A dam for use with a duct having a longitudinal axis. The dam employs a single piece insert having a first lateral flange and a second lateral flange configured to engage opposing interior lateral surfaces of the duct. The insert engages the duct in sealing contact in a seated position. The first and second lateral flanges are offset longitudinally along the longitudinal axis and joined with a curved wall having a curvature shaped to be received, with the insert oriented at an insert angle about a normal axis perpendicular to the longitudinal axis, in an aperture in the duct.

A dam for use with a duct having a longitudinal axis. The dam employs a single piece insert having a first lateral flange and a second lateral flange configured to engage opposing interior lateral surfaces of the duct. The insert engages the duct in sealing contact in a seated position. The first and second lateral flanges are offset longitudinally along the longitudinal axis and joined with a curved wall having a curvature shaped to be received, with the insert oriented at an insert angle about a normal axis perpendicular to the longitudinal axis, in an aperture in the duct.

A duct stringer assembly with a bulkhead. The duct stringer assembly has duct walls providing a duct with a closed cross-section. The duct is adapted to transport fluid. A bulkhead is in the duct, and the bulkhead is adapted to block the flow of fluid along the duct. The bulkhead has a bulkhead body, and a gasket sealing a gap between the bulkhead body and the duct walls.

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 system and method of controlling a fuel system on an aircraft includes selectively supplying fuel from either a main fuel tank or at least one wing fuel tank to a fuel consumer by varying a speed of at least one main fuel tank pump associated with the main fuel tank relative to a speed of at least one wing fuel tank pump associated with the at least one wing fuel tank.

A system and method of controlling a fuel system on an aircraft includes selectively supplying fuel from either a main fuel tank or at least one wing fuel tank to a fuel consumer by varying a speed of at least one main fuel tank pump associated with the main fuel tank relative to a speed of at least one wing fuel tank pump associated with the at least one wing fuel tank.

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.

A method of pumping fuel in a fuel system of a composite aircraft having a gas turbine engine includes feeding un-heated fuel from a fuel tank to the gas turbine engine, by using an ejector pump to draw the fuel from the fuel tank and feeding the fuel through an engine fuel pump within a main fuel line upstream of the gas turbine engine. Fuel from the main fuel line is bled and directed to the ejector pump via a motive flow pump assembly, the motive flow pump assembly including a motive flow pump generating a motive flow for the ejector pump. The bleed fuel flow is then passed through a hydrophobic fuel screen located upstream of the motive flow pump.

A method of pumping fuel in a fuel system of a composite aircraft having a gas turbine engine includes feeding un-heated fuel from a fuel tank to the gas turbine engine, by using an ejector pump to draw the fuel from the fuel tank and feeding the fuel through an engine fuel pump within a main fuel line upstream of the gas turbine engine. Fuel from the main fuel line is bled and directed to the ejector pump via a motive flow pump assembly, the motive flow pump assembly including a motive flow pump generating a motive flow for the ejector pump. The bleed fuel flow is then passed through a hydrophobic fuel screen located upstream of the motive flow pump.