In accordance with at least one aspect of this disclosure, there is provided a fuel system for a gas turbine engine of an aircraft, including a main inlet feed conduit fluidly connected to a primary manifold feed conduit and a secondary manifold feed conduit. A primary manifold fluidly connects the primary manifold feed conduit to a plurality of primary fuel injectors, and a secondary manifold fluidly connects the secondary manifold feed conduit to a plurality of secondary fuel injectors.

A fuel oxygen conversion unit for a vehicle or an engine of the vehicle includes a contactor; a mechanically-driven, first fuel gas separator defining a liquid fuel outlet and a stripping gas outlet, the fuel oxygen conversion unit defining a liquid fuel outlet path in fluid communication with the liquid fuel outlet of the first fuel gas separator; and a second fuel gas separator positioned in fluid communication with the liquid fuel outlet path at a location downstream of the first fuel gas separator.

A fuel oxygen conversion unit for a vehicle or an engine of the vehicle includes a contactor; a mechanically-driven, first fuel gas separator defining a liquid fuel outlet and a stripping gas outlet, the fuel oxygen conversion unit defining a liquid fuel outlet path in fluid communication with the liquid fuel outlet of the first fuel gas separator; and a second fuel gas separator positioned in fluid communication with the liquid fuel outlet path at a location downstream of the first fuel gas separator.

A method of repairing a rod guide assembly of a fuel control unit of an aircraft engine is provided. The method comprises disconnecting a used spring seat from the rod of the rod guide assembly and welding a replacement spring seat to the rod using an electron beam controlled using a circular beam deflection pattern.

A method of operating a fuel delivery system of an aircraft engine of an aircraft includes operating the aircraft engine in a standby mode by maintaining combustion in a combustor of the aircraft engine by supplying fuel to the combustor via a first set of fuel nozzles of a first fuel manifold while providing a trickle flow of fuel via a second set of fuel nozzles of a second fuel manifold into the combustor during engine operation, the trickle flow being defined as a fuel flow rate selected to prevent flame-out of the combustion while providing one of: substantially no motive power to the aircraft, and no motive power to the aircraft, via the combustion of the trickle flow of fuel. An aircraft gas turbine engine is also described.

A method of operating a fuel delivery system of an aircraft engine of an aircraft includes operating the aircraft engine in a standby mode by maintaining combustion in a combustor of the aircraft engine by supplying fuel to the combustor via a first set of fuel nozzles of a first fuel manifold while providing a trickle flow of fuel via a second set of fuel nozzles of a second fuel manifold into the combustor during engine operation, the trickle flow being defined as a fuel flow rate selected to prevent flame-out of the combustion while providing one of: substantially no motive power to the aircraft, and no motive power to the aircraft, via the combustion of the trickle flow of fuel. An aircraft gas turbine engine is also described.

An assembly is provided for an aircraft propulsion system. This assembly includes a first drain tube, a second drain tube, a container and a gas tube. The container fluidly couples the first drain tube to the second drain tube. The container is configured to receive fluid from the first drain tube. The gas tube is fluidly coupled with the container. The gas tube is configured to direct gas into the container for propelling the fluid received within the container into the second drain tube.

An assembly is provided for an aircraft propulsion system. This assembly includes a first drain tube, a second drain tube, a container and a gas tube. The container fluidly couples the first drain tube to the second drain tube. The container is configured to receive fluid from the first drain tube. The gas tube is fluidly coupled with the container. The gas tube is configured to direct gas into the container for propelling the fluid received within the container into the second drain tube.

A metering valve comprising a solenoid having: a coil mounted on a core; and an armature moveable axially with respect to the core and against a return bias in response to a current in the coil; a variable capacitor having a first plate mounted for movement with the armature and a second plate fixed with respect to the core. The metering valve comprises an electronic feedback loop which is used to adjust the current in the coil based on a feedback signal derived from of the capacitance of the variable capacitor. A reference capacitor may be provided having opposing third and fourth plates at a set separation. A valve body may house the solenoid, the variable capacitor and the reference capacitor.

A metering valve comprising a solenoid having: a coil mounted on a core; and an armature moveable axially with respect to the core and against a return bias in response to a current in the coil; a variable capacitor having a first plate mounted for movement with the armature and a second plate fixed with respect to the core. The metering valve comprises an electronic feedback loop which is used to adjust the current in the coil based on a feedback signal derived from of the capacitance of the variable capacitor. A reference capacitor may be provided having opposing third and fourth plates at a set separation. A valve body may house the solenoid, the variable capacitor and the reference capacitor.