As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAINTENANCE REPORTED THE APU INOPERATIVE/OVERSPEED SHUTDOWN. LOUD BANG HEARD AFTER RUNNING. MAINTENANCE FOUND APU TURBINE WHEEL SEPARATION/UNCONTAINED FAILURE. REMOVED AND REPLACED APU ASSEMBLY PER J/C 03L70349004. ALSO, ACCOMPLISHED APU TURBINE WHEEL SEPARATION INSPECTION PER AMM 05-51-40-212-001 AND REPLACED APU EXHAUST MUFFLER PER AMM 49-81-11-4 DUE TO SEVERAL HOLES IN LINER. APU LEAK CHECK AND OPS CHECK OK.