As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT AT 250 KTS, AIRCRAFT FELT AS IF RUDDER WAS SWAYING AND AIRCRAFT YAWING SLIGHTLY; MOVEMENT INCREASED WITH ACCELERATION AFTER FL100. AS PRECAUTIONARY MEASURE, FLIGHT CREW ELECTED TO RETURN TO ATL AND LANDED WITHOUT INCIDENT OR HAVING TO TAKE EMERGENCY ACTION. REPLACED STAB AUGMENTATION COMPUTER IAW MM 22-11-1.