What was found
DURING CRUISE, THE NR 1 AP, NR 1 FD TRIPPED OFF NUMEROUS TIMES. RESET THEN TRIPPED AGAIN FIRST OFFICER SELECTED THE OTHER FD ON SWITCHING PANEL SOMETIMES BROUGHT BACK NORMAL DISPLAY. CHECKED PREVIOUS FAULTS, FMC 1 FLAGGED FOR PAST SEVERAL FLIGHT LEGS. REMOVED AND REPLACED THE NR 1 FMC IAW AMM 34-68-34-04, OPS CHECKED GOOD. CROSSLOADED NAV DATABASE WITH NR 2 FMC AND VERIFIED CURRENT DATA BASE AND DATES IAW AMM 34-60-00-03. ALSO PERFORMED AFS TEST AND LAND TEST IAW AMM 22-40-00-05, LAND ENGAGE OKAY.