As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STL - AIR TURN BACK - FLT 454 - CREW REPORTED THAT THE RT F/O'S SLIDING WINDOW CRACKED DURING CLIMB. CREW RETURNED TO STL AND LANDED WITHOUT FURTHER EVENT. MAINTENANCE REMOVED AND REPLACED THE F/O'S SLIDING WINDOW IAW AIRBUS 319 AMM 56-12-11-400. VENDOR TEARDOWN IDENTIFIED A FRACTURED OUTER GLASS PLY. THE CAUSE OF THE FRACTURE WAS BEING STRUCE WITH A FOREIGN OBJECT (FOD). THE WINDOW WAS NOT REPAIRABLE AND WAS SCRAPPED