As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. ON FINAL APPROACH AT APPROX. 500 THE RUDDER KICKED TO THE RIGHT CAUSING NOSE OF AIRCRAFT TO SWING RAPIDLY WITHOUT PILOT RUDDER PEDAL INPUT. YAW DAMPER THEN DISENGAGED WITH AN AMBER CAUTION LIGHT. REMOVED AND REPLACED PRIMARY RUDDER POWER CONTROL UNIT PER AMM 27-21-91. OPERATIONAL CHECK GOOD.