The turboshaft engine for a rotorcraft includes a low pressure spool having a low pressure compressor and a low pressure turbine section, and a high pressure spool having a high pressure compressor and a high pressure turbine section. The spools are independently rotatable relative to one another. The low pressure compressor section includes a mixed flow rotor. A set of variable guide vanes (VGVs) are discposed upstream of each of the low pressure and high pressure compressors, the VGVs being configured to be independently operable relative to one another.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.

A hybrid propulsion system includes a heat engine configured to drive a heat engine shaft. An electric motor is configured to drive an electric motor shaft. A transmission system includes at least one gearbox. The transmission system is configured to receive rotational input power from each of the heat engine shaft and the electric motor shaft and to convert the rotation input power to output power.

A hybrid propulsion system includes a heat engine configured to drive a heat engine shaft. An electric motor is configured to drive an electric motor shaft. A transmission system includes at least one gearbox. The transmission system is configured to receive rotational input power from each of the heat engine shaft and the electric motor shaft and to convert the rotation input power to output power.

A thrust producing unit with a fail-safe electrical drive unit that drives a rotor of a rotary-wing aircraft. Fail-safe electrical drive unit may include input shafts, fixedly attached belt pulleys that are fixedly attached to the respective input shafts, output shaft that is coupled to rotor, freewheeling belt pulleys that are mounted to output shaft by means of respective freewheels such that output shaft rotates freely when output shaft rotates faster than one of the freewheeling belt pulleys belts that connect fixedly attached belt pulleys with the respective freewheeling belt pulleys, and electric motors that are coupled with the respective input shafts.

A rotorcraft has a drive system including a main rotor coupled to a main rotor gearbox to rotate the main rotor at a rotor speed, a main engine coupled to the drive system to provide a first power, a supplemental engine coupled, when a first clutch is engaged, to the drive system to provide a second power additive to the first power, and a control system operable to control the main engine and the supplemental engine to provide a total power demand, where the main engine is controlled based on variations in rotor speed and a power compensation command to produce the first power, and the supplemental engine is controlled to produce the second power in response to a supplemental power demand.

A propulsion system (1) for a helicopter, comprising a turboshaft engine (2) with a linked turbine and an electric machine (3) capable of operating as an electric motor, the turboshaft engine (2) and the electric machine (3) being capable of driving in rotation at least one main rotor (5) intended to be coupled to a rotating wing (6) characterised in that it comprises means of coupling and decoupling (14) in rotation between a rotor (3a) of the electric machine (3) and a rotor (2a) of the turboshaft engine (2), the means of coupling and decoupling (14) being capable of allowing the rotor (2a) of the turboshaft engine (2) to be driven in rotation with the aid of the electric machine (3), in a first state of the propulsion system (1), and capable of allowing the rotor (2a) of the turboshaft engine (2) and the rotor (3a) of the electric machine (3) to be decoupled in rotation, in a second state of the propulsion system (1).

A propulsion system (1) for a helicopter, comprising a turboshaft engine (2) with a linked turbine and an electric machine (3) capable of operating as an electric motor, the turboshaft engine (2) and the electric machine (3) being capable of driving in rotation at least one main rotor (5) intended to be coupled to a rotating wing (6) characterised in that it comprises means of coupling and decoupling (14) in rotation between a rotor (3a) of the electric machine (3) and a rotor (2a) of the turboshaft engine (2), the means of coupling and decoupling (14) being capable of allowing the rotor (2a) of the turboshaft engine (2) to be driven in rotation with the aid of the electric machine (3), in a first state of the propulsion system (1), and capable of allowing the rotor (2a) of the turboshaft engine (2) and the rotor (3a) of the electric machine (3) to be decoupled in rotation, in a second state of the propulsion system (1).

A driveshaft misalignment measurement system for a drivetrain of an aircraft includes a driveshaft having a first end forming a driveshaft spline and a drivetrain subsystem including a spline adapted to connect to the driveshaft spline to form a splined connection. Rotational energy is transferred between the drivetrain subsystem and the driveshaft via the splined connection. The driveshaft misalignment measurement system also includes accelerometers coupled to the drivetrain configured to detect acceleration data and a flight control computer configured to measure misalignment at the splined connection using the acceleration data.

A modular power plant for a rotorcraft comprising at least one lift rotor, the power plant comprising: at least one combustion or electric engine; a main gearbox, comprising a gearbox housing and a toothed wheel arranged in an internal space at least partially delimited by the gearbox housing, the toothed wheel having a degree of rotational freedom about a primary axis of rotation relative to the gearbox housing, the toothed wheel mechanically transmitting an engine torque generated by the at least one engine to the at least one lift rotor; and at least two mechanical connection interfaces, a first mechanical connection interface mechanically connecting the main gearbox to a first engine, and a second mechanical connection interface being left free or mechanically connecting the main gearbox to a second engine.