B757-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft; Procedure
Two [Functional Check Flights] on two consecutive days after contractor heavy maintenance; on the same aircraft. Both days returned single engine due to engine valve discrete while placing fuel control switch to run for inflight restart. After first flight contractor replaced FFG [Fuel Flow Governor]. Fix failed to rectify problem resulting in second single engine return. Engineering evaluating replacement of LP/HP engine driven fuel pumps. Technical crew chiefs provided excellent inflight assistance; evaluation and system debrief to Maintenance. Placement of company technical crew chiefs (Avionics and Systems) should be standard practice on all FCF's after Contractor Maintenance. Their input is invaluable during [irregular flight operations] and for system debrief to the contractor postflight for a positive fix so as to avert a repeat occurrence.
The reporter stated that FFG stands for Fuel Flow Governor.
B757 Captain describes two single engine returns on the same aircraft when an engine cannot be restarted in flight during a maintenance test flight after Contractor Maintenance.