Abstract: An apparatus for measuring the circumferential distribution of temperature in a fluid, comprising a plurality of sensor ladders, each incorporating a plurality of temperature sensors, wherein a first one of the sensor ladders partially overlaps a second one of the sensor ladders, part of the first sensor ladder not overlapping the second sensor ladder.

Abstract: A position sensor system for use in sensing the position of a component located within a housing and disposed, at least in part, within a fluid, the system comprising a first acoustic position sensor operable to transmit a first acoustic signal through the fluid and to sense a reflection of the first acoustic signal from a first surface to derive a first position signal, a second acoustic position sensor operable to transmit a second acoustic signal through the fluid and to sense a reflection of the second acoustic signal from a second surface to derive a second position signal, and means operable, using the first and second position signals, to derive a position signal indicative of the position of the component within the housing.

Abstract: A fault tolerant electric drive system comprises an alternator, a motor controller and an electric motor, wherein the alternator and motor each have a plurality of corresponding independent phase windings, the motor controller having a plurality of independent phase drives corresponding to the phase windings, and a plurality of independent electric drive phases is defined by connecting each corresponding phase winding of the alternator and motor to a corresponding phase drive of the motor controller.

Abstract: A fuel system comprises a fuel actuation arrangement 28 operable to split a metered flow of fuel into at least a first stream and a second stream, a control unit 25 controlling the operation of the fuel actuation arrangement 28, and wherein the control unit 25 controls the operation of the fuel actuation arrangement 28 in response to the output of a temperature sensor 34 sensitive to a gas temperature downstream of the high pressure compressor 14 of an associated engine and the output of a gas sensor 24 sensitive to at least one parameter of the composition of a gas downstream of a combustor 15 of the engine.

Abstract: A fuel system comprises a supply unit operable to deliver a metered supply of fuel to a supply manifold, a staging valve operable to control the supply of fuel from the supply manifold to a pilot outlet and a main outlet, and control means operable to control the operation of the staging valve to control whether fuel is delivered through the pilot and/or main outlet thereof.

Abstract: An aircraft fuel pumping arrangement comprises a first fuel pump, an electrically powered motor operable to drive the first fuel pump to deliver fuel to an outlet, a second fuel pump, a gas driven turbine operable to drive the second fuel pump to deliver fuel to the outlet, and a controller operable to control the operation of the gas driven turbine to determine the rate at which the second fuel pump is driven.

Abstract: A fuel staging system is described which comprises a staging valve 28 operable to divide a metered fuel supply between a pilot delivery line 18 and a mains delivery line 16, and a recirculation valve 54 connected to the mains delivery line 16 and operable to permit a recirculation fuel flow to be supplied to the mains delivery line 16 when the staging valve 28 occupies a position in which substantially no fuel is delivered to the mains delivery line 16 through the staging valve 28.

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 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.

Abstract: A shut-down arrangement comprises a shut-off actuation device operable under the control of a control unit, a switch whereby a first shut-down signal can be supplied to the control unit and whereby a second shut-down signal can be supplied to the shut-off actuation device, and delay means whereby the transmission of the second shut-down signal to the shut-off actuation device is delayed relative to the transmission of the first shut-down signal to the control unit.

Abstract: A staging valve arrangement is described that comprises an arrangement of electrically driven staging valves that are located, in use, in the high temperature core zone of an engine. Each staging valve may comprise a housing having an inlet, a pilot flow outlet and a mains flow outlet, a valve member movable between a closed position in which the mains flow outlet is closed and an open position in which the mains flow outlet is open, a motor operable to drive the valve member for movement, and a cooling arrangement.

Abstract: An apparatus for detecting the accumulation of particulate material on a filter medium formed of dielectric material and disposed in a chamber is provided. The apparatus is operable for generating and transmitting an RF signal through the filter medium and for monitoring the transmission loss of the signal through at least a portion of the filter medium so as to provide an indication of the content of particulate material accumulated on the filter medium. The apparatus includes an input antenna for transmitting the signal and having at least one antenna element extending longitudinally of the chamber and disposed within the filter medium; and an output antenna for receiving the signal transmitted by the input antenna and having at least one antenna element extending longitudinally of the chamber and disposed within the medium in parallel, spaced apart, axially overlapping relation with respect to the input antenna element.