B777 Undifferentiated or Other Model
Flight Crew Last 90 Days 210; Flight Crew Total 12000; Flight Crew Type 3000
Human-Machine Interface
Aircraft Equipment Problem Critical
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Gate; General Flight Cancelled / Delayed
Aircraft
Dispatched with fire loop 1 ENG R and overheat circuit R1 deferred. On taxi out; we got EICAS 'Det Fire Right Engine' with a status message that read 'overheat circuit R2 and fire loop 2 ENG R'. After talking to ground about our issue they directed us to the holding pad. On our way there; we decided to shut down the right engine since it appeared that we had no fire detection on that engine. As I'm about to reach down to go to cut off; the fire warning sounded along with all the lights associated with Engine fire right (we also got the EICAS). We proceeded to do the checklist and advised ATC to 'roll the equipment'. The fire bell and lights were intermittent but we went ahead and fired both bottles. The relief First Officer went back to the cabin and along with the fire department confirmed that there was no fire. We were towed back to the gate; along the way the fire bell went off intermittently. The fire lights on the fire handle and the engine cut off switch never did go off. When Maintenance came to the cockpit the fire lights were still on.
During taxi out to runway; an ENG (R) FIRE DET EICAS illuminated. While coordinating with ATC and Dispatch for return to blocks the engine fire warning aural alert sounded along with red fire lights. Crew accomplished the required checklist to include releasing both fire bottles to the right engine. Visible confirmation from both crew and fire fighters confirmed no fire was present. Aircraft was towed to the gate.
B777 flight crew reports being dispatched with one fire loop on the right engine deferred. During taxi out the EICAS annunciates the failure of the second loop followed shortly by fire warning. Although thought to be false; both fire bottles are discharged and the aircraft is eventually towed to the gate.