This Air Force accident report has been professionally converted for accurate flowing-text e-book format reproduction. Contractor workers were performing structural repairs when a fire broke out on July 5, 2017 resulting in an estimated $30 million in damage to an air-mixing facility at the McKinley Climatic Laboratory, located at Eglin Air Force Base, Fla., according to a recently released Air Force Materiel Command Ground Accident Investigation Board report. The Fort Walton Beach-based Reliance Test & Technology performs Operations and Maintenance services for the McKinley Climatic Lab as a prime contractor with the United States Air Force. At the time of the incident, a subcontractor, Universal Fabricators, Inc., was replacing heavily corroded structural I-beams to one of the two Air Makeup Units, which mix and condition temperature and humidity of air, which is then blown into the McKinley Climatic Lab to perform tests on aircraft and various equipment. The report noted a contractor was using an oxy-acetylene torch to remove a corroded steel I-beam located in close proximity to coils which contained methylene chloride, commonly called R-30 refrigerant. Although stable at room temperature and pressure, R-30 can rupture or explode when exposed to heat.