As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU BAY CUTOUT LEFT LOWER FRAME APPEARS TO BE CORRODED STARTING AT STA 1156 FORWARD BULKHEAD TOWARDS AFT. INSTALLED NEW ANGLE ASSY ON APU BAY CUTOUT LEFT SIDE IAW B737-800 SRM 51-40-02-0G PAR.4 AND 7. REMOVED AND REPLACED L/H LOWER FRAME (ANGLE ASSY) ON APU BAY CUTOUT IAW SRM 51-40-02-0G.