An adapter system for a check valve which comprises a housing open at the bottom and a lateral wall pierced by a hole, and a flap fitted inside the housing and movable between a shut-off position in which the flap shuts off the hole and a free position in which the flap does not shut off the hole. A plug is provided for being inserted into the hole through an end face and a stop is provided for being placed against the lateral wall of the housing opposite the lateral wall pierced by the hole and comprising an attachment device provided for attaching the stop to the housing and provided so that the plug comes to rest against the stop. Such an adapter system may be installed without it being necessary to dismantle the housing.

A system comprises a non-transitory machine readable storage medium storing instructions and a database identifying a plurality of assets and a state of each asset. The instructions configure a processor for receiving updates to a distributed electronic ledger managed by plural peer processors. Each update includes an event or change affecting one of the assets. The peer processors verify portions of the ledger describing each event or change. At least one of the updates has not yet been recorded in the ledger at a time of the receiving. The processor computes a state of each asset, based on the updates, receives a request for a state of one of the assets; and responds to the request, reflecting each event and change affecting that asset. The response is performed without waiting for the peer processors to verify an update that has not yet been recorded in the ledger.

A duct stringer is disclosed and forms at least part of a duct with a closed cross-section along which a fluid flows. An aperture is formed through a duct wall of the duct stringer and communicates with the duct. An insert is adhered in the duct stringer and is configured to engage with a fastening member to mount a fluid transporting conduit, such as a pipe, over the aperture.

A duct stringer is disclosed and forms at least part of a duct with a closed cross-section which is adapted to transport fluid. The duct stringer has a duct wall and a female bayonet fitting in the duct wall. The female bayonet fitting is configured to engage with a male bayonet fitting on a fluid transporting conduit to connect the fluid transporting conduit with the duct. The present application also relates to an aircraft assembly comprising the duct stringer and the fluid transporting conduit.

A fuel storage system is disclosed having a fuel tank configured to store a liquid fuel; a controllable pressure source for altering the pressure in an ullage space of the fuel tank; and a controller. The controller is configured to determine a target pressure for the ullage space at a given time based on information relating to a temperature of fuel inside the fuel tank at the given time; and to control the pressure source such as to cause the pressure in the ullage space to be substantially equal to the target pressure.

A fuel storage system is disclosed having a fuel tank configured to store a liquid fuel; a controllable pressure source for altering the pressure in an ullage space of the fuel tank; and a controller. The controller is configured to determine a target pressure for the ullage space at a given time based on information relating to a temperature of fuel inside the fuel tank at the given time; and to control the pressure source such as to cause the pressure in the ullage space to be substantially equal to the target pressure.

Aircraft systems including a pressurized fuel tank containing a pressurized fuel, a turbo expander configured to receive the pressurized fuel from the fuel tank, the turbo expander configured to decrease a pressure of the pressurized fuel to generate low pressure fuel having pressure less than the pressurized fuel, a fuel-to-air heat exchanger configured to receive the low pressure fuel from the turbo expander as a first working fluid and air as a second working fluid, the heat exchanger configured to cool the air and warm the fuel, an aircraft cabin configured to receive the cooled air, and a fuel consumption system configured to consume the fuel to generate power.

Aircraft systems including a pressurized fuel tank containing a pressurized fuel, a turbo expander configured to receive the pressurized fuel from the fuel tank, the turbo expander configured to decrease a pressure of the pressurized fuel to generate low pressure fuel having pressure less than the pressurized fuel, a fuel-to-air heat exchanger configured to receive the low pressure fuel from the turbo expander as a first working fluid and air as a second working fluid, the heat exchanger configured to cool the air and warm the fuel, an aircraft cabin configured to receive the cooled air, and a fuel consumption system configured to consume the fuel to generate power.

Aircraft hydrogen fuel systems and methods and systems of starting such systems are described. The aircraft hydrogen fuel systems include a hydrogen burning main engine, a main tank configured to contain liquid hydrogen to be supplied to the main engine during a normal operation, and a starter tank configured to contain gaseous hydrogen to be used during a startup operation of the main engine. Methods and processes for starting and/or restarting such systems are described.

A fuel system is provided for an aircraft having a fuel source. The fuel system includes a fuel oxygen reduction unit defining a liquid fuel supply path, a stripping gas supply path, a liquid fuel outlet path, and a stripping gas return path, wherein the stripping gas return path is in airflow communication with the fuel source.