As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LHR - CREW REPORTED RUDDER RATIO ANNUNCIATOR AND EICAS MESSAGE DISPLAYED DURING CRUSE FLIGHT. EMERGENCY DECLARED FLIGHT LANDED LHR WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED RUDDER RATIO CHANGER. SYSTEM GROUND CHECK NORMAL OPERATION.