As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 4469 - DURING FLIGHT FROM YYZ TO ATL, CREW RECEIVED STAB TRIM AND MACH TRIM CAUTION MESSAGE ON RANDOM INTERVALS. CREW RESET SYSTEM, BUT MESSAGE WOULD START AGAIN. STAB AND MACH TRIM FAILED AGAIN UPON APPROACH. CREW DECLARED AN EMERGENCY AND LANDED SAFELY. MAINTENANCE REMOVED AND REPLACED HSTCU. OPERTIONAL CHECKS WERE GOOD. AIRCRAFT RETURNED TO SERVICE. (M)