Narrative:

Shortly after top of climb. PNF observed using 'rsv fuel' message on the FMC. PNF corrected performance page reserve fuel amount to comply with company policy. Center tank fuel pumps turned off at 1000 pounds quantity to comply with ad. 20 mins later, PNF observed imbalance of 400 pounds on left engine (#1) and commenced crossfeeding to balance fuel load. Fuel configuration returned to normal after wing tanks balanced. 15 mins later PF noticed imbalance on right engine (#2) of 800 pounds. PNF commenced crossfeeding to rebalance wing tanks. PNF also observed total fuel quantity decreasing at an abnormal rate and called for QRH, checklist in-flight engine fuel leak. Leak was confirmed by crew, but crew was unable to identify source. Diversion to ZZZ was initiated after contacting mx and dispatch of problem. Flight continued to ZZZ without incident. Upon landing and turn off for taxi, noticeable odor of fuel detected and engines immediately shutdown. Fire crews notified crew of no fire or danger thereof, and aircraft towed to gate for passenger. Deplaning. Callback conversation with reporter revealed the following information: maintenance determined that there was a leak from the hydro mechanical unit of the fuel control. The hmu had recently been replaced. This was done because the carrier had noted that their engines had not been producing thrust per specifications. They determined that it was not caused by a software problem in the fuel control system so they were changing out of hmu's for investigation of the problem. The reinstallation of the unit is apparently difficult and requires a special tool due to the location of some of the fasteners securing the unit. There have been other reported incidents at the airline. One of these included an engine flame out. The flight crew was questioned about their apparent non compliance with the QRH procedures which included an engine shutdown. During simulations of the problem at their training facility it was determined that they, with the condition described, handled the situation appropriately.

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Original NASA ASRS Text

Title: HAVING DIFFICULTY WITH A FUEL IMBALANCE CONDITION IN A B737-800 THE CREW DETERMINES THERE MAY BE A FUEL LEAK AT AN UNKNOWN LOCATION. DIVERSION IS ACCOMPLISHED AND ENGS SHUTDOWN FOR A TOW TO THE GATE WHEN FUEL FUMES ARE DETECTED AFTER LNDG.

Narrative: SHORTLY AFTER TOP OF CLB. PNF OBSERVED USING 'RSV FUEL' MSG ON THE FMC. PNF CORRECTED PERFORMANCE PAGE RESERVE FUEL AMOUNT TO COMPLY WITH COMPANY POLICY. CENTER TANK FUEL PUMPS TURNED OFF AT 1000 LBS QUANTITY TO COMPLY WITH AD. 20 MINS LATER, PNF OBSERVED IMBALANCE OF 400 LBS ON L ENG (#1) AND COMMENCED CROSSFEEDING TO BALANCE FUEL LOAD. FUEL CONFIG RETURNED TO NORMAL AFTER WING TANKS BALANCED. 15 MINS LATER PF NOTICED IMBALANCE ON R ENG (#2) OF 800 LBS. PNF COMMENCED CROSSFEEDING TO REBALANCE WING TANKS. PNF ALSO OBSERVED TOTAL FUEL QUANTITY DECREASING AT AN ABNORMAL RATE AND CALLED FOR QRH, CHKLIST INFLT ENG FUEL LEAK. LEAK WAS CONFIRMED BY CREW, BUT CREW WAS UNABLE TO IDENTIFY SOURCE. DIVERSION TO ZZZ WAS INITIATED AFTER CONTACTING MX AND DISPATCH OF PROB. FLT CONTINUED TO ZZZ WITHOUT INCIDENT. UPON LNDG AND TURN OFF FOR TAXI, NOTICEABLE ODOR OF FUEL DETECTED AND ENGS IMMEDIATELY SHUTDOWN. FIRE CREWS NOTIFIED CREW OF NO FIRE OR DANGER THEREOF, AND ACFT TOWED TO GATE FOR PAX. DEPLANING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: MAINT DETERMINED THAT THERE WAS A LEAK FROM THE HYDRO MECHANICAL UNIT OF THE FUEL CTL. THE HMU HAD RECENTLY BEEN REPLACED. THIS WAS DONE BECAUSE THE CARRIER HAD NOTED THAT THEIR ENGS HAD NOT BEEN PRODUCING THRUST PER SPECIFICATIONS. THEY DETERMINED THAT IT WAS NOT CAUSED BY A SOFTWARE PROB IN THE FUEL CTL SYSTEM SO THEY WERE CHANGING OUT OF HMU'S FOR INVESTIGATION OF THE PROB. THE REINSTALLATION OF THE UNIT IS APPARENTLY DIFFICULT AND REQUIRES A SPECIAL TOOL DUE TO THE LOCATION OF SOME OF THE FASTENERS SECURING THE UNIT. THERE HAVE BEEN OTHER RPTED INCIDENTS AT THE AIRLINE. ONE OF THESE INCLUDED AN ENG FLAME OUT. THE FLT CREW WAS QUESTIONED ABOUT THEIR APPARENT NON COMPLIANCE WITH THE QRH PROCS WHICH INCLUDED AN ENG SHUTDOWN. DURING SIMULATIONS OF THE PROB AT THEIR TRAINING FAC IT WAS DETERMINED THAT THEY, WITH THE CONDITION DESCRIBED, HANDLED THE SIT APPROPRIATELY.

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.