Narrative:

We received all appropriate checklists and manuals we had for landing with a fuel load that was now 1000 pounds in each wing tank and 7000 pounds in the center tank. I was referring to the fact that we had completed the QRH checklist and we were now burning out of the center tank. Our position was between ZZZ2 and ZZZ3 on the arrival. I believe that our fuel problem was stabilized and if the wing tanks had any further fuel loss below 1000 pounds per tank, I would have declared an emergency and diverted to one of the airports below us. We landed with about 1000 pounds in each main tank and 5500 pounds in the center tank. I was flying with first officer on aircraft from ZZZ to ZZZ1. We did our normal preflight duties and in the process we checked the center fuel pumps as per the flight manual. On reviewing the log book we noted that the aft center fuel pump circuit breaker #J-21 had tripped on flight the night before. ZZZ mechanic had replaced the circuit breaker with a new one and noted the repair in the logbook. The fuel load was 9200 pounds in each main tank and 12400 pounds in the center tank with 500 pounds in the auxiliary tank. At 10000 ft we completed the 10000 ft checklist and had turned on the auxiliary pumps to burn 500 pounds of fuel that was in the auxiliary tank. Shortly after the auxiliary fuel was depleted we turned off the auxiliary pumps. At 31000 ft and over ZZZ4 we marked down the time and total fuel with a center fuel amount which was 8000 pounds. ATC then cleared us direct to ZZZ5 removing ZZZ6 and ZZZ7 from our flight plan. We entered ZZZ5 in the box and went direct. Just prior to ZZZ5 (our next time/fuel check) we noted the fuel was burning out of the wing tanks and stopped burning out of the center tank. Our fuel load was then 1800 pounds per side and 7000 pounds in the main tank. We ran the QRH for wing tanks burning fuel and main tank and found circuit breaker #J-21 had tripped again. We reviewed all appropriate checklists and manuals we had for landing with a fuel load that was now 1000 pounds in each wing tank and 7000 pounds in the center tank. We found no information except for go around with low fuel. I then called dispatch and told them of our fuel balance problem and asked if they had any information that would help us in the landing (ie flaps 40 or 28, cg or structural problems etc). They checked and found no useful information on that type of fuel load for landing. We landed flaps 28 without any problem and taxied to the gate. Callback conversation with reporter revealed the following information: the reporter stated the aircraft is flown with all tank boost pumps operating and the fuel is normally burned out of the center tank first and this is because center tank check valves are set at a lower pressure level. The reporter said when one center tank boost pump failed it is believed the single operating pump will not override the wing tank pumps at or about the 7000 pounds level. The reporter stated the center tank aft boost pump had again tripped the circuit breaker leaving the center tank with one operating pump.

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Original NASA ASRS Text

Title: THE FLT CREW OF AN MD-80 IN CRUISE NOTED THE CENTER TANK BOOST PUMP FAILED WITH 7000 LBS OF UNUSABLE FUEL IN THE TANK.

Narrative: WE RECEIVED ALL APPROPRIATE CHKLISTS AND MANUALS WE HAD FOR LNDG WITH A FUEL LOAD THAT WAS NOW 1000 LBS IN EACH WING TANK AND 7000 LBS IN THE CENTER TANK. I WAS REFERRING TO THE FACT THAT WE HAD COMPLETED THE QRH CHKLIST AND WE WERE NOW BURNING OUT OF THE CENTER TANK. OUR POSITION WAS BTWN ZZZ2 AND ZZZ3 ON THE ARRIVAL. I BELIEVE THAT OUR FUEL PROB WAS STABILIZED AND IF THE WING TANKS HAD ANY FURTHER FUEL LOSS BELOW 1000 LBS PER TANK, I WOULD HAVE DECLARED AN EMER AND DIVERTED TO ONE OF THE ARPTS BELOW US. WE LANDED WITH ABOUT 1000 LBS IN EACH MAIN TANK AND 5500 LBS IN THE CENTER TANK. I WAS FLYING WITH FO ON ACFT FROM ZZZ TO ZZZ1. WE DID OUR NORMAL PREFLT DUTIES AND IN THE PROCESS WE CHECKED THE CENTER FUEL PUMPS AS PER THE FLT MANUAL. ON REVIEWING THE LOG BOOK WE NOTED THAT THE AFT CENTER FUEL PUMP CB #J-21 HAD TRIPPED ON FLT THE NIGHT BEFORE. ZZZ MECH HAD REPLACED THE CB WITH A NEW ONE AND NOTED THE REPAIR IN THE LOGBOOK. THE FUEL LOAD WAS 9200 LBS IN EACH MAIN TANK AND 12400 LBS IN THE CENTER TANK WITH 500 LBS IN THE AUX TANK. AT 10000 FT WE COMPLETED THE 10000 FT CHKLIST AND HAD TURNED ON THE AUX PUMPS TO BURN 500 LBS OF FUEL THAT WAS IN THE AUX TANK. SHORTLY AFTER THE AUX FUEL WAS DEPLETED WE TURNED OFF THE AUX PUMPS. AT 31000 FT AND OVER ZZZ4 WE MARKED DOWN THE TIME AND TOTAL FUEL WITH A CENTER FUEL AMOUNT WHICH WAS 8000 LBS. ATC THEN CLRED US DIRECT TO ZZZ5 REMOVING ZZZ6 AND ZZZ7 FROM OUR FLT PLAN. WE ENTERED ZZZ5 IN THE BOX AND WENT DIRECT. JUST PRIOR TO ZZZ5 (OUR NEXT TIME/FUEL CHECK) WE NOTED THE FUEL WAS BURNING OUT OF THE WING TANKS AND STOPPED BURNING OUT OF THE CENTER TANK. OUR FUEL LOAD WAS THEN 1800 LBS PER SIDE AND 7000 LBS IN THE MAIN TANK. WE RAN THE QRH FOR WING TANKS BURNING FUEL AND MAIN TANK AND FOUND CB #J-21 HAD TRIPPED AGAIN. WE REVIEWED ALL APPROPRIATE CHKLISTS AND MANUALS WE HAD FOR LNDG WITH A FUEL LOAD THAT WAS NOW 1000 LBS IN EACH WING TANK AND 7000 LBS IN THE CENTER TANK. WE FOUND NO INFO EXCEPT FOR GAR WITH LOW FUEL. I THEN CALLED DISPATCH AND TOLD THEM OF OUR FUEL BALANCE PROB AND ASKED IF THEY HAD ANY INFO THAT WOULD HELP US IN THE LNDG (IE FLAPS 40 OR 28, CG OR STRUCTURAL PROBS ETC). THEY CHECKED AND FOUND NO USEFUL INFO ON THAT TYPE OF FUEL LOAD FOR LNDG. WE LANDED FLAPS 28 WITHOUT ANY PROB AND TAXIED TO THE GATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT IS FLOWN WITH ALL TANK BOOST PUMPS OPERATING AND THE FUEL IS NORMALLY BURNED OUT OF THE CENTER TANK FIRST AND THIS IS BECAUSE CENTER TANK CHECK VALVES ARE SET AT A LOWER PRESSURE LEVEL. THE RPTR SAID WHEN ONE CENTER TANK BOOST PUMP FAILED IT IS BELIEVED THE SINGLE OPERATING PUMP WILL NOT OVERRIDE THE WING TANK PUMPS AT OR ABOUT THE 7000 LBS LEVEL. THE RPTR STATED THE CENTER TANK AFT BOOST PUMP HAD AGAIN TRIPPED THE CB LEAVING THE CENTER TANK WITH ONE OPERATING PUMP.

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.