What was found
AT CRUISE, CAPTAIN'S ND DISPLAY HAD A "VTK", BOTH MCDU'S LOST FMC INFO. ACCOMPLISHED FMC FAIL QRH FOR LT FMC FAIL. RT FMC OPERATING NORMAL. ACFT GROUNDED. ACCOMPLISHED LT AND RT FMC BITE REF FIM 34-61, TASK 801. RT FMC NO CURRENT FAULTS. LT FMC NO CURRENT FAULTS. ACCOMPLISHED DFCS BITE REF FIM 22-11, TASK 801. LEFT FMC SHOWS 7 FAULT MESSAGES ON LEG 6. MESSAGE 22-11071, REF FIM 22-11, TASK 811 FLIGHT MANAGEMENT COMPUTER, FMC-1, PROBLEM - FAULT ISOLATION. DUE TO HISTORY, R & R FMC-1 REF AMM 34-61-02.