Narrative:

Departed las-phx with fuel xfeed valve open (probably due to maintenance activity on the aircraft). Just prior to descent, during a normal panel scan, a fuel imbalance of 3100 pounds between the left and right main tanks was noted. We immediately began fuel balancing, but due to the short leg length, were unable to correct the imbal to less than 2700 pounds. A normal approach and landing was conducted with absolutely no roll tendency or adverse handling. Landing fuel in the low tank was over 4000 pounds. The fuel differential was, no doubt, due to stronger pump pressures in the right tank. The fuel confign warning on the 757, with the FAA requirement to maintain 1000 pounds in the center tank, becomes a 'flight crew trap.' this light comes on numerous times on each leg, and although we make every effort to check for low fuel or an imbal, under high workloads, this can be neglected. This light has become a 'normal' light as well as an 'abnormal' light, which is a very poor situation! If we are to have a requirement of 1000 pounds in the center tank, then we must also be given an adequate warning system, not one that we have become accustomed to for 99% as normal, while 1% of the time, a serious warning. Supplemental information from acn 574466: upon arriving at aircraft, found that aircraft had been misfueled with fuel put in center tank without main tanks being filled. Unknown to us, someone evidently tried to xfer fuel, because it was later discovered that the xfeed valve was open. On preflight cockpit set up, I missed the fact that the xfeed valve was open. (Should be closed for normal flight.) at this point, though not fueled in the normal way, it was within limitations. For the last several months, 757 operation (ad?) with 1000 pounds of fuel in the center tanks at all times is required. Upon burning down center fuel to 1000 pounds, center fuel pumps are turned off. Because this is not a 'normal' procedure (though is required right now), this turns on a 'fuel confign' light, which can mean, among other things, full in center tank with pumps off or fuel imbal between left and right main tanks. Thus, for the past few months, we have become accustomed to 'ignoring' the 'fuel confign' light as it is a 'temporary normal' for our operating conditions. Unfortunately, this time, it applied also to an imbal between main tanks. Because the xfeed valve had inadvertently been left open during flight, there was xfeeding of fuel, which created an imbal greater than the aircraft limitation of 1800 pounds. We caught the imbal's shortly before arriving at phx, but did not have time to correct the imbal condition prior to shutdown. Though, over the past months, crews have even discussed how we could be lulled into missing an imbal like this, because of getting used to the 'fuel confign' light as a 'temporary normal' until a maintenance fix is done, this happened to us.

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Original NASA ASRS Text

Title: A B757-200 CREW HAD A FUEL IMBAL EXCEEDING CROSS SHIP LIMITS.

Narrative: DEPARTED LAS-PHX WITH FUEL XFEED VALVE OPEN (PROBABLY DUE TO MAINT ACTIVITY ON THE ACFT). JUST PRIOR TO DSCNT, DURING A NORMAL PANEL SCAN, A FUEL IMBALANCE OF 3100 LBS BTWN THE L AND R MAIN TANKS WAS NOTED. WE IMMEDIATELY BEGAN FUEL BALANCING, BUT DUE TO THE SHORT LEG LENGTH, WERE UNABLE TO CORRECT THE IMBAL TO LESS THAN 2700 LBS. A NORMAL APCH AND LNDG WAS CONDUCTED WITH ABSOLUTELY NO ROLL TENDENCY OR ADVERSE HANDLING. LNDG FUEL IN THE LOW TANK WAS OVER 4000 LBS. THE FUEL DIFFERENTIAL WAS, NO DOUBT, DUE TO STRONGER PUMP PRESSURES IN THE R TANK. THE FUEL CONFIGN WARNING ON THE 757, WITH THE FAA REQUIREMENT TO MAINTAIN 1000 LBS IN THE CTR TANK, BECOMES A 'FLT CREW TRAP.' THIS LIGHT COMES ON NUMEROUS TIMES ON EACH LEG, AND ALTHOUGH WE MAKE EVERY EFFORT TO CHK FOR LOW FUEL OR AN IMBAL, UNDER HIGH WORKLOADS, THIS CAN BE NEGLECTED. THIS LIGHT HAS BECOME A 'NORMAL' LIGHT AS WELL AS AN 'ABNORMAL' LIGHT, WHICH IS A VERY POOR SIT! IF WE ARE TO HAVE A REQUIREMENT OF 1000 LBS IN THE CTR TANK, THEN WE MUST ALSO BE GIVEN AN ADEQUATE WARNING SYS, NOT ONE THAT WE HAVE BECOME ACCUSTOMED TO FOR 99% AS NORMAL, WHILE 1% OF THE TIME, A SERIOUS WARNING. SUPPLEMENTAL INFO FROM ACN 574466: UPON ARRIVING AT ACFT, FOUND THAT ACFT HAD BEEN MISFUELED WITH FUEL PUT IN CTR TANK WITHOUT MAIN TANKS BEING FILLED. UNKNOWN TO US, SOMEONE EVIDENTLY TRIED TO XFER FUEL, BECAUSE IT WAS LATER DISCOVERED THAT THE XFEED VALVE WAS OPEN. ON PREFLT COCKPIT SET UP, I MISSED THE FACT THAT THE XFEED VALVE WAS OPEN. (SHOULD BE CLOSED FOR NORMAL FLT.) AT THIS POINT, THOUGH NOT FUELED IN THE NORMAL WAY, IT WAS WITHIN LIMITATIONS. FOR THE LAST SEVERAL MONTHS, 757 OP (AD?) WITH 1000 LBS OF FUEL IN THE CTR TANKS AT ALL TIMES IS REQUIRED. UPON BURNING DOWN CTR FUEL TO 1000 LBS, CTR FUEL PUMPS ARE TURNED OFF. BECAUSE THIS IS NOT A 'NORMAL' PROC (THOUGH IS REQUIRED RIGHT NOW), THIS TURNS ON A 'FUEL CONFIGN' LIGHT, WHICH CAN MEAN, AMONG OTHER THINGS, FULL IN CTR TANK WITH PUMPS OFF OR FUEL IMBAL BTWN L AND R MAIN TANKS. THUS, FOR THE PAST FEW MONTHS, WE HAVE BECOME ACCUSTOMED TO 'IGNORING' THE 'FUEL CONFIGN' LIGHT AS IT IS A 'TEMPORARY NORMAL' FOR OUR OPERATING CONDITIONS. UNFORTUNATELY, THIS TIME, IT APPLIED ALSO TO AN IMBAL BTWN MAIN TANKS. BECAUSE THE XFEED VALVE HAD INADVERTENTLY BEEN LEFT OPEN DURING FLT, THERE WAS XFEEDING OF FUEL, WHICH CREATED AN IMBAL GREATER THAN THE ACFT LIMITATION OF 1800 LBS. WE CAUGHT THE IMBAL'S SHORTLY BEFORE ARRIVING AT PHX, BUT DID NOT HAVE TIME TO CORRECT THE IMBAL CONDITION PRIOR TO SHUTDOWN. THOUGH, OVER THE PAST MONTHS, CREWS HAVE EVEN DISCUSSED HOW WE COULD BE LULLED INTO MISSING AN IMBAL LIKE THIS, BECAUSE OF GETTING USED TO THE 'FUEL CONFIGN' LIGHT AS A 'TEMPORARY NORMAL' UNTIL A MAINT FIX IS DONE, THIS HAPPENED TO US.

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.