What was found
DURING A SCHEDULED INSPECTION, FOUND THE AIR DATA COMPUTER (ADC) BROKE LOOSE FROM ITS MOUNT. UPON FURTHER INVESTIGATION FOUND THE MOUNTING BRACKET FLANGE CRACKED COMPLETELY OFF THE AIRFRAME STRUCTURE IT WAS RIVETED TO. AFTER REMOVAL OF THE BRACKET, AND FURTHER INSPECTION, IT IS BELIEVED THAT THE FLANGE WAS NOT MANUFACTURED WITH THE PROPER RADIUSES IN THE CUTOUT FOR THE THUMBNAIL SCREW CAUSING IT TO CRACK. VIBRATION FROM GENERAL AIRCRAFT OPERATION CONTRIBUTED TO THE ISSUE. THIS ADC WAS INSTALLED AS PART OF THE STC NR SA02203AK EFIS-SV SYSTEM IN APRIL OF 2004.