What was found
WINDOW, LOCATED IN UPPER CABIN DOOR, WAS FOUND TO HAVE 4 CONSECUTIVE MOUNTING HOLES BROKEN ALONG LOWER EDGE. A RETAINING RING, CALLED OUT IN PARTS BOOK, WAS NOT INSTALLED ON THIS WINDOW. THE INSTALLATION APPEARS TO HAVE BEEN DONE AT THE FACTORY, DUE TO DATE ON WINDOW. NOTE: OTHER WINDOWS ON THIS AIRCRAFT USE RETAINING RINGS.