A fuel system for a composite aircraft is described which includes an ejector pump having a vacuum inlet in communication with a fuel storage tank, an engine feed pump having an inlet in fluid communication with an outlet of the ejector pump, a primary outlet in communication with an engine, and a motive flow outlet, upstream of an oil-fuel heat exchanger, that is in fluid communication with an inlet of the ejector pump. A motive flow pump assembly is disposed between the motive flow outlet of the engine feed pump and the inlet of the ejector pump. The motive flow pump assembly includes an inlet screen and a motive flow pump, the inlet screen having a plurality of openings therein and a hydrophobic upstream surface. The openings are dimensioned to prevent passage of particles greater than a selected threshold size while allowing liquids to flow therethrough.

A fuel system for a composite aircraft is described which includes an ejector pump having a vacuum inlet in communication with a fuel storage tank, an engine feed pump having an inlet in fluid communication with an outlet of the ejector pump, a primary outlet in communication with an engine, and a motive flow outlet, upstream of an oil-fuel heat exchanger, that is in fluid communication with an inlet of the ejector pump. A motive flow pump assembly is disposed between the motive flow outlet of the engine feed pump and the inlet of the ejector pump. The motive flow pump assembly includes an inlet screen and a motive flow pump, the inlet screen having a plurality of openings therein and a hydrophobic upstream surface. The openings are dimensioned to prevent passage of particles greater than a selected threshold size while allowing liquids to flow therethrough.

A combustion staging system includes a splitting unit which receives a metered fuel flow and controllably splits the received fuel flow into pilot and mains flows. Pilot and mains fuel manifolds distribute fuel from the splitting unit to the pilot and mains stages. The splitting unit selects and deselects pilot-only operation. Both pilot and mains manifolds are selectable for pilot and mains operation. A cooling flow recirculation line has a delivery section arranged to provide a cooling flow of fuel to the mains manifold when it is deselected during pilot-only operation. Cooling flow enters the delivery section from a high pressure fuel zone of the engine and exits the return section to a low pressure fuel zone of the engine. A controller adjusts the splitting unit during pilot-only operation to partially select the mains manifold thereby increasing the pressure in the mains manifold to meet a target fuel pressure therein.

A combustion staging system includes a splitting unit which receives a metered fuel flow and controllably splits the received fuel flow into pilot and mains flows. Pilot and mains fuel manifolds distribute fuel from the splitting unit to the pilot and mains stages. The splitting unit selects and deselects pilot-only operation. Both pilot and mains manifolds are selectable for pilot and mains operation. A cooling flow recirculation line has a delivery section arranged to provide a cooling flow of fuel to the mains manifold when it is deselected during pilot-only operation. Cooling flow enters the delivery section from a high pressure fuel zone of the engine and exits the return section to a low pressure fuel zone of the engine. A controller adjusts the splitting unit during pilot-only operation to partially select the mains manifold thereby increasing the pressure in the mains manifold to meet a target fuel pressure therein.

A gas turbine engine shut-down system includes a pump configured to draw a flow of fuel from a source, a fuel nozzle configured to receive the flow of fuel from the pump, a fuel shut-off valve in fluid communication with the pump, a recirculation circuit for circulating excess fuel to a location upstream of the pump; a solenoid valve in communication with the pump and the recirculation circuit; and a fuel-bypass valve. The fuel-bypass valve includes a first opening connected to the fuel pump, a second opening connected to the fuel shut-off valve, a third opening connected to the recirculation circuit, a fourth opening connected to the solenoid valve, and a piston disposed within the fuel-bypass valve and movable between a plurality of positions.

A gas turbine engine shut-down system includes a pump configured to draw a flow of fuel from a source, a fuel nozzle configured to receive the flow of fuel from the pump, a fuel shut-off valve in fluid communication with the pump, a recirculation circuit for circulating excess fuel to a location upstream of the pump; a solenoid valve in communication with the pump and the recirculation circuit; and a fuel-bypass valve. The fuel-bypass valve includes a first opening connected to the fuel pump, a second opening connected to the fuel shut-off valve, a third opening connected to the recirculation circuit, a fourth opening connected to the solenoid valve, and a piston disposed within the fuel-bypass valve and movable between a plurality of positions.

A gas turbine combustor assembly includes: a primary combustion chamber in fluid communication with a primary fuel outlet of a primary fuel injector; a torch igniter coupled to the primary combustion chamber, the torch igniter including an auxiliary combustion chamber and an auxiliary fuel injector having an auxiliary fuel outlet in fluid communication with the auxiliary combustion chamber; and a fuel circuit including a first supply flowpath between a fuel inlet and the primary fuel injector, a second supply flowpath between the fuel inlet and the auxiliary fuel injector, and a bypass flowpath between the auxiliary fuel injector and the primary fuel injector.

A gas turbine combustor assembly includes: a primary combustion chamber in fluid communication with a primary fuel outlet of a primary fuel injector; a torch igniter coupled to the primary combustion chamber, the torch igniter including an auxiliary combustion chamber and an auxiliary fuel injector having an auxiliary fuel outlet in fluid communication with the auxiliary combustion chamber; and a fuel circuit including a first supply flowpath between a fuel inlet and the primary fuel injector, a second supply flowpath between the fuel inlet and the auxiliary fuel injector, and a bypass flowpath between the auxiliary fuel injector and the primary fuel injector.

A fuel system for an aircraft engine comprises a fuel metering unit and a separate flow divider. The flow divider has an inlet port fluidly connected to the fuel metering unit via a fuel line. A primary and a secondary fuel manifold are fluidly connected to the flow divider. The fuel metering unit and the flow divider have a fuel supply mode in which fuel is allowed to flow in a first direction through the fuel line from the fuel metering unit to the flow divider to feed the primary and secondary fuel manifolds, and an ecology mode in which fuel is allowed to flow in a second direction through the same fuel line from the flow divider towards the fuel metering unit. A same fuel line is thus used as a fuel supply line and an ecology line.

A method for reducing an engine core speed is disclosed, which includes determining a condition of an engine during operation of the engine, and controlling an engine turbine clearance based on the condition of the engine so as to influence the engine core speed. An engine system comprising an engine core speed reducing system is also disclosed.