As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUXILIARY POWER UNIT COMPARTMENT, RT BS 1125, VERTICAL STIFFENER IS CORRODED AT AFT END OF INLET CUTOUT. REMOVED CORRODED STIFFENER AND INSTALLED NEW VERTICAL STIFFENER AT STATION 1125 AT APU INLET IAW DWG 148A8650 AND AARD 51-10-05-1.