Abstract: A bypass valve for a fuel control includes a sleeve, a spool, and a biasing member. The sleeve has a body extending between a first end and a second. The first end defines a first bypass valve port. The body defines a second bypass valve port, a third bypass valve port, and a shutoff port. The second end defines a fourth bypass valve port. The spool is received within the inner bore and is movable between a first position and a second position. The biasing member biases the spool toward the first position.

Abstract: A system and methods of estimating and controlling fuel flow in a gas turbine engine are disclosed. The system and methods include providing a metering valve and a pressure regulating valve. The system and methods further include determining a differential pressure error of the pressure regulating valve based on a metering valve inlet pressure, a discharge pressure, and a bypass fuel flow and determining a metering valve fuel flow based on a metering valve position and the differential pressure error.

Abstract: A method of operating a fail-fixed hydraulic actuator system is provided. The method includes providing an actuator in an initial position, electromechanically operating a valve assembly to hydraulically drive actuator movement and halting the hydraulic driving of the actuator movement by the valve assembly.

Abstract: A bypass valve for a fuel control includes a sleeve, a spool, and a biasing member. The sleeve has a body extending between a first end and a second. The first end defines a first bypass valve port. The body defines a second bypass valve port, a third bypass valve port, and a shutoff port. The second end defines a fourth bypass valve port. The spool is received within the inner bore and is movable between a first position and a second position. The biasing member biases the spool toward the first position.

Abstract: A system and methods of estimating and controlling fuel flow in a gas turbine engine are disclosed. The system and methods include providing a metering valve and a pressure regulating valve. The system and methods further include determining a differential pressure error of the pressure regulating valve based on a metering valve inlet pressure, a discharge pressure, and a bypass fuel flow and determining a metering valve fuel flow based on a metering valve position and the differential pressure error.

Abstract: A rotary metering valve assembly includes a stationary body plate having a first contact surface. Also included is a valve plate having a second contact surface disposed in contact with the first contact surface of the stationary body plate, wherein the valve plate is configured to rotate relative to the stationary body plate. At least one of the first contact surface and the second contact surface comprises a surface flatness of less than about 2.4 ?m (about 93 ?in) and a surface roughness of at least about 0.2 ?m (about 8 ?in).

Abstract: A fuel system for a gas turbine engine includes an engine fuel manifold, a hydraulic actuator, and a drain piston assembly. The hydraulic actuator actuates in response to a change in pressures within the hydraulic actuator. The drain piston assembly is fluidically connected to both the hydraulic actuator and the engine fuel manifold. The drain piston assembly receives fuel from the engine fuel manifold and sends fuel to the hydraulic actuator during engine shut down.

Abstract: A fluid flow valve includes a movable valve piston positioned in a valve body, the valve piston configured to flow a fluid therethrough. A metering window is interactive with the movable valve piston to meter flow through the movable valve piston. A flow meter is positioned at the valve piston to measure a flow rate of fluid through the valve piston. A valve controller is operable connected to the flow meter and the movable valve piston to control position of the valve piston based on flow rate measured at the flow meter.

Abstract: A metering valve for a gas turbine engine fuel system includes a sleeve including first, second, third, fourth, fifth and sixth ports respectively axially spaced apart from one another. A spool is slidably received in the sleeve and includes first, second and third seal lands. The first seal land selectively connects the first and second ports to one another, and the third seal land selectively connects the third and fourth ports to one another and the fifth and sixth ports to one another.

Abstract: A method of metering fuel with a fuel valve. The method includes arranging a spool within to a sleeve along an axis, wherein the spool includes four seal lands. The sleeve includes a fuel inlet aperture, a fuel outlet aperture, and a shutoff port. A first cavity and a second cavity are defined between the spool, the sleeve, and subsets of the seal lands. The fuel inlet port and the fuel outlet port abut one such cavity. Sliding the spool along the axis results in the fuel outlet aperture extending longitudinally beyond the second seal land in the upstream direction.

Abstract: A fuel system, such as for use in an aircraft, comprises a main pump, a servo pump, a modulating valve, a shut-off valve, an actuator and a pump sharing valve. The main pump and the servo pump receive fuel from a source. The metering valve receives main flow from the main pump. The shut-off valve receives fuel flow from the metering valve. The actuator receives fuel flow from the servo pump. The pump sharing valve receives circulating flow from the servo pump and alternatively directs shared flow to the main flow or an inlet of the servo pump. The pump sharing valve also sends main pump flow to supplement the servo pump during shutdown conditions.

Abstract: A rotary metering valve assembly includes a stationary body plate having a first contact surface. Also included is a valve plate having a second contact surface disposed in contact with the first contact surface of the stationary body plate, wherein the valve plate is configured to rotate relative to the stationary body plate. At least one of the first contact surface and the second contact surface comprises a surface flatness of less than about 2.4 ?m (about 93 ?in) and a surface roughness of at least about 0.2 ?m (about 8 ?in).

Abstract: A fuel metering system includes a bypass valve configured to receive a fuel flow under a pressure P1, a pressure regulating valve in fluid communication with the bypass valve and configured to receive a fuel flow under a pressure PQ, a metering valve in fluid communication with the bypass valve and the pressure regulating valve, and configured to receive the fuel flow under the pressure P1 and to output a fuel flow under a pressure P2, a single stage servo valve in fluid communication with the bypass valve, the pressure regulating valve and the metering valve, and configured to receive the fuel flow under the pressure P1, and to output the fuel flow under the pressure PQ, and to output a fuel flow under a pressure PM, and a linear variable differential transformer coupled to the metering valve.

Abstract: A method of metering fuel with a fuel valve. The method includes arranging a spool within to a sleeve along an axis, wherein the spool includes four seal lands. The sleeve includes a fuel inlet aperture, a fuel outlet aperture, and a shutoff port. A first cavity and a second cavity are defined between the spool, the sleeve, and subsets of the seal lands. The fuel inlet port and the fuel outlet port abut one such cavity. Sliding the spool along the axis results in the fuel outlet aperture extending longitudinally beyond the second seal land in the upstream direction.

Abstract: A fuel system, such as for use in an aircraft, comprises a main pump, a servo pump, a modulating valve, a shut-off valve, an actuator and a pump sharing valve. The main pump and the servo pump receive fuel from a source. The metering valve receives main flow from the main pump. The shut-off valve receives fuel flow from the metering valve. The actuator receives fuel flow from the servo pump. The pump sharing valve receives circulating flow from the servo pump and alternatively directs shared flow to the main flow or an inlet of the servo pump. The pump sharing valve also sends main pump flow to supplement the servo pump during shutdown conditions.

Abstract: A fuel system for a gas turbine engine includes an engine fuel manifold, a hydraulic actuator, and a drain piston assembly. The hydraulic actuator actuates in response to a change in pressures within the hydraulic actuator. The drain piston assembly is fluidically connected to both the hydraulic actuator and the engine fuel manifold. The drain piston assembly receives fuel from the engine fuel manifold and sends fuel to the hydraulic actuator during engine shut down.

Abstract: A low hysteresis fluid metering valve includes a valve body having an interior portion, an inlet port, an outlet port including a fluid delivery passage, and a shut-off port. A flow control member is arranged in the interior portion. The flow control member includes a first portion and a second portion. The first portion includes a first end extending to a second end through an intermediate portion having a first metered passage, a second metered passage, and a seal element. The first metered passage is configured and disposed to selectively register with the inlet port and the outlet port when the flow control member is arranged in a first position, and the second metered passage is configured and disposed to register with the shut-off port when the flow control member is arranged in a second position.

Abstract: A fluid flow valve includes a movable valve piston positioned in a valve body, the valve piston configured to flow a fluid therethrough. A metering window is interactive with the movable valve piston to meter flow through the movable valve piston. A flow meter is positioned at the valve piston to measure a flow rate of fluid through the valve piston. A valve controller is operable connected to the flow meter and the movable valve piston to control position of the valve piston based on flow rate measured at the flow meter.

Abstract: A metering valve for a gas turbine engine fuel system includes a sleeve including first, second, third, fourth, fifth and sixth ports respectively axially spaced apart from one another. A spool is slidably received in the sleeve and includes first, second and third seal lands. The first seal land selectively connects the first and second ports to one another, and the third seal land selectively connects the third and fourth ports to one another and the fifth and sixth ports to one another.

Abstract: A fuel metering system includes a bypass valve configured to receive a fuel flow under a pressure P1, a pressure regulating valve in fluid communication with the bypass valve and configured to receive a fuel flow under a pressure PQ, a metering valve in fluid communication with the bypass valve and the pressure regulating valve, and configured to receive the fuel flow under the pressure P1 and to output a fuel flow under a pressure P2, a single stage servo valve in fluid communication with the bypass valve, the pressure regulating valve and the metering valve, and configured to receive the fuel flow under the pressure P1, and to output the fuel flow under the pressure PQ, and to output a fuel flow under a pressure PM, and a linear variable differential transformer coupled to the metering valve.