What was found
IN IAD, DURING FLIGHT, NOTICED L AUTO XFLOW STAY ON FOR LONGER THAN NORMAL. FUEL IMBALANCE CONTINUED TO DEVELOP WITH THE LEFT SIDE LOW AND XFLOW RUNNING, TOTAL FUEL WAS NOT BELOW EXPECTED. DECLARED AN EMERGENCY AND LANDED WITH 600LB IMBALANCE. NO MESSAGES POSTED OTHER THAN THOSE ASSOCIATED WITH SFP ARFF & POST FLT INSP REPORT NO VISIBLE LEAKS. FLIGHT 6331. TROUBLESHOT LT AUTO XFLOW ON STATUS MESSAGE WITH NO FUEL TRANSFER IAW FIM 28-13-00-810-808. R & R THE CROSS FLOW PUMP CARTRIDGE IAW AMM 28-13-47. PERFORMED AN OPS TEST OF THE FUEL TRANSFER SYS IAW AMM 28-13-00. OPS CHKD GOOD. TRANSFERRED FUEL FROM LT WING TANK INTO THE RT WING TANK TO CREATE A 300 LB FUEL IMBALANCE TO VERIFY AUTO XFLOW OPERATION L AUTO XFLOW ON, STATUS MESSAGE APPEARED, & FUEL WAS TRANSFERRED BACK INTO THE LT WING TANK, BALANCING THE FUEL OPS CHECK GOOD AT THIS TIME.