EE WAS REMOVING 3/4"" MOUNTING BOLT FROM BASE OF 150 HP MOTOR. A 1 1/8"" COMBINATION WRENCH WAS BEING USED. AS EMPLOYEE PUSHED WITH EXCESSIVE FORCE TO REMOVE BOLT, WRENCH SLIPPED CAUSING WRENCH TO HIT EE ON CHIN RESULTING IN LACERATION TO CHIN THAT REQUIRED SUTURES.