As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNCOMMANDED SMALL RUDDER MOVEMENTS IN CHOPPY AIR. NOSE MADE SMALL YAW CHANGES, ACTED LIKE NO YAW DAMP ON. NO PROBLEM NOTED WHILE IN SMOOTH AIR. NEITHER AUTOPILOT ON. PROBLEM STOPPED WHEN RUDDER HYDRAULIC CONT TURNED OFF. REMOVED AND REPLACED YAW DAMPENER ACTUATOR.