As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL FLT 9010 EN ROUTE ZRH TO PHL. STEADY RYTHMIC YAWING MOTION. NOTICEABLE THRU OUT AIRCRAFT. LASTED APPROX 45 MINUTES. CEASED WHEN TURNED OFF CENTER TANK FUEL PUMPS. ACCOMPLISHED RECOMMENDED TROUBLESHOOTING TASKS; CHECKED ALL FLIGHT CONTROL MODULES FOR FAULT BALLS, MCDP "LAST FLIGHT" FAULTS, MCDP TESTS 30, 40, & TEST 66, AND YAW DAMPER TEST. NO FAULTS NOTED.