Abstract: THIS ACCIDENT OCCURRED AT THE CASA GRAND BLOCK COMPANY, A MANUFACTURER OF CONCRETE BLOCKS. THE BLOCKS ARE CURED IN A STEAM KILM, HEATED BY NATURAL GAS. THE SOUTHWEST GAS COMPANY NOTICED A LARGE INCREASE IN GAS COMSUMPTION AND SENT A FIELD TECHNICIAN TO CHECK FOR LEAKS. ON OCTOBER 27, 1986, THE TECHNICIAN COMPLETED A LINE PRESSURE DROP TEST AND LEAK DETECTOR TEST, WHICH INCLUDED A GROUND PROBE AND A FITTING SOAP TEST UP TO THE KILN BURNER. NO LEAKS WERE FOUND. THE BURNER IS A PEABODY GORDON-PIATT GAS/OIL BURNER, MODEL R6-GO-03. STEAM IS CREATED IN A NON-PRESSURIZED TANK INSIDE THE KILM. THE BURNER AND CONTROLS ARE LOCATED ON THE OUTSIDE WALL AT THE REAR OF THE KILN. AROUND 4 PM ON OCTOBER 27TH, EMPLOYEE #1 WAS AT THE REAR OF THE KILN, CHECKING THE BURNER OR WATER LEVEL. AN EXPLOSION OCCURRED WHICH BLEW THE WALLS OUT AND CAUSED THE ROOF TO CAVE IN. THE REAR WALL STRUCK EMPLOYEE #1, AND PORTIONS OF IT LANDED ON HIM. HE SUFFERED SEVERE HEAD AND INTERNAL INJURIES AND DIED AT 9 PM THE SAME DAY. THERE WERE NO WITNESSES. WITHOUT ANY APPARENT GAS LEAKS, IT IS BELIEVED THE EXPLOSION WAS CAUSED BY FAULTY BURNER OPERATION, WHICH ALLOWED A BUILD UP OF EXPLOSIVE GASES INSIDE THE KILN. CARBON BUILD-UP INSIDE THE KILN AND BLOWER INDICATES POOR CONBUSTION AND POSSIBLE CARBON MONOXIDE BUILDUP.