Date: 201709
Local time of day: 0601-1200
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
ATC / advisory: Center ZZZZ
Aircraft component: Fire Protection System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Human factors: Troubleshooting; Communication Breakdown
Second reporter function: Relief Pilot
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed
Contributing factors: Company Policy; Procedure; Aircraft
Primary problem: Aircraft

Narrative: On the initial climb out of ZZZZ the upper EICAS had the advisory 'DET FIRE ENG L'; which lasted for approximately 3 minutes. After contacting Dispatch/Maintenance Control we had two lower EICAS status messages: 'Overheat Circuit L2 ' and 'Fire Loop 2 Eng L' which appeared for about 1 minute (Additionally the left engine vibration system was previously deferred inop). We referred to flight manual guidance which only advised that fire and overheat detection was inop. At best we had intermittent fire/overheat detection on the left engine with no guidance in the event of total system failure.After discussing the messages with Maintenance Control/Dispatch; Operations Manager; crew and I decided that the fire detection on the left engine was possibly intermittent and as such; undependable. If we had gone oceanic and the messages reappeared; or new messages concerning the fire detection system appeared I would consider the system undependable and unable to detect an engine fire - making a divert to the closest alternate necessary. After relating this to Maintenance Control/Operations Manager/Dispatch I was told that it would be preferable to divert to ZZZZ2 where there was a 'fire card' that could fix the issue. We coordinated with Center and turned towards ZZZZ2 after dumping 45;000 lbs. of fuel. Subsequently Dispatch contacted us and through satcom communications and told us that a 'company' NOTAM prohibited us from going to ZZZZ2 unless we declared an emergency. We requested Center to ask ZZZZ2 if we could land at ZZZZ2 without declaring an emergency. The answer was yes. Despite being allowed to land at ZZZZ2; Dispatch refused to release us. Instead Dispatch directed us to go to ZZZZ [our departure airport]- to go to ZZZZ2 we would need to declare an emergency. We assumed that all involved in the satcom discussion (Operations Manager; Maintenance Control; Dispatch) were in agreement or that they saw ZZZZ as a better divert for the passengers. After the decision to divert to ZZZZ we sent messages to ZZZZ ops and the Operations Manager. It later came to our attention that ZZZZ had not been advised until just before our return to ZZZZ. We also learned that Maintenance Control and Dispatch had not advised ZZZZ of the divert change (ZZZZ2 to ZZZZ). We also were told that Maintenance Control had a shift change and did not relay the diversion change to ZZZZ.I was surprised that an entire engine fire/overheat detection system could be inop and no guidance given! Also; that the APU fire detection also ran through this card - I assume this would mean that in the event of a card failure that the APU would not start- another system/redundancy unavailable! Why is there no guidance of what to do if the fire detection system is inop? Is it expected that someone would sit by a window and watch the engine for flames the entire flight. The company NOTAM for ZZZZ2: if ZZZZ2 rescinds the requirement of declaring an emergency to be able to divert into ZZZZ2 is that flight in violation of the NOTAM?  Was Dispatch correct in refusing to release us to ZZZZ2?


Second narrative: I was the IRO (International Relief Officer) for this flight. The Captain was flying this leg. Just after liftoff; a DET FIRE ENG L Advisory message appeared on EICAS (Engine Indicating & Alert System) and remained on for approximately 3 minutes. Automated reports were sent by the aircraft to Maintenance Control. The Captain continued flying until the aircraft was cleaned up and at a safe altitude and then passed aircraft control and radio communication to the First Officer. We continued climbing on our flight planned route. After ensuring we were safely airborne I looked up the malfunction in the Flight Manual; the MEL; and log history (of which we had none in the last 14 days) and presented this information to the Captain. The Captain then directed me to establish a SATCOM phone patch with Dispatch and Maintenance Control. As the phone patch was being set up; two STATUS messages appeared: FIRE LOOP 2 ENG L and OVERHEAT CIRCUIT L2. These messages stayed active for a few minutes. Discussing the situation as a crew we concluded that we first lost all fire and overheat detection on the left engine and then subsequently; lost fire and overhead detection on loop 2 for the left engine. The system appeared to return to normal operation; but had proven itself unreliable.Once the phone patch was connected; I explained our indications to Maintenance Control. Unfamiliar with the system; he looked to the flight manual. The manual gives no guidance except to confirm that the fire detect system was inoperative; at least temporarily. At first Maintenance Control recommended that since the flight manual gave no guidance we should continue to destination. I explained that we were about to cross the Atlantic and didn't want to lose all fire detection over the ocean and needed more information. Also; the aircraft already had a deferred Vibration Meter on the left engine. Maintenance Control then conferred with someone in his office; I assume a systems expert. They eventually determined both loops of the left engine detect system go through the same 'card'. The Captain who had been listening to my conversation came on the line and discussed the situation with Maintenance Control. I believe it was Maintenance Control who then recommended the Operations Manager be consulted. The Operations Manager and the Captain discussed the situation and the Operations Manager seemed to agree that crossing the Atlantic with a possible faulty fire detection system was not the best idea and he would support the Captain's decision. The Captain pointed out that if he did start the crossing and the Advisory appeared again; he would divert; probably to Keflavik or another alternate. Maintenance Control stated that he would rather we take the aircraft to ZZZZ2 now; where he knew there was a replacement 'card'; than take the aircraft to an ETOPS (Extended-Range Twin Engine Operational Performance Standards) alternate. The Captain made the decision to go to ZZZZ2 and everyone on the conference call agreed. Just as the conference was concluding; Dispatch did state that there was a company NOTAM which stated that aircraft diverting ZZZZ2 should declare an emergency and we may need to do that. After the call was concluded; the Captain decided that since we were planning a normal landing; declaring an emergency was unnecessary. As we were dumping fuel and then heading toward ZZZZ2 he coordinated with ATC and got permission to land at ZZZZ2 without declaring an emergency. They would take us.When we were about 30 minutes from ZZZZ2; Dispatch sent us a SELCAL. He stated that he would not release us to ZZZZ2 because of the company NOTAM. I believe the Captain told him he had permission; but Dispatch insisted we return to ZZZZ instead and sent us a flight plan. Enroute to ZZZZ; the Captain sent an ACARS to the Station and Operations Manager stating our new destination. On arrival in ZZZZ; the Station was surprised and distressed that we had returned. They were not consulted. They did not have hotel rooms for everyone and could not fix our problem. Our duty day expired waiting for the part to arrive from ZZZZ2. If we had proceeded to ZZZZ; I believe we could have been repaired and continued the flight to destination within our duty day. Instead; the flight was canceled.


Synopsis: B777 flight crew reported managing a defective fire detection system on one engine after takeoff and the subsequent problems that occurred after the divert.