As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE FLIGHT, FRONT SEAT PASSENGER ALERTED PILOT AN ODOR OF SOMETHING BURNING THEN SAW SMOKE BY HIS FEET (HEATER VENT AREA). PILOT TURNED OFF HEATER AND RETURNED TO BASE. ACFT EQUIPPED WITH ENGINE BLEED AIR HEATER. SUSPECTING AN ENGINE INTERNAL SEAL FAILURE, MX REMOVED ENGINE AND SENT TO ENGINE SHOP. NO FURTHER DETAILS AT THIS TIME.