Inspection Detail

Inspection: 307183236 - Mc Gill Corporation

Inspection Information - Office: Monrovia District Office

Investigation Summary

At approximately 2:35 p.m. on December 3, 2006, Employee #1 was working as a machine operator for the M. C. Gill Corporation, which manufactured composite paneling for aircraft. These composite panels were made of a fire retardant material that had been dipped in a phenolic impregnating resin. The resulting blocks of material were air purged to remove free isopropanol (isopropyl alcohol). The material was then placed in an oven, where the vapors were recovered as fuel or incinerated. The flash point of phenol is 175 degrees Fahrenheit. Its lower explosive limit (LEL) is 1.8, and its upper explosive limit (UEL) is 9.5. The flashpoint for isopropyl alcohol is 79.2 degrees Fahrenheit. Its LEL is 2, and its UEL is 11.8. The blocks were baked at a temperature higher than 175 degrees Fahrenheit. On the day of the accident, the incinerator had been malfunctioning. It had shut down, and there had been more than one attempt at restarting it. During this time, the oven was down, and off-gas from the blocks had accumulated within. The atmosphere within the incinerator and oven system was at or above the LEL and low in oxygen. A final attempt was made at restarting the incinerator. When the oven doors were opened, air and oxygen were introduced to the fuel rich atmosphere. Due to this sudden increase in oxygen, the flammable gas within the oven exploded. Employee #1 was by the back door of curing oven Number 3, near the control panel for the incinerator, and he was killed. A subsequent investigation determined that "the most significant source of ignition (was) the restart of the incinerator."

Keywords: OXYGEN, AIRCRAFT, HEAD, FLAMMABLE VAPORS, OVEN, EXPLOSION, INCINERATOR, STRUCK BY, MECH MALFUNCTION, HIGH TEMPERATURE