As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ON DESCENT WITH AUTOPILOT ENGAGED, STAB FAIL AND MACH FAIL MESSAGES APPEARED. THE STAB AND MACH TRIM WOULD NOT REENGAGE, EMERGERNCY DECLARED AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE PERSONNEL REPLACED THE HSTCU AND PERFOREMED A SATISFACTORY OPERTIONAL CHECK. AIRCRAFT WAS RELEASED FOR CONTINUED SERVICE