Abstract: An aircraft gas turbine engine fuel metering unit incorporating a memory device for storing data relevant to that unit, and an electrical connection arrangement whereby data can be read from and/or written to said memory device by an associated electronic engine controller, said stored data including data relating to at least one of the performance, the identification, the health, and the service life of that fuel metering unit. The invention further resides in an aircraft gas turbine engine fuel supply system and a method of operating such a system.

Abstract: A fuel control system as claimed in claim 1 wherein, the pressure raising valve includes: a pressure raising valve member exposed to fuel pressure within a reference chamber, an inlet to which fuel at supply pressure is supplied, wherein the pressure raising valve member is movable against a force due to pressure within the reference chamber by means of fuel at supply pressure, an outlet through which fuel at delivery pressure is supplied to the engine, and feedback means for permitting fuel at delivery pressure to flow to the reference chamber. There is also disclosed a pressure raising valve for use in such a system.

Abstract: According to the present invention there is provided a fuel injection system for a combustion engine, comprising: a fuel metering unit for providing a metered supply of pressurized fuel, at least one first fuel injector, at least one second fuel injector, a fuel supply passage arrangement for supplying fuel from the fuel metering unit to the at least one first fuel injector and the at least one second fuel injector. The fuel supply passage arrangement including a first valve for controlling the flow of fuel from the fuel metering unit to the at least one second fuel injector. The first valve having a fuel inlet communicating with the fuel metering unit, a fuel supply outlet communicating with the at least one second injector.

Abstract: A fuel system for a gas turbine engine having a main burner fuel supply line and a pilot burner fuel supply line, a high pressure pump supplying fuel to the main and pilot burner supply lines in use, a throttle valve controlling the flow of fuel in the main burner supply line, a metering valve controlling the flow of fuel in the pilot burner supply line, and a pressure raising valve between the pilot burners and the metering valve, the pressure raising valve serving to maintain the upstream fuel pressure to a pre-determined amount in excess of the pressure of fuel supplied from the throttle valve to the main burners.

Abstract: A switching circuit controls at least one semiconductor switch TR1 using drive signals generated from logic circuitry 4 that generates complementary drive signals on an upper and lower drive path. Validation circuitry is provided between the logic circuitry and the semiconductor switch that inhibits any uncontrolled switching of the semiconductor switch TR1 due to noise, such as lightning strike, appearing at the load.