What was found
CRUISE ALTITUDE, IC1 FAN FAILURE. IMMEDIATELY, EXPERIENCED A FAILURE OF AUTOPILOT & YAW DAMPER, ASSOCIATED MESSAGES PRESENTED ON EICAS. F/O TOOK MANUAL CONTROL, RAN CHECKLIST FOR AUTOPILOT FAILURE. ALSO, FAILURE OF PITCH TRIM MAIN & BACKUP SYS. EICAS SHOWED BOTH FAILED. RAN QRH PROCEDURES, STARTED DESCENT. CHECKLIST STATES, PULL F11 & C24 CIRCUIT BREAKERS AT SAFE ALTITUDE. AT FL280, PULLED & RESET BREAKERS, THEN RESET PITCH TRIM MAIN & BACKUP SYSTEMS. SYSTEMS SEEMED TO WORK. F/A PREPARED CABIN FOR POSSIBLE DIVERSION. MX ADVISED, NO HISTORY OF OCCURRENCE ON THIS A/C. SYSTEM FAILED AGAIN. DECLARED EMERGENCY, LANDED UNEVENTFULLY. MX FOUND IC600 FAN FAILED. REMOVED & REPLACED IC600, OPS CHECK GOOD.