What was found
DURING DESCENT, LEFT FMC FAILED WITH NO FMC DATA ON CA NAV DISPLAY IN MAP AND NO FMC DATA ON BOTH CDU'S. APPROXIMATELY 30 SECONDS LATER, SYSTEM AUTOMATICALLY RETURNED TO NORMAL OPS AND NO FURTHER INCIDENT FOR REMAINDER OF THE FLIGHT. ACFT GROUNDED. REMOVED & REPLACED THE NR 1 FMC, IAW AMM 34-61-02. ACCOMPLISHED FMCS PERFORMANCE FACTORS ADJUSTMENTS, IAW AMM 34-61-00, NO FAULTS NOTED, OPS CHECKED NORMAL.