As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOTS REPORTED THE APU WAS MAKING A HIGH PITCHED UNUSUAL NOISE. INSPECTION REVEALED A PIECE OF ONE COMPRESSOR BLADE HAD BROKEN AND STRUCK SEVERAL OTHER BLADES. NO OTHER DAMAGE NOTED AT THIS TIME. APU IS BEING SENT TO A REPAIR FACILITY FOR FURTHER EVALUATION. CYCLES, 1,146.