Abstract: A method of balancing the supply of bleed air from a plurality of gas turbine engines, there being an air bleed line from each of the engines to a common distribution line which distributes the bled air to at least one ancillary system, each air bleed line including a control valve which is controllable by a controller to vary the flow rate of air bled from the associated engine, the method including providing to the controller a demand signal indicative of the demand for bleed air by the ancillary system, sensing air pressure in the distribution line and comparing the demand signal with the sensed air pressure to derive a command signal, flow rates the air pressure individually in each of the air bleed lines from the engines with respective air flow rate sensors which provide air flow rate signals to the controller, comparing the air flow rates in each of the air bleed lines to derive individual flow matching signals for each of the engines, comparing each of the flow matching signals to the command signal t

Abstract: A method of providing an indication of the position of a valve member of a valve in a fluid path where the valve member is moveable between a fully open position in which a maximum flow of fluid past the valve member is permitted and a closed position in which fluid flow past the valve member is at least substantially prevented, the method including sensing the fluid pressure in the fluid path upstream of the valve member to provide a first signal to a controller, sensing fluid pressure in the fluid path downstream of the valve member to provide a second signal to the controller, and sensing fluid flow downstream of the valve member to provide a third signal to the controller, the controller comparing the first and second signals and applying the third signal, and depending on the comparison of the first and second signals and the third signal, the controller signalling an alerting device which indicates whether the valve member is in at least one of an open and closed position.

Abstract: A method of providing an indication of the position of a valve member of a valve in a fluid path where the valve member is moveable between a fully open position in which a maximum flow of fluid past the valve member is permitted and a closed position in which fluid flow past the valve member is at least substantially prevented, the method including sensing the fluid pressure in the fluid path upstream of the valve member to provide a first signal to a controller, sensing fluid pressure in the fluid path downstream of the valve member to provide a second signal to the controller, and sensing fluid flow downstream of the valve member to provide a third signal to the controller, the controller comparing the first and second signals and applying the third signal, and depending on the comparison of the first and second signals and the third signal, the controller signalling an alerting device which indicates whether the valve member is in at least one of an open and closed position.

Abstract: An electronic gas turbine fuel control of the slave datum type, i.e. one including a circuit which generates a speed error signal, an electronic integrator which integrates that error signal to produce a speed datum signal and a difference amplifier comparing the speed datum signal with the actual engine speed to produce a fuel error signal, incorporates a surge detection and recovery circuit. For detection the rate of change of the fuel error signal is derived and compared with a reference value varying with engine conditions. For recovery, if the rate of change exceeds the reference value for a predetermined time during acceleration, the speed error signal is caused to go negative for a fixed period to ramp the integrator output downwards, after which acceleration is allowed to recommence.