As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER REMOVING THE PASSENGER DOOR AFT FORMER FOR REPLACEMENT, FOUND THE THE INTERCOSTAL AT DD4 FROM FS338.96 TO FS347.25 TO BE CORRODED. (C-CHECK RO 8/29/2021) REMOVED AND REPLACED PAX DOOR INTERCOSTAL DD4 AT FS 338.96 - FS347.25 IAW CRJ 200 SRM 51-42-06, 51-42-21, AND 51-40-11. COMPLETED TASK CARD 51-900-1003-SKY AND ATTACHED COMPLETED FORM 337. NO WEIGHT CHANGE NOTED.