As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT HAD TWO INCIDENTS OF HIGH FREQUENCY LATERAL OSCILLATIONS AT FL 390. TURNED YAW DAMPNER OFF NO EFFECT, RUDDER TRIM 1-2 UINTS EITHER SIDE, SLIGHT DAMPENING EFFECT. REMOVED AND REPLACED NR 2 ENGINE HMU, FUEL PUMP AND RUDDER PCU PER MM.