Abstract: An assembly for a gas turbine engine of an aircraft includes a rotational assembly, a starter generator, and a control relay. The starter generator is coupled with the rotational assembly. The starter generator is configured to selectively drive rotation of the rotational assembly. The starter generator includes a motor winding including a first electrical terminal and a second electrical terminal. The control relay includes a switch electrically connected to the first electrical terminal. The switch is positionable in a first contact position and a second contact position, in the first contact position, the first electrical terminal is electrically isolated from the second electrical terminal through the switch. In the second contact position, the first electrical terminal is electrically connected to the second electrical terminal through the switch such that a closed electrical circuit is formed through the motor winding, the first electrical terminal, the second electrical terminal, and the switch.

Abstract: Methods and systems for operating an aircraft having two or more engines are described. The method comprises receiving an engine availability confirmation when a set of engine parameters meet engine operating conditions for an asymmetric operating regime, receiving an aircraft availability confirmation when a set of aircraft parameters meet aircraft operating conditions for the asymmetric operating regime, outputting an availability message to a cockpit of the aircraft in response to receiving the engine availability confirmation and the aircraft availability confirmation, receiving a pilot-initiated request to operate the engine in the asymmetric operating regime, and commanding the engines to operate in the asymmetric operating regime in response to the pilot-initiated request.

Abstract: Methods and systems for controlling windmilling in an engine are described. An electric starter motor is coupled to the engine, a circuit element is coupled to the electric starter engine and to a DC signal source, and a control system coupled to the engine and to the circuit element. The control system is configured for: determining whether the engine is in a windmilling state; when the engine is in a windmilling state, commanding the circuit element to apply a DC signal to the electric starter motor; and modulating the DC signal applied to the electric starter motor to control a level of rotational motion of the engine.

Abstract: Methods and systems for operating an aircraft having two or more engines are described. The method comprises operating the two or more engines of the aircraft in an asymmetric operating regime, wherein a first of the engines is in an active mode to provide motive power to the aircraft and a second of the engines is in a standby mode to provide substantially no motive power to the aircraft, receiving a request to exit the asymmetric operating regime, the request having at least one parameter associated therewith, selecting one of a plurality of available exit protocols as a function of the at least one parameter, and applying the exit protocol by commanding the engines accordingly.

Abstract: Systems and methods for operating an engine are described herein. The engine is operated at low power by supplying fuel to a combustor through a first set of fuel nozzles of at least one first manifold and without supplying fuel to the combustor through a second set of fuel nozzles of at least one second manifold. An amount of fuel to at least in part fill the at least one second manifold to impede fuel coking of the second set of fuel nozzles is determined. The amount of fuel is periodically supplied to the at least one second manifold.

Abstract: Methods and systems for operating a gas turbine engine in a multi-engine aircraft are described. The method comprises operating the gas turbine engine in a standby mode to provide substantially no motive power to the aircraft when another engine of the multi-engine aircraft is operated in an active mode to provide motive power to the aircraft, transitioning the gas turbine engine from the standby mode to the non-standby mode, and applying pulse width modulation to an air switching system of the gas turbine engine while transitioning the gas turbine engine from the standby mode to the non-standby mode.

Abstract: The present disclosure provides methods and systems for operating a rotorcraft comprising a plurality of engines configured to provide motive power to the rotorcraft. The rotorcraft is operated in a first flight regime. A target output power range for at least one of the plurality of engines is determined, the target output power range associated with operating the rotorcraft in a second flight regime different from the first flight regime in which at least one first engine of the plurality of engines is operated in an active mode to provide motive power to the rotorcraft and at least one second engine of the plurality of engines is operated in a standby mode to provide substantially no motive power to the rotorcraft. A graphical representation of the target output power range for the second flight regime is produced via a flight display in a cockpit of the rotorcraft.

Abstract: Methods and systems for operating a rotorcraft comprising a plurality of engines are provided. A request to enter into an asymmetric operating regime (AOR), in which at least one active engine of the plurality of engines is operated in an active mode to provide motive power to the rotorcraft and at least one standby engine of the plurality of engines is operated in a standby mode to provide substantially no motive power, is obtained. Engine usage data for the plurality of engines, including at least one first engine and at least one second engine, is determined. Based on the engine usage data, one of the at least one first and second engines is operated as the at least one active engine for the AOR, and the other one of the at least one first and second engines is operated as the at least one standby engine for the AOR.

Abstract: Systems and Methods are described for testing engine performance in-flight in an aircraft having a first engine and a second engine. The method comprises operating the first engine at a first power level in an output speed governing mode, operating the second engine at a second power level greater than the first power level in a core speed governing mode concurrently with the first engine operating at the first power level in the output speed governing mode, and performing an engine performance test on the second engine while the second engine is at the second power level in the core speed governing mode.

Abstract: A method of operating a gas turbine engine having a bleed air system with a switching valve, operable to switch between multiple air sources depending on an operating mode of the gas turbine engine (e.g. a motive powered mode or a standby mode), is described. The method includes operating the switching valve to provide pressurized air from a selected one or more of the multiple air sources to a cavity of the gas turbine engine having seals, and testing the switching valve to determine if the switching valve is functioning normally or abnormally. The switching valve is functioning normally when operable to switch between the multiple air sources and is functioning abnormally when switching between the multiple air sources is not possible. If the switching valve is determined to be functioning abnormally, the gas turbine engine is controlled to prevent a change of the operating mode.

Abstract: A method of determining a state of a switching valve of a bleed air system in a gas turbine engine of an aircraft includes determining a temperature in a main gas path of the gas turbine engine at a location at or downstream of the combustor and then actuating the switching valve of the bleed air system to bleed air from a different bleed location. The temperature is determined after actuating the switching valve. In response to determining that a difference between the temperatures before and after the actuation of the switching valve meets a threshold, executing at least one of a first action and a second action with respect to the gas turbine engine and/or the switching valve.

Abstract: Systems and methods for operating an engine of a rotorcraft are described herein. An engine parameter indicative of torque of the engine is obtained. A decrease of the torque of the engine is detected. At least one rotorcraft parameter indicative of at least one command to control the rotorcraft is obtained and evaluated to determine whether one of an autorotation mode and a powered flight mode of the rotorcraft has been commanded. When the powered flight mode of the rotorcraft has been commanded and the decrease of the torque has been detected, a shaft shear of the engine is detected and a signal indicative of the shaft shear is transmitted. When the autorotation mode of the rotorcraft has been commanded and the decrease of the torque has been detected, detection of the shaft shear is disabled during operation in the autorotation mode.

Abstract: A method of monitoring bleed air provided from a first engine to a second engine of a multi-engine aircraft includes operating the first engine in a powered mode to provide motive power to the multi-engine aircraft; and when the first engine is in the powered mode: actuating an air valve to open an air flow path from a compressor section of the first engine to a plurality of parts of the second engine, after the step of actuating the air valve, determining a change in a temperature in a main gas path of the first engine at a location in the main gas path at or downstream of a combustor of the first engine, and in response to determining that the change is below a threshold, executing an action with respect to the first engine, the air valve, and/or the second engine.

Abstract: The present disclosure provides methods and systems for operating a rotorcraft comprising a plurality of engines configured to provide motive power to the rotorcraft and at least one rotor coupled to the plurality of engines. Failure of an active engine of the rotorcraft is detected when the rotorcraft is operated in an asymmetric operating regime (AOR), in which at least one first engine of the plurality of engines is the active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine of the plurality of engines is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft. At least one flight control input is adjusted to compensate for a reduction in rotational speed of the at least one rotor resulting from the failure of the active engine. An increase in a power output of the standby engine of the rotorcraft is commanded.

Abstract: Systems and methods for operating an engine in a multi-engine rotorcraft are described herein. A first parameter indicative of torque of a first engine is obtained. A decrease of the first parameter is detected. In response to detecting the decrease of the first parameter, an autorotation of the rotorcraft is accommodated, A second parameter indicative of torque of a second engine of the rotorcraft is assessed while accommodating the autorotation. If the second parameter has not decreased, a shaft shear of the first engine is identified and accommodating of the autorotation is ended. If the second parameter has decreased, the accommodating is maintained.

Abstract: Systems and Methods are described for testing engine performance in-flight in an aircraft having a first engine and a second engine. The method comprises operating the first engine at a first power level in an output speed governing mode, operating the second engine at a second power level greater than the first power level in a core speed governing mode concurrently with the first engine operating at the first power level in the output speed governing mode, and performing an engine performance test on the second engine while the second engine is at the second power level in the core speed governing mode.

Abstract: Methods and systems for operating a gas turbine engine in a multi-engine aircraft are described. The method comprises operating the gas turbine engine in a standby mode to provide substantially no motive power to the aircraft when another engine of the multi-engine aircraft is operated in an active mode to provide motive power to the aircraft, transitioning the gas turbine engine from the standby mode to the non-standby mode, and applying pulse width modulation to an air switching system of the gas turbine engine while transitioning the gas turbine engine from the standby mode to the non-standby mode.

Abstract: A method of monitoring bleed air provided from a first engine to a second engine of a multi-engine aircraft includes operating the first engine in a powered mode to provide motive power to the multi-engine aircraft; and when the first engine is in the powered mode: actuating an air valve to open an air flow path from a compressor section of the first engine to a plurality of parts of the second engine, after the step of actuating the air valve, determining a change in a temperature in a main gas path of the first engine at a location in the main gas path at or downstream of a combustor of the first engine, and in response to determining that the change is below a threshold, executing an action with respect to the first engine, the air valve, and/or the second engine.

Abstract: The present disclosure provides methods and systems for operating a rotorcraft comprising a plurality of engines configured to provide motive power to the rotorcraft. The rotorcraft is operated in a first flight regime. A target output power range for at least one of the plurality of engines is determined, the target output power range associated with operating the rotorcraft in a second flight regime different from the first flight regime in which at least one first engine of the plurality of engines is operated in an active mode to provide motive power to the rotorcraft and at least one second engine of the plurality of engines is operated in a standby mode to provide substantially no motive power to the rotorcraft. A graphical representation of the target output power range for the second flight regime is produced via a flight display in a cockpit of the rotorcraft.

Abstract: Systems and methods for operating an engine of a rotorcraft are described herein. An engine parameter indicative of torque of the engine is obtained. A decrease of the torque of the engine is detected. At least one rotorcraft parameter indicative of at least one command to control the rotorcraft is obtained and evaluated to determine whether one of an autorotation mode and a powered flight mode of the rotorcraft has been commanded. When the powered flight mode of the rotorcraft has been commanded and the decrease of the torque has been detected, a shaft shear of the engine is detected and a signal indicative of the shaft shear is transmitted. When the autorotation mode of the rotorcraft has been commanded and the decrease of the torque has been detected, detection of the shaft shear is disabled during operation in the autorotation mode.