A system and method for adaptively controlling a cooldown cycle of an auxiliary power unit (APU) that is operating and rotating at a rotational speed includes reducing the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value, determining, based on one or more of operational parameters of the APU, when a lean blowout of the APU is either imminent or has occurred, and when a lean blowout is imminent or has occurred, varying one or more parameters associated with the shutdown/cooldown cycle.

A health monitoring system including an array of microphones, a data collection system, and analytic software used to detect health status, pending malfunctions, or faults of several disparate, engine subsystems. The system can be used to monitor health of the main engines, the engine nacelles, and auxiliary power units (APU) on the aircraft.

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 aircraft includes a fuselage, a main entry door with an associated passenger loading zone, an auxiliary power unit (APU) in the fuselage, and an APU inlet assembly. The APU inlet assembly has an inlet duct, and inlet door, and means for redirecting sound waves coupled to or integrated with an interior side of the inlet door. The inlet duct has a first end coupled to the APU, and a second end associated with the inlet door. The inlet door moves between a closed position and an open position. The means for redirecting sound waves is positioned at a particular location on the interior side of the inlet door, and includes certain acoustic features and characteristics. The particular location and the acoustic features and characteristics cooperate to redirect sound waves generated by the APU away from the passenger loading zone when the inlet door is in the open position.

An air filtering system having: an air box, which has at least one inlet opening and at least one outlet opening; and an air filter, which is arranged inside the air box. The air box has two opposite twin mounting openings, which are obtained in two parallel and opposite walls of the air box and are shaped to allow the air filter to be inserted and removed through each one of them. Two removable doors are provided, each having an outer panel configured to overlap a respective mounting opening to close the mounting opening and two inner appendages, which project perpendicularly from two opposite ends of the outer panel so as to be arranged on the two opposite sides of the air filter, when the door is coupled to the respective mounting opening.

Embodiments described herein provide for a compartment based inlet barrier for foreign object debris to an auxiliary power unit of an aircraft or watercraft. The apparatus is configured to fit within an inlet compartment of an auxiliary power unit and provides a particulate separator for fluid flow to the auxiliary power units using a porous pleated filter media having a corrosion resistant exterior frame and enables a minimal pressure differential throughout the apparatus while in use. The apparatus may further be releasably secured/unsecured using a plurality of fasteners which enable a user to readily assemble and disassemble.

An aircraft tailcone comprising a tailcone fuselage, a turbomachine, for example an APU, housed inside the tailcone, a ram air intake on the tailcone fuselage for the ingestion of ram air towards the interior of the turbomachine compartment, an inlet flap operable reciprocately from an open position in which ingestion of ram air is allowed, and a closed position in which ram air ingestion is prevented. The ram air intake extends annularly along a perimeter of the tailcone fuselage, and the inlet flap is configured such in its closed position that a surface of the inlet flap is substantially flush with the tailcone fuselage.

An inlet door state control system for an auxiliary power unit (APU) includes an inlet door configured to allow air into an inlet of the APU. The system also includes an actuator configured to open the inlet door. The system also includes an APU threshold switch connected to the actuator, the APU threshold switch configured to automatically change from an open position to a closed position when a predetermined APU operating condition is met. In the system, the actuator opens the inlet door when the APU threshold switch is in the closed position.

The invention relates to a system (2) for generating non-propulsive energy in an aircraft, including: an auxiliary power unit (20) including a gas turbine (21) and a fuel cell (22); a pathway (23) for the intake of outside air into the aircraft; an exhaust pipe (24) of the gas turbine, the system being characterized in that the air intake pathway (23) includes a pipe (230) for cooling the fuel pipe, in that the pipe is in fluid communication with the exhaust pipe (24) of the gas turbine such that the ejection of the gas from the gas turbine into the exhaust pipe causes a suction of the air outside the aircraft into the cooling pipe (230) by Venturi effect. The invention also relates to a method for generating non-propulsive energy.

An auxiliary power unit for an aircraft includes a turbine engine. An inlet includes an opening and a passageway between the opening and the turbine engine. An acoustic splitter is supported within the passageway for attenuating noise within the inlet. An inlet door is movable between a closed position and a fully open position. A portion of the inlet door aligns with a part of the passageway in at least a first position and divides the passageway to deflect ice and noise in at least a second position. An air inlet and a method are also disclosed.