As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING MAINTENANCE BASE VISIT THE AUXILIARY POWER UNIT SHUNT ATTACHED TO FRAME 80 SHORTED CAUSING A BURNED HOLE THROUGH FRAME 80. THE AIRCRAFT WAS REMOVED FROM SERVICE. PERFORMED PERMANENT REPAIR TO REAR FUSELAGE FRAME 80 IAW EO EM-53MR-1745. THE AIRCRAFT WAS RETURNED TO SERVICE.