Abstract: There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has rotating the first shaft at a flight rotation speed when clutched and rotating the second shaft at a first idle rotation speed when unclutched, the first idle rotation speed above the placarded zone; decreasing a rotation speed of the first shaft from the flight rotation speed to a given rotation speed within the placarded zone; decreasing a rotation speed of the second shaft to the given rotation speed; clutching the second shaft; and decreasing the rotation speeds of the first and second shafts to a second idle rotation speed below the placarded zone.

Abstract: A method of operating a multi-engine system of a rotorcraft includes, during a cruise flight segment of the rotorcraft, controlling a first engine to provide sufficient power and/or rotor speed demands of the cruise flight segment; and controlling a second engine to by providing a fuel flow to the second engine that is between 70% and 99.5% less than a fuel flow provided to the first engine. A turboshaft engine for a multi-engine system configured to drive a common load is also described.

Abstract: In an asymmetric operating regime, a first engine is operating in an active mode to provide motive power to an aircraft while a second engine is operating in a standby mode and de-clutched from a gearbox of the aircraft. In response to an emergency exit request, the second engine's speed is increased, at a maximum permissible rate, to a re-clutching speed while increasing the first engine's power output at a maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a maximum permissible rate. In response to a normal exit request, the second engine's speed is increased to the re-clutching speed at a rate lower than the maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a rate lower than the maximum permissible rate.

Abstract: A method of operating a multi-engine system of an aircraft having first and second engines includes accumulating compressed air in a pressure vessel external to the engines, and operating the first and second engines asymmetrically, by controlling the first engine to operate in an active operating condition providing sufficient power and/or rotor speed for demands of the aircraft, and controlling the second engine to operate in a standby operating condition wherein the second engine produces less power output than the first engine. In response to a power demand request, the second engine is accelerated out of the standby operating condition by introducing therein compressed air from the pressure vessel at a location upstream of a combustor of the second engine.

Abstract: A method of operating an engine of an aircraft, the engine having a bleed air system. The method includes in flight, directing pressurized air from a source of pressurized air external to the engine to the bleed air system of the engine. An aircraft, comprising a first engine having a bleed air system, a second engine having a bleed air system, and a source of pressurized air that is external to the first and/or the second engine, the source of pressurized air being selectively fluidly connectable to the bleed air system of the first and/or the second engine, is also disclosed.

Abstract: A method for calibrating a position sensor of a variable vane assembly for a gas turbine engine includes positioning an actuator member in at least one predetermined position, determining a first measured position of the actuator member in the at least one predetermined position with a first channel of a position sensor, determining a second measured position of the actuator member in the at least one predetermined position with a second channel of a position sensor, determining a measured position difference between the first measured position and the second measured position, and calibrating the second channel of the position sensor by adjusting the second measured position by the measured position difference to determine a second calibrated position.

Abstract: The present disclosure provides methods and systems for operating a multi-engine rotorcraft. The method comprises driving a rotor of the rotorcraft with a first engine while a second engine is de-clutched from a transmission clutch system that couples the rotor and the second engine, instructing the second engine to accelerate to a re-clutching speed, and controlling an output shaft speed of the second engine during acceleration of the second engine to the re-clutching speed by applying a damping function to a speed control loop of the second engine.

Abstract: Systems and method for filling a fuel manifold comprising at least a primary and a second manifold of a gas turbine engine are described. The method comprises providing fuel flow to the secondary manifold of the gas turbine engine, the secondary manifold being partly or completely empty; monitoring at least one engine operational parameter of the gas turbine engine as fuel fills the secondary manifold; and accelerating the engine when a transition threshold is reached, the transition threshold being associated with the engine operational parameter and indicative that fuel has reached the combustor.

Abstract: A method is provided involving a turbine engine. During this method, data is received indicative of twist of a shaft of the turbine engine. The data is monitored over time to identity one or more reversal events while the turbine engine is operating, where each of the reversal events corresponds to a reversal in a value sign of the data. Shaft shear is identified in the shaft based on occurrence of N number of the reversal events.

Abstract: The method can include monitoring a current value of a rate of reduction of rotation speed of the shaft; providing a threshold value of a rate of reduction of rotation speed of the shaft; and generating a signal indicative of the shaft shear event when the current value exceeds threshold value.

Abstract: An aircraft engine comprises an air inlet duct extending from an inlet through which air is configured to enter the aircraft engine, to an outlet within the aircraft engine. At least one strut has a leading edge and a trailing edge and extends across at least part of the air inlet duct. The at least one strut has a strut passage and a plurality of static pressure measurement taps spaced apart on the trailing edge and in fluid communication with the strut passage.

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: In an asymmetric operating regime, a first engine is operating in an active mode to provide motive power to an aircraft while a second engine is operating in a standby mode and de-clutched from a gearbox of the aircraft. In response to an emergency exit request, the second engine's speed is increased, at a maximum permissible rate, to a re-clutching speed while increasing the first engine's power output at a maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a maximum permissible rate. In response to a normal exit request, the second engine's speed is increased to the re-clutching speed at a rate lower than the maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a rate lower than the maximum permissible rate.

Abstract: There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has: rotating the first and second shafts at a flight rotation speed above the placarded zone when clutched to a load; decreasing a rotation speed of the first shaft from the flight rotation speed to a first idle rotation speed above the placarded zone; unclutching the first shaft from the load during the decreasing; and subsequently to the decreasing and the unclutching, simultaneously decreasing the rotation speeds of the first shaft and of the second shaft to a second idle rotation speed below the placarded zone, the simultaneously decreasing including clutching the first shaft to the load.

Abstract: There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has rotating the first shaft at a flight rotation speed when clutched and rotating the second shaft at a first idle rotation speed when unclutched, the first idle rotation speed above the placarded zone; decreasing a rotation speed of the first shaft from the flight rotation speed to a given rotation speed within the placarded zone; decreasing a rotation speed of the second shaft to the given rotation speed; clutching the second shaft; and decreasing the rotation speeds of the first and second shafts to a second idle rotation speed below the placarded zone.

Abstract: There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has: rotating the first and second shafts at a first idle rotation speed below the placarded zone when clutched to a load; increasing a rotation speed of the first shaft from the first idle rotation speed to a flight rotation speed above the placarded zone; unclutching the second shaft from the load during the increasing; and increasing a rotation speed of the second shaft to a second idle rotation speed when the second shaft is unclutched from the load, the second idle rotation speed above the placarded zone and below the flight rotation speed.

Abstract: There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has: rotating the first and second shafts at a flight rotation speed above the placarded zone when clutched to a load; decreasing a rotation speed of the first shaft from the flight rotation speed to a first idle rotation speed above the placarded zone; unclutching the first shaft from the load during the decreasing; and subsequently to the decreasing and the unclutching, simultaneously decreasing the rotation speeds of the first shaft and of the second shaft to a second idle rotation speed below the placarded zone, the simultaneously decreasing including clutching the first shaft to the load.

Abstract: In an asymmetric operating regime, a first engine is operating in an active mode to provide motive power to an aircraft while a second engine is operating in a standby mode and de-clutched from a gearbox of the aircraft. In response to an emergency exit request, the second engine's speed is increased, at a maximum permissible rate, to a re-clutching speed while increasing the first engine's power output at a maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a maximum permissible rate. In response to a normal exit request, the second engine's speed is increased to the re-clutching speed at a rate lower than the maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a rate lower than the maximum permissible rate.

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.