What was found
AIRCRAFT WAS GROUNDED. INFLIGHT AIRCRAFT EXPERIENCED A DEGRADATION OF THE NAVIGATION SYSTEM. FLIGHT DIVERTED TO PIT. EMERGENCY DECLARED AND LANDED WITHOUT INCIDENT. INFLIGHT, AUTOPILOT, AUTOTHRUST AND FLIGHT DIRECTORS FAILED. THEN NAV/POS DISAGREE APPEARED. DIVERTED TO PIT. DURING DECENT, RECOVERED FDS AND A/P IRR 3 FAULT APPEARED ON TAXI IN. REPLACED AIR DATA AND INERTIAL UNIT 3 PER AMM 34-12-34-0401. PERFORMED SATISFACTORY CAT 3 AUTOLAND TEST PER 22-97-00-740-001. AIRCRAFT LMP STATUS TO REMAIN CAT 3 DUAL.