As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLIGHT, SELECTED WINDOW HEAT SWITCHED ON AND IMMEDIATELY HAD RIGHT SIDE WINDOW PRODUCE LARGE SPARK AND AND BEGIN SMOKING. WINDOW SPIRAL HEAT CORD AND TEST WINDOW HEAT, BOTH ACCOMPLISHED, ALSO REF AMM 30-41-00-5 FOR WINDOW HEAT TEST OK.