Narrative:

At cruise; fuel imbal noted between main fuel tanks and fuel confign light came on. Fuel quantity in left tank was decreasing at an abnormal rate. Fuel leak was suspected on the left side. Had difficulty communicating with dispatch and lost contact with maintenance. Complied with in-flight fuel leak checklist -- left engine was shut down; declared an emergency and diverted to ZZZ.

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Original NASA ASRS Text

Title: B757-200 FLT CREW ENCOUNTER APPARENT FUEL LEAK IN L WING TANK. DECLARE EMER AND DIVERT WITH L ENG SHUT DOWN.

Narrative: AT CRUISE; FUEL IMBAL NOTED BTWN MAIN FUEL TANKS AND FUEL CONFIGN LIGHT CAME ON. FUEL QUANTITY IN L TANK WAS DECREASING AT AN ABNORMAL RATE. FUEL LEAK WAS SUSPECTED ON THE L SIDE. HAD DIFFICULTY COMMUNICATING WITH DISPATCH AND LOST CONTACT WITH MAINT. COMPLIED WITH INFLT FUEL LEAK CHKLIST -- L ENG WAS SHUT DOWN; DECLARED AN EMER AND DIVERTED TO ZZZ.

Data retrieved from NASA's ASRS site as of January 2009 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.