Abstract: A hybrid-electric propulsion system for an aircraft includes a propulsor and a turbomachine. The turbomachine includes a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. The hybrid electric propulsion system further includes an electrical system including a first electric machine, a second electric machine, and an electric energy storage unit electrically connectable to the first and second electric machines. The first electric machine is coupled to the high pressure spool of the turbomachine and the second electric machine is coupled to the propulsor for driving the propulsor to provide a propulsive benefit for the aircraft. The hybrid electric propulsion system also includes a controller configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

Abstract: A start-up system including a control system controlling a partial opening of an air intake valve of a start-up turbine during a first phase of the start-up. The start-up turbine is capable of turning a rotor of the turbomachine for the purpose of the start-up, so as to prevent the rotor from encountering critical frequencies of the turbomachine.

Abstract: A propulsion system for an aircraft includes an electric power source, an electric propulsor assembly having an electric motor and a propulsor configured to generate thrust for the aircraft, and a power bus electrically connecting the electric power source to the electric propulsor assembly such that the electric power source powers the electric propulsor assembly. The power bus includes an electric line and a fluid cooling system, the fluid cooling system extending along at least a portion of a length of the electric line. The fluid cooling system is in thermal communication with the electric line for cooling the electric line during operation and is further in thermal communication with the electric motor of the electric propulsor assembly for cooling the electric motor of the electric propulsor assembly.

Abstract: Systems and methods for shutting down a gas turbine engine in response to a severe mechanical failure include determining a rate of change of one or more process conditions. If the rate of change of the one or more process conditions exceeds a respective predetermined failure threshold, a potential severe mechanical failure of the gas turbine engine may be determined. Steps may be taken to confirm the potential severe mechanical failure of the gas turbine engine. In response, an engine restart is prevented.

Abstract: A method of operating a turbine engine that includes actuating a starter motor of the turbine engine such that a motoring speed of the turbine engine increases, and actuating a plurality of variable stator vanes of the turbine engine such that the plurality of variable stator vanes are at least partially open to control the motoring speed of the turbine engine.

Abstract: A method of operating a turbine engine that includes shutting down the turbine engine such that a rotational speed of the turbine engine decreases, and actuating a starter motor of the turbine engine at one of as the rotational speed of the turbine engine decreases or at a preset time after the turbine engine receives a full stop command such that residual heat is exhausted from the turbine engine.

Abstract: A method of starting a gas turbine engine having a rotor comprising at least a shaft mounted compressor and turbine, with a casing surrounding the rotor.