Abstract: On June 2, 2012, an employee was working for a firm that manufactured extruded aluminum parts for the aerospace industry. Employee #1 was a fulltime permanent employee of the employer. Aluminum parts were being processed on the day of the incident. Hot aluminum extruded parts were quenched in a water solution that caused a small amount of deformation. To remove the deformation, parts were then stretched in a 150-ton (1,334-kilonewton) stretcher. One side of the stretcher was the live end, which did the pulling, and the other end was the dead end, which only held the end of the part being stretched. After quenching, parts were brittle, making them vulnerable to breaking or collapse. Because of that tendency, the portions of a part between the horizontal ends of the anchor were often supported by blocks, which had the dimensions 2.5 inches by 6 inches by 1 inch (64 millimeters by 152 millimeters by 25 millimeters). Such blocks were placed on either side and at both ends of a part, before it was placed into the jaws of the stretcher. Only the ends of parts were held within the machine. The middle sections of the parts were suspended between the ends of the machine. The entire operation was fully enclosed within a metal guard. The operator was required to stand behind an interlocked gate. On the day of the incident, employees were working on a part that had become more deformed than usual during quenching. The piece being stretched was 30 feet (9.1 meters) long. In cross section, the piece was shaped somewhat like an anchor, with a longer pointed horizontal end about 5 inches (127 millimeters) across, a shorter horizontal end 2 inches (51 millimeters) across, and a vertical length of 3 inches (76 millimeters). Two of Employees #1's coworkers made a decision to work around the deformation by placing the blocks away from the ends. The area around the jaws was enclosed by a metal box guard, and the area in front of the box, where the aluminum part was sticking out, had adjustable finger guards surrounding the piece being stretched. As the process of stretching began on a fully guarded stretcher, the live end of the machine began pulling. Suddenly a block shot out. It slid along a two inch (51 millimeter) or less opening within the aluminum part before flying out. It traveled a distance of approximately 20 feet (6.1 meters). The block then hit a transverse beam. It ricocheted off that into Employee #1, who was standing 40 feet (12.2 meters) from the point of operation. Employee #1 sustained a serious jaw fracture that necessitated surgery. The injury required hospitalization of more than 24 hours. During the incident, the entire end of the aluminum part was enclosed along with the jaws that held the piece. Accordingly, no violations were observed, and therefore no citations were issued. On June 3, 2012, the employer reported this serious injury in a timely manner to the Santa Ana District office of DOSH.