Aircraft turbomachine including a centrifugal compressor, a combustion chamber, the combustion chamber being supplied by the compressor via a diffuser and via a straightener, and a heat exchanger, the exchanger including a first circuit, supplied with exhaust gas from the turbomachine, and a second circuit, which are connected by volutes on the one hand to an outlet of the diffuser and on the other hand to an inlet of the straightener, the volutes having reversed winding directions such that their connection ports to the exchanger are independent of one another and are substantially diametrically opposed, and such that the minimum cross section of each duct is situated at a larger cross section of the other duct.

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.

Various implementations described herein are directed to an aircraft having a multi-engine configuration with multiple engines. The aircraft may have a flight control system coupled to the multiple engines with a multi-engine interface. The flight control system may be configured to shutdown at least one engine of the multiple engines during reduced-engine operation by continuously calculating altitude for the reduced-engine operation based on one or more of an aircraft descent rate of the aircraft and an engine restart time of the at least one engine.

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.

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 manifold 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 supplying pressurized air to 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.

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 fully compounding rotorcraft includes a fuselage having first and second wings extending therefrom and configured to provide lift compounding responsive to forward airspeed. A twin boom includes first and second tail boom members that extend aftward from the first and second wings. An empennage is coupled between the aft ends of the tail boom members. An anti-torque system includes a tail rotor that is rotatably coupled to the empennage. An engine is disposed within the fuselage and is configured to provide torque to a main rotor assembly via an output shaft and a main rotor gearbox. An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight, thereby providing propulsion compounding to increase the forward airspeed of the rotorcraft.

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.

An exemplary aircraft includes a turbine engine having a gas generator spool and a power spool, the power spool operational to drive a rotor, a first generator coupled to the gas generator spool, and a controller operable to increase a load on the gas generator spool when the gas generator spool is on a speed limit thereby increasing a speed limit margin in order to increase power available from the turbine engine.