Narrative:

At liftoff from jfk (runway 4L), the aircraft exhibited a distinct desire to roll to the right. I corrected with opp aileron and rudder inputs to keep the wings level and heading on course. The captain noticed the roll and checked for proper thrust output from the engines and rechked the rudder and aileron trim settings. Everything was normal. He and the F/east also checked the fuel gauges to make sure the load was balanced. It was! We concluded we had some sort of control problem or misrigging, so we dumped fuel to maximum landing weight and returned to jfk. The landing was uneventful and we returned to gate to have maintenance troubleshoot the problem. They found no control misrigging or anything that could possibly cause a roll to the right. As they were refueling, however, they noted that the left wing tank was approximately 10000# emptier than the right! After further troubleshooting, it was determined that either a bad gauge or fuel tank probe was sending erroneous information, because the cockpit fuel gauges all showed a balanced fuel load. (They showed a balanced load before takeoff, during climb, during fuel dumping and at the gate after landing.) the pronounced roll was due to the right wing being more than 5 tons heavier than the left. After the fuel sensing and indicating system was thoroughly repaired and after dip-sticking the tanks, we continued our merry flight to lax. No further problems with roll control or with the fuel system were encountered.

Google
 

Original NASA ASRS Text

Title: ACR WDB MADE A TKOF FROM JFK WITH A NOTICEABLE FUEL IMBALANCE.

Narrative: AT LIFTOFF FROM JFK (RWY 4L), THE ACFT EXHIBITED A DISTINCT DESIRE TO ROLL TO THE RIGHT. I CORRECTED WITH OPP AILERON AND RUDDER INPUTS TO KEEP THE WINGS LEVEL AND HDG ON COURSE. THE CAPT NOTICED THE ROLL AND CHKED FOR PROPER THRUST OUTPUT FROM THE ENGS AND RECHKED THE RUDDER AND AILERON TRIM SETTINGS. EVERYTHING WAS NORMAL. HE AND THE F/E ALSO CHKED THE FUEL GAUGES TO MAKE SURE THE LOAD WAS BALANCED. IT WAS! WE CONCLUDED WE HAD SOME SORT OF CTL PROB OR MISRIGGING, SO WE DUMPED FUEL TO MAX LNDG WT AND RETURNED TO JFK. THE LNDG WAS UNEVENTFUL AND WE RETURNED TO GATE TO HAVE MAINT TROUBLESHOOT THE PROB. THEY FOUND NO CTL MISRIGGING OR ANYTHING THAT COULD POSSIBLY CAUSE A ROLL TO THE RIGHT. AS THEY WERE REFUELING, HOWEVER, THEY NOTED THAT THE LEFT WING TANK WAS APPROX 10000# EMPTIER THAN THE RIGHT! AFTER FURTHER TROUBLESHOOTING, IT WAS DETERMINED THAT EITHER A BAD GAUGE OR FUEL TANK PROBE WAS SENDING ERRONEOUS INFO, BECAUSE THE COCKPIT FUEL GAUGES ALL SHOWED A BALANCED FUEL LOAD. (THEY SHOWED A BALANCED LOAD BEFORE TKOF, DURING CLB, DURING FUEL DUMPING AND AT THE GATE AFTER LNDG.) THE PRONOUNCED ROLL WAS DUE TO THE RIGHT WING BEING MORE THAN 5 TONS HEAVIER THAN THE LEFT. AFTER THE FUEL SENSING AND INDICATING SYS WAS THOROUGHLY REPAIRED AND AFTER DIP-STICKING THE TANKS, WE CONTINUED OUR MERRY FLT TO LAX. NO FURTHER PROBS WITH ROLL CTL OR WITH THE FUEL SYS WERE ENCOUNTERED.

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.