Abstract: Systems and methods to operate an engine in a bowed rotor mitigation mode. An engine starting system includes a starter coupled to the engine and with a compressor. A conduit system communicates a portion of the compressed air from the compressor to the starter. A load control valve controls compressed air from the compressor to the starter and to other loads. A starter air valve controls compressed air through the conduit system to the starter. At least one controller: receives a start signal from the engine; determines whether to initiate a bowed rotor mitigation of the engine; operates either the load control valve or the starter air valve to move to a predetermined static position; and operates the other of the load control valve or the starter air valve to achieve a target speed of the engine.

Abstract: Systems and methods to operate an engine in a bowed rotor mitigation mode. An engine starting system includes a starter coupled to the engine and with a compressor. A conduit system communicates a portion of the compressed air from the compressor to the starter. A load control valve controls compressed air from the compressor to the starter and to other loads. A starter air valve controls compressed air through the conduit system to the starter. At least one controller: receives a start signal from the engine; determines whether to initiate a bowed rotor mitigation of the engine; operates either the load control valve or the starter air valve to move to a predetermined static position; and operates the other of the load control valve or the starter air valve to achieve a target speed of the engine.

Abstract: An aircraft engine system includes a main engine having a main engine speed; a starter coupled to the main engine and configured to drive the main engine with compressed air; and an auxiliary power unit (APU) system coupled to the starter and configured to provide the compressed air to the starter. The APU system includes an APU with a compressor to generate the compressed air, and an APU electronic control unit (ECU) coupled to the APU, the APU ECU configured to receive the engine speed of the main engine and to control operation of the APU to modify an amount of the compressed air to the starter based on the main engine speed.

Abstract: An aircraft engine system includes a main engine having a main engine speed; a starter coupled to the main engine and configured to drive the main engine with compressed air; and an auxiliary power unit (APU) system coupled to the starter and configured to provide the compressed air to the starter. The APU system includes an APU with a compressor to generate the compressed air, and an APU electronic control unit (ECU) coupled to the APU, the APU ECU configured to receive the engine speed of the main engine and to control operation of the APU to modify an amount of the compressed air to the starter based on the main engine speed.

Abstract: A valve assembly includes a valve body, a valve element, a valve actuator, and a fluid-operated switch. The valve body defines a flow passage. The valve element is disposed at least partially within the flow passage and is moveable between an open position and a closed position. The valve actuator is coupled to the valve element and is responsive to pressurized fluid supplied thereto and vented therefrom to move the valve element between the open position and the closed position, respectively. The fluid-operated switch has a first fluid inlet, a second fluid inlet, a third fluid inlet, an actuator port, and an actuator vent port. The fluid-operated switch is in fluid communication with the valve actuator and is operable to selectively supply pressurized fluid to the actuator via the actuator port, and vent the pressurized fluid from the actuator via the actuator port and the actuator vent port.

Abstract: A valve assembly includes a valve body, a valve element, a valve actuator, and a fluid-operated switch. The valve body defines a flow passage. The valve element is disposed at least partially within the flow passage and is moveable between an open position and a closed position. The valve actuator is coupled to the valve element and is responsive to pressurized fluid supplied thereto and vented therefrom to move the valve element between the open position and the closed position, respectively. The fluid-operated switch has a first fluid inlet, a second fluid inlet, a third fluid inlet, an actuator port, and an actuator vent port. The fluid-operated switch is in fluid communication with the valve actuator and is operable to selectively supply pressurized fluid to the actuator via the actuator port, and vent the pressurized fluid from the actuator via the actuator port and the actuator vent port.

Abstract: An inlet door assembly and method for reducing noise from an auxiliary power unit (APU) contained within an aircraft housing is provided. The inlet assembly includes an inlet duct, an actuator, and a door. The inlet duct is configured to extend from the auxiliary power unit to the aircraft housing and has a sidewall that defines a flow passage through which APU noise propagates. The actuator is disposed at least partially within the inlet duct. The door coupled to the actuator. The actuator is also configured to selectively rotate the door between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction.

Abstract: An inlet door assembly and method for reducing noise from an auxiliary power unit (APU) contained within an aircraft housing is provided. The inlet assembly includes an inlet duct, an actuator, and a door. The inlet duct is configured to extend from the auxiliary power unit to the aircraft housing and has a sidewall that defines a flow passage through which APU noise propagates. The actuator is disposed at least partially within the inlet duct. The door coupled to the actuator. The actuator is also configured to selectively rotate the door between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction.

Abstract: An inlet door assembly and method for reducing noise from an auxiliary power unit (APU) contained within an aircraft housing is provided. The inlet assembly includes an inlet duct, an actuator, and a door. The inlet duct is configured to extend from the auxiliary power unit to the aircraft housing and has a sidewall that defines a flow passage through which APU noise propagates. The actuator is disposed at least partially within the inlet duct. The door coupled to the actuator. The actuator is also configured to selectively rotate the door between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction.