Flight Crew Last 90 Days 80; Flight Crew Total 15000; Flight Crew Type 2700
Troubleshooting; Communication Breakdown; Situational Awareness; Training / Qualification
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL
General None Reported / Taken
Procedure; Company Policy; MEL
After 4:30 hours of flight; we had a 2;200 LB imbalance of fuel between the wing tanks. The center tank was empty for the flight and read zero always. We never suspected a fuel leak because the fuel flow was exactly even on each engine and the totalizer and calculated fuel levels were within 100 LBS of each other. Notwithstanding the possibility of a fuel leak; the aft engine fuel cross feed valve was deferred. How can this be a legal deferral for an ETOPS flight? It seems that this was an improper deferral and we should never have accepted it. The deferral of the crossfeed valve; I believe; is possibly the culprit in our unexplained fuel imbalance. We the flight crew are not given enough information concerning MELs and the maintenance compliance with them to make safe; sound; and informed decisions before accepting the aircraft. Instead; I feel we were duped into flying a fully loaded aircraft all the way to Hawaii.
A B737-300 First Officer reported flying the aircraft on an ETOPS flight with the fuel crossfeed valve MEL'ed and subsequently developing an unexplained 2;200 LB fuel imbalance which they could not equalize.