EMPLOYEE AND A CO-WORKER WERE SETTING TIMBERS IN THE #5 ENTRY. WHEN HE WALKED BACK TO THE SCOOP TO DISENGAGE THE PTA AND MOVE THE SCOOP OVER, A RIB ROLL 81""L X 16""W & UP TO 6"" THICK FELL STRIK ING HIS LOWER LEFT LEG AS HE WAS GETTING INTO THE OPERATOR'S DECK.