A turbomachine dual spool transmission system can include a transmission assembly configured to connect to a combination output of a dual spool differential at a transmission input to be driven by the combination output to turn a transmission output. The transmission assembly can be configured to provide a first output gear ratio in a first state and a second output gear ratio in a second state. The system can include the dual spool differential. The dual spool differential can include a gear assembly configured to combine a low pressure spool input and a high pressure spool input into a combination output to provide an output speed range smaller than a low pressure speed range alone.

An auxiliary power unit, in particular for an aircraft, includes a gas generator and an electric generator. The electric generator has an input shaft that is connected to an output shaft of the gas generator. The auxiliary power unit also has an accessories housing directly connected to a rotor shaft of the electric generator, wherein the electric generator is interposed between the gas generator and the accessories housing.

An auxiliary power unit, in particular for an aircraft, includes a gas generator and an electric generator. The electric generator has an input shaft that is connected to an output shaft of the gas generator. The auxiliary power unit also has an accessories housing directly connected to a rotor shaft of the electric generator, wherein the electric generator is interposed between the gas generator and the accessories housing.

A gas turbine engine according to an example of the present disclosure may include, among other things, a fan section including a fan having a plurality of fan blades and including an outer housing surrounding the fan blades to establish a bypass duct, a geared architecture, a first spool including a first shaft that interconnects a first compressor and a fan drive turbine, the fan drive turbine driving the fan through the geared architecture. The gas turbine engine is rated to provide an amount of thrust at ground idle, and the gas turbine engine is rated to provide an amount of thrust at maximum takeoff. A thrust ratio is defined as a ratio of the amount of thrust at ground idle divided by the amount of thrust at maximum takeoff. The thrust ratio can be less than or equal to 0.050.

A gas turbine engine according to an example of the present disclosure may include, among other things, a fan section including a fan having a plurality of fan blades and including an outer housing surrounding the fan blades to establish a bypass duct, a geared architecture, a first spool including a first shaft that interconnects a first compressor and a fan drive turbine, the fan drive turbine driving the fan through the geared architecture. The gas turbine engine is rated to provide an amount of thrust at ground idle, and the gas turbine engine is rated to provide an amount of thrust at maximum takeoff. A thrust ratio is defined as a ratio of the amount of thrust at ground idle divided by the amount of thrust at maximum takeoff. The thrust ratio can be less than or equal to 0.050.

A gas turbine engine includes a primary gas path having, in fluid series communication: a primary air inlet, a compressor fluidly connected to the primary air inlet, a combustor fluidly connected to an outlet of the compressor, and a turbine fluidly connected to an outlet of the combustor. The turbine is operatively connected to the compressor to drive the compressor. A turbine cooling air conduit extends from an air inlet of the turbine cooling air conduit to an air outlet of the turbine cooling air conduit.

A gas turbine engine includes a primary gas path having, in fluid series communication: a primary air inlet, a compressor fluidly connected to the primary air inlet, a combustor fluidly connected to an outlet of the compressor, and a turbine fluidly connected to an outlet of the combustor. The turbine is operatively connected to the compressor to drive the compressor. A turbine cooling air conduit extends from an air inlet of the turbine cooling air conduit to an air outlet of the turbine cooling air conduit.

A fuel supply system for a turbomachine, comprising a fuel circuit comprising pressurizer at the output of the circuit, a pump arranged to send into the circuit a fuel flow rate which is an increasing function of the rotational speed of a shaft of the pump, and a control circuit arranged to control the device to comply with a flow rate setpoint at the output of the fuel circuit. The system further comprises a feedforward corrector circuit configured to calculate an increment of the flow rate setpoint as a function of the engine speed of the turbomachine and of a variation in the engine speed of the turbomachine, and to add this increment to the flow rate setpoint. A method of regulating the pump is also described.

A fuel supply system for a turbomachine, comprising a fuel circuit comprising pressurizer at the output of the circuit, a pump arranged to send into the circuit a fuel flow rate which is an increasing function of the rotational speed of a shaft of the pump, and a control circuit arranged to control the device to comply with a flow rate setpoint at the output of the fuel circuit. The system further comprises a feedforward corrector circuit configured to calculate an increment of the flow rate setpoint as a function of the engine speed of the turbomachine and of a variation in the engine speed of the turbomachine, and to add this increment to the flow rate setpoint. A method of regulating the pump is also described.

A gas turbine engine comprises a turbomachine defining a core flow therethrough during operation. A flow tap is provided in fluid communication with the turbomachine, wherein the flow tap is configured to receive a portion of the core flow therethrough as a bleed flow. A bleed assembly includes a machine load, a bleed flow machine, and a bleed regulator. The bleed flow machine is disposed in fluid communication with the turbomachine through the flow tap, and is configured to drive the machine load. The bleed regulator is configured to regulate a bleed output provided to the bleed flow machine by controlling a capture rate of the bleed flow by the bleed flow machine.