An air intake including an air duct inside an aircraft, an inlet at one end of the air duct, a flap door and driving mechanism that moves the flap door between closed and open positions. The flap door includes a barrier filter configured to filter an incoming airflow into the air duct, and wherein the driving mechanism is configured to pivot the flap door about a first end of the door.

A system that filters airborne particles when the aircraft is in a dusty environment and is disengaged when the aircraft is flying up and away from the dusty environment.

A system that filters airborne particles when the aircraft is in a dusty environment and is disengaged when the aircraft is flying up and away from the dusty environment.

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.

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 gas turbine engine includes a core section including a compressor, a main combustor, and a main turbine. Combustion products from the main combustor drive rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. The gas turbine engine further includes a fan section having a fan rotor located fluidly upstream of the core section. The power turbine is operably connected to the fan rotor to drive rotation of the fan rotor via rotation of the power turbine. The gas turbine engine includes a bleed arrangement having one or more bleed passages configured to divert a bleed airflow from the compressor around the main combustor and main turbine, and reintroduce the bleed airflow into the power turbine.

A gas turbine engine includes a core section including a compressor, a main combustor, and a main turbine. Combustion products from the main combustor drive rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. The gas turbine engine further includes a fan section having a fan rotor located fluidly upstream of the core section. The power turbine is operably connected to the fan rotor to drive rotation of the fan rotor via rotation of the power turbine. The gas turbine engine includes a bleed arrangement having one or more bleed passages configured to divert a bleed airflow from the compressor around the main combustor and main turbine, and reintroduce the bleed airflow into the power turbine.

An air intake system for an aircraft, which is switchable between a performance mode and a filtered mode, includes a duct forming filtered air inlet slits. The air intake system also includes interconnected gills adjacent to the filtered air inlet slits. The gills are movable between various gill positions including a closed position substantially covering the filtered air inlet slits and an open position substantially exposing the filtered air inlet slits. The air intake system also includes an actuator configured to move the gills into the closed position in the performance mode and the open position in the filtered mode.

A multi-angle multi-wave array may comprise a first set of sensing elements, a second set of sensing elements, and a third set of sensing elements wherein the first set of sensing elements, the second set of sensing elements, and the third set of sensing elements are collectively configured to detect and discriminate between categories of foreign object debris including solid objects and particulates including silicate sand, water vapor, dust, volcanic ash, and smoke.

A multi-angle multi-wave array may comprise a first set of sensing elements, a second set of sensing elements, and a third set of sensing elements wherein the first set of sensing elements, the second set of sensing elements, and the third set of sensing elements are collectively configured to detect and discriminate between categories of foreign object debris including solid objects and particulates including silicate sand, water vapor, dust, volcanic ash, and smoke.