As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN AVIONICS BAY STR 21L BACK-UP SILL CORRODED BETWEEN FS310.00 AND FS333.00 (C-CHECK RO 7/28/2021) REMOVED AND REPLACED STR 21L BETWEEN FS310 - FS333 BACK UP SILL. REF CRJ900 SRM 51-42-06-001-001-A01 AND DWG SH670-3810 REV AE. COMPLIED WITH TAS CARD 51-900-1002-SKY.