As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED AIRCRAFT HAD SMOKE IN THE CABIN. AIRCRAFT RETURNED TO AIRPORT LANDING WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, REMOVED AND REPLACED THE LEFT ENGINE AND OXYGEN EQUIPMENT PER AIRCRAFT MANUALS. CHECKS WERE PERFORMED PER THE AIRCRAFT MANUALS AND AIRCRAFT WAS RELEASED FOR SERVICE.