As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 270, BEGINNING DESCENT, EXPERIENCED UNCOMMANDED ABRUPT ROLL APPROX 35-40 DEGREES TO THE LEFT. AUTOPILOT REVERTED TO CWS PITCH AND ROLL. YAW DAMPER IND SHOWED NO ABNORMAL INDICATIONS. NO TURBULENCE IN AREA. A/C IN CLEAN CONFIG. A AUTOPILOT ENGAGED AT THE TIME OF OCCURANCE. REPLACED THE A SYSTEM AUTOPILOT ACTUATOR PER MM. ALSO, REPLACED A CHANNEL FCC.