As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKOFF, NR 3 ENGINE B FAULT DETECTOR LIGHT CAME ON. COMPLIED WITH POM, APPROXIMATELY 15 MINUTES LATER B-LOOP ILLUMINATED, SHUTDOWN ENGINE AND DISCHARGED BOTH BOTTLES. INDICATION REMAINED UNTIL SHUTDOWN AT GATE. FOUND LOWER FIRE DETECTOR LOOP SHORTED. REPLACED LOOP ASSEMBLY AND BOTTLES.