Abstract: A fuel control system for a turbine engine includes a fuel flow regulator comprising a double differential piston slidable in a sleeve to vary the opening and closing of a fuel inlet or outlet and thereby regulate the output flow of fuel from the regulator. A first fixed stop limits the movement of the piston in one direction to define the maximum output flow of fuel permitted by the regulator, while a second stop, in an operative safety position, limits the movement of the piston in the opposite direction to define a minimum fuel output threshold. The second stop can, however, be retracted to an inoperative position by actuation of a control circuit to allow the minimum fuel output threshold to be overcome and the regulator piston to reach an extreme nil outflow position.

Abstract: A modular control sub-assembly in a fuel control system for a turbine engine such as a jet engine, comprises a pressure drop detector constituted by a slide axially movable in a bore of a casing, and an overspeed limiter disposed coaxially in said casing at one end of the bore containing the detector slide. The slide is rotatably driven by the overspeed limiter through a fork coupling and, when the plant overspeed threshold is exceeded, the slide is moved axially by the overspeed limiter in the same direction as on detecting an increase in the pressure drop across a fuel flow feed regulator to reduce an output control pressure signal and thereby cause a control valve to open which reduces the fuel flow and hence the overspeed.