A twin-engine system includes a gas turbine engine comprising a core and a first output shaft drivable by the core. An electric engine has an electric motor configured to drive a second output shaft. A reduction gear box (RGB) has an RGB input drivingly engaged to both the first output shaft and the second output shaft. The RGB has an RGB output to provide rotational output to a rotatable load.

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 assembly is provided for an aircraft propulsion system. This assembly includes an exhaust center body and a duct system. The exhaust center body includes an exterior skin. The duct system is fluidly coupled with a plurality of exterior skin perforations in the exterior skin. The duct system is configured to direct bypass air received from a bypass flow path within the aircraft propulsion system to the exterior skin perforations.

An assembly is provided for an aircraft propulsion system. This assembly includes an exhaust center body and a duct system. The exhaust center body includes an exterior skin. The duct system is fluidly coupled with a plurality of exterior skin perforations in the exterior skin. The duct system is configured to direct bypass air received from a bypass flow path within the aircraft propulsion system to the exterior skin perforations.

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.

An aircraft cabin blower system comprises a cabin blower including a compressor configured to provide air to a cabin of the aircraft; a variable drive system configured to drive the compressor and including an electric variator and a summing gearbox; and a main transmission configured, when operating in a blower mode, to receive mechanical power from a gas turbine engine and input mechanical power to the summing gearbox in a forward direction; and configured, when operating in a starter mode, to receive mechanical power from the summing gearbox and input mechanical power to the gas turbine engine. The aircraft cabin blower system further includes a first one-way rotation device adapted to permit free rotation of the main transmission in the forward direction and to prevent rotation of the main transmission in a reverse direction opposite to the forward direction.

An aircraft cabin blower system comprises a cabin blower including a compressor configured to provide air to a cabin of the aircraft; a variable drive system configured to drive the compressor and including an electric variator and a summing gearbox; and a main transmission configured, when operating in a blower mode, to receive mechanical power from a gas turbine engine and input mechanical power to the summing gearbox in a forward direction; and configured, when operating in a starter mode, to receive mechanical power from the summing gearbox and input mechanical power to the gas turbine engine. The aircraft cabin blower system further includes a first one-way rotation device adapted to permit free rotation of the main transmission in the forward direction and to prevent rotation of the main transmission in a reverse direction opposite to the forward direction.

A maritime sulfur dioxide emissions switch monitoring system has an emissions sampling apparatus that is self-powered and requires a low power for operation. The emissions sampling apparatus has sensitive and selective chemical sensing technology capable of quantification of sulfur dioxide and carbon dioxide. Relative humidity, temperature and pressure sensors, in addition to sulfur dioxide and carbon dioxide are used for monitoring the exhaust gas. Filters are used to eliminate solid and liquid aerosolized components in marine engine exhaust.

An assembly is provided for a turbine engine. This turbine engine assembly includes a first rotating structure, a turbine engine apparatus, a rotating coupler and a seal assembly. The first rotating structure is configured to rotate about a rotational axis. The turbine engine apparatus includes an electric machine and a second rotating structure. The electric machine includes an electric machine rotor and an electric machine stator. The second rotating structure is configured to rotate about the rotational axis and is coupled to the electric machine rotor. The rotating coupler is coupled to the first rotating structure by a first connection. The rotating coupler is coupled to the second rotating structure by a second connection. The seal assembly includes a rotating seal land and a stationary seal element. The rotating seal land is mounted onto the rotating coupler. The stationary seal element sealingly engages the rotating seal land.

An assembly is provided for a turbine engine. This turbine engine assembly includes a first rotating structure, a turbine engine apparatus, a rotating coupler and a seal assembly. The first rotating structure is configured to rotate about a rotational axis. The turbine engine apparatus includes an electric machine and a second rotating structure. The electric machine includes an electric machine rotor and an electric machine stator. The second rotating structure is configured to rotate about the rotational axis and is coupled to the electric machine rotor. The rotating coupler is coupled to the first rotating structure by a first connection. The rotating coupler is coupled to the second rotating structure by a second connection. The seal assembly includes a rotating seal land and a stationary seal element. The rotating seal land is mounted onto the rotating coupler. The stationary seal element sealingly engages the rotating seal land.