UNINTENTIONAL ROOF FALL WAS DISCOVERED BY PRESHIFT EXAMINER IN #4 ENTRY, #6 X-C OF LEFT CONNECTION FROM 1ST NORTH TO 1ST NORTH SUBMAINS. FALL IS APPROX. 30'L X 18'WIDE, DOMED. FALL HAS NOT IMPEDED TRAVEL, VENTILATION OR ESCAPEWAYS. AREA WAS BOLTED W/5' RESIN BOLTS PRIOR TO CHANGE IN OPERATOR'S ROOF PLAN TO 6' RESIN BOLTS. AREA WAS TIMBERED & DANGERED OFF.