THE EMPLOYEE WAS INSTALLING SPLIT SET BOLTS. AS HE WAS DRIVING A BOLT, THE CHUCK RETAINER BOLT BROKE CAUSING THE BOLT DRIVER TO LEAVE THE DRILL. THE DRIVER HIT THE BACK AND WHEN IT CAME BACK D OWN, IT STRUCK HIS CHIN, CAUSING A LACERATION. HE WAS TAKEN TO THE E.R. FOR EVALUATION AND TREATMENT. THE LACERATION REQUIRED SUTURES TO CLOSE AND HE WAS RELEASED TO FULL DUTY.