B777-200
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Diverted; General Declared Emergency
Aircraft
At cruise 45 minutes into flight had a status message of 'overheat Circuit R 1 and Fire Loop 1 Eng R'. Sent Maintenance a message and continued. 2+30 into flight got EICAS message 'Det Fire Eng R'. Consulted with Maintenance and Operations and determined we had no fire detection on right engine. [We were] concerned due to time lapse between status message and EICAS message. [We] still had 4+30 enroute over sparsely populated area with few airports to divert to. Consulted with Duty Officer and determined safest course of action to divert to [a nearby airport] rather to continue with no fire detection on right engine. Upon landing stopped on taxiway and had fire and rescue inspect right engine after we shut it down to confirm no fire indication prior to entering ramp. [We] advised ATC reason to divert due to maintenance precaution.
B777 First Officer reported losing fire detection on right engine 2 1/2 hours into a long international flight. They elected to declare an emergency and divert to a nearby airport.