The invention relates to an electric machine, comprising a first rotor (1), a second rotor (2), and a common stator (3), wherein the rotors (1, 2) are disposed axially to each other and are set up for different rotary speeds and/or direction of rotation.

A gas turbine engine has a first spool having a low pressure compressor section disposed forward of an air inlet along a direction of travel of the engine, and a low pressure turbine section disposed forward of the low pressure compressor section and drivingly engaged thereto. A second spool has a high pressure compressor section disposed forward of the low pressure compressor section, and a high pressure turbine section disposed forward of the high pressure compressor section and drivingly engaged thereto. The high pressure turbine section is disposed aft of the low pressure turbine section. An output drive shaft drivingly engages the low pressure turbine section and extends forwardly therefrom to drive a rotatable load. A method of operating a gas turbine engine is also discussed.

A gas turbine engine for an aircraft has an engine core comprising turbine, compressor, and core shaft connecting the turbine to the compressor, the turbine being the lowest pressure turbine of the engine, and having turbine blades, and the compressor being the lowest pressure compressor of the engine; fan located upstream of the engine core; and gearbox that receives an input from the core shaft and outputs drive to the fan. The engine core further has three bearings arranged to support the core shaft, the three bearings having two rearward bearings located downstream of the leading edge of the lowest pressure turbine blade of the turbine at the root of the blade, and/or, when the turbine comprises four sets of turbine blades, downstream of the trailing edge of a turbine blade of the third set of turbine blades from the front of the turbine, at the root of the blade.

An example system for providing mechanical power to an aircraft accessory with a turbine engine, where the turbine engine includes a low-speed spool and a high-speed spool, includes an accessory gearbox disposed between the low-speed spool and the high-speed spool and a clutch disposed within or external to the accessory gearbox. The accessory gearbox is configured to drive the aircraft accessory, and the clutch is configured to enable either the high-speed spool or the low-speed spool to provide mechanical power to the aircraft accessory via the accessory gearbox.

A rotor assembly adapted for a gas turbine engine includes a shaft, a wheel, and a retaining nut. The shaft extends along an axis and includes a first tapered surface. The wheel is arranged circumferentially around the shaft and includes a second tapered surface. The retaining nut is fastened to the shaft and applies an axial force to the wheel to couple the wheel with the shaft.

A method and decoupler for disengaging an output member from an engine in a back drive event with a backdrive decoupler. The backdrive decoupler includes a shaft and a retention mechanism selectively coupling the output member to the shaft. In a backdrive event, the decoupler decouples the member from a drive shaft.

A journal bearing comprising a central member and at least a first end member separated from the central member by a first undercut having an undercut diameter U1, an outer cylindrical surface of the first end member being axially spaced from an outer cylindrical surface of the central member, wherein the outer cylindrical surface of the first end member has a diameter A, the outer cylindrical surface of the central member has a diameter B, and wherein diameter B is greater than diameter A, and diameter A is greater than diameter U1.

A bearing is mounted to a static structure outwardly of the shaft, and supporting the shaft. A bearing compartment is defined by face seal arrangements on each of two axial sides of a bearing. Each face seal arrangement includes a seal seat rotating with the shaft and a non-rotating sealing ring. The seal housing is exposed to high pressure air outward of the bearing compartment. A coil spring biases the seal housing towards the seal seat, such that the sealing face is biased into contact with the seal seat by a bias force including a net fluid force acting on the seal housing and the coil spring. The sealing face is defined by a contact portion contacting the seal seat and a feed portion recessed from the seal seat. The feed portion includes a plurality of circumferentially spaced feed slots fluidly connected to at least one annular groove.

A gas turbine engine with an accessory gearbox. The accessory gearbox has a gear shaft rotatable about a gear shaft axis. The gear shaft has a first end drivingly engaged to a first accessory and a second end drivingly engaged to a second accessory. The gearbox has a spline made of a polymer material and rotatably coupled to one of the first and second ends of the gear shaft, and to a corresponding one of a first and second accessory shafts of the first and second accessories. The spline is rotatable about the gear shaft axis.

A gas turbine engine for an aircraft includes an engine core including a turbine, a compressor, and a core shaft connecting the turbine to the compressor; and a fan located upstream of the engine core. The engine core further includes three bearings arranged to support the core shaft including a forward bearing and two rearward bearings, with a minor span defined as the distance between the two rearward bearings. A minor span to turbine length ratio is equal to or less than 1.05.