Monitoring arrangement to determine the status of a valve in a fuel supply system

An apparatus for determining the status of a shut-off valve arrangement (28) forming part of a fuelling system of an engine comprises a metering valve arrangement (24) comprising a metering valve member (32) for regulating fuel flow from a pump (16) forming part of the fuelling system to the engine and means (46) for monitoring the position of the metering valve member (32). The shut-off valve arrangement (28) is operable between open and closed positions and the metering valve arrangement (24) is operable between a maximum flow position, in which the flow of fuel through the metering valve arrangement (24) to the shut-off valve arrangement (28) is a maximum, and a minimum flow position in which the flow of fuel through the metering valve arrangement (24) to the shut-off valve arrangement (28) is a minimum. The position of the metering valve member (32) is controlled by controlling fuel pressure acting on the metering valve member (32). The apparatus futher comprises means (61,63) for varying fuel pressure acting on the metering valve member (32) upon closure of the shut-off valve arrangement (28), and means (46,43) for monitoring the response of the metering valve arrangement to the variation in fuel pressure applied to the metering valve member (32) so as to provide an indication that the shut-off valve arrangement (28) has closed.