As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C-CHECK, APU FIREWALL CRACKED AT LOWER RT POSITION ON EXTERNAL SIDE. REPAIRED THE FIRWALL IAW SRM 53-32-13, FIG. 205. RESTORED THE APU FIREWALL VIBRATION REDUCER IAW TASK 53-32-01-300-801-A. THE ACFT WAS APPROVED FOR RETURN TO SERVICE.