Abstract: A fuel control system for a gas turbine engine which has a gas generator and a separate work turbine, comprises a metering device and an arrangement of throttle valves downstream of the metering device for controlling the fuel pressure drop through the metering device. A first throttle valve is responsive to a difference between desired and actual gas generator speeds to maintain the metering pressure drop constant for a selected speed. This throttle valve is also operable to restrict fuel flow if the work turbine exceeds a predetermined speed. A second throttle valve, in parallel with the first valve controls fuel flow at low engine speeds, and first valve controls fuel flow during acceleration.

Abstract: A fuel control system for a gas turbine engine has a pump which delivers fuel to a supply passage. A spill valve downstream of the pump is responsive to a servo pressure signal to spill fuel from the supply passage. A pilot valve is controlled by a torque motor to regulate the servo pressure signal. The torque motor is responsive to an electrical signal dependent on a difference between desired and actual engine speeds.

Abstract: A priming valve for a liquid fuel supply system is arranged in parallel with a fuel metering device and includes a shuttle control element which opens the priming valve during movement, the priming valve being shut at opposite ends of movement of the shuttle. The shuttle is moved by an operating pressure derived from the priming valve inlet via a restrictor and applied to respective ends of the shuttle by a change-over control valve which is operated to deliver a priming charge of fuel.