An aircraft engine, has: a low-pressure compressor and a high-pressure compressor located downstream of the low-pressure compressor; a gaspath valve upstream of the high-pressure compressor, the gaspath valve movable between an open configuration and a closed configuration; and a bypass flow path having in flow series a bypass inlet, a bypass valve, and a bypass outlet, the bypass inlet fluidly communicating with the gaspath upstream of at least one stage of the low-pressure compressor, the bypass valve having an open configuration in which the bypass valve allows a bypass flow and a closed configuration in which the bypass valve blocks the bypass flow, the bypass outlet fluidly communicating with the bypass inlet via the bypass valve and with the gaspath at a location in the gaspath fluidly downstream of the gaspath valve, downstream of the low-pressure compressor, and upstream of the high-pressure compressor.

An aircraft engine, has: a low-pressure compressor and a high-pressure compressor located downstream of the low-pressure compressor; a gaspath valve upstream of the high-pressure compressor, the gaspath valve movable between an open configuration and a closed configuration; and a bypass flow path having in flow series a bypass inlet, a bypass valve, and a bypass outlet, the bypass inlet fluidly communicating with the gaspath upstream of at least one stage of the low-pressure compressor, the bypass valve having an open configuration in which the bypass valve allows a bypass flow and a closed configuration in which the bypass valve blocks the bypass flow, the bypass outlet fluidly communicating with the bypass inlet via the bypass valve and with the gaspath at a location in the gaspath fluidly downstream of the gaspath valve, downstream of the low-pressure compressor, and upstream of the high-pressure compressor.

An aircraft defining a longitudinal direction and a lateral direction is provided. The aircraft includes: a fuselage; an engine mounted at a location spaced from the fuselage of the aircraft, the engine comprising a plurality of rotor blades; and a fuselage shield attached to or formed integrally with the fuselage at a location in alignment with the plurality of rotor blades along the lateral direction, the fuselage shield comprising a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

An aircraft defining a longitudinal direction and a lateral direction is provided. The aircraft includes: a fuselage; an engine mounted at a location spaced from the fuselage of the aircraft, the engine comprising a plurality of rotor blades; and a fuselage shield attached to or formed integrally with the fuselage at a location in alignment with the plurality of rotor blades along the lateral direction, the fuselage shield comprising a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

Methods, apparatus, systems, and articles of manufacture are to control air flow separation of an engine. An example turbofan includes a nacelle having an outer lip surface, an inner lip surface, a first opening and a second opening, the first opening coupled to a first region forward of a fan of the turbofan, the second opening coupled to a second region aft of the fan, the nacelle including a first pressure sensor coupled to the outer lip surface, a second pressure sensor coupled to the inner lip surface, and an actuator, and a conduit coupled to the actuator, the conduit configured to have a first end and a second end, the first end coupled to the first opening, the second end coupled to the second opening.

Methods, apparatus, systems, and articles of manufacture are to control air flow separation of an engine. An example turbofan includes a nacelle having an outer lip surface, an inner lip surface, a first opening and a second opening, the first opening coupled to a first region forward of a fan of the turbofan, the second opening coupled to a second region aft of the fan, the nacelle including a first pressure sensor coupled to the outer lip surface, a second pressure sensor coupled to the inner lip surface, and an actuator, and a conduit coupled to the actuator, the conduit configured to have a first end and a second end, the first end coupled to the first opening, the second end coupled to the second opening.

A feedback device for use in a gas turbine engine, and methods and systems for controlling a pitch for an aircraft-bladed rotor, are provided. The feedback device is composed of a circular disk and a plurality of position markers. The circular disk is coupled to rotate with a rotor of the gas turbine engine, to move along a longitudinal axis of the rotor, and has first and second opposing faces defining a root surface that extends between and circumscribes the first and second faces. The plurality of position markers extend radially from the root surface, are circumferentially spaced around the circular disk, and extending along the longitudinal axis from a first end portion to a second end portion. At least part of the first end portion and/or of the second end portion comprises a material having higher magnetic permeability than that of a remainder of the position markers.

A feedback device for use in a gas turbine engine, and methods and systems for controlling a pitch for an aircraft-bladed rotor, are provided. The feedback device is composed of a circular disk and a plurality of position markers. The circular disk is coupled to rotate with a rotor of the gas turbine engine, to move along a longitudinal axis of the rotor, and has first and second opposing faces defining a root surface that extends between and circumscribes the first and second faces. The plurality of position markers extend radially from the root surface, are circumferentially spaced around the circular disk, and extending along the longitudinal axis from a first end portion to a second end portion. At least part of the first end portion and/or of the second end portion comprises a material having higher magnetic permeability than that of a remainder of the position markers.

A variable vane includes a first vane portion and a second vane portion adjacent the first vane portion. The second vane portion includes a trunnion projecting outward from a radial end of the second vane portion. The second vane portion is configured to rotate about a trunnion axis of the trunnion from a first rotational position to a second rotational position.

A variable vane includes a first vane portion and a second vane portion adjacent the first vane portion. The second vane portion includes a trunnion projecting outward from a radial end of the second vane portion. The second vane portion is configured to rotate about a trunnion axis of the trunnion from a first rotational position to a second rotational position.