As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CORROSION ON FRAME GROUNDS GS1839 AND GS1841 EXTENDS ON FRAME BETWEEN FS 319.70 TO FS 333.00 LOCATED AT LEFT STRINGER 21. (C-CHECK RO 8/19/2021) REMOVED AND REPLACED CORRODED INTERCOSTAL/BACK-UP SILL AT STR21L BETWEEN FS319.70 TO FS333.00 IAW CRJ700 SRM 51-21-06, 51-42-06 AND 51-40-11. NO FURTHER ACTION REQUIRED AT THIS TIME.