N9987M

THE PILOT'S CONTINUED FLIGHT INTO KNOWN FORECASTED ICING CONDITIONS, IN AN AIRPLANE NOT CERTIFICATED FOR SUCH FLIGHT, WHICH RESULTED IN AN ENGINE FLAMEOUT DUE TO ENGINE ICE/WATER INJESTION, AND THE PILOT'S INABILITY TO RESTART THE ENGINE DUE TO INADEQUATE INSTALLATION OF THE PNEUMATIC AIR LINES ON THE COWL DOOR SEQUENCING VALVES WHICH PREVENTED THE ALTERNATE AIR DOORS TO COMPLETELY CYCLE OPEN. THE INADEQUATE SYSTEM DESIGN LED TO A BLOCKED COMPRESSOR INLET. FACTORS IN THE ACCIDENT WERE: ICING CONDITIONS, INADEQUATE ENGINE AND INDUCTION ANTI-ICING SYSTEM DESIGN, FAILURE OF THE MANUFACTURER TO PERFORM ADEQUATE SYSTEM TESTING TO ENSURE ADEQUATE OPERATION, AND MOUNTAINOUS TERRAIN.