There is provided a rotor bow mitigation system and method for an aircraft engine. At least one value of at least one engine parameter prior to a shutdown of the engine is obtained, the at least one engine parameter comprising a first temperature internal to the engine. A second temperature external to the engine is measured and a motoring duration and a motoring interval for the engine are determined based on at least the first temperature and on the second temperature. Upon detecting a start indication for the engine, the engine is motored for the motoring duration and at the motoring interval.

A high efficiency multifunction power system for an aircraft is provided. The system includes an AC generator and a multifunction power converter-controller module including at least one multifunction power converter-controller. The at least one multifunction power converter-controller is configured to function as a power converter and a controller to perform multiple operation modes.

A high efficiency multifunction power system for an aircraft is provided. The system includes an AC generator and a multifunction power converter-controller module including at least one multifunction power converter-controller. The at least one multifunction power converter-controller is configured to function as a power converter and a controller to perform multiple operation modes.

A method of mitigating thermal rotor bow in a rotor assembly of a turbine engine may include performing a plurality of motoring cycles. The plurality of motoring cycles may include receiving feedback on a temperature within a turbine engine in a post-shutdown state, actuating a starter motor when the temperature is greater than a predetermined threshold, operating the starter motor for a motoring time to exhaust some residual heat from the turbine engine, and shutting down the starter motor after the motoring time.

A method of mitigating thermal rotor bow in a rotor assembly of a turbine engine may include performing a plurality of motoring cycles. The plurality of motoring cycles may include receiving feedback on a temperature within a turbine engine in a post-shutdown state, actuating a starter motor when the temperature is greater than a predetermined threshold, operating the starter motor for a motoring time to exhaust some residual heat from the turbine engine, and shutting down the starter motor after the motoring time.

Gas turbine engines and methods of starting gas turbine engines, the gas turbine engine including: an electronic engine controller; one or more spools designated a starting spool for starting the engine, and has a required starting torque τs; a permanent magnet alternator mechanically coupled with the starting spool, the alternator, in a motor mode, provides a peak torque of τa, and, in a generator mode, generates electrical power for the electronic engine controller; and an electrical starter-generator mechanically coupled with the starting spool. The starter-generator in a motor mode, provides a peak torque of τsg, and, in a generator mode, generates electrical power for an external load. τsg+τa≥τs and τsg, τa<τs, and the electronic engine controller, during a start procedure, operates both the permanent magnet alternator and the starter-generator in a motor mode to drive the starting spool.

Gas turbine engines and methods of starting gas turbine engines, the gas turbine engine including: an electronic engine controller; one or more spools designated a starting spool for starting the engine, and has a required starting torque τs; a permanent magnet alternator mechanically coupled with the starting spool, the alternator, in a motor mode, provides a peak torque of τa, and, in a generator mode, generates electrical power for the electronic engine controller; and an electrical starter-generator mechanically coupled with the starting spool. The starter-generator in a motor mode, provides a peak torque of τsg, and, in a generator mode, generates electrical power for an external load. τsg+τa≥τs and τsg, τa<τs, and the electronic engine controller, during a start procedure, operates both the permanent magnet alternator and the starter-generator in a motor mode to drive the starting spool.

The hybrid propulsion system for a multi-engine aircraft includes a plurality of free-turbine engines, each having a gas generator, among which at least a first engine, or hybrid engine, is suitable for operating in at least one standby mode during stabilized flight of the aircraft, while other engines of the plurality of engines operate alone during such stabilized flight. The hybrid engine is associated with first and second identical electric powertrains, each including a respective electrical machine capable of operating as a starter and as a generator, itself connected to a respective electronic power module, itself selectively connected to a specific electrical power supply network, such as an onboard network, and to a respective at least one electrical energy storage member. Each of the electric powertrains is adapted to deliver maximum power not less than half the total power needed for rapid reactivation of the hybrid engine.

The hybrid propulsion system for a multi-engine aircraft includes a plurality of free-turbine engines, each having a gas generator, among which at least a first engine, or hybrid engine, is suitable for operating in at least one standby mode during stabilized flight of the aircraft, while other engines of the plurality of engines operate alone during such stabilized flight. The hybrid engine is associated with first and second identical electric powertrains, each including a respective electrical machine capable of operating as a starter and as a generator, itself connected to a respective electronic power module, itself selectively connected to a specific electrical power supply network, such as an onboard network, and to a respective at least one electrical energy storage member. Each of the electric powertrains is adapted to deliver maximum power not less than half the total power needed for rapid reactivation of the hybrid engine.

An accessory drive for an engine includes a power takeoff (PTO) configured to couple power from a rotating shaft of the engine and to convey the power through an opening in a housing of the engine. A gearbox is coupled to and configured to be driven by the PTO. The gearbox is disposed external to the housing and includes a planetary gear train. At least one engine accessory is coupled to and configured to be driven by the planetary gear train.