What was found
LEFT FILTER BYPASS LIGHT ILLUMINATED AFTER ENGINE START. ACFT GROUNDED. PERFORMED FIM TASK 73-05-TASK 801 IN REF OF MEL 73-4B, FUEL FILTER LIGHT OFF ON ENGINE SHUTDOWN. REPLACED NR 1 FUEL FILTER IAW AMM 73-11-02-000-801-F00. FOUND FILTER CLEAN, NO CONTAMINATION FOUND. CONTINUE WITH FIM TASK AND REPLACED FUEL FILTER DIFFERENTIAL PRESSURE. SWITCH IAW AMM 73-34-01-000-801-F00 & 73-34-01-400-801-F00. PERFORMED ENG NR 1 RUN, NO LEAKS FOUND, PERFORMED TEST ON FMCS CDU NO FAULTS FOUND, NO LIGHT ON, SUCCESSFUL GROUND TEST. AC OK FOR SERVICE.