Abstract: At approximately 4:30 p.m. on December 22, 2007, Employee #1, a company employee responsible for checking the furnaces, and Employee #2, a contractor's employee who also checked furnaces and who was training Employee #1, were initiating a fluid transfer of quench oil from the Shallow Case department to a holding tank in the Triple Holding area. The piping containing the quench oil was under pressure throughout the plant. A bypass valve at the Planet Gear Heat Treat Furnaces was incorrectly opened after the fluid transfer, causing the Planet Gear quench oil holding tank and the Plant Gear Heat Treat Furnaces to overfill. Planet Gear Furnace Number 1 was in process and Planet Gear Furnace Number 2 was in a "burnout" procedure to recondition the furnace for normal process. Quench oil from the overfilled holding tank entered Planet Gear Furnace Number 2 and a fire ignited in Building KK, Transmission Business Unit (TBU) of the company. The fire suppression system in Planet Gear Furnace Number 2 released and triggered an alarm. Employee #3 and Employee #4 were responsible for plant security and responded to the fire with fire extinguishers. At some point, a fire ignited in Planet Gear Furnace Number 1. Employee #5 was responsible for maintenance and responded to a high oil level alarm from the Planet Gear Furnace oil holding tank. Employee #1 and Employee #2 returned to the Planet Gear Furnace Number 2 to turn off the flow of oil and assist in rendering the furnaces to a safe mode. A small explosion occurred in the furnaces resulting in burns to Employee #2, Employee #3, and Employee #4. The fire department was summoned and Employee #2, Employee #3, Employee #4, and Employee #5 were taken to the hospital. Employee #5 was treated for smoke inhalation and released. Employee #2, Employee #3, and Employee #4 were admitted to the hospital for burn injuries. Employee #2 was released within days and Employee #3 and Employee #4 were transferred to a burn unit in another hospital. Employee #3 and Employee #4 were released several days later. Employee #1 sustained no injuries.