AN UNINTENTIONAL ROOF FALL OCCURRED IN THE 4 WAY INTERSECTIONAL ENTRY 27 & 50 PT. THE 2ND MAIN EAST. THE FALL 30' LONG 20' WIDE AND 6' THICK, DID NOT OF IMPREDE TRAVEL BUT DID AFFECT VENTILATI ON IN THE RETURN AIRQUISE. THE STEPPING LINE IS BEING MOVED OVER TO RESTABLISH A GOOD RETURN AIRCOURSE, THE TOP WAS SUPPORTED BY 4 BLUE AND 6' POSBLOCK BOLTS AND CRIBBED OFF. DEVOLPMENT RATE