Narrative:

During preflight we determined that the center fuel tank gauge was deferred to mco for reading 600 pound high. Some time later we discovered that the left center tank fuel pump was inoperative and maintenance was informed. Maintenance was unable to replace the defective pump. After consulting the MEL we found that we could not defer the fuel pump if the fuel (6000 pound) in the center tank was required for the flight. We changed the hold time to zero and determined a closer alternate. With a new flight release the (6000 pound) was changed to show as unusable and its weight was added to the zero fuel weight per the MEL. Thus redispatched, we accepted the aircraft and departed. Once en route dispatch called and pointed out that they considered the center fuel tank gauge inoperative, an interpretation not necessarily suggested by the write up and signoff. However the MEL clearly states that in order to defer to mco the center fuel tank gauge, both center fuel pumps must be operating. If it is correct that the center fuel tank gauge was inoperative instead of just reading 600 pounds high, then I accepted the aircraft and flew it contrary to the MEL.

Related reports:

Google
 

Original NASA ASRS Text

Title: AFTER DEPARTING DEFERRING A CENTER FUEL GAUGE THAT WAS READING HIGH, FLT CREW WAS ADVISED BY DISPATCH THEY INTERPRETED THE GAUGE AS INOPERATIVE AND FLT WAS ILLEGAL PER MEL.

Narrative: DURING PREFLT WE DETERMINED THAT THE CTR FUEL TANK GAUGE WAS DEFERRED TO MCO FOR READING 600 LB HIGH. SOME TIME LATER WE DISCOVERED THAT THE L CTR TANK FUEL PUMP WAS INOP AND MAINT WAS INFORMED. MAINT WAS UNABLE TO REPLACE THE DEFECTIVE PUMP. AFTER CONSULTING THE MEL WE FOUND THAT WE COULD NOT DEFER THE FUEL PUMP IF THE FUEL (6000 LB) IN THE CTR TANK WAS REQUIRED FOR THE FLT. WE CHANGED THE HOLD TIME TO ZERO AND DETERMINED A CLOSER ALTERNATE. WITH A NEW FLT RELEASE THE (6000 LB) WAS CHANGED TO SHOW AS UNUSABLE AND ITS WEIGHT WAS ADDED TO THE ZERO FUEL WT PER THE MEL. THUS REDISPATCHED, WE ACCEPTED THE ACFT AND DEPARTED. ONCE ENRTE DISPATCH CALLED AND POINTED OUT THAT THEY CONSIDERED THE CTR FUEL TANK GAUGE INOPERATIVE, AN INTERPRETATION NOT NECESSARILY SUGGESTED BY THE WRITE UP AND SIGNOFF. HOWEVER THE MEL CLRLY STATES THAT IN ORDER TO DEFER TO MCO THE CTR FUEL TANK GAUGE, BOTH CTR FUEL PUMPS MUST BE OPERATING. IF IT IS CORRECT THAT THE CTR FUEL TANK GAUGE WAS INOPERATIVE INSTEAD OF JUST READING 600 LBS HIGH, THEN I ACCEPTED THE ACFT AND FLEW IT CONTRARY TO THE MEL.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.