What was found
THE AIR CONDITIONING SYSTEM WAS INSTALLED ON THE AIRCRAFT UNDER STC SH3509SW. DURING AN INSPECTION, THE AIR CONDITIONER CIRCUIT BREAKER WAS POPPED. THE CIRCUIT BREAKER WAS RESET AND THE SYSTEM FUNCTIONALY TESTED. SPARKS WERE SEEN AT THE BACK OF THE FAN ASSEMBLY. ON DISASSEMBLY, FOUND ONE RETAINING SCREW HAD LOOSENED ENOUGH TO CONTACT THE ARMATURE AND WORE OVER HALF THROUGH WHILE SPINNING AND HAD LODGED IN THE ARMATURE TO NOT ALLOW THE ARMATURE TO SPIN.