A B757 WAS DISPATCHED WITH THE R CTR TANK FUEL PUMP AND PRESSURE INDICATION DEFERRED INOP PER THE MEL. PROB WAS INTERMITTENT EICAS MESSAGE 'CTR R FUEL PUMP.' PUMP AND PRESSURE SWITCH OP OK.

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THIS RPT COVERS 2 FLTS; ACR X ZZZ-ZZZY; NOV/XA/06 AND ACR X ZZZY-ZZZ NOV/XB/06 AND SUBSEQUENT MAINT ACTION ON NOV/XZ/06 REGARDING ACFT B757. THE SAME CREW WAS ASSIGNED FOR BOTH FLTS IN THE SAME ACFT. PRIOR TO OUR INITIAL FLT OF ACR X; THE PREFLT LOGBOOK INSPECTION REVEALED REPEATED WRITE-UPS ON CTR R FUEL PUMP EICAS MESSAGE. WRITE-UPS INDICATED THAT REGARDLESS OF R CTR TANK SWITCH POS OR CTR FUEL QUANTITY; THE CTR R FUEL PUMP EICAS APPEARED. MESSAGE CONTINUED TO APPEAR INTERMITTENTLY EVEN AFTER CTR TANK FUEL EXHAUSTED AND THE PUMP TURNED OFF. FUEL LOAD WAS ROUGHLY 45000 LBS WITH 5000 LBS BEING TANKER FUEL; INCLUDING ROUGHLY 16.5 IN CTR TANK. MAINT PERSONNEL WERE ONBOARD UPON ARR AND WERE IN THE PROCESS OF REAPPLYING THE SAME MEL'S ONCE AGAIN; PUMP LOW PRESSURE LIGHTS INOP; PUMP AND CTR TANK FUEL PUMPS. THIS MEL COMBINATION REQUIRED R CTR FUEL PUMP TO BE DEACTIVATED. THE CIRCUIT BREAKER WAS PULLED AND COLLARED. I EXPRESSED MY OPINION TO THE MAINT PERSONNEL THAT NEITHER OF THESE MEL'S ADDRESSED THE ANOMALY AS THE PUMP LOW PRESSURE LIGHT LOCATED IN THE PUMP SWITCH WAS NOT BEING DESCRIBED AT FAULT AND NEITHER WAS PUMP OP. BOTH THE PUMP AND ITS ASSOCIATED LIGHT WERE OPERATING NORMAL IN ALL RESPECTS. IN MY OPINION THE ANOMALY WAS IN THE ELECTRICAL SIGNAL BEING SENT FROM THE FUEL SYS TO THE EICAS SYS FOR DISPLAY. THEIR SYS KNOWLEDGE APPEARED LIMITED AND THEY WERE ONLY APPLYING THE MEL'S AS DIRECTED BY MAINT CTL. UPON RELAYING MY CONCERNS TO MAINT CTL; THEY RELAYED TO ME THAT MAINT CTL INDICATED THIS WOULD SUFFICIENTLY ADDRESS THE ISSUE AT HAND AND THAT THE ACFT WAS RELEASED FOR FLT. BY THIS TIME DISPATCH WAS INVOLVED TRYING TO INTERJECT THAT NOW ALL CTR TANK FUEL NOW HAD TO BE CONSIDERED PAYLOAD AND THAT THE ACFT WOULD HAVE TO BE DEFUELED DOWN TO A TOTAL QUANTITY OF 38.6 IN ORDER TO CARRY THE LOAD. A GOOD CATCH BY DISPATCH; THANKS. WHEN THE CAPT ARRIVED WITH THE ORIGINAL AND NOW NEW PAPERWORK FOR RELEASE 2 WITH THE MEL'S APPLIED AND THE NEW FUEL LOAD; I EXPRESSED MY OPINION TO HIM THAT THE INCORRECT MEL'S WERE BEING APPLIED AND THAT NEITHER APPLIED TO THESE CIRCUMSTANCES. MY 8 YRS EXPERIENCE ON THIS ACFT AND MY 25+ YRS OF AVIATION MAINT EXPERIENCE SUGGESTED TO ME THAT A WIRING ISSUE WAS THE CAUSE OF THIS DISCREPANCY AND IT WAS LIKELY RELATED TO RECENT MAINT ON THE FUEL SYS; PERHAPS THE RECENT CTR TANK FUEL AIRWORTHINESS DIRECTIVE. THE CAPT TALKED TO MAINT CTL AND TO DISPATCH REGARDING THE OP. HE REITERATED THAT MAINT CTL WAS REMAINING FIRM THAT THE ACTION OF DEACTIVATING THE R CTR FUEL PUMP WOULD SOLVE THE PROB AND CONCLUDED THE ACFT WAS SAFE FOR FLT AND APPROPRIATE FOR THIS OP REGARDLESS OF THE FACT THAT IN THE PAST THE SAME ACTION HAD HAD NO EFFECT ON THE EICAS MESSAGE. BY THIS TIME PAX AND CARGO WERE LOADED. AFTER SOME ADDITIONAL DELAY; THE APPROPRIATE FUEL LOAD WAS ESTABLISHED AND BALANCED IN THE APPROPRIATE TANKS. I RELUCTANTLY ACQUIESCED TO THE CAPT'S EXPERIENCE AND AUTH AND UPON THE SUBSTANTIAL ASSURANCE THAT MAINT CTL PUT IN THEIR ACTIONS. GIVEN OUR LIMITED SYS TRAINING THESE DAYS; IT'S DIFFICULT TO ASSESS EVERY SYS PROB. ENRTE TO ZZZY; FUEL HAD TO BE XFERRED FROM THE CTR TANK TO THE L MAIN TANK AND THEN VIA THE XFEED VALVE TO THE R MAIN TANK. NO SPECIFIC GUIDANCE IS PROVIDED FOR THIS EVENTUALITY. ENRTE TO ZZZY THE IDENTICAL CTR R FUEL PUMP EICAS MESSAGE REAPPEARED INTERMITTENTLY ON AT LEAST 7 OCCASIONS REGARDLESS OF CTR TANK FUEL QUANTITY. BY THIS TIME I THOUGHT I HAD CONVINCED THE CAPT THAT THE MEL'S WERE IN FACT MISAPPLIED TO THESE CIRCUMSTANCES. WE SPENT 45+ MINS REVIEWING AOM; THE COM; THE MEL BOOK AND THE VARIOUS FAULT CODES THAT WOULD BE APPROPRIATE FOR THIS CIRCUMSTANCE AND CAME TO THE CONCLUSION THAT NO SPECIFIC FAULT CODE IDENTED THIS ANOMALY; NOR ANY APPROPRIATE MEL RELIEF. THE CAPT DEVELOPED AND ENTERED AN APPROPRIATE LOGBOOK ENTRY AND SENT SAME VIA ACARS. UPON ARR IN ZZZY WE RECEIVED AN ACARS MESSAGE TO CONTACT MAINT CTL REGARDING THE WRITE-UP. THE CAPT TALKED WITH MAINT CTL. THE ESSENCE OF THAT CONVERSATION RELAYED TO ME WAS THAT THIS MAINT CTL SUPVR ACKNOWLEDGED THE PREVIOUS MEL ATTEMPTS WERE AND WOULD CONTINUE TO BE FRUITLESS AND; THAT NO MEL WAS AVAILABLE FOR RELIEF AND THAT MAINT ACTION WAS REQUIRED TO FIX THE PROB.