Narrative:

Flying from fll to lga airport in a B767-200, we were using fuel management procedures mandated by FAA due to center tank pump problems. These procedures require that center tank pumps remain off with less than 5000 pounds of fuel in center tank. In our case, 1300 pounds of center fuel was on board. This causes a constant 'fuel confign' discrete warning and EICAS message. This effectively deletes the confign warning system. In this case, it bit us because the xfeed valve had been left open by overnight crew, and we missed it on preflight. After 2 1/2 hours of flight with a confign warning the whole way we noticed an 8000 pound fuel imbal, exceeding the 1500 pound maximum allowable. Control, handling and trim setting were surprisingly unaffected. I have found xfeeds left this way many times and anecdotal evidence suggests that fuel imbals are commonplace. In my opinion, if the fuel confign warning system is to be inactivated operationally, there should be some indications that the xfeed is latched open. Callback conversation with reporter revealed the following information: reporter stated that they had an 8000 pound imbal between the left and right wing of the aircraft because the fuel xfeed valve had been left on from the previous night. They missed the proper setting of the valve during their preflight. They would ordinarily see a fuel imbal developing with the EICAS message illuminating. In this case though, the fuel EICAS message is on most of the time because of having less than 1500 pounds in the center tank with the boost pumps off. This is a recent procedural change for all B767-200 aircraft. Reporter further stated that the fuel xfeed valve is opened during night time layover of an aircraft to xfer fuel out of the center tank. Fuel drains from the wing tanks into the center tank during periods of inactivity. Fuel is xferred out of the center tank during layover periods with the use of the xfeed valve. Maintenance activates the valve, but does not reset it to off much of the time. Although the flight crew should check to see that it is off during preflight, it is a difficult switch to easily determine what position it is in, when there is an abundance of light in the cockpit.

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Original NASA ASRS Text

Title: A B767-200 HAS AN 8000 LB IMBAL BTWN L AND R WING DURING CRUISE BECAUSE THE FUEL XFEED VALVE IS LEFT ON AFTER PREFLT.

Narrative: FLYING FROM FLL TO LGA ARPT IN A B767-200, WE WERE USING FUEL MGMNT PROCS MANDATED BY FAA DUE TO CTR TANK PUMP PROBS. THESE PROCS REQUIRE THAT CTR TANK PUMPS REMAIN OFF WITH LESS THAN 5000 LBS OF FUEL IN CTR TANK. IN OUR CASE, 1300 LBS OF CTR FUEL WAS ON BOARD. THIS CAUSES A CONSTANT 'FUEL CONFIGN' DISCRETE WARNING AND EICAS MESSAGE. THIS EFFECTIVELY DELETES THE CONFIGN WARNING SYS. IN THIS CASE, IT BIT US BECAUSE THE XFEED VALVE HAD BEEN LEFT OPEN BY OVERNIGHT CREW, AND WE MISSED IT ON PREFLT. AFTER 2 1/2 HRS OF FLT WITH A CONFIGN WARNING THE WHOLE WAY WE NOTICED AN 8000 LB FUEL IMBAL, EXCEEDING THE 1500 LB MAX ALLOWABLE. CTL, HANDLING AND TRIM SETTING WERE SURPRISINGLY UNAFFECTED. I HAVE FOUND XFEEDS LEFT THIS WAY MANY TIMES AND ANECDOTAL EVIDENCE SUGGESTS THAT FUEL IMBALS ARE COMMONPLACE. IN MY OPINION, IF THE FUEL CONFIGN WARNING SYS IS TO BE INACTIVATED OPERATIONALLY, THERE SHOULD BE SOME INDICATIONS THAT THE XFEED IS LATCHED OPEN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THEY HAD AN 8000 LB IMBAL BTWN THE L AND R WING OF THE ACFT BECAUSE THE FUEL XFEED VALVE HAD BEEN LEFT ON FROM THE PREVIOUS NIGHT. THEY MISSED THE PROPER SETTING OF THE VALVE DURING THEIR PREFLT. THEY WOULD ORDINARILY SEE A FUEL IMBAL DEVELOPING WITH THE EICAS MESSAGE ILLUMINATING. IN THIS CASE THOUGH, THE FUEL EICAS MESSAGE IS ON MOST OF THE TIME BECAUSE OF HAVING LESS THAN 1500 LBS IN THE CTR TANK WITH THE BOOST PUMPS OFF. THIS IS A RECENT PROCEDURAL CHANGE FOR ALL B767-200 ACFT. RPTR FURTHER STATED THAT THE FUEL XFEED VALVE IS OPENED DURING NIGHT TIME LAYOVER OF AN ACFT TO XFER FUEL OUT OF THE CTR TANK. FUEL DRAINS FROM THE WING TANKS INTO THE CTR TANK DURING PERIODS OF INACTIVITY. FUEL IS XFERRED OUT OF THE CTR TANK DURING LAYOVER PERIODS WITH THE USE OF THE XFEED VALVE. MAINT ACTIVATES THE VALVE, BUT DOES NOT RESET IT TO OFF MUCH OF THE TIME. ALTHOUGH THE FLC SHOULD CHK TO SEE THAT IT IS OFF DURING PREFLT, IT IS A DIFFICULT SWITCH TO EASILY DETERMINE WHAT POS IT IS IN, WHEN THERE IS AN ABUNDANCE OF LIGHT IN THE COCKPIT.

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.