What was found
PILOT REPORTED THEY DEPARTED KSNA AT 1501Z ON 10/23/2025. DESTINATION WAS KADS. WEATHER WAS NOT A FACTOR. FLIGHT WAS UNEVENTFUL UNTIL INITIAL CLIMB. APPROXIMATELY 15 MIN AFTER TAKEOFF, DURING AN INTERMEDIATE LEVEL OFF AT FL270 AND MACH 0.78, THEY HEARD A VERY LOUD “BOOM” NOISE AND NOTICED THE LEFT COCKPIT SIDE WINDOW WAS SHATTERED. IT WAS DIFFICULT TO DETERMINE WHICH WINDOW PANE WAS AFFECTED. THEY REFERENCED THE QRH AND FOLLOWED THE “CRACKED WINDOW” PROCEDURE AND RETURNED TO KSNA. DESCENT, APPROACH, LANDING, AND TAXI IN WERE UNEVENTFUL. MAINTENANCE IDENTIFIED THE CENTER HEATED PANE SHATTERED AND NOT THE INTERIOR OR EXTERIOR GLASS PANES AND THAT THIS IS THE ORIGINAL SIDE WINDOW ON THE PILOT SIDE.