As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED BLACK SMOKE IN THE CABIN. MAINTENANCE INSPECTED C/B PANELS AND AREA UNDER COCKPIT CENTER FLOOR WITH NO DEFECTS NOTED, PERFORMED ENGINE RUNS WITH NO SMOKE NOTED, RAN HEATER AND VERIFIED BLACK SMOKE COMING FROM COCKPIT VENTS AND IN NOSE BAGGAGE COMP. R & R HEATER FOUND CRACK IN COMBUSTION CHAMBER, R & R COMBUSTION BLOWER AND HEATER FUEL PUMP WITH NO FURTHER DEFECTS NOTED.