The present disclosure provides methods and systems for operating a multi-engine rotorcraft. The method comprises driving a rotor of the rotorcraft with a first engine while a second engine is de-clutched from a transmission clutch system that couples the rotor and the second engine, instructing the second engine to accelerate to a re-clutching speed, and controlling an output shaft speed of the second engine during acceleration of the second engine to the re-clutching speed by applying a damping function to a speed control loop of the second engine.

An aircraft power system includes an auxiliary power unit (APU), a transmission unit, and a generator. The APU is configured to output a first APU rotational power in response to determining a first condition and a second APU rotational power in response to a determining a second condition. The transmission unit is configured to receive the first APU rotational output power from the APU. The transmission unit outputs a transmission rotational power based on the first APU rotational output power and outputs the transmission rotational power based on the second APU rotational output power. The generator receives the transmission rotational power and produces an alternating current (AC) voltage having a target frequency based on the transmission rotational power.

An aircraft defining a longitudinal direction and a lateral direction is provided. The aircraft includes: a fuselage; an engine mounted at a location spaced from the fuselage of the aircraft, the engine comprising a plurality of rotor blades; and a fuselage shield attached to or formed integrally with the fuselage at a location in alignment with the plurality of rotor blades along the lateral direction, the fuselage shield comprising a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

Systems, methods, and devices are provided for a turbine driven pump gearbox. A turbine engine may drive a primary shaft having gears. The gears may selectably engage with gears of a secondary shaft that drives a machine (e.g., pump). By changing which gears of the primary shaft engage with which gears of the secondary shaft, a gear ratio may be changed. A power takeoff device (e.g., a generator) may be connected to the primary shaft and may be operated in reverse as a motor to rotate, slow, stop, and/or reverse rotation of the primary shaft. Brakes may be associated with one or more of the primary and secondary shafts. The power takeoff device and one or more of the brakes may be controlled to shift engagement of the shafts between different positions, changing the gear ratio and/or disengaging the shafts from each other.

A pumping device for a vehicle seat is proposed. The pumping device includes: a housing made of plastic, including a bottom surface having a through hole, a side wall arranged along an outer circumferential surface of the bottom surface, and an open upper surface, with a clutch device and a brake device, and a lever being connected to the housing at an outside of the bottom surface through the through hole so that the housing is configured to transmit drive force from the lever to the clutch device; and a housing cover made of metal, including a first side surface covering the open upper surface of the housing, a plurality of bending parts at an edge thereof such that the bending parts are bent toward the housing to achieve coupling between the housing cover and the housing, and a second side surface coupled to a seat frame.

There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has: rotating the first and second shafts at a flight rotation speed above the placarded zone when clutched to a load; decreasing a rotation speed of the first shaft from the flight rotation speed to a first idle rotation speed above the placarded zone; unclutching the first shaft from the load during the decreasing; and subsequently to the decreasing and the unclutching, simultaneously decreasing the rotation speeds of the first shaft and of the second shaft to a second idle rotation speed below the placarded zone, the simultaneously decreasing including clutching the first shaft to the load.

An aircraft defining a longitudinal direction and a lateral direction is provided. The aircraft includes: a fuselage; an engine mounted at a location spaced from the fuselage of the aircraft, the engine comprising a plurality of rotor blades; and a fuselage shield attached to or formed integrally with the fuselage at a location in alignment with the plurality of rotor blades along the lateral direction, the fuselage shield comprising a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

An aircraft power system includes an auxiliary power unit (APU), a transmission unit, and a generator. The APU is configured to output a first APU rotational power in response to determining a first condition and a second APU rotational power in response to a determining a second condition. The transmission unit is configured to receive the first APU rotational output power from the APU. The transmission unit outputs a transmission rotational power based on the first APU rotational output power and outputs the transmission rotational power based on the second APU rotational output power. The generator receives the transmission rotational power and produces an alternating current (AC) voltage having a target frequency based on the transmission rotational power.

Engine bleed air power recovery systems and related methods are disclosed. An example power recovery system for an aircraft engine includes a power recovery turbine coupled to aa shaft-driven device. A bleed air valve coupled between the power recovery turbine and a bleed air source. A controller configured to operate the bleed air valve to allow bleed air to flow to the power recovery turbine when the aircraft engine operates in a predetermined mode of operation.

The gas turbine generator includes: a first gas turbine element 2; a second gas turbine element 3; a single combustor 4 connected to the gas turbine elements 2 and 3; a first supply pipe 51 that connects the first compressor 21 to the combustor 4; a second supply pipe 52 that connects the second compressor 31 to the combustor 4; a first discharge pipe 53 that connects the combustor 4 to the first turbine 22; a second discharge pipe 54 that connects the combustor 4 to the second turbine 32; and a flywheel 7 that is connected to at least one of the first rotation shaft 23 and the second rotation shaft 33 and absorbs a torque fluctuation generated in the connected gas turbine element.