As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FINAL APPROACH, AIRCRAFT EXPERIENCED YAW MOTION (LEFT RUDDER) FOR BRIEF MOMENT WHEN 2ND A/P (NR 1) WAS ENGAGED. A/P WAS RE-ENGAGED AND COULD NOT DUPLICATE DISCREPANCY. MAINTENANCE PERFORMED AFS TEST PER AMM 22-46-00-710-001 AND EFCS GRND SCAN PER AMM 27-96-00-740-001. NO FAULTS NOTED.