As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE-N/A, LOWER AFT CARGO FIRE WARNING DURING CLIMB, BOTH FIRE BOTTLES DISCHARGED AS PER AOM. AIR TURNBACK TO SEL. REMOVED AND REPLACED NR 4 SMOKE DETECTOR IN AFT LWR CARGO COMP, OPS CHK NORMAL PER B747 M/M. REMOVED AND REPLACED BOTH FIRE BOTTLES IAW MM 26-23-01, OPS SQUIB AND PRESS SYSTEM CHECK GOOD.