A vane pump is disclosed for use with gas turbine engines that is adapted
and configured to provide a failure mode similar to that of a traditional
gear pump. The vane pump includes a pump housing, a cam member, a
cylindrical rotor member and a mechanism for communicating a high
pressure fluid from the discharge arc region to the inlet arc region when
the tip surface of each vane element has experienced a predetermined
amounted of wear so as to prevent pump startup. The tip surface of each
vane element wears as a result the sliding contact with the
circumferential surface of the pumping cavity.