IN FLT WX ENCOUNTER; DISABLED HEATER CAUSES LACK OF VISION TO LAND. ACFT SLIDS OFF RWY.

Narrative

I WAS GIVEN VECTORS FOR AN ILS RWY 18 APCH INTO CLARK COUNTY ARPT. IN PREPARATION FOR POSSIBLE ICING ON THE APCH; AS WE BEGAN OUR DSCNT; I TURNED THE HEATER ALL THE WAY UP; DIRECTED ALL HEAT THROUGH THE DEFROSTER AND TURNED THE BLOWER ON THE DEFROSTER ALL THE WAY UP. AS WE DSNDED THROUGH APPROX 3500 FT; WE ENCOUNTERED MODERATE FREEZING RAIN. WE HAD NO PROB WITH VISIBILITY UNTIL WE TURNED IN FOR THE APCH. APPARENTLY; THE FREEZING RAIN HAD EXTINGUISHED THE HEATER. THE WINDSHIELD ALCOHOL DEICE SYS HAD BEEN TURNED ON AS SOON AS THE FREEZING RAIN WAS ENCOUNTERED AND WAS LEFT ON THROUGH THE APCH; HOWEVER; THE FORWARD VISIBILITY WAS REDUCED TO A POINT THAT I WAS UNABLE TO MAKE A SAFE LNDG ON THE RWY AND DECLARED A MISSED APCH. I WENT AROUND AGAIN AND STARTED MY FINAL APCH TO THE ARPT. WHILE IT WAS CLR THAT THE DEICE EQUIP ON THE AIRFRAME WAS WORKING WELL ( I HAD NO DIFFICULTY IN CLBING ON THE MISSED APCH); FORWARD VISIBILITY WAS EXTREMELY POOR. IT WAS VERY DIFFICULT TO SEE THROUGH THE AREA CLRED BY THE FLOW OF THE ALCOHOL WHILE THE ALCOHOL WAS RUNNING AND WHEN THE ALCOHOL WAS TURNED OFF; ICE FORMED TOO RAPIDLY TO EVEN GET A SHORT GLIMPSE. BEING FAMILIAR WITH THE PARTICULARLY CLR APCHS TO CLARK COUNTY ARPT (MY HOME ARPT); I ELECTED TO CONTINUE THE APCH AS BEST I COULD. VISIBILITY OUT THE SIDE WINDOWS WAS UNIMPAIRED; HOWEVER; FORWARD VISIBILITY WAS SO BAD I WAS UNABLE TO DISCERN THE RED/WHITE GLIDE PATH LIGHTS LOCATED ON THE L OF THE RWY. WE LANDED HARD ON THE RWY IMMEDIATELY PAST THE GS LIGHTS. BECAUSE OF ICE ON THE RWY WE SLID OFF OF THE RWY TO THE L; BUT I WAS ABLE TO MAINTAIN FORWARD CTL OF THE AIRPLANE AND PERHAPS BECAUSE THE GND WAS FROZEN; THE ROLLOUT WAS ROUGH BUT UNEVENTFUL. WHEN THE ACFT SLOWED TO APPROX 15 TO 20 KTS INDICATED AIR SPD; I TURNED TOWARD THE RWY AND INCREASED PWR. I WAS ABLE TO RE-ENTER THE RWY. I TAXIED BACK TO THE HANGAR AND MADE A CURSORY INSPECTION OF THE ACFT THAT EVENING. THAT INSPECTION INDICATED NO PROBS WITH THE ACFT WITH THE EXCEPTION OF ONE DOOR GEAR HAVING COME LOOSE. BECAUSE OF RECORD SNOWFALL IN THE AREA; THE ACFT WAS NOT INSPECTED FOR A FEW DAYS. WHEN IT WAS INSPECTED; IT WAS FOUND THAT THERE WAS SIGNIFICANT DAMAGE TO THE WING; APPARENTLY AS A RESULT OF THE HARD LNDG OR IMPACTS WHICH MAY HAVE OCCURRED ON THE ROLLOUT OFF THE RWY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES AT THE 1ST MISSED APCH HE REALIZED THE HEATER HAD QUIT. HIS WIFE NOTICED THE TEMP CHANGE IN CABIN. THERE WAS PLENTY OF FUEL FOR THE HEATER. APPARENTLY THERE HAVE BEEN SOME VENT PROBS WITH THIS HEATER. RPTR FEELS THIS WAS AN EXTREME SIT SINCE HE HAS BEEN IN CONDITIONS WHEN HE WAS LOADED WITH ICE; IN CLOUDS; DSNDED BELOW CLOUDS; SHUT OFF ALCOHOL ON WINDSHIELD AND COULD SEE JUST FINE. ALWAYS CARRIES EXTRA SPD IN SUCH CONDITIONS. ON THIS OCCASION HE CAME IN AT ABOUT 110 KTS. NORMAL APCH SPD IS 90 KTS. PART OF THE PROB WAS A LIGHT XWIND. THERE WAS ALSO AN AREA OF RWY WHICH HAD BEEN WORKED ON WITH A 6 INCH LIP OF ASPHALT. IF HE HAD NOT STILL HAD THE NOSE HELD UP; IT WOULD HAVE SHEARED THE NOSE STRUT. RPTR STRONGLY BELIEVES HE SHOULD HAVE GONE STRAIGHT IN AND LANDED WHEN HE BECAME VFR INSTEAD OF FLYING THE APCH. THERE IS A KIT OUT. IT CAN BE CERTIFIED FOR KNOWN ICING CONDITIONS. A MAJOR PART OF THIS INCIDENT WAS VERY POOR WX INFO XMITTED TO RPTR.