Examples described herein provide a computer-implemented method that includes controlling a high spool motor of an aircraft to cause the high spool motor to drive rotation of a high speed spool of a gas turbine engine of the aircraft to maintain a desired compressor pressure and a desired flow within a combustor of the gas turbine engine. The method further includes commanding fuel flow to the combustor responsive to a trigger event to cause the gas turbine engine to start to a fuel-burning mode.

An engine system for an aircraft includes a first gas turbine engine, a second gas turbine engine, and a control system. The control system is configured to operate the first gas turbine engine with a sub-idle fuel burn schedule based on detecting landing of the aircraft, where the sub-idle fuel burn schedule includes a reduction of an idle fuel burn schedule. The control system is configured to operate the second gas turbine engine with the idle fuel burn schedule based on detecting landing of the aircraft.

An engine system for an aircraft includes a first gas turbine engine, a second gas turbine engine, and a control system. The control system is configured to operate the first gas turbine engine with an idle fuel burn schedule in a taxi mode of the aircraft and operate the second gas turbine engine with a sub-idle fuel burn schedule in the taxi mode of the aircraft. The sub-idle fuel burn schedule includes a reduction of the idle fuel burn schedule. A fuel flow of the first gas turbine engine and the second gas turbine engine is increased above the idle fuel burn schedule prior to takeoff of the aircraft.

A method of operating a multi-engine aircraft includes operating a first engine of the aircraft to provide motive power; and operating a second engine of the aircraft in a standby mode to provide substantially no motive power, a rotor of the second engine having an idle rotational speed in the standby mode, and in the standby mode, sequentially executing cycles, a given cycle of the cycles including: opening a set of variable guide vanes upstream a compressor section of the second engine, spiking a rate of a fuel flow to a combustor of the second engine, the spiking and the opening timed to increase a rotational speed of the rotor of the second engine to an upper threshold above the idle rotational speed of the rotor, and in response to the rotational speed reaching the upper threshold, at least substantially closing the set of variable guide vanes.

A system and method for increasing power output of a gas turbine. A method of increasing a power output of a gas turbine comprises providing an auxiliary system configured to be coupled to the gas turbine. The auxiliary system includes a natural gas engine, a compressor, and a heat exchanger fluidly coupled to the compressor. The method includes fluidly coupling the auxiliary system to a combustor case of the gas turbine. The method comprises operating the natural gas engine to drive the compressor to compress air to form compressed air and directing exhaust of the natural gas engine to the heat exchanger. The method includes heating the compressed air in the heat exchanger using the exhaust of the natural gas engine to form heated compressed air and injecting the heated compressed air into the combustor case of the gas turbine.

Electrical power systems, including generating capacity of a gas turbine, where additional electrical power is generated utilizing a separately fueled system during periods of peak electrical power demand.

A method of operating a turbofan engine includes coupling an electric motor to drive a fan rotatable within a nacelle, detecting an in-flight operating condition indicative of an increase in drag, and driving rotation of the fan with the electric motor to redirect a flow of air through the nacelle to reduce drag. A turbofan engine is also disclosed.

A system includes a gas turbine engine having a low speed spool, a high speed spool, and a combustor. The system also includes a low spool motor configured to augment rotational power of the low speed spool. The system further includes a controller configured to cause fuel flow. The controller is operable to control the low spool motor to drive rotation of the low speed spool responsive to a thrust command while the controller does not command fuel flow to the combustor.

A method of operating a multi-engine aircraft includes operating a first engine of the aircraft to provide motive power; and operating a second engine of the aircraft in a standby mode to provide substantially no motive power, a rotor of the second engine having an idle rotational speed in the standby mode, and in the standby mode, sequentially executing cycles, a given cycle of the cycles including: opening a set of variable guide vanes upstream a compressor section of the second engine, spiking a rate of a fuel flow to a combustor of the second engine, the spiking and the opening timed to increase a rotational speed of the rotor of the second engine to an upper threshold above the idle rotational speed of the rotor, and in response to the rotational speed reaching the upper threshold, at least substantially closing the set of variable guide vanes.

A propulsion system is disclosed comprising a gas turbine engine and an acceleration schedule which determines the rate of acceleration of the gas turbine engine from an idle condition in response to a demand for increased thrust off-idle. The acceleration schedule determines the rate of acceleration in dependence upon the value of an engine parameter of the engine the value of which is substantially unaltered by variation in the magnitude of an electrical load drawn from the engine while it is operating in the idle condition.