A320
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft; Procedure
Diverted to [an alternate airport] as the result of fuel valve malfunction (outer to inner tank valves; right wing tank). This [has] been a recurring maintenance issue on this aircraft. It required a repetitive inspection and maintenance action prior to each departure. We had a mechanic assigned to travel with us as contract maintenance was unavailable. Prior to departure our mechanic experienced difficulty accomplishing the prescribed maintenance action per MEL and contacted Maintenance Control. After repeated attempts to secure the fuel valves open; the left valves indicated fully open; but the right valve indicator indicated approximately 1/2 open. Maintenance Control assured us that this was a valid position and met the criteria for the MEL action required as it allowed the fuel in the outer wing tanks to migrate to the inner wing tank; which it did. We strenuously disagreed with this assessment as it was not consistent with the previous 3 legs that we had flown this day. He insisted it was in compliance and we departed. Climbing through 10;000 feet we reviewed the systems pages and discovered that the outer to inner fuel valves had closed and there was now about 200 pounds of fuel in the outer wing tanks. As the flight progressed we noted that the outer tanks were filling at an alarming rate. In about 30 minutes we had 3;000 pounds in the outer wing tanks and felt that if if this continued we would not have enough fuel in the inner tanks to reach [destination] if the valves did not open on schedule as the result of the maintenance action performed before departure. We contacted Dispatch and suggested a diversion to [a nearby alternate]. The Dispatcher concurred and we proceeded to [divert] and landed uneventfully. The maintenance crew that met us upon reviewing the maintenance log and speaking with the Mechanic that was assigned to our trip felt that the procedure that was applied [before departure] was incorrect. [They] produced a printed page from the maintenance manual and applied the procedure with positive results. An entry was made into our logbook reflecting this assessment. We boarded our passengers and continued uneventfully.
A320 Captain reported diverting to an alternate when their fuel system; which was on MEL restrictions; was not performing as expected.