As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB THROUGH FL 180, AUTOPILOT GAVE AN UNCOMMANDED RIGHT RUDDER INPUT. AN UNCOMMANDED RIGHT RUDDER INPUT OCCURRED WITH AUTOPILOT DISENGAGED, USED MANUAL RUDDER WITH YAW DAMPER ON AND SERVO ON. REPLACED THE STABILITY AUGMENTATION COMPUTER IAW DC-9 MM 22-11-01-2.