As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT HEATER DUCTS ARE FOAMED LINED. THE DUCTS START TO BREAK DOWN AND THE FOAM CAUSED SMOKE IN THE COCKPIT. ACFT AND LOGS ARE NO LONGER AT THIS FACILITY. TIMES AND PN ARE ESTIMATIONS. NO OTHER INFORMATION IS AVAILABLE FROM THIS LOCATION. THIS SDR IS BEING GENERATED FROM A PAST MECHANICAL INTERRUPTION SUMMARY REPORT.