Abstract: At approximately 8:15 a.m. on August 7, 2017, an employee was working by himself repairing a drive shaft universal joint with a C-clamp, socket for a socket wrench, a hex nut which had a smaller O.D. than the shaft yoke I.D., and a ball peen hammer. The employee was pressing a needle bearing cap in place into the shaft yoke a standard 12-inch C-clamp with a hex nut between the swivel end of the clamp and the bearing cap. The bearing cap was becoming difficult to press so the employee began tapping on the assembly with a ball peen hammer. The employee reported hearing a pop and his next memory was waking up on the concrete shop floor. The hex nut dislodged while under high pressure and was propelled through the air. The hex nut struck the employee in the forehead. The employee received a cut with a swollen knot to the forehead. He also lost consciousness. The employee was incoherent and had memory loss. The employee as hospitalized.