ROOF FALL WAS DISCOVERED DURING THE WEEKLY EXAMINATION OF THE RETURN AIR COURSE. TWO ROOF FALLS OCCURRED IN THE LAST OPEN CROSSCUT OF THE 3 RIGHT PANEL OF 2 RIGHT MAIN HEADINGS, MEASURING 20 F EET WIDE, 20 FEET LONG AND 42"" HIGH IN THE NUMBERS 2 AND 3 INTERSECTIONS. TIME THAT THE ROOF FALLS OCCURRED COULD NOT BE DETERMINED.