TURBO COMMANDER 690C FLT CREW REPORTS DOUBLE ENGINE FAILURE ON SHORT FINAL. BOTH ENGINES ARE FEATHERED AND A SUCCESSFUL POWER OFF LANDING ENSUES.

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PRIOR TO THE EVENT WE HAD USED DEICE; AND ANTI-ICING EQUIP WHILE ENRTE; AND FOR THAT PORTION OF THE DSCNT WHILE IN ICING CONDITIONS. ICING WAS ESTIMATED TO BE LIGHT TO MODERATE CLR; CHANGING TO RIME THROUGH THE DSCNT. ENG INLET HEATS WERE NOT TURNED ON AT ANY TIME DURING THE FLT. AFTER BREAKING OUT OF THE BASES AND ACQUIRING VISUAL CONTACT WITH THE ARPT; WE WERE CLRED FOR THE VISUAL AND SUBSEQUENTLY CANCELED OUR IFR CLRNC. DSCNT; APCH AND BEFORE LNDG CHKS WERE COMPLETED. ACFT WAS CONFIGURED PER SOP AND WE WERE ESTABLISHED ON FINAL APCH. AT APPROX 1/4 - 1/2 MI FINAL; THE R ENG STOPPED PRODUCING PWR; FOLLOWED ALMOST IMMEDIATELY BY THE L ENG. THE CAPT IDENTED BOTH ENGS HAD FAILED AND PULLED THE CONDITION LEVERS INTO THE EMER SHUTOFF/FEATHER POS. I CALLED OUT AIRSPDS AND THE CAPT CONTINUED TO FLY THE ACFT ONTO THE RWY. THE ACFT TOUCHED DOWN APPROX ON THE NUMBERS AND WE ROLLED TO A STOP JUST OFF THE RWY WITH BOTH ENGS STOPPED/FEATHERED. IN SPEAKING WITH ONE OF THE PAX; THEY NOTED ICE BUILDUP ON A VENT ORIFICE PROTRUDING FROM ONE OF THE HEATED INLETS. I AM NOT CERTAIN IF THIS WAS BOTH ENGS OR JUST ONE. CONSIDERING THE SURFACE TEMP WAS 10 DEGS C; AND THE FACT THE ENG INLET HEAT WAS NOT TURNED ON DURING THE FLT; A POSSIBLE CAUSE OF THE FLAMEOUTS WAS MELTING ICE BEING INGESTED INTO EACH ENG. PROPER PROC WILL BE ADHERED TO IN THE FUTURE WITH REGARD TO USE OF ENG INLET HEAT. PROPER PROC IS TO TURN ENG IGNITIONS ON FOLLOWED BY ENG INLET HEAT PRIOR TO ENTERING ICING CONDITIONS. UPON EXITING ICING CONDITIONS; ENG INLETS ARE TURNED OFF FIRST; FOLLOWED BY ENG IGNITIONS. IF ICE REMAINS ON THE ACFT STRUCTURE; IGNITIONS ARE TO BE LEFT ON FOR THE DURATION OF THE FLT UNTIL THE ACFT IS ON THE GND.