As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT THE CDU DATA BUS FAILED FOR THE NO2 FMS. OPERATIONS WERE CONTINUED PER MEL 34-60-01. DURING THE MAINTENANCE EVENT THE MAINTENANCE PROVIDER DETERMINED A FAILED FMS. THE FAILED UNIT WAS REMOVED AND A MODIFIED UNIT WAS INSTALLED. PERFORMANCE AND NAVIGATIONS DATABASES WERE INSTALLED OPERATIONAL CHECKS WERE SATISFACTORY. THE AIRCRAFT WAS THEN RETURNED TO SERVICE.