As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR TWO ENGINE FAILED UPON APPLICATION OF TAKEOFF POWER. LIBERATED ENGINE PARTS PENETRATED ENGINE CASE AND COWLING. THE BOLTS AT THE FIRST LPT DISK TO SECOND DISK ATTACH FLANGE WERE FOUND FAILED ALLOWING THE FIRST DISK TO RUB THROUGH THE LPT STATOR CASE. UAL REVISING PROCEDURES TO USE ONLY NEW BOLTS AND NUTS AT THE FLANGE JOINT AS A PRECAUTION.