A pressure control system includes an overboard valve in indirect communication with a first enclosed environment and in direct communication with a second enclosed environment. The first environment is suitable for human occupancy and configured to receive pressurized air from an environmental control system. The second environment is configured to receive the pressurized air from the first environment. An inboard valve is configured to supply a discharge of pressurized air from the second environment. An outflow valve is configured to regulate a discharge of air from the first environment to an area outside the first and second environments. A positive pressure relief valve configured to regulate a discharge of air from the first environment. A negative pressure relief valve configured to regulate an ingress of air into the first environment. A control valve is configured to regulator and supply pressurized air from the first environment to a compressor.

An aircraft extending between a forward end and an aft end is provided. The aircraft includes an auxiliary power unit positioned proximate the aft end of the aircraft, the auxiliary power unit having an auxiliary power unit inlet duct and an auxiliary power unit exhaust duct, and a boundary layer ingestion fan positioned proximate the aft end of the aircraft, the boundary layer ingestion fan having a support shaft, wherein the auxiliary power unit exhaust duct extends through a portion of the support shaft of the boundary layer ingestion fan.

An auxiliary power unit (APU) system for an aircraft can include a fuel consuming system configured to generate and output electrical energy for use by one or more aircraft systems and a battery system configured to output stored electrical energy for use by the one or more aircraft systems. The fuel consuming system can include a fuel consuming APU, and an APU generator operatively connected to the fuel consuming APU and configured to convert APU motion into APU generator alternating current (AC). The system can include a high voltage AC line operatively connected to the generator. The battery system can include a battery configured to output battery direct current (DC).

A Laminar Inducing Apparatus (LIA) inducing laminar airflow to a turbine engine or a propulsion fan. The LIA produces turbulent-free airflow with a light aerospace structure that can replace single purpose structure in the wing or empennage. Laminar airflow to the propulsion fan or the turbine engine is ensured in a greater number of flight conditions and angles of attack. Active control of flight can be enhanced by the manipulating the turbulent boundary surface as a flight control surface. LIA simply reduces the risk of FOD or bird strike damage. In addition to the engineered, laminar benefits, LIA provides greater safety from ground ingested FOD and more silent vertical take-off and landing. In summary, LIA ensures laminar airflow and acoustic attenuation to a propulsion fan or a turbine engine for a greater number of flight conditions, angles of attack, and from ground ingested FOD during vertical takeoff and landing.

Aspects of this disclosure relate to externally accessible auxiliary power unit (APU) pump assembly, comprising: a pump configured to pressurize an accumulator that is used to start an APU of an aircraft; a pressure gauge for the accumulator; and a support frame configured to be mounted within an outer wall of the aircraft, wherein the support frame defines an externally accessible compartment and secures the pump and the pressure gauge within the externally accessible compartment.

A suspension system for an aircraft auxiliary power unit (1) located in a fuselage structure (2) including: auxiliary power unit attachment brackets (3) arranged to be attached to the auxiliary power unit (1); fuselage attachment brackets (4) attached to the auxiliary power unit attachment brackets (3) and coupled to the fuselage structure (2); two longitudinal elements (5) arranged to be attached to the fuselage structure (2) in the longitudinal direction of the aircraft for supporting the auxiliary power unit (1), the two longitudinal elements (5) and the plurality of fuselage attachment brackets (4) being connected such that the two longitudinal elements (5) support the plurality of fuselage attachment brackets (4), being the fuselage attachment brackets (4) slidably movable along the longitudinal elements (5) for introducing or extracting the auxiliary power unit (1) into the fuselage structure (2).

An engine assembly for an aircraft, including an internal combustion engine having a liquid coolant system in fluid communication with a heat exchanger, an exhaust duct in fluid communication with air passages of the heat exchanger, a fan in fluid communication with the exhaust duct for driving a cooling air flow through the air passages of the heat exchanger and into the exhaust duct, and an intermediate duct in fluid communication with an exhaust of the engine and having an outlet positioned within the exhaust duct downstream of the fan and upstream of the outlet of the exhaust duct. The outlet of the intermediate duct is spaced inwardly from a peripheral wall of the exhaust duct. The engine assembly may be configured as an auxiliary power unit. A method of discharging air and exhaust gases in an auxiliary power unit having an internal combustion engine is also discussed.

A safety open and closing system for an overpressure door on fuselage of an aircraft. Wherein the safety opening and closing system allows safe access through the overpressure door to the compartment. The safety open and closing system including an assembly of a hollow beam, a blocking bar in the hollow beam, a spring biasing the blocking bar with respect to the hollow beam and a lever at the end of the blocking beam which pivots between a position A that allows closure of the overpressure door and a position B preventing closure of the door.

Aircraft fuselage apparatus having embedded structural batteries are disclosed. An example apparatus includes a fuselage having a wall. The wall has an outer surface, an inner surface, and a structural battery embedded in the wall between the outer surface and the inner surface.

An airborne docking method is provided for an unmanned aerial vehicle. The airborne docking method includes securing an unmanned aerial vehicle (UAV) to a host aircraft via a docking assembly having a base coupled to the host aircraft, a tug device, and a cable connecting the tug device to the base, the tug device being engaged with the base, and the UAV being engaged to the tug device. The tug device is deployed from the base and the cable is extended therebetween to distance the tug device from the base. The UAV is then disengaged from the tug device.