AN MD80 CAPT RPTS SEVERAL MAINT LOG SIGNOFFS ON FUEL LEAK AND FUEL INDICATION DISCREPANCIES. RPTR SUGGESTS THE CAUSE WAS LIKELY A FUEL LEAK TOTALING 1000 LBS.

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PREFLT LOGBOOK REVIEW REVEALED THE FOLLOWING: DISCREPANCY RPT OF FUEL LEAKING FROM ONE OF THE INBOARD BOOST PUMP COVERS. SIGNED OFF AS WITHIN LIMITS. DISCREPANCY RPT OF 1000 LB DIFFERENCE BTWN FUEL TOTALIZER AND FUEL USED INDICATIONS. SIGNED OFF FIRST WITH A PLACARD OF FUEL TOTALIZER; THEN AS TROUBLESHOT FUEL QUANTITY INDICATING SYS; CHKS OK; OK FOR SVC. MEL ITEM AS 'NO PROB.' OVERWING HEAT SYS PLACARDED DUE TO FUEL LEAK. I SHOULD HAVE QUESTIONED MAINT AS TO HOW THE FUEL LEAK FROM THE BOOST PUMP COVER WAS WITHIN LIMITS BUT STILL REQUIRED PLACARDING OF THE OVERWING HEAT SYS. DURING FLT; WE NOTED A GROWING DISCREPANCY BTWN THE FUEL QUANTITY INDICATORS AND THE FUEL USED INDICATORS. FUEL USED INDICATORS WERE VERY CLOSE TO WHAT WE EXPECTED FROM THE FLT PLAN. DISCREPANCY GREW TO WHERE THE FUEL QUANTITY (READ FROM THE TOTALIZER AND FROM ADDING THE INDIVIDUAL TANK INDICATIONS) WAS ABOUT 1100 LBS BELOW EXPECTATIONS. THIS WAS NOT A CRITICAL AMOUNT ON THIS FLT (GOOD WX; ETC) SO WE DID NOT TROUBLESHOOT FOR A LEAK; BUT WE DID WRITE UP THE DISCREPANCY FOR ZZZ1 MAINT. UPON POSTFLT DEBRIEF AND REFLECTION; I REALIZED I SHOULD HAVE QUESTIONED MAINT AT ZZZ BEFORE DEP ABOUT THIS SERIES OF WRITE-UPS AND SIGNOFFS AND PLACARDS; AND I SHOULD HAVE INVESTIGATED FUEL LEAKS. IT IS LIKELY THAT WE LEAKED ABOUT 1000 LBS OF OUR 8000 LB CTR TANK FUEL LOAD DURING CLBOUT; WHICH IS UNLIKELY TO BE WITHIN LIMITS. WE ARRIVED IN ZZZ1 ABOUT 1000 LBS SHY; WITH ABOUT A 1000 LB DISCREPANCY BTWN THE FUEL USED INDICATION AND THE FUEL QUANTITY INDICATION. THERE WAS NO DIFFERENCE BTWN THE 'A' AND 'B' CHANNELS.