As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 410 CABIN FILLED WITH BLACK SMOKE. IN-FLIGHT EMERGENCY WAS DECLARED AND AN EMERGENCY DESCENT FROM FL410 INITIATED. O2 MASKS WERE DEPLOYED AND USED. LANDING AND TAXI WERE UNEVENTFUL. LEARJET ENGINEERING AND JET SOLUTIONS REPRESENTATIVES ARE INVOLVED IN THE CAUSAL INVESTIGATION. PRELIMINARY DATA SUGGESTS A PRESSURIZATION PACK FAILURE.