Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft
A little over 6 hours into flight a hot electrical smell suddenly occurred in the cabin (mainly forward cabin). The pilots on break; flight attendants; and passengers were aware of the problem. We received a call to the cockpit and told of the situation while the crew began investigating the source and shutting down electrical systems. In the cockpit we checked weather for alternates and started Smoke and Fumes Checklist. The associated smoke and smell began to dissipate. Entire crew convened in the cockpit; checklists were completed. The company notified. Maintenance Control; through onboard telemetry; notified us that a recirc fan was indicating a problem. The recirc fans were secured when we accomplished the Smoke and Fumes Checklist.  An uneventful precautionary landing was made. Approximately 65;000 LBS fuel dumped in order to land below 460;000 gross weight (we landed at 458;000 LBS). ATC was notified of start and stop dump times. An emergency was not officially declared however once we asked for altitude relief on the STAR in order to stay as high as possible during dumping ATC began to refer to us as an emergency aircraft and ask us for souls on board. Passengers remained on board after landing. Aircraft was redispatched on MEL for recirc fan and flight completed.
Takeoff plus 5 hours; cabin crew detected a hot electrical smell along with a haze in the cabin around Business Class. Captain returned to cockpit and flight crew accomplished the Smoke; Fire or Fumes Checklist from the QRH. After turning off the RECIRC FANS switches per checklist fumes started to dissipate. Finished the checklist and Captain decided to divert to [an airport] which was about an hour away. Flight crew concurred. Contacted Dispatch to coordinate our diversion and contacted ATC for fuel dumping and diversion. Dumped fuel to below maximum landing weight (460;000 LBS) and First Officer made the landing. Maintenance determined cause was overheating RECIRC fan.
B777 flight crew and flight attendants detect smoke five hours into a flight to Asia. QRH procedures are complied with; the likely source (a recirculation fan) is determined and the flight diverts to a suitable airport after dumping fuel down to maximum landing weight. The fan failure is confirmed and the flight continues to destination with the fan on MEL.