As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DTW - FLT 1374 - DURING DESCENT INTO DFW, APU FIRE WARNING FOLLOWED BY APU AUTO SHUTDOWN. DISCHARGED APU FIRE BOTTLE AND AIRCRAFT LANDED DTW WITHOUT INCIDENT. PLACARDED APU AND APU FIRE EXTINGUISHING SYSTEM. SUBSEQUENTLY, REPLACED APU AT ORD ON SAME DATE. REPLACED APU FIRE BOTTLE. ACCOMPLISHED LEAK AND SYSTEM GROUND CHECKS WITH NO DEFECTS FOUND. SYSTEM GROUND CHECKED NORMAL OPERATION. (X)