As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED SMOKE IN CABIN DURING HEATER OPERATION. TROUBLESHOT SYSTEM, FOUND ENGINE OIL IN HEATER. FOUND OIL LEAKING OUT OF TORQUE PSI LINE. THE OIL SPRAY WAS INJESTED BY HEATER. REPLACE TORQUE PSI LINE AND HEATER SYSTEM, CHECKED OKAY. LINE WAS MFG IN 1988 AND WAS TEFLON RATED TO 1500 PSI.