EE WAS ASSISTING IN HELPING TO TRY TO TIGHTEN UP THE CONVEYOR TAIL PIECE WHEN THE WRENCH HE WAS USING TO HELP TENSION THE TAILPIECE BROKE, CAUSING A PORTION OF THE WRENCH TO FLY LOOSE AND STRI KING HIM ON THE RIGHT SIDE OF HIS FACE. CAUSE OF INJURY WAS AWARENESS COMPLIANCE WITH RULES AND REGS WAS NOT A FACTOR, PROTECTIVE ITEMS OR TRAINING NOT A FACTOR.