As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THIRTY MINUTES INTO FLIGHT, AT FL350, APU FIRE DETECTOR INOPERATIVE LIGHT ILLUMINATED. WENT OUT 30 SECONDS LATER. FAULT COMFIRMED. PERFORMED APU/ENGINE FIRE DETECT MODULE BITE. FOUND APU TAIL DETECTOR INOPERATIVE. REMOVED APU TAIL DETECTOR 26-15-01-000-801. INSTALLED ELEMENT 26-15-01-400-801. PERFORMED OPS CHECKED APU DETECTOR 26-15-00. SYS CHECKED NORMAL.