A cabin blower for an aircraft, the system comprising: a cabin blower compressor; an electric machine; and a controller configured to control the cabin blower system so that: in a cabin blower mode of operation, the cabin blower compressor is driven by power extracted from one or more spools of a gas turbine engine of the aircraft and provides a flow of air to a cabin of the aircraft. The controller may be further configured to control the system so that: in a rotor bow mitigation mode of operation, the cabin blower compressor is driven by the electric machine using electrical power from an electrical power source and provides a flow of air through a core of the gas turbine engine to remove heat from the core. A method of operating a cabin blower system of an aircraft is also provided.

An aircraft power plant comprising novel air management features for high-power fuel cell applications, the features combine supercharging and turbocharging elements with air and hydrogen gas pathways, utilize novel airflow concepts and provide for much stronger integration of various fuel cell drive components.

A method of controlling the oil flow in an engine is provided. In preferred embodiments, the method comprises: flowing oil to a first oil pump upstream or downstream of a fuel oil heat exchanger and flowing oil to a second oil pump upstream or downstream of an air oil heat exchanger. One of two control functions to control the oil mass flow rate through the first oil pump is selected wherein the first control function minimizes specific fuel consumption (“SFC”) by the engine and the second control function minimizes average oil temperature. Preferably, the oil pumps are electric and the total combined oil mass flow rate of the first and second oil pumps is maintained constant.

A method of controlling the oil flow in an engine is provided. In preferred embodiments, the method comprises: flowing oil to a first oil pump upstream or downstream of a fuel oil heat exchanger and flowing oil to a second oil pump upstream or downstream of an air oil heat exchanger. One of two control functions to control the oil mass flow rate through the first oil pump is selected wherein the first control function minimizes specific fuel consumption (“SFC”) by the engine and the second control function minimizes average oil temperature. Preferably, the oil pumps are electric and the total combined oil mass flow rate of the first and second oil pumps is maintained constant.

A redundant propulsion device includes a propeller and electric motors. The electric motors are configured to drive the propeller. The electric motors are disposed with respect to a propeller shaft of the propeller so that, around the propeller shaft, at least one of the electric motors is disposed at each of the locations in the longitudinal direction of the propeller shaft. The electric motors are disposed at positions such that an output shaft of each of the electric motors does not overlap an output shaft of any other one of the electric motors as viewed in the longitudinal direction of the propeller shaft from the propeller.

A redundant propulsion device includes a propeller and electric motors. The electric motors are configured to drive the propeller. The electric motors are disposed with respect to a propeller shaft of the propeller so that, around the propeller shaft, at least one of the electric motors is disposed at each of the locations in the longitudinal direction of the propeller shaft. The electric motors are disposed at positions such that an output shaft of each of the electric motors does not overlap an output shaft of any other one of the electric motors as viewed in the longitudinal direction of the propeller shaft from the propeller.

In the method for propelling an aircraft, to obtain electric energy, a fuel is combusted, and an electric machine is used, wherein the fuel is used to cool at least one part of the electric machine and contains natural gas. The propulsion system is configured to propel an aircraft, in particular according to the above-mentioned method. The propulsion system has an electric machine configured to obtain electric energy by combusting a fuel. The propulsion system further includes a natural gas tank configured to supply the fuel formed with natural gas, and a cooling device configured to cool at least one part of the electric machine. The aircraft has such a propulsion system.

In the method for propelling an aircraft, to obtain electric energy, a fuel is combusted, and an electric machine is used, wherein the fuel is used to cool at least one part of the electric machine and contains natural gas. The propulsion system is configured to propel an aircraft, in particular according to the above-mentioned method. The propulsion system has an electric machine configured to obtain electric energy by combusting a fuel. The propulsion system further includes a natural gas tank configured to supply the fuel formed with natural gas, and a cooling device configured to cool at least one part of the electric machine. The aircraft has such a propulsion system.

A system and method for adaptively controlling a cooldown cycle of an auxiliary power unit (APU) that is operating and rotating at a rotational speed includes reducing the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value, determining, based on one or more of operational parameters of the APU, when a lean blowout of the APU is either imminent or has occurred, and when a lean blowout is imminent or has occurred, varying one or more parameters associated with the shutdown/cooldown cycle.

A system and method for adaptively controlling a cooldown cycle of an auxiliary power unit (APU) that is operating and rotating at a rotational speed includes reducing the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value, determining, based on one or more of operational parameters of the APU, when a lean blowout of the APU is either imminent or has occurred, and when a lean blowout is imminent or has occurred, varying one or more parameters associated with the shutdown/cooldown cycle.