A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through an engine accessory gearbox. The bowed rotor prevention system also includes a controller operable to engage the bowed rotor prevention motor and drive rotation of the starting spool until a bowed rotor prevention threshold condition is met or a bowed rotor prevention shutdown request to halt rotation of the starting spool is received.

A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through an engine accessory gearbox. The bowed rotor prevention system also includes a controller operable to engage the bowed rotor prevention motor and drive rotation of the starting spool until a bowed rotor prevention threshold condition is met or a bowed rotor prevention shutdown request to halt rotation of the starting spool is received.

A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a gear train and a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through the gear train at a substantially constant speed upon engine shutdown until an energy storage source is depleted.

A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a gear train and a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through the gear train at a substantially constant speed upon engine shutdown until an energy storage source is depleted.

A bowed rotor start mitigation system for a gas turbine engine is provided. The bow rotor start mitigation system includes a controller operable to receive a speed input indicative of a rotor speed of the gas turbine engine and a measured temperature of the gas turbine engine. The controller is further operable to drive motoring of the gas turbine engine by oscillating the rotor speed within a motoring band for a motoring time based on the measured temperature when a start sequence of the gas turbine engine is initiated.

An aspect includes a hybrid gas turbine engine system of a hybrid electric aircraft. The hybrid gas turbine engine system includes a gas turbine engine having a low speed spool and a high speed spool, a generator operably coupled to the low speed spool, a high spool electric motor operably coupled to the high speed spool, and a controller. The controller is configured to control the hybrid gas turbine engine system in a powered warm-up state to add heat to one or more components of the gas turbine engine by operating the gas turbine engine with a higher engine power setting above idle to drive rotation of the generator, transfer power from the generator to the high spool electric motor, and produce thrust. The gas turbine engine transitions from the powered warm-up state after reaching a target temperature of the one or more components in the powered warm-up state.

An aspect includes a hybrid gas turbine engine system of a hybrid electric aircraft. The hybrid gas turbine engine system includes a gas turbine engine having a low speed spool and a high speed spool, a generator operably coupled to the low speed spool, a high spool electric motor operably coupled to the high speed spool, and a controller. The controller is configured to control the hybrid gas turbine engine system in a powered warm-up state to add heat to one or more components of the gas turbine engine by operating the gas turbine engine with a higher engine power setting above idle to drive rotation of the generator, transfer power from the generator to the high spool electric motor, and produce thrust. The gas turbine engine transitions from the powered warm-up state after reaching a target temperature of the one or more components in the powered warm-up state.

An electric machine and a turning gear system for aircraft gas turbine engines are provided. The system has an electric machine designed for dual mode operation and a controller. The stator winding arrangement in the electric machine enables operation in either generating mode, during normal flight or motoring mode, during active engine turning. The controller is configured to reconfiguration connections of the windings external to the electric machine.

An electric machine and a turning gear system for aircraft gas turbine engines are provided. The system has an electric machine designed for dual mode operation and a controller. The stator winding arrangement in the electric machine enables operation in either generating mode, during normal flight or motoring mode, during active engine turning. The controller is configured to reconfiguration connections of the windings external to the electric machine.

A starter/generator arrangement includes a starter/generator, a power converter electrically connected to the starter/generator, and coolant circuit with a pump and a condenser in fluid communication with the power converter. The power converter is arranged to flow start mode electrical power in a first direction in a start mode and a second direction in a generate mode. The coolant circuit fluidly couples the pump to the condenser for storing heat in a coolant disposed within the coolant circuit while flowing the start mode electrical power in the first direction. Gas turbine engines and methods of cooling starter/generator arrangements are also described.