EE WAS USING AN IMPACT WRENCH TO REMOVE BOLTS. THE SOCKET IS SECURED TO THE WRENCH WITH A PIN AND O-RING TO KEEP IT IN POSITION. THE O-RING SLIPPED OFF CAUSING THE PIN TO BE EXPOSED, CAUSING A LACERATION ON THE PALM OF HIS LEFT HAND. THE LACERATION REQUIRED STITCHES AND PLACED ON MODIFIED DUTY.