Abstract: At approximately 6:00 a.m. on February 7, 2003, Employee #1 was working for Bodycote Thermal Processing, a metal heat treating company that thermal processes metal for use in aerospace. Employee #1, a heat-oven operator, was performing what is called a burn-out on a "BeaverMatic" oven, 18 in. by 48 in., which was built in 1967, Oven Number 5, preparing it for maintenance and a quality control survey. Employee #1 was standing in front of the oven and a coworker, a maintenance mechanic, was to the side of it. The burn-out procedures requires that the operator turns off the endothermic gas, open the inner and outer doors of the oven and raise the temperature to 1800 degrees to burn off all the carbon and all the endothermic gas with the flame curtain on. Based on this investigation, Employee #1 did the follow burn-out procedures as directed. His actions were contrary to the employer's procedures. Employee #1 opened the outer door before all the endothermic gas was burned off, did not have the inner door opened (during the entire burn), did not have the flame curtain on, and did not have his face shield on. The unburned heated endothermic gas from the heat zone of the oven diffused outward and mixed with air entering the oven when the outer door was opened which caused an explosion. Employee #1 was burned by the explosion. He sustained second degree burns to his face and both hands and was hospitalized. Employee #1 did not recall if the flame curtain was on. There is some contradictory information regarding when the inner oven door was opened and closed as well as when the endothermic gas was turned off. Employee #1 said the inner door was closed during the burn process but the Supervisor of the area reported that the inner door was opened. However the supervisor is not certain of his report because after the accident he observed the inner door closed. The Supervisor indicated that the inner door could have been closed later after the accident. The Supervisor said there is a hole in the inner door where the flame could have come out even if the inner door was closed. The General Manager of the company believed that Employee #1: shut off the endothermic gas and opened the outer door with the flame curtain on while leaving the middle door closed; let the furnace sit for two hours to do the endothermic burn; then shut off the flame curtain and opened the inner door (outer door was open during the process). The injured employee in his interview indicated he was doing a burn out but this was inconsistent with his statement of just lowering the endothermic gas just prior to having Maintenance inspect the oven.