There is provided an engine assembly for an aircraft, comprising a heat engine in driving engagement with an engine shaft having a first end coupled to a mechanical gearbox and a second end opposite the first end, an electric generator coupled to the second end to provide a generator output voltage, the electric generator separate from the mechanical gearbox, a power electronics module connected to the electric generator and configured to regulate the generator output voltage to provide a regulated output voltage that meets an electrical power demand of at least one aircraft accessory, and a voltage bus connected to the power electronics module and configured to supply the regulated output voltage to the at least one aircraft accessory.

An engine comprises a first power input and a second power input, a main load, and a transmission engaged with the first power input, the second power input, and the main load. An epicyclic gear train is engaged with the first power input and the main load. A brake in a drive condition engages with the epicyclic gear train to transfer power from the first power input to the main load. The brake in a start condition disengages from the epicyclic gear train to decouple the first power input from the main load. A start assist motor is engaged with part of the transmission separate from the epicyclic gear train. The start assist motor in the start condition rotates the main load to initiate start up of the engine, and in the drive condition prevents transferring power to the main load.

A helicopter turbomachine includes an electric starter motor configured to rotate a drive shaft, a heat sink for cooling the electric motor, and a reversible ventilation wheel driven by the electric motor. The turbomachine also includes an overrunning clutch that transmits the torque from the electric motor to the drive shaft. The electric motor is configured such that, in the first direction of rotation, the motor rotates the drive shaft and the ventilation wheel to generate an air flow through the heat sink in a direct direction, and, in the reverse direction of rotation, the motor rotates only the ventilation wheel to generate an air flow through the heat sink in a direction opposite the direct direction.

A helicopter turbomachine includes an electric starter motor configured to rotate a drive shaft, a heat sink for cooling the electric motor, and a reversible ventilation wheel driven by the electric motor. The turbomachine also includes an overrunning clutch that transmits the torque from the electric motor to the drive shaft. The electric motor is configured such that, in the first direction of rotation, the motor rotates the drive shaft and the ventilation wheel to generate an air flow through the heat sink in a direct direction, and, in the reverse direction of rotation, the motor rotates only the ventilation wheel to generate an air flow through the heat sink in a direction opposite the direct direction.

Disclosed herein are apparatus, assemblies, and methods for mitigating thermal bow in the rotor of an engine at start-up. One apparatus includes a control module that facilitates operating the rotor prior to starting the engine and an acceleration module that facilitates accelerating the rotor to at least a threshold speed prior to starting the engine. An assembly includes a start-up device coupleable to the rotor and configured to start the rotor and a start-up module coupled to the start-up device in which the start-up device and the start-up module are configured to coordinate operations to accelerate the rotor to at least a threshold speed prior to starting the aircraft engine. One method includes transmitting a control signal to control the rotor prior to starting the engine and commanding the start-up device to accelerate the rotor to at least a threshold speed prior to starting the engine.

Disclosed herein are apparatus, assemblies, and methods for mitigating thermal bow in the rotor of an engine at start-up. One apparatus includes a control module that facilitates operating the rotor prior to starting the engine and an acceleration module that facilitates accelerating the rotor to at least a threshold speed prior to starting the engine. An assembly includes a start-up device coupleable to the rotor and configured to start the rotor and a start-up module coupled to the start-up device in which the start-up device and the start-up module are configured to coordinate operations to accelerate the rotor to at least a threshold speed prior to starting the aircraft engine. One method includes transmitting a control signal to control the rotor prior to starting the engine and commanding the start-up device to accelerate the rotor to at least a threshold speed prior to starting the engine.

An engine system includes a gas turbine engine with a first compressor, a first combustor, and a first turbine. The engine system also includes a secondary power unit with a second compressor, a second combustor, a second turbine, a third compressor coupled to the second compressor, and an electric motor-generator, where the secondary power unit is coupled to the gas turbine engine. A controller is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.

An air starter for starting a turbine engine that includes a housing, a turbine member, a drive shaft, and at least one bearing assembly. The housing can define an interior where the turbine couples to the drive shaft that is rotatably supported by the least one bearing assembly. A lubricant passageway can provide lubrication to the at least one bearing assembly.

An air starter for starting a turbine engine that includes a housing, a turbine member, a drive shaft, and at least one bearing assembly. The housing can define an interior where the turbine couples to the drive shaft that is rotatably supported by the least one bearing assembly. A lubricant passageway can provide lubrication to the at least one bearing assembly.

Systems and methods for starting a gas turbine engine can comprise a generator to be driven by the gas turbine engine to supply power to a grid system, a first switch to electrically couple and decouple the generator from the grid system, a first static frequency converter having a first capacity, a second static frequency converter having a second capacity, control means for electrically coupling and decoupling the first and second static frequency converters from the grid system, a synchronizer and a controller configured to operate the generator as a starter-motor with power from: the first static frequency converter to turn the gas turbine engine at a first rate sufficient to start the gas turbine engine within a first time period or the first static frequency converter and the second static frequency converter in synchronization to turn the gas turbine engine at a second rate greater than the first rate.