Abstract: A fuel control system according to an exemplary aspect of the present disclosure includes, among other things, a fuel delivery valve selectively moveable to a closed position to shut off a flow of fuel to a downstream location. The system further includes a windmill bypass valve, and a shutoff pressure line between the windmill bypass valve and the fuel delivery valve. The windmill bypass valve is selectively operable to direct fuel to the shutoff pressure line to assist the movement of the fuel delivery valve to the closed position. A method is also disclosed.

Abstract: A fuel control system according to an exemplary aspect of the present disclosure includes, among other things, a fuel delivery valve selectively moveable to a closed position to shut off a flow of fuel to a downstream location. The system further includes a windmill bypass valve, and a shutoff pressure line between the windmill bypass valve and the fuel delivery valve. The windmill bypass valve is selectively operable to direct fuel to the shutoff pressure line to assist the movement of the fuel delivery valve to the closed position. A method is also disclosed.

Abstract: A method of sensing a reduction in fuel screen area in a fuel system. The method includes detecting an engine shutdown, initiating an electronic engine control (EEC) built in test, shifting a metering valve from a first position to a second position, determining a travel time of the metering valve, and sensing a reduction in fuel screen area based on the travel time of the metering valve.

Abstract: A metering valve assembly includes a metering valve sleeve and a metering valve spool. The metering valve sleeve includes an inlet window set and an outlet window set with a first outlet window having a first logarithmic contour and a second outlet window having a second logarithmic contour. A ratio of an inner width of the first outlet window to an inner length of the first outlet window is between 1.48 and 1.52. A ratio of an inner width of the second outlet window to an inner length of the second outlet window is between 2.21 and 2.29. The metering valve spool includes first, second, and third cylindrical portions. The metering valve spool is configured to move bi-directionally along a longitudinal axis of the metering valve sleeve and control fluid flow between the inlet window set and the outlet window set relative to the first, second, and third cylindrical portions.

Abstract: A method of operating an electronic engine control to compensate for speed changes. The method includes receiving a fuel flow request, sensing actual engine rotor speed, calculating a fuel flow correction factor, establishing a final fuel flow request based on the fuel flow correction factor, and adjusting the actual set point of the MV to compensate for the actual engine rotor speed.

Abstract: A method of sensing a reduction in fuel screen area in a fuel system. The method includes detecting an engine shutdown, initiating an electronic engine control (EEC) built in test, shifting a metering valve from a first position to a second position, determining a travel time of the metering valve, and sensing a reduction in fuel screen area based on the travel time of the metering valve.

Abstract: A method of operating an electronic engine control to compensate for speed changes. The method includes receiving a fuel flow request, sensing actual engine rotor speed, calculating a fuel flow correction factor, establishing a final fuel flow request based on the fuel flow correction factor, and adjusting the actual set point of the MV to compensate for the actual engine rotor speed.

Abstract: According to the present invention, a fuel control has an electronic primary control for scheduling a flow of fuel to an engine in a primary mode and hydromechanical secondary control for scheduling the flow of fuel to the engine in a backup mode. The fuel control also has a tracking piston and link whose position is responsive to the HMU during the operation of the electronic primary control. The tracking piston and link effectively changes the power lever angle sensed by the HMU so that in the event of a transfer of control from the electronic primary control to the HMU, changes in the scheduled fuel flow to the engine are minimized.

Abstract: Fuel flow to a gas turbine engine is controlled in response to power lever position and CDP. Fuel is supplied to the engine through three fuel flow regulating circuits which are in parallel. In one of these circuits there is a valve which establishes a minimum fuel flow which decreases with increasing power lever advance. In a second circuit there is a valve which modifies fuel flow in response to CDP. In a third circuit there is a valve which modifies fuel flow in response to CDP and receives fuel from a valve which opens with increasing power lever advance. The fuel control system includes a low power sensitive torque motor which may be activated to increase the pressure drop across the three circuits whose flow thus increases proportionally. Normal engine operation is obtainable without the use of the torque motor which provides an interface to an electronic control unit which senses various engine and ambient parameters and activates the torque motor in order to modify fuel flow accordingly.