What was found
DURING PUSHBACK FROM THE GATE IT WAS OBSERVED THAT THE NR 4 TIRE WAS DEFLATED. FURTHER INVESTIGATION REVELED THAT 5 OF THE BOLTS JOINING THE WHEEL HALVES WERE SHEARED. THE BOLTS WERE BROKEN FLUSH WITH THE OTBD WHEEL HALF AT THE THREADS. THE O-RING WAS VISIBLE. ALL 5 FAILED BOLTS WERE FROM BENDING FATIGUE. CRACKS WOULD BE IN THE INTERMEDIATE FATIGUE RANGE WHICH MEANS STRESS WAS NOT NEAR THE YIELD POINT. BOLTS NR 1, 3 AND 4 HAD LARGER AREAS OF FATIGUE5. ALL BOLTS WERE BENDING FATIGUE IN NATURE.