Narrative:

On dec/xx/94, upon arrival at aircraft xx, the #1 fuel quantity indicator was placarded inoperative and aircraft was on MEL 28-11A. On preflight, the #2 fuel tank left aft boost pump was discovered inoperative. When the quantity dropped below 4400 pounds, maintenance placarded the aircraft with an additional MEL 28- 4C. Flight crew dispatch released the aircraft to fly in compliance with MEL 28-4C. 3 segments were flown using alternate fuel procedures for inoperative #1 fuel quantity. The morning of dec/xx/94 dispatch discovered a note under MEL 28-11A that all boost pumps in all tanks must be working. This flight crew had the same aircraft for this complete series of events. The left aft boost pump in #2 tank was, in fact, working properly, so maintenance control and dispatch removed MEL 28-4C from the aircraft. If each MEL would state all conditions that must be met for dispatch, this occurrence would not have happened. Conditions for dispatch under MEL 28-4C (inoperative boost) did not state gauges must be all working. The crew did not catch the not under the existing MEL 28- 11A (inoperative gauge) when added to the logbook. The requirements under alternate fueling procedures for the #1 gauge are very complicated, which distracted the crew and maintenance from catching this problem. Callback conversation with reporter revealed the following information: during callback, pilot verified that 1 book was being used that contained all MEL for the aircraft. It is important that only 1 book contain everything pertaining to the aircraft system. In this case, the fuel inoperative pump section did not refer to the fuel gauge section. Flight crew and dispatch did not catch the fact that, if one part of system is inoperative, the other related system has to be fully operational. This points up that further editing and proof reading are needed to the MEL book. The air carrier is aware of this discrepancy and is working to correct all omissions and mistakes in the book.

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Original NASA ASRS Text

Title: MISUNDERSTANDING OF MEL.

Narrative: ON DEC/XX/94, UPON ARR AT ACFT XX, THE #1 FUEL QUANTITY INDICATOR WAS PLACARDED INOP AND ACFT WAS ON MEL 28-11A. ON PREFLT, THE #2 FUEL TANK L AFT BOOST PUMP WAS DISCOVERED INOP. WHEN THE QUANTITY DROPPED BELOW 4400 LBS, MAINT PLACARDED THE ACFT WITH AN ADDITIONAL MEL 28- 4C. FLC DISPATCH RELEASED THE ACFT TO FLY IN COMPLIANCE WITH MEL 28-4C. 3 SEGMENTS WERE FLOWN USING ALTERNATE FUEL PROCS FOR INOP #1 FUEL QUANTITY. THE MORNING OF DEC/XX/94 DISPATCH DISCOVERED A NOTE UNDER MEL 28-11A THAT ALL BOOST PUMPS IN ALL TANKS MUST BE WORKING. THIS FLC HAD THE SAME ACFT FOR THIS COMPLETE SERIES OF EVENTS. THE L AFT BOOST PUMP IN #2 TANK WAS, IN FACT, WORKING PROPERLY, SO MAINT CTL AND DISPATCH REMOVED MEL 28-4C FROM THE ACFT. IF EACH MEL WOULD STATE ALL CONDITIONS THAT MUST BE MET FOR DISPATCH, THIS OCCURRENCE WOULD NOT HAVE HAPPENED. CONDITIONS FOR DISPATCH UNDER MEL 28-4C (INOP BOOST) DID NOT STATE GAUGES MUST BE ALL WORKING. THE CREW DID NOT CATCH THE NOT UNDER THE EXISTING MEL 28- 11A (INOP GAUGE) WHEN ADDED TO THE LOGBOOK. THE REQUIREMENTS UNDER ALTERNATE FUELING PROCS FOR THE #1 GAUGE ARE VERY COMPLICATED, WHICH DISTRACTED THE CREW AND MAINT FROM CATCHING THIS PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: DURING CALLBACK, PLT VERIFIED THAT 1 BOOK WAS BEING USED THAT CONTAINED ALL MEL FOR THE ACFT. IT IS IMPORTANT THAT ONLY 1 BOOK CONTAIN EVERYTHING PERTAINING TO THE ACFT SYS. IN THIS CASE, THE FUEL INOP PUMP SECTION DID NOT REFER TO THE FUEL GAUGE SECTION. FLC AND DISPATCH DID NOT CATCH THE FACT THAT, IF ONE PART OF SYS IS INOP, THE OTHER RELATED SYS HAS TO BE FULLY OPERATIONAL. THIS POINTS UP THAT FURTHER EDITING AND PROOF READING ARE NEEDED TO THE MEL BOOK. THE ACR IS AWARE OF THIS DISCREPANCY AND IS WORKING TO CORRECT ALL OMISSIONS AND MISTAKES IN THE BOOK.

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.