Abstract: At approximately 7:15 a.m. on September 29, 1992, an afterburner assembly was being added to a gas curing oven to meet pollution requirements. Three employees and the lead operator were making the modifications. The oven's energy sources were not locked out during the three week project and there was no written lockout procedure for the oven. Employee #1 believed the oven was ready to operate, while other members of the modification crew were waiting for the manufacturer's representative to arrive and address some inconsistencies in the installation blueprints. Employee #1 attempted to cure a block of material coated with an alcohol resin solution and the oven exploded. Employee #1 sustained a cracked rib, a concussion, and lung irritation that led to pneumonia. The explosion may have occurred as a result of a sequencing problem between the oven and the afterburner, which led to the oven igniting prematurely. The oven was not equipped with explosion venting. The accident occurred at Aerocell, Inc. a Marysville company that manufactures a composite material used to fabricate interior panels in passenger aircraft.