Abstract: Employee #1, a service technician, was assisting a customer to attach a reamer to the end of a Horizontal Directional Earth Drilling machine by using a pipe wrench to hold the connection. Employee #1 then instructed the machine operator use the power of the machine to rotate the drill. The pipe wrench was lodged against a dirt embankment with a 4-in. by 4-in. wood block to absorb the torque of the drill twist. Employee #1 had hoisted the reamer approximately 6-in. above the ground with a lifting device. Employee #1 was struck in the back of the head, when the pipe wrench, under extreme torque, slipped and spun around. Employee #1's jaw was broken as his face struck the ground. Employee #1 received severe head, ear, and jaw injuries and was hospitalized.