The method can include sensing operating conditions of the gas turbine engine; generating a base value signal of a control parameter of the bleed valve based on the sensed operating conditions and on control data; determining whether a contaminant management condition is met; generating a control value signal of the control parameter including the base value signal and, when the contaminant management conditions is met, the control value signal further including a contaminant management signal of the control parameter value of the valve superposed to the base value signal, the contaminant management signal including at least three successive back and forth fluctuations of the control parameter value relative the base value signal over a period of 10 seconds or less; and controlling an actuator of the bleed valve based on the control value signal.

A system includes an air manifold, a fuel manifold, and a plurality of fuel injectors. At least one of the fuel injectors includes a heat exchanger portion for supplying compressed, cooled air form the heat exchanger portion to the air manifold. An air valve is operatively connected to an outlet of the air manifold for controlling release of air from the air manifold. A controller is operatively connected to the air valve, wherein the controller includes machine readable instructions configured to control the air valve to regulate flow of air through the air valve based on fuel temperatures in the fuel channel. The machine readable instructions can be configured to cause the controller to flow air through the air valve in a heat exchange mode if a fuel temperature in the fuel injectors is below a predetermined fuel temperature.

An auxiliary power unit for an aircraft, having a compressor, an intercooler including first conduit(s) having an inlet in fluid communication with the compressor outlet and second conduit(s) configured for circulation of a coolant therethrough, an engine core having an inlet in fluid communication with an outlet of the first conduit(s), and a bleed conduit in fluid communication with the outlet of the first conduit(s) through a bleed air valve. The auxiliary power unit may include a generator in driving engagement with the shaft of the engine core to provide electrical power for the aircraft. A method of providing compressed air and electrical power to an aircraft is also discussed.

An auxiliary power unit for an aircraft, having a compressor, an intercooler including first conduit(s) having an inlet in fluid communication with the compressor outlet and second conduit(s) configured for circulation of a coolant therethrough, an engine core having an inlet in fluid communication with an outlet of the first conduit(s), and a bleed conduit in fluid communication with the outlet of the first conduit(s) through a bleed air valve. The auxiliary power unit may include a generator in driving engagement with the shaft of the engine core to provide electrical power for the aircraft. A method of providing compressed air and electrical power to an aircraft is also discussed.

Methods and systems for controlling a bleed-off valve of a gas turbine engine are described. The method comprises maintaining a first bleed-off valve associated with a first compressor of the gas turbine engine at least partially open upon detection of an unintended engine disturbance causing a drop in pressure of a combustion chamber of the engine; monitoring a rotor acceleration of the first compressor; and controlling closure of the first bleed-off valve when the rotor acceleration of the first compressor reaches a first threshold for a first duration.

Methods and systems for controlling a bleed-off valve of a gas turbine engine are described. The method comprises maintaining a first bleed-off valve associated with a first compressor of the gas turbine engine at least partially open upon detection of an unintended engine disturbance causing a drop in pressure of a combustion chamber of the engine; monitoring a rotor acceleration of the first compressor; and controlling closure of the first bleed-off valve when the rotor acceleration of the first compressor reaches a first threshold for a first duration.

The aircraft can have a first engine secured to a first wing on a first side of a fuselage, and a second engine secured to a second wing on a second side of the fuselage, the second wing having a proximal end secured to the fuselage, and a distal end extending away from the fuselage. While operating the first engine, compressed gas can be conveyed from the first engine to a thrust generating device located at the distal end of the second wing.

The aircraft can have a first engine secured to a first wing on a first side of a fuselage, and a second engine secured to a second wing on a second side of the fuselage, the second wing having a proximal end secured to the fuselage, and a distal end extending away from the fuselage. While operating the first engine, compressed gas can be conveyed from the first engine to a thrust generating device located at the distal end of the second wing.

A gas turbine engine having an improved air delivery system that includes features for pressurizing and/or cooling various components of the engine while minimizing the impact to the cycle efficiency of the engine, reducing the weight of the engine, and reducing the specific fuel consumption of the engine is provided.

A gas turbine engine having an improved air delivery system that includes features for pressurizing and/or cooling various components of the engine while minimizing the impact to the cycle efficiency of the engine, reducing the weight of the engine, and reducing the specific fuel consumption of the engine is provided.