B777 Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 101; Flight Crew Total 24950; Flight Crew Type 15075
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport
Aircraft
Our flight was dispatched with a flaperon status message displayed. Maintenance disconnected 1 of 2 sensors and sent us on our way. About 35 minutes into the flight we felt a sharp jolt then an aircraft vibration which was significant. We checked all systems and found we had an Amber X on the right flaperon along with a 20 degree left yoke displacement.We had a complete system failure at that point. After the Captain conferred with Maintenance; dispatch and the crew it was mutually agreed upon not to continue the flight and return to ZZZ. None of the personnel contacted could give us information on how our fuel burn would be over a XA:06 min flight. Flying over [international] airspace with all these unknowns and the possibility of landing short was not a good decision; we returned to ZZZ where proper maintenance could be performed.
During briefing it was noted an inbound write-up 'FLAPERON ACTUATOR STATUS MESSAGE DISPLAYED.' Maintenance performed a procedure to disconnect a sensor prior to departure and sent a valid maintenance release. According to the Maintenance Personnel; this was the second incident with the issue during the airplane's last two legs.35 minutes after departure we felt a 'bump' and then experienced a slight airframe vibration. After about 10 minutes; the yoke displaced 20 degree to the left. We contacted dispatch/[Maintenance Control] and discussed the situation. We ended up with [Maintenance Control]; Dispatch; Chief Pilot; and Fleet Technical Manager on the line.While the Fleet Technical Manager did a satisfactory job explaining the situation; the question that could not be answered was what was the additional fuel burn we would experience in the next 13 hours with the additional drag produced by the drooping flaperon. The Chief Pilot and fleet technical solution was to continue and 'just see' how much fuel we burn; and if necessary land short of destination. This; along with a 'sick' airplane; flying over the most hostile environment we operate in; was not a good decision; and as a crew the decision was made to return to ZZZ.We dumped 90K of fuel per the checklist.
B777 flight crew reported the right flaperon malfunction during cruise resulted in a return to the departure airport.