The hybrid propulsion system for a multi-engine aircraft includes a plurality of free-turbine engines, each having a gas generator, among which at least a first engine, or hybrid engine, is suitable for operating in at least one standby mode during stabilized flight of the aircraft, while other engines of the plurality of engines operate alone during such stabilized flight. The hybrid engine is associated with first and second identical electric powertrains, each including a respective electrical machine capable of operating as a starter and as a generator, itself connected to a respective electronic power module, itself selectively connected to a specific electrical power supply network, such as an onboard network, and to a respective at least one electrical energy storage member. Each of the electric powertrains is adapted to deliver maximum power not less than half the total power needed for rapid reactivation of the hybrid engine.

The hybrid propulsion system for a multi-engine aircraft includes a plurality of free-turbine engines, each having a gas generator, among which at least a first engine, or hybrid engine, is suitable for operating in at least one standby mode during stabilized flight of the aircraft, while other engines of the plurality of engines operate alone during such stabilized flight. The hybrid engine is associated with first and second identical electric powertrains, each including a respective electrical machine capable of operating as a starter and as a generator, itself connected to a respective electronic power module, itself selectively connected to a specific electrical power supply network, such as an onboard network, and to a respective at least one electrical energy storage member. Each of the electric powertrains is adapted to deliver maximum power not less than half the total power needed for rapid reactivation of the hybrid engine.

A system and a method for the automatic starting of the engines of a twin-engine aircraft. When a first engine is made by the pilots of the aircraft to follow an automatic starting procedure, this engine follows the conventional four-phase starting cycle. The rotor of the high-pressure stage of the second engine is spun up for a predetermined duration and to a speed that is substantially constant and less than the nominal value during the starting cycle for the first engine. Once the starting cycle for the first engine is complete, the second engine is made by the pilots of the aircraft to follow an automatic starting procedure. The starting cycle for the second engine comprises just three phases.

A method for controlling an aircraft with a rotary wing provided with a power plant comprising a plurality of engines, the aircraft comprising a human-machine interface controlling a control member capable of acting on a longitudinal acceleration of the aircraft. During the economy operating mode during which one of the engines does not supply power, the method comprises measuring a forward speed of the aircraft, and adjusting an authority of the human-machine interface over the longitudinal acceleration with a flight control computer as a function of the forward speed.

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.

The rapid assistance device applies to a free turbine engine of an aircraft having at least a first free turbine engine provided with a gas generator and associated with an electrical machine capable of operating both as a starter and as a generator, the first engine being capable of being put into a standby mode or into an unwanted shut-down mode, the electrical machine being powered from on on-board electrical energy power supply network. The device further includes at least one electrical energy storage member adapted to be electrically connected to the electrical machine associated with the first engine in order to provide a burst of assistance to the gas generator of that engine. The electrical energy storage member constitutes a non-rechargeable “primary” energy storage member that can be used once only. The device includes a system for activating the electrical energy storage member and a device for coupling the electrical energy storage member with an electrical power supply system of the electrical machine.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual fuel flow value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual fuel flow value and a nominal fuel flow value at the ambient condition; commanding each GT in the set of GTs to a part load level, the part load level representing a fraction of the base load level, and subsequently measuring an actual fuel flow value for each GT at the part load level; and calibrating the set of GTs based upon a difference between the measured actual fuel flow value at the part load level and the measured actual fuel flow value after adjusting the output to match the nominal mega-watt power output value.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual fuel flow value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual fuel flow value and a nominal fuel flow value at the ambient condition; commanding each GT in the set of GTs to a part load level, the part load level representing a fraction of the base load level, and subsequently measuring an actual fuel flow value for each GT at the part load level; and calibrating the set of GTs based upon a difference between the measured actual fuel flow value at the part load level and the measured actual fuel flow value after adjusting the output to match the nominal mega-watt power output value.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual emissions value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual emissions value and a nominal emissions value at the ambient condition; and further adjusting an operating condition of each GT in the set of GTs based upon a determined emissions measurement error.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual emissions value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual emissions value and a nominal emissions value at the ambient condition; and further adjusting an operating condition of each GT in the set of GTs based upon a determined emissions measurement error.