What was found
DURING AN ANNUAL INSPECTION NOTED BULKHEAD WAS CRACKED IN THE FLANGE WHERE HOLES HAD BEEN DRILLED FOR A FACTORY ANTENNA INSTALLATION (ANTENNA STILL INSTALLED). NO DOUBLER WAS INSTALLED AT THE FACTORY, AND WASHERS USED UNDER THE SECURING HARDWARE WERE NOT RADIUSED TO MATCH THE BEND RADIUS OF THE BULKHEAD. A CALL TO THE FACTORY REVEALED MOST AIRCRAFT OF THIS SERIES DID NOT RECEIVE DOUBLERS UNDER THE ANTENNAS, AND THIS IS A STANDARD FACTORY INSTALLATION.