As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FIRE ALARM AND LIGHT CAME ON WITH APU FIRE LEVEL 3 ALERT AT 12000 FEET DESCENT ONTO FINAL APPROACH PULLED APU FIRE HANDLE AND DISCHARGED FIRE BOTTLE LIGHT WENT OUT AFTER 30 SECONDS BLEED AIR NR 2 AND NR 2 PACK AUTO SHUT DOWN. APU COMPARTMENT INSPECTION REVEALED NO SIGNS OF FIRE OR HOT AIR LEAK. APU WAS NOT RUNNING DURING OCCURRENCE. MAINTENANCE REPLACED NR 2 FIRE EXTINGUISHER BOTTLE AND APU FIRE DETECT ELEMENT LOOP B.