As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
"AWR: HIDDEN DAMAGE ; AFTER REMOVE INSULATION ON MAIN AVIONICS COMPARTMENT, CORROSION ON INTERCOSTAL AT STGR 21L AND FS310/319 WAS FOUND IN REF EO: R25120 (SM) [E/E]. "SUMMARY:INTERCOSTAL AT STGR 21L AND FS310/319 WAS REPLACED PER CRJ 900 SRM 51-42-06-001-001-A01 AND 51-42-21-001-001-A01 "