A ROOF FALL WAS DISCOVERED IN AN INTERSECTION OF #7 ENTRY AT SPAD #4147 IN THE PRIMARY ESCAPEWAY ON THE 4 BELT MAINS PANEL.THE FALL WAS APPROXIMATELY 7' IN HEIGHT, 19' IN WIDTH AND 20' IN LENGTH. ALL APPROACHES WERE DANGERED OFF,TIMBERS SET, CRIBS BUILT AND STEEL JACKS SET. NO EMPLOYEES WERE INJURED, NO EQUIPMENT INVOLVED. VENTILATION WAS NOT AFFECTED. THE LIFELINE WAS RE-ROUTED.