A valve apparatus for an aircraft fluid system is disclosed including a valve housing and a valve member. The valve member is configured to move between a first position in which fluid is able to flow along the fluid flow path, and a second position in which the fluid flow path restricted. A valve member drive means is configured to operate the valve member via an actuator external to the housing. The valve apparatus further includes a sensor configured to monitor a feature in the housing to determine the position of the valve member.