As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH FLIGHT 3123 THE CREW REPORTED A LOUD THUMPING NOISE 3 OR 4 TIMES AFTER GEAR RETRACTION. THE ACFT RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MX INSPECTED THE ACFT, OPS CHECKED THE LANDING GEAR EXTENSION AND RETRACTION MULTIPLE TIMES WITH NO DEFECTS NOTED AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.