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.

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.

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 multi-engine system includes a first gas turbine engine that includes a first compressor and a first turbine. The multi-engine system may further include a second gas turbine engine that has a second compressor and a second turbine. Still further, the multi-engine system may include a first crossover cooling network configured to route a first crossover airflow from the first compressor of the first gas turbine engine to the second turbine of the second gas turbine engine and a second crossover cooling network configured to route a second crossover airflow from the second compressor of the second gas turbine engine to the first turbine of the first gas turbine engine.

A multi-engine system includes a first gas turbine engine that includes a first compressor and a first turbine. The multi-engine system may further include a second gas turbine engine that has a second compressor and a second turbine. Still further, the multi-engine system may include a first crossover cooling network configured to route a first crossover airflow from the first compressor of the first gas turbine engine to the second turbine of the second gas turbine engine and a second crossover cooling network configured to route a second crossover airflow from the second compressor of the second gas turbine engine to the first turbine of the first gas turbine engine.

A method for detecting wear before failure of a free-wheel, the free-wheel comprising a driving part integrated into an upstream mechanical power transmission system and a driven part integrated into a downstream mechanical power transmission system. The method comprises determining an oscillation measurement of a monitoring parameter within the upstream or downstream mechanical power transmission system, determining a value of at least one dynamic parameter characteristic of the oscillation measurement or of a transform of the oscillation measurement in a frequency reference frame, and generating an alarm when the value of the dynamic parameter reaches at least one wear threshold.

A multi-engine system for an aircraft, has: a first engine having a first output shaft, a first core shaft, and a first electric machine drivingly engaged by the first output shaft or the first core shaft; a second engine having a second output shaft, a second core shaft, and a second electric machine drivingly engaged to the second core shaft; a reduction gearbox drivingly engaged by the first output shaft and by the second output shaft for driving a common load; and a transmission path between the first engine and the second engine, the transmission path being independent from the reduction gearbox and being one or more of: a torque-transfer connection between the second core shaft and the first core shaft or the first output shaft via a coupling gearbox, and an electrical connection between the generator and the electric motor to transmit electrical power to the electric motor.

A multi-engine system for an aircraft, has: a first engine having a first output shaft, a first core shaft, and a first electric machine drivingly engaged by the first output shaft or the first core shaft; a second engine having a second output shaft, a second core shaft, and a second electric machine drivingly engaged to the second core shaft; a reduction gearbox drivingly engaged by the first output shaft and by the second output shaft for driving a common load; and a transmission path between the first engine and the second engine, the transmission path being independent from the reduction gearbox and being one or more of: a torque-transfer connection between the second core shaft and the first core shaft or the first output shaft via a coupling gearbox, and an electrical connection between the generator and the electric motor to transmit electrical power to the electric motor.

Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifolds and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and using a pump to drive gas into the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.