A metering valve has a shutoff position at which it blocks flow from the metering valve outlet line from reaching an outlet to a use. A spool has a first end and a second end. The housing has a first shoulder associated with the first end and a second shoulder associated with the second end. In the shutoff position, the spool has the first end spaced from the first shoulder, and the second end spaced from the second shoulder. A fuel system for a gas turbine engine is also disclosed.

A fuel control device includes a stem fuel valve opening degree determination unit, a branch line flow rate determination unit, and a correction value determination unit. The stem fuel valve opening degree determination unit is configured to determine an opening degree of a flow rate adjustment valve of a stem fuel supply line. The branch line flow rate determination unit is configured to determine an opening degree of a flow rate adjustment valve of at least one branch line. The correction value determination unit is configured to determine a correction value of the opening degree of the flow rate adjustment valve of the at least one branch line based on a value of a pressure difference between a fuel pressure upstream of a nozzle connected to the at least one branch line and a corrected fuel pressure for a fuel pressure at an outlet.

A fuel system for a gas turbine engine includes an augmentor pump having an inlet communicating with a fuel supply source and a discharge communicating with an augmentation stage of the engine. An electric motor is operatively connected to drive the augmentor pump for selectively activating and deactivating the augmentor pump.

A fuel system for a gas turbine engine includes an augmentor pump having an inlet communicating with a fuel supply source and a discharge communicating with an augmentation stage of the engine. An electric motor is operatively connected to drive the augmentor pump for selectively activating and deactivating the augmentor pump.

A combustion staging system for fuel injectors of a multi-stage combustor of a gas turbine engine. The system includes plural fuel injectors, each having respective pilot and mains injection stages. It further includes a splitting unit which, to perform staging control of the combustor, receives a metered fuel flow and, for pilot and mains operation, controllably splits the received fuel flow into a pilot flow for injecting at the pilot stages of the injectors and a mains flow for injecting at the mains stages of the injectors, and for pilot-only operation, controllably splits the received fuel flow into a first part of the pilot flow for injecting at the pilot stages of a first portion of the injectors and a second part of the pilot flow for injecting at the pilot stages of a second portion of the injectors.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.

In a method for operating a combustor of an embodiment, before ignition in the combustor, a mixed gas containing oxygen is circulated through the combustor as a circulating gas. Then, in an operating time from the time of ignition in the combustor to the time of a rated load of a turbine, from the time of ignition until reaching stable combustion conditions allowing stable combustion, a combustion gas in which a controller controls a flow rate of a fuel supplied from a fuel supply part and a flow rate of an oxidant supplied from an oxidant supply part to maintain the same oxygen concentration as an oxygen concentration in the mixed gas is circulated as the circulating gas.

A fuel pump system has a start stage pump and a main stage pump. Fuel is supplied to the start stage pump at lower engine speeds. As the engine speed increases, the fuel system restricts fuel to the start stage pump via a pressure regulating valve and the main stage pump takes over. An electronically controlled shut-off valve limits the amount of fuel supplied to the pressure regulating valve and, hence, the start stage pump when closed to safeguard against operating the start stage pump at unsafe engine speeds.

In accordance with at least one aspect of this disclosure, there is provided a system for an aircraft engine. In embodiments, the system includes an accessory box and a fuel accessory located in an interior space within the accessory box, where a vent is defined through a wall of the accessory box. In embodiments, the vent includes a plurality of holes or slots in an outer wall of the accessory box for passage of gaseous fuel from the interior space. In embodiments, the vent is configured for passive ventilation of the interior space.