B747-400
Flight Crew Air Transport Pilot (ATP)
Troubleshooting
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
Immediately after takeoff; we received a Master Warning for Cargo Fire Aft. We knew there was much condensation prior to the flight and used the [company advisories] to mitigate. We proceeded with the QRH items and the warning ceased. Approximately 2 minutes later we received the Master Warning and Cargo Fire Aft message again followed by a new message Fire Warning Main Deck. When we pulled up the status page there was indications of multiple Cargo Loops failed. I made the decision to return and have the fire trucks meet us. All QRH items were followed but no depressurization. Upon landing I had the fire department clear the airplane and then Maintenance proceeded to deal with the issues.[Company advisories] for this aircraft had been followed and maintenance ended up replacing 4 detectors.
[Report narrative contained no additional information.]
During climb in a B747 cargo plane; the crew received a master warning for cargo fire.