As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE BELL AND INDICATION CAME ON 3-6 MINUTES AFTER APU WAS SHUTDOWN AND TAKEOFF OUT OF PIT. CREW DISCHARGED APU FIRE EXTINGUISHER BOTTLE AND RETURNED TO PIT. NO VISIBLE SIGNS OF SOOT, FIRE OR BURNING FOUND. ALL SYSTEMS OPS GOOD. MAINTENANCE ELECTED TO REPLACE FIRE SENSE LOOP AND FIRE DETECTION UNIT. (M)