What was found
DURING AN AVIONICS INSTALLATION EVENT WITH THE AIRCRAFTS' INTERIOR REMOVED IT WAS NOTED THAT THE FUSELAGES' UPPER CROWN SKIN, ABOUT THE CENTERLINE HAD BEEN PREVIOUSLY MODIFIED AT ONE TIME TO "BLANK OUT" A ANTENNA INSTALLATION NO LONGER IN USE. EXTREMELY POOR WORKMANSHIP AND NON STANDARD PRACTICES WERE EXHIBITED IN THE INSTALLATION OF TWO INTERNAL DOUBLERS, THAT INCLUDED LARGE HOLES CUT IN THE UPPER CENTERLINE STRINGER ABOUT BL 0.00 AT APPROX. FUSELAGE STATION 240.00. THE TWO HOLES CREATED SIGNIFICANT VOIDS IN THE "T"S' FLANGE, IN CONTACT WITH THE FUSELAGE SKIN, WHICH WERE UNREINFORCED.