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.

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.

A drive unit, particularly for the main rotor of a rotary wing aircraft, comprises: a planetary gear mechanism including a plurality of planetary gears. Each planetary gear has at least one planet wheel with toothing and the planetary gears are arranged concentrically to a central axis inside the planetary gear mechanism so that a rotatable shaft, in particular a rotor shaft of the rotary wing aircraft, can be driven by the planetary gears or the sun wheel. A compact and simplified drive unit can be provided in a very wide range of fields of use, particularly for driving a main rotor of a rotary wing aircraft. This can be achieved in that a first drive, particularly an electric drive, is integrated into at least one planetary gear, comprising a planet wheel and a planet wheel carrier, to form a first drive unit, so that the shaft can be set rotating by the first drive.

A drive unit, particularly for the main rotor of a rotary wing aircraft, comprises: a planetary gear mechanism including a plurality of planetary gears. Each planetary gear has at least one planet wheel with toothing and the planetary gears are arranged concentrically to a central axis inside the planetary gear mechanism so that a rotatable shaft, in particular a rotor shaft of the rotary wing aircraft, can be driven by the planetary gears or the sun wheel. A compact and simplified drive unit can be provided in a very wide range of fields of use, particularly for driving a main rotor of a rotary wing aircraft. This can be achieved in that a first drive, particularly an electric drive, is integrated into at least one planetary gear, comprising a planet wheel and a planet wheel carrier, to form a first drive unit, so that the shaft can be set rotating by the first drive.

A propulsion system is provided, including a first propulsion unit, a second propulsion unit, a rotor, a first coupling and a second coupling. The first propulsion unit is configured for being fixedly mounted to an airframe. The rotor is configured for being pivotably mounted with respect to the first propulsion unit to allow selectively pivoting of the rotor from a horizontal mode to a vertical mode. The first coupling is configured for selectively coupling and decoupling the rotor with respect to the first propulsion unit. The second coupling is configured for selectively coupling and decoupling the rotor with respect to the second propulsion unit, independently of the first coupling.

A method and a device for controlling a coupling mechanism arranged between an engine and a main mechanical power transmission gearbox MGB of a rotary wing aircraft. First determination means enable a first measurement to be taken giving the speed of rotation of said engine, which speed, on being compared with a setpoint speed for said engine, makes it possible to determine a “ready to engage” state for said coupling mechanism. Third determination means serve to determine a maximum torque that can be accepted by said MGB. While engaging the coupling mechanism, a control system for controlling said engine regulates said speed of rotation of said engine on said setpoint speed, while ensuring that the torque delivered by said engine is less than or equal to said maximum acceptable torque.

A hybrid-electric propulsion system for an aircraft is provided herein that can include a propulsor and a turbomachine comprising a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. An auxiliary power unit can be operably coupled with a starter motor. An electrical system can comprise a first electric machine coupled to the turbomachine. The first electric machine can be separate from the starter motor. A controller can be 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.

A hybrid-electric propulsion system for an aircraft is provided herein that can include a propulsor and a turbomachine comprising a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. An auxiliary power unit can be operably coupled with a starter motor. An electrical system can comprise a first electric machine coupled to the turbomachine. The first electric machine can be separate from the starter motor. A controller can be 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.

An engine (100) is provided with a powertrain including a heat engine (1) and an output shaft (A1), an electric motor (2), a battery (40) for supplying the electric motor (2) and a propeller propulsion system including a propeller (3) and a propeller shaft (A3), to which the propeller (3) is coupled. The powertrain includes a system of clutches (E123, E14, E23, E324) designed for different configurations to selectively drive the propeller using the heat engine without transmission of the rotation of the electric motor to the propeller; using the electric motor without transmission of the rotation of the heat engine to the propeller; using combined transmission of the rotation of the heat engine and the rotation of the electric motor to the propeller. The electric motor includes a stator and a rotor mounted for rotation about a shaft rigidly connected, or capable of being coupled, to the propeller shaft.

An engine (100) is provided with a powertrain including a heat engine (1) and an output shaft (A1), an electric motor (2), a battery (40) for supplying the electric motor (2) and a propeller propulsion system including a propeller (3) and a propeller shaft (A3), to which the propeller (3) is coupled. The powertrain includes a system of clutches (E123, E14, E23, E324) designed for different configurations to selectively drive the propeller using the heat engine without transmission of the rotation of the electric motor to the propeller; using the electric motor without transmission of the rotation of the heat engine to the propeller; using combined transmission of the rotation of the heat engine and the rotation of the electric motor to the propeller. The electric motor includes a stator and a rotor mounted for rotation about a shaft rigidly connected, or capable of being coupled, to the propeller shaft.