Discovered a roof fall in 1 nw butt when doing weekly air course run. Fall was in #2 entry 2 X-cuts inby spad #173, extending about halfway into the intersection. Fall was about 40' long by 18' wide and 4-7' high. The area was bolted with 4' fully grouted resin bolts. The area was dangered off with two rows of posts and danger signs and all sides.