Date: 201508
Local time of day: 1801-2400
Location: ZZZZ.ARTCC, FO
Flight conditions: VMC
Aircraft: Widebody; Low Wing; 3 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Cruise
Airspace: Class C ZZZ
ATC / advisory: Center ZZZZ; Tower ZZZ
Aircraft component: Fire Protection System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Inflight Shutdown
Contributing factors: Aircraft; Company Policy
Primary problem: Aircraft

Narrative: At cruise altitude of FL350; received an engine fire warning on the number three engine. One of the two fire loops for the number three engine was already deferred and on MEL. Engine was shutdown according to procedures and all QRH items accomplished.We [advised] Center and initiated a descent to FL250 in accordance with performance on two engines. The decision was made to divert based on the current weather and proximity of the airfield. Clearance was received to proceed direct to the field.While descending; engine number one was indicating intermittent failure of one of its fire loops without any other indications. This intermittent failure was also written up on the previous flight (same crew) on the flight the day before.With calm winds; we received vectors for an immediate visual and coordinated with tower to clear the runway and meet the crash/fire team to inspect the number three engine.Captain; assumed control of the aircraft on final and landed.Upon clearing the runway and setting the parking brake; we accomplished the After Landing checklist and coordinated with crash/fire to inspect the aircraft. It was at that time that we received a 'Cabin Smoke' alert indicating smoke in the rear of the aircraft.The decision was made to immediately exit the aircraft. Crash/Fire was advised of the indicated smoke in the rear of the aircraft along with the decision to evacuate. We ran the evacuation checklist and then exited the aircraft via the escape slide on the left side of the aircraft.Upon initial inspection from the crash/fire team; no external indications of a fire were perceived on the number three engine.Upon initial inspection from the crash/fire team; no indications of fire were perceived from inside the aircraft in the aft section of the main deck cargo area or via thermal imaging of the aircraft hull in the rear section.All issues were written up in the aircraft AML along with the repeat write up for the intermittent Loop 'A' failure on engine number one during the descent to the divert field.The fire detection system for number three engine was already written up and one loop placed on MEL. The fire detection system for number one engine Loop 'A' was a repeat write up. The Cabin Smoke indication in the rear of the aircraft was a new write up. No further indication of fire was noted upon inspection. Unsure if and how all three items are interrelated but a thorough inspection and test of the Fire/Smoke system should be accomplished.


Second narrative: Inbound to ZZZ VOR at FL350 got intermittent then steady Engine #3 Fire indication. Accomplished QRH; shutdown engine and started drift down. [Advised] Center. Destination airport not considered suitable; FO (PF) suggested ZZZ which was closer; less congested and had good weather. Uneventful engine out landing (Captain-PF). Turned off on taxiway N to let fire department check out # 3. While waiting got intermittent LVL 3 CABIN SMOKE alert with activated sensor in aft main deck and elected to evacuate aircraft. Upon going into courier area noted smoke/mist. Uneventful evacuation. Fire department found no fire (engine or freight). #3 engine fire indication (operating with Loop B - Loop A MELed).


Synopsis: Flight crew reported being dispatched with loop A of the number three engine fire detection system on MEL. At cruise altitude a fire warning was annunciated on the number three engine and it was shut down. Flight diverted to a suitable airport for an uneventful landing. After landing a cabin smoke alert was activated and the crew elected to evacuate the aircraft. No evidence of fire was found on the engine or in the cabin.