What was found
AIRCRAFT YAWS LEFT AND RIGHT UNCOMMANDED (SAME CONDITION WITH YAW DAMP 'OFF'). SELECTED RUDDER BOOST TO 'OFF' AND CONTINUED FLIGHT WITH NO ADDITIONAL PROBLEMS. TROUBLESHOOTING BY MAINTENANCE PERSONNEL FOUND PRIMARY RUDDER SERVO TO BE DRIVING RUDDER IN WRONG DIRECTION. REMOVED AND REPLACED RUDDER SERVO. POST-INSTALLATION TESTS PERFORMED SATISFACTORILY. TEAR DOWN OF RUDDER SERVO REVEALED IMPROPER ASSEMBLY FOLLOWING REPAIRS BY CERTIFIED REPAIR STATION. COMPONENT P/N SVO656225734002.