As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE WARNING LIGHT ILLUMINATED AND WARNING HORN SOUNDED DURING FLIGHT, PULLED FIRE HANDLE AND DISCHARGED FIRE BOTTLE. LIGHT EXTINGUISHED AND CIRCUIT CHECKED GOOD. REMOVED AND REPLACED APU FWD TAILPIPE FIRE DETECTOR AND HARNESS PER MM.