rotates with the first stage gear. The second stage gear is meshed with the output gear to drive the compressor shaft at a second stage of speed change. Landmarks are provided for aligning the gears during assembly in a desired orientation.

Abstract: A carrier assembly for a planetary gear assembly includes a planet frame defining a central aperture therethrough, the central aperture defining a rotation axis, the planet frame configured to rotatably support a plurality of planet gears, and a carrier connected to the planet frame via a stud. At least one of a portion of the carrier proximate the stud and a portion of the stud between the carrier and the planet frame has a dimension reduction, such as a thickness reduction, therein.

Abstract: An aircraft includes first and second engines, one or more aircraft rotors associated with the first and second engines, a first epicyclic gearbox having: a) an output operatively connected at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the first epicyclic gearbox; and a second epicyclic gearbox having: a) an output operatively connected to at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the second epicyclic gearbox. Output of the first epicyclic gearbox is defined by the carrier. Output of the second epicyclic gearbox is defined by its ring gear. A multi-engine aircraft and a method of operating a multi-engine aircraft are also described.

Abstract: A multi-spool gas turbine engine comprises a low pressure (LP) spool and a high pressure (HP) spool independently rotatable about a central axis extending through an accessory gear box (AGB). The LP spool has an LP compressor, which is axially positioned between the HP compressor of the HP spool and the AGB. A tower shaft drivingly connects the HP spool to the AGB.

Abstract: A carrier assembly for a planetary gear assembly includes a planet frame defining a central aperture therethrough, the central aperture defining a rotation axis, the planet frame configured to rotatably support a plurality of planet gears, and a carrier connected to the planet frame via a stud. At least one of a portion of the carrier proximate the stud and a portion of the stud between the carrier and the planet frame has a dimension reduction, such as a thickness reduction, therein.

Abstract: A gas turbine engine has an in-line mounted accessory gear box (AGB) and an accessory drivingly connected to the AGB, the accessory being oriented transversally to the engine centerline.

Abstract: Apparatus and methods for generating electrical power for powering a device associated with a bladed rotor driven by a gas turbine engine of an aircraft are disclosed. The apparatus includes a rotor shaft coupled the bladed rotor of the aircraft and driven by a turbine shaft of the engine via a speed-reducing gear train. A speed-augmenting power transfer device has an input coupled to the rotor shaft and an output for outputting a rotation speed higher than a rotation speed of the rotor shaft received at the input of the speed-augmenting power transfer device. An electric generator disposed in a hub of the bladed rotor is coupled to the output of the speed-augmenting power transfer device and configured to generate electrical power for the device associated with the bladed rotor.

Abstract: A clutch device for a gas turbine engine having a sliding coupling mounted to the engine and slidingly displaceable therein. The sliding coupling is mountable between the gearbox and the output shaft. The sliding coupling is continuously engageable with the gearbox and is selectively engageable with the output shaft to mechanically couple the output shaft to the gearbox. The sliding coupling is slidingly displaceable between a first position in which the sliding coupling is mechanically coupled to the output shaft to transmit a rotational drive of the output shaft to the gearbox, and a second position in which the sliding coupling is disengaged from the output shaft. A piston is disposed within the engine and acts on the sliding coupling to displace the sliding coupling to at least the second position.

Abstract: A compound engine assembly with an inlet duct, a compressor, an engine core including at least one internal combustion engine, and a turbine section including a turbine shaft configured to compound power with the engine shaft. The turbine section may include a first stage turbine and a second stage turbine. The turbine shaft and the engine shaft are parallel to each other. The turbine shaft, the engine shaft and at least part of the inlet duct are all radially offset from one another. A method of driving a rotatable load of an aircraft is also discussed.

Abstract: A multi-spool gas turbine engine comprises a low pressure (LP) spool and a high pressure (HP) spool independently rotatable about a central axis extending through an accessory gear box (AGB). The LP spool has an LP compressor, which is axially positioned between the HP compressor of the HP spool and the AGB. A tower shaft drivingly connects the HP spool to the AGB.

Abstract: A compound engine assembly with an engine core including at least one internal combustion engine, a compressor, and a turbine section where the turbine shaft is configured to compound power with the engine shaft. The turbine section may include a first stage turbine and a second stage turbine. The turbine shaft is rotationally supported by a plurality of bearings all located on a same side of the compressor rotor(s) and all located on a same side of the turbine rotor(s), for example all located between the compressor rotor(s) and the turbine rotor(s), such that the compressor rotor(s) and the turbine rotor(s) are cantilevered. A method of driving a rotatable load of an aircraft is also discussed.

Abstract: A method of operating a twin engine helicopter power plant, the power plant comprising: two turboshaft engines each having an engine shaft with a turbine at a distal end and a one-way clutch at a proximal end; a gear box having an input driven by the one way clutch of each engine and an output driving a helicopter rotor; a bypass clutch disposed between the proximal end of each engine shaft and the input of the gear box; and power plant management system controls for activating the bypass clutch; the method comprising: detecting when a rotary speed of an associated engine shaft is less than a rotary speed of the gear box input; activating the bypass clutch to drive the associated engine shaft using the rotation of the gear box input; and starting an associated engine by injecting fuel when the bypass clutch is activated.

Abstract: A compound engine assembly with an engine core including at least one internal combustion engine, a turbine section, and a compressor having an outlet in fluid communication with an inlet of the engine core. A casing is connected to the turbine section, compressor and engine core. A mount cage is connected to mounts attached to the casing between the compressor and a hot zone including the turbine section and exhaust pipe(s). The struts are separated from the hot zone by at least one firewall. The mount cage may include a plurality of struts all extending from the mounts away from the turbine section and engine core. The casing may be a gearbox module casing through which the turbine shaft in engaged with the engine shaft. The mount cage may be completely contained within an axial space with the turbine section and exhaust pipe(s) being located outside of the axial space.

Abstract: A compound engine assembly with an engine core including at least one internal combustion engine, a turbine section, and a compressor having an outlet in fluid communication with an inlet of the engine core. A casing is connected to the turbine section, the compressor and the engine core. A mount cage is connected to mounts attached to the casing between the compressor and a hot zone including the turbine section and the engine core. The mount cage includes a plurality of struts all extending from the mounts away from the turbine section and engine core. The casing may be a gearbox module casing through which the turbine shaft in engaged with the engine shaft. The mount cage may be completely contained within an axial space with the turbine section and engine core being located outside of the axial space.

Abstract: A multi-spool gas turbine engine comprises a low pressure (LP) spool and a high pressure (HP) spool independently rotatable about a central axis extending through an accessory gear box (AGB). The LP spool has an LP compressor, which is axially positioned between the HP compressor of the HP spool and the AGB. A tower shaft drivingly connects the HP spool to the AGB.

Abstract: A gear assembly for a gas turbine engine has an input gear adapted to be secured to a turbine shaft. An output gear is adapted to be secured to a compressor shaft, the input gear and the output gear having the same number of teeth. A pair of idler gear shafts is provided, each said idler gear shaft having a first stage gear meshed with the input gear to be driven by the turbine shaft at a first stage of speed change. A second stage gear is axially spaced from the first stage gear and rotates with the first stage gear. The second stage gear is meshed with the output gear to drive the compressor shaft at a second stage of speed change. Landmarks are provided for aligning the gears during assembly in a desired orientation.

Abstract: An engine assembly including an engine core with at least one internal combustion engine, a first casing, a turbine module including a second casing located outside of the first casing, and a compressor module including a third casing located outside of the first and second casings. The turbine shaft extends into the first casing, is rotationally supported by a bearings all contained within the first casing, and is free of rotational support within the second casing. The first casing may be a gearbox module casing through which the turbine shaft is in driving engagement with the engine shaft. A method of driving a rotatable load of an aircraft, and an engine assembly with a rotary engine core, a gearbox module with a first casing, and a second module including a second casing located outside of the first casing and detachably connected to the first casing are also discussed.

Abstract: A reduction gearbox for an aircraft engine, including an input pinion configured to be driven by the aircraft engine, a input gear meshed with the input pinion, a drive gear meshed with the input gear, an output pinion, and an output gear meshed with the output pinion and configured to drive an output shaft of the aircraft engine. The reduction gearbox is selectively configurable between an engaged configuration where the input gear and output pinion are drivingly engaged and a disengaged configuration where the input gear is rotatable independently of the output pinion. The output shaft may drive a propeller and the gearbox may include a propeller brake. A method of driving a generator of a turboprop engine is also discussed.

Abstract: A radial air inlet for a gas turbine engine. The air inlet has an inlet duct defined between two axially-spaced radially-extending annular walls and has a plurality of circumferentially-spaced axially-extending struts extending between the annular walls adjacent a radially-outer portion of the air inlet. At least one of the struts has an internal passage extending between a first opening in a forward end of the strut and a second opening in an aft end of the strut, the first and second openings being axially spaced apart. A transmission shaft extends through the internal passage of said strut.