Abstract: A rotor for a dynamo electric machine comprises a rotor body 12 defining a plurality of poles in the form of limbs 16 around which windings 18 are provided, and a wedge arrangement 20 spanning the space 42 between adjacent limbs 16 and serving to secure the windings 18 in position, and a discharge passage 44 for delivering coolant to the said space.

Abstract: A piezoelectric perovskite mixed oxide compound has the general formula (BiFeO3)x—(PbTiO3)1-X and contains up to 5 at % lanthanum or other rare earth substitution, in which x has a value in the range 0.5 to 0.9. Such compounds are capable of withstanding gas turbine operating temperatures and are suitable for use in sensing and actuation functions in aerospace and other applications.

Abstract: A drive disconnect device for releasably connecting an electrical generator to a drive shaft, the drive disconnect device comprising an output shaft and at least one drive transfer element movable from a first position where it drivingly connects the drive shaft and the output shaft to a second position where the driving connection is removed, wherein operation of the disconnect device causes the electrical generator to become electrically isolated or excitation for the generator to be inhibited.

Abstract: A drive transfer device comprising: a first rotating element having a plurality of apertures therein; a second rotating element adjacent the first rotating element; a plurality of transfer elements; and a control element mounted for rotation with the first element and moveable with respect to the first element between a first position in which the control element holds the transfer elements in an engaged position where the transfer elements extend through the apertures of the first rotating element to engage with the second rotating element to urge them to rotate together, and a second position where the transfer elements are moved and held out of engagement with the second rotating element.

Abstract: A fuel staging system comprises a splitter valve arranged to split an input fuel stream into a pilot fuel stream and a main fuel stream, the splitter valve comprising a spool slidable within a bore, the spool and bore together defining first and second control chambers, the fluid pressures in which determine the position occupied by the spool, the system further comprising a control line which, in use, controls fuel delivery through a plurality of main burners, the fluid pressure in the control line being a combination of the fluid pressures in the first and second control chambers.

Abstract: An aerospace control arrangement comprising a control unit connected to a plurality of connecting node sets, each connecting node set having associated therewith a plurality of connecting nodes, and each node having associated therewith at least one effecter and/or sensor, resulting in at least some of the nodes being connected to the control unit in a fault isolated star, point to point, arrangement.

Abstract: A driver circuit for an electronic switch, the driver circuit having a first input for receiving a first control signal, and a second input for receiving a signal from a current sensor, the driver circuit further including a shut-off circuit for operating the electronic switch to cause an interruption to current flow in the event of a fault condition arising, such as current through the electronic switch exceeding a predetermined threshold, wherein operation of the shut-off circuit can be invoked by a predetermined event at the first input.

Abstract: A fuel supply system for a gas turbine engine comprises a first positive displacement pump (16), a second positive displacement pump (27), said first and second positive displacement pumps (16, 27) being operable simultaneously for the supply of fuel from a low pressure source, and switching valve means (14) downstream of said first positive displacement pump (16) for changing a connection mode between said first and second positive displacement pumps (16, 27) between a series mode and a parallel mode.

Abstract: A method of operating a fuel system to determine the extent of internal wear of a fuel pump thereof comprises driving the fuel pump, moving a metering valve member to a closed position in which the metering valve bears against a resilient stop, increasing the operating speed of the fuel pump to increase the pressure applied to the metering valve member urging the valve member towards the resilient stop to a point beyond which further movement of the metering valve member occurs, sensing when the further movement of the metering valve member occurs, and sensing the operating speed of the pump at the time when the further movement occurs.

Abstract: A generator controller for controlling a permanent magnet generator where each phase of the generator is connectable to a DC link via electrically controllable switches, the controller characterized by a data processor adapted to receive a measurement of generator current output and a demand current, and to form a current error between the demanded value and the measured generator current; derive a target voltage as a function of the current error; and form control signals for the electrically controllable switches as a function of the target voltage.

Abstract: A fault diagnostics technique for use with an engine controller and a hydromechanical device including a memory device comprises the steps of using diagnostics characteristics data stored in the memory device to modify a fault diagnostics algorithm of the engine controller, and using the modified fault diagnostics algorithm in conjunction with real time operating data from the hydromechanical device to determine whether the hydromechanical device is operating correctly.

Abstract: A TGT measurement system comprises a plurality of thermocouples connected in parallel to a distributor, and a data storage device carrying calibration data relating to at least one of the thermocouples.

Abstract: A method of monitoring the health of a positive displacement hydraulic pump comprising the steps of: establishing a flow path having a known flow number between a high pressure outlet line of the pump (and a low pressure line of the system; progressively changing the speed of operation of the pump; and, noting the speed of operation of the pump at a parameter responsive to the output pressure of the pump changes in response to said change in rotational speed of the pump.

Abstract: A fuel system comprises a first, variable displacement fuel pump operable to supply fuel through a metering valve to an engine, a control servo operable to control the operation of the first pump, a pressure drop control valve (PDCV) responsive to a pressure drop across the metering valve, a second fuel pump, and a spill valve movable between an open position in which substantially all of the fuel supplied by the second fuel pump is returned to an inlet side thereof, and a closed position, or partially closed position, wherein a proportion of the fuel supplied by the second pump is delivered to the engine.

Abstract: A rotatable rectifier arrangement comprises a rectifier component 14a, 14b electrically connected to a bus bar 16, 18 the bus bar 16, 18 being provided with at least one fan blade formation 30.

Abstract: A fuel control system for reheat burners of a gas turbine engine has a plurality of metering valves for respective burners, and throttle valves in series with the respective metering valves. A pressure regulating valve is provided for introducing pressurized fuel into fuel manifolds downstream of the respective throttle valves when the metering and throttle valves are shut. The pressure regulating valve also acts to relieve pressure in low pressure parts of the system when the latter is closed down and to prevent excessive temperature rise at the inlet of a fuel supply pump. The metering valves include pressure return ports which communicate with the metering valve outlets when those valves are shut.

Abstract: A system comprises a pressure raising valve having a valve member movable within a bore between a closed position and an open position in which fuel supplied to the pressure raising valve from a metering valve, in use, is delivered to an engine manifold, the valve member being urged towards its closed position by the fuel pressure within a control chamber, the pressure raising valve including a low pressure port which communicates with the control chamber when the valve member is in its closed position, the valve member closing the low pressure port upon movement thereof away from its closed position beyond a predetermined distance.

Abstract: A fuel system comprises a pressure raising valve operable to control communication between a fuel delivery line and an engine manifold line, and an ecology valve comprising a piston movable within a bore, the piston and bore together defining a control chamber and an ecology chamber, the ecology chamber communicating with the engine manifold line, the pressure within the control chamber being controllable to control the position occupied by the piston, the ecology valve further comprising seal means whereby, when the piston occupies a first position in which it engages the seal means, only a first, relatively small, effective area of the piston is exposed to a fuel pressure within the engine manifold line, a second, larger, effective area being exposed to the fuel pressure within the engine manifold line when the piston occupies a position in which it does not engage the seal. An ecology valve for use in the fuel system is also described.

Abstract: A method and apparatus are provided in which control data for a generator system is multiplexed onto a synchronization signal.

Abstract: A fuel system comprises a spill valve 38 operable to relieve the fuel pressure differential across at least one positive displacement pump 16, 18, a shut-off valve 32 operable to control the supply of fuel to an engine 84, and a two stage servo-valve 62 operable to control the operation of the shut-off valve 32, the spill valve 38 having a control chamber 40 the fluid pressure within which is controlled so as to be held at an intermediate level during engine shut-down.