Abstract: A method of controlling the operation of a fuel metering unit of the type incorporating a temperature sensor is disclosed, the method comprising the steps of: sensing a change in temperature; using the sensed change in temperature to derive a fast temperature correction factor; using the sensed change in temperature to derive a slow temperature correction factor; using the fast and slow temperature correction factors in combination with a fuel demand to determine a metering valve position; and moving the metering valve to the determined metering valve position.

Abstract: A fuel control system comprises a metering valve operable to control the flow of fuel between a supply line and a delivery line, a spill valve operable to control fuel flow within the supply line, a pressure raising valve connected to the delivery line, and a control servo valve movable between a thrust control mode in which it modifies the control of the spill valve to reduce the fuel flow delivered via the metering valve and an outlet of the pressure raising valve, and a windmill relight position in which it modifies the control of the pressure raising valve to allow fuel delivery through the outlet of the pressure raising valve at a reduced system pressure.

Abstract: A fuel metering unit (FMU) comprising a metering valve operable to control the supply of fuel to a delivery chamber of a pressure raising valve (PRV), the PRV including a valve member movable under the influence of the pressure within the delivery chamber between a closed position and an open position in which fuel is able to flow from the delivery chamber to an outlet port, and a push piston movable under the influence of the pressure within a control chamber to urge the valve member towards its open position, wherein the control chamber communicates with a valve control port.