In one aspect, the present disclosure is directed to a gas turbine starting system that includes a shaft coupling a compressor and a turbine. An annular housing extends circumferentially around the shaft such that the annular housing defines a compartment. A flange extends radially outward from the annular housing for mounting the annular housing to a stationary wall. A starter is positioned in the compartment. A collar rotatably couples to the annular housing and selectively couples to the starter. The collar includes a radially inner surface having a plurality of splines for engaging the shaft. The starter, when activated, rotates the collar, which rotates the shaft to start the gas turbine.

An aspect includes a system for pre-start motoring control for multiple engines of an aircraft. The system includes a first engine starting system of a first engine and a controller. The controller is operable to control a motoring time of the first engine starting system relative to one or more other engine starting systems of one or more other engines of the aircraft by adjusting the motoring time of the first engine starting system within a tolerance of the motoring time of the one or more other engine starting systems in a pre-start motoring sequence.

An aspect includes a system for pre-start motoring control for multiple engines of an aircraft. The system includes a first engine starting system of a first engine and a controller. The controller is operable to control a motoring time of the first engine starting system relative to one or more other engine starting systems of one or more other engines of the aircraft by adjusting the motoring time of the first engine starting system within a tolerance of the motoring time of the one or more other engine starting systems in a pre-start motoring sequence.

There is described a method and system for in-flight start of an engine. The method comprises rotating a propeller; generating electrical power at an electric generator embedded inside a propeller hub from rotation of the propeller; transmitting the electrical power from the electric generator to an engine starter mounted on a core of the engine via an electric power link; and driving the engine with the engine starter to a sufficient speed while providing fuel to a combustor to light the engine to achieve self-sustaining operation of the engine.

There is described a method and system for in-flight start of an engine. The method comprises rotating a propeller; generating electrical power at an electric generator embedded inside a propeller hub from rotation of the propeller; transmitting the electrical power from the electric generator to an engine starter mounted on a core of the engine via an electric power link; and driving the engine with the engine starter to a sufficient speed while providing fuel to a combustor to light the engine to achieve self-sustaining operation of the engine.

A gas turbine engine and methods of operation include a low pressure electric motor-generator arranged for selective operation in a generator mode to generate electrical power or a drive mode to assist rotation of a low pressure drive shaft of the engine.

A gas turbine engine and methods of operation include a low pressure electric motor-generator arranged for selective operation in a generator mode to generate electrical power or a drive mode to assist rotation of a low pressure drive shaft of the engine.

An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.

An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.

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.