As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SCHEDULED HEAVY MX WAS BEING PERFORMED ENGINE. DURING SEPARATION OF THE STAGE 1 AND 2 HIGH PRESSURE TURBINE DISKS, ONE RETAINING STUDS WAS HEARD TO UNSEAT AND FALL ONTO THE STAGE 2 DISK. WHEN THE 2 DISKS WERE SEPARATED, THE NUT WAS EVALUATED AND WITNESS MARKS ON THE NUT-THREADS INDICATED THAT ONLY ONE THREAD WAS RETAINING ON THE THE STUD.