As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON TAXIING FOR TAKEOFF, THE PILOT'S DISCOVERED SMOKE ENTERING THE COCKPIT VIA THE HEATER DUCTS. THE HEATER WAS SUBSEQUENTLY SHUT DOWN AND THE AIRCRAFT RETURNED TO THE FBO. THE AIRCRAFT WAS INSPECTED BY AN A.M.E. AND WAS FLOWN BACK TO BASE WITHOUT HEAT. THE HEATER WAS PRESSURE DECAY TESTED AND FOUND TO BE LEAKING. THE UNIT WAS REPLACED.