As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - INFLIGHT DFW-HDN - CREW REPORTED HAD SMOKE IN AFT PORTION OF MAIN CABIN. EMERGENCY DECLARED, DIVERTED DEN LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND RIGHT AIR CYCLE MACHINE INOPERATIVE. REPLACED AIR CYCLE MACHINE. SYSTEM GROUND CHECKED NORMAL OPERATION.