As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 3144 - IAD - FLIGHT CREW REPORTED SMOKE IN CABIN DURING CLIMB. CREW PERFORMED AIR RETURN AND LANDED BACK IN IAD WITHOUT INCIDENTS. MX FOUND TUBE UNDER SEAT 9A DISCONNECTED. MX RECONNECTED DUCT AND PERFORMED OPERATIONAL CHECK SUCCESSFULLY. AIRCRAFT WAS APPROVED TO RETURN TO SERVICE. (A)