A cable that includes a conductor defining a hollow interior, a casing surrounding the conductor, an electrical insulator positioned between the conductor and the casing, and a fluid positioned within the hollow interior of the conductor.

A tiltrotor aircraft having a propulsion configuration that divorces the engine core power from the thrust fan, using a combined gearbox with a plurality of clutches to couple and decouple one or more rotor systems and one or more thrust fans. The aircraft can be operable for vertical takeoff and landing (VTOL) in a helicopter mode, forward flight in a proprotor mode, and high-speed forward flight in an airplane (jet) mode. The propulsion configuration provides shaft horsepower (SHP) to rotors for VTOL flight, while also providing SHP to the thrust fan for high speed flight. Allowing the rotor and the thrust fan to be clutched on and off, sequentially, enables transition from rotor-borne VTOL flight to wing-borne thrust fan flight, and back.

Method for monitoring the operation of a pair of turboprop engines of an aircraft comprising the steps of: detecting the sound pressure generated by the first or second turboprop engine generating a respective first or second signal x(t); iteratively calculating by means of a function Rx/Ry the similarity between the first/second signal x(t)/y(t) at a time T1 and at a time T2 subsequent to time T1; and storing the degrees of similarity calculated in successive iterations in order to detect situations of normal operation of the engines when the degrees of similarity fall in successive iterations within the interval of a first value and to detect a potential fault situation in the engines when the degrees of similarity depart from this interval.

A method of optimizing the operation of a fleet of gas turbine engines is provided. The method comprises the steps of: (a) measuring respective values for plural control actuator settings within each of the gas turbine engines; (b) deriving, based on data external to the operation of the gas turbine engines, a desired performance modification of the gas turbine engines; (c) determining, based on the measured control actuator settings, one or more respective trim signals for varying selected of the control actuator settings to achieve the desired performance modification; and (d) transmitting the trim signals to respective electronic controllers of the engines to vary the selected control actuator settings accordingly.

An aircraft includes a fuselage, a wing connected to and extending outward from the fuselage, and an engine mounted to the wing. The engine includes turbomachine defining a centerline axis, a fan, and an exhaust section with an outlet nozzle. The turbomachine defines a centerline axis. The fan is connected to and is disposed upstream from the turbomachine. The fan is disposed to rotate about the centerline axis. During operation of the engine, an exhaust stream is expelled from the outlet nozzle of the exhaust section. The exhaust stream defines a mean direction of flow in the downstream direction from the exhaust section. The mean direction of flow defines a first angle with the centerline axis of the turbomachine that is greater than zero such that the centerline axis is oriented downwardly along the vertical direction relative to the mean direction of flow of the exhaust stream.

The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.

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.

An engine system of an aircraft includes a gas turbine engine comprising at least one spool and at least one electric machine operably coupled with the at least one spool. A controller is configured to detect if the at least one spool of the gas turbine engine is in or is approaching an overspeed condition and apply a load to the at least one spool via the at least one electric machine.

A propeller control unit (PCU) has: a pitch angle actuator; a valve operable to selectively fluidly connect the pitch angle actuator with a source of oil for controlling pitch angles of blades of a propeller and with a drain line for draining oil out of the pitch angle actuator for feathering the blades; and a bypass line having an inlet hydraulically between the valve and an inlet of the drain line, the bypass line having an outlet hydraulically between the inlet of the drain line and an outlet of the drain line.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine having a low speed spool and a high speed spool; a rotor assembly coupled to the low speed spool; an electric machine rotatable with the low speed spool for extracting power from the low speed spool, for adding power to the low speed spool, or both; and an inter-spool clutch positioned between the low speed spool and the high speed spool for selectively coupling the low speed spool to the high speed spool.