What was found
(CAN) FORWARD LT WINDOW SLIDER DEPARTED WHILE AIRCRAFT IN FLIGHT. THE FELT ON THE SLIDER WINDOW WAS WORN OR MISSING, WHICH CAUSES AN EXCESSIVE GAP BETWEEN THE SLIDER WINDOW AND THE TRACK. THE SLIDER WINDOW, NOW LOOSE, VIBRATES WHILE IN FLIGHT AND CAUSES THE LOWER PORTION OF THE SLIDER WINDOW TRACK TO FRACTURE. THE SLIDER WINDOW MIGRATES OUT THROUGH THE CRACKED TRACK AND DEPARTS THE AIRCRAFT.