As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN HYDRAULIC PITCH TRIM IS ACTIVATED UNCOMMANDED RUDDER MOVEMENT RESULTS. RUDDER MOVEMENT IS MORE PRONOUNCED WITH DOWN TRIM THAN UP. YAW DAMPER WAS TURNED OFF WITH SAME RESULTS. C/W VISUAL INSPECTION OF RUDDER PACK, AND PERFORMED GROUND OPERATIONAL CHECK PER RUDDER OPER AND TRAVEL LIMITS. DC-8 MM 27-20-02. NO DEFECTS NOTED.