As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW WAS UNABLE TO ENGAGE VERTICAL NAVIGATION NO COMMAND BARS WERE PRESENT. AUTO THROTTLE AND STAB TRIM WERE OPERATING ERATICALLY AND AUTOPILOT WOULD NOT ENGAGE. FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED AIR DATA INERTIAL REFERENCE UNIT. SYSTEM GROUND CHECKED NORMAL OPERATION.