An inlet door for an auxiliary power unit includes a door body with opposed interior and exterior surfaces. The interior surface of the inlet door is curved to diffuse sound waves received by the interior surface.

Auxiliary power unit inlet apparatus and methods are disclosed. An example apparatus includes an air inlet for an aircraft including a first air flow path and a second air flow path. The first air flow path is immediately adjacent the second air flow path. The first air flow path is at least partially separated from the second air flow path by a first panel. The example apparatus includes a door hingably coupled adjacent the air inlet. The door includes a second panel extending from an interior surface of the door to substantially prevent air from flowing across the interior surface between the first air flow path and the second air flow path.

An assembly for an aircraft includes an aircraft housing, an auxiliary power unit (APU), an oil system, a door actuator, and a controller. The aircraft housing forms a compartment. The aircraft housing includes an intake door. The intake door is movable between a closed position, an open position, and intermediate positions between the closed position and the open position. The APU is disposed within the compartment. The APU includes an engine. The engine includes an air inlet and a rotational assembly. The oil pump is operatively connected to the rotational assembly. The door actuator is operatively connected to the intake door. The door actuator is operable to position the intake door in the closed position, the open position, and the intermediate positions to control an ambient air flow to the air inlet. The controller is operatively connected to the door actuator. The controller is configured to identify a fire condition within the compartment, identify a fire position of the intake door, and control the door actuator to position the intake door in the fire position. The fire position is one of the open position or the intermediate positions.

An apparatus comprising is provided including an auxiliary power unit positioned within an aircraft. A reverse thrust assembly is driven by the auxiliary power unit to provide reverse thrust during landing of the aircraft. An air flow surface having a first boundary layer of moving fluid when external air is flowed along the airflow surface which could be a nacelle, pylon or any other aircraft surface. A movable member is configured to move between a first position to direct the boundary layer to the auxiliary power unit during climb and cruise of the aircraft, and to a second position to direct a free stream air feed to the auxiliary power unit during landing of the aircraft. Further, the movable member may switch to a third conduit to extract the boundary layer from the interior surface of an engine air intake to reduce the main engine inlet losses and distortion.

An aircraft heating assembly including an internal combustion engine having a liquid coolant system distinct from any fuel and lubricating system of the engine and including cooling passages in the internal combustion engine for circulating a liquid coolant from a coolant inlet to a coolant outlet, a coolant circulation path outside of the internal combustion engine and in fluid communication with the coolant inlet and the coolant outlet, and a heating element in heat exchange relationship with a portion of the aircraft to be heated. The coolant circulation path extends through a heat exchanger configured to remove a portion of a waste heat from the liquid coolant. The heating element is in heat exchange relationship with the coolant circulation path to receive another portion of the waste heat therefrom. A method of heating a portion of an aircraft is also discussed.

An inlet system for an auxiliary power unit includes an inlet duct, and a frame coupled about the inlet duct. The frame defines an opening configured to be in fluid communication with the inlet duct. The inlet system includes a door having a first end opposite a second end. The door is coupled to the frame at the second end. The door is configured to move relative to the frame between a first position in which the door cooperates with the frame to inhibit airflow into the inlet duct and a second position in which the door is configured to enable the airflow into or out of the inlet duct. The door defines a ramp at the second end. A hook is spaced a distance apart from the ramp to define a gap configured to enable the airflow into or out of the inlet duct in the second position.

A power transmission gearbox having at least one driving gear with spur teeth presenting a large radius. The gearbox includes at least one mechanical outlet drive system suitable for driving an accessory, the mechanical outlet drive system having a gear with face teeth referred to as an accessory pinion, the accessory pinion presenting a small radius (R2) lying orthogonally between each face tooth and its axis of rotation, the small radius (R2) being smaller than the large radius (R1).

The invention relates to an acoustic insulation assembly for an auxiliary power unit having a centrifugal compressor (1), comprising a ring-shaped casing (8) for an air inlet (3) and comprising a plurality of reinforcing arms (9) connecting its inner walls, a plurality of removable mechanical acoustic insulation parts (10), each mechanical part (10) being ring-shaped and comprising attachment means (11) intended to engage with the casing (8), such that the mechanical part (10) and the flow surface of the casing (8), defined by a pair of reinforcing arms (9), overlie one another.

An assembly for an aircraft includes an aircraft housing, an auxiliary power unit (APU), an oil system, a door actuator, and a controller. The aircraft housing forms a compartment. The aircraft housing includes an intake door. The intake door is movable between a closed position, an open position, and intermediate positions between the closed position and the open position. The APU is disposed within the compartment. The APU includes an engine. The engine includes an air inlet and a rotational assembly. The oil pump is operatively connected to the rotational assembly. The door actuator is operatively connected to the intake door. The door actuator is operable to position the intake door in the closed position, the open position, and the intermediate positions to control an ambient air flow to the air inlet. The controller is operatively connected to the door actuator. The controller is configured to identify a fire condition within the compartment, identify a fire position of the intake door, and control the door actuator to position the intake door in the fire position. The fire position is one of the open position or the intermediate positions.

A sealing device for covering an aperture in a wing part of an aircraft. The sealing device has a cover plate covering at least a part of the aperture and having an outer surface delimited by a cover plate edge, and at least one holding device coupled with the cover plate. The at least one holding device having a resilient element, the at least one holding device resiliently holds the cover plate in a distance to an actuation element. The distance is variable in a first direction substantially perpendicular to the outer surface. The at least one holding device holds the cover plate in a substantially fixed spatial alignment in a second direction perpendicular to the first direction. The resilient element urges the cover plate towards the actuation element in a mounted state of the sealing device.