As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HIDDEN CORROSION IN REF NRC S/N 00189, DURING INTERCOSTAL REMOVAL, CORROSION ON 21R STRINGER FS 280 TO 333 WAS FOUND. STRINGER 21R BTW FS280/FS333 WAS REPLACED FOR A NEW ONE (P/N: SH670-31636-1) PER CRJ-900 SRM 51-42-06-001-001-A01. (LEVEL CORROSION 2)