DURING WEEKLY EXAMS, AN AREA OF ROOF WAS DISCOVERED TO HAVE FALLED OUT BETWEEN RIB AND FIRST ROW OF BOLTS. APPROXIMATELY 3 TO 6 BOLTS WERE PULLED AND 7 TO 10 WERE SHEARED. THE AFFECTED AREA WA S APPROXIMATELY 26'LONG, 4 TO 6 FT WIDE X 4 TO 6'THICK. THE COMPANY DOES NOT BELIEVE THIS WAS REPORTABLE.