As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDED UNDER AMBER ALERT FOR RUDDER VIBRATION. SUPPLEMENTAL DATA UPDATE NUMEROUS FLIGHT CONTROL AND HYDRAULIC SYSTEM COMPONENTS WERE TESTED. A VERIFICATION TEST FLIGHT WAS PERFORMED TO CHECK FOR VIBRATION. DURING THE TEST FLIGHT; THERE WERE NO VIBRATIONS.