Narrative:

We were close at fl 380 in smooth air when we felt the aircraft bank to the right quite rapidly. We thought we were entering an area of turbulence so the captain turned on the fasten seat belt sign. A few moments later we had an EICAS 'spoilers'. The captain ask me to run the appropriate checklist 'spoilers.'after finishing the spoilers checklist we pulled up the flight controls synoptic page and noticed that the #10 spoiler had failed. We could also feel an airframe buffet and noticed a slight right wing down per the sky pointer and left rudder deflection of about 2.5 deg left.the captain woke up one of the international relief officer's and subsequently had the international relief officer look out the window in the cabin and report back. The international relief officer informed us that the #10 spoiler was indeed not stowed. The captain then woke up the other international relief officer. Once the non-normal checklist was complete and the situation stabilized we contacted dispatch along with a patch to [maintenance control]. [Maintenance] ran an airplane diagnostic and informed us that a circuit breaker had tripped and no solution could be attempted to reconcile the situation and get the #10 spoiler back. Dispatch along with the [operations] and [maintenance] suggested that we could continue to [the destination] where an attempted fix or deferral could be made.at this point as a complete crew we once again reviewed the non-normal 'spoiler' checklist to bring up to speed the international relief officer's regarding that checklist.it was clear that we would have to divert so as a crew we referenced the 'diversion planning guide' for guidance. We also referenced the 'emergencies/non-normal' section in the fom. As a crew we now entered into discussion as to where to divert. ZZZ was discussed as recommended by dispatch. However; all four of us crew members felt very uncomfortable with continuing in airspace [further north] as diversion options become more challenging and possibly less safe.there was also an increase in fuel burn because of the drag created by our flight control issue. Dispatch and [maintenance] were not able to give us a fuel burn analysis with the #10 spoiler deployed. As a crew we all agreed a turn back was the safest option. Not knowing what caused a circuit breaker to open and cause a flight control to fail caught our attention and a turn back with lots of diversion airport options was the safest and most logical conclusion.taken all input from dispatch; [maintenance]; [operations]; diversion guide; emergency/non-normal chapter; weather and pilot crew member input; the captain with the support of all pilot crew members made the decision to divert to ZZZ1.as a crew we felt that this was the safest plan while considering the needs of the company to recover the operation with the capabilities of ZZZ1. A normal approach and landing was made in ZZZ1. We landed with approx. 40.0 pounds of fuel. We had approx. 7.0 pounds over burn from the revised flight plan showing the diversion. We credit this do to the increased drag from the flight control failure.

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Original NASA ASRS Text

Title: B787 pilot reported experiencing an un-commanded roll due to a malfunctioning spoiler system. After a discussion with crew members; Dispatch; and Maintenance; a decision was made to divert to a suitable airport; where a successful landing was accomplished.

Narrative: We were close at FL 380 in smooth air when we felt the aircraft bank to the right quite rapidly. We thought we were entering an area of turbulence so the Captain turned on the Fasten Seat Belt sign. A few moments later we had an EICAS 'Spoilers'. The Captain ask me to run the appropriate checklist 'Spoilers.'After finishing the Spoilers checklist we pulled up the Flight Controls synoptic page and noticed that the #10 spoiler had failed. We could also feel an airframe buffet and noticed a slight right wing down per the sky pointer and Left rudder deflection of about 2.5 deg Left.The Captain woke up one of the IRO's and subsequently had the IRO look out the window in the cabin and report back. The IRO informed us that the #10 spoiler was indeed not stowed. The Captain then woke up the other IRO. Once the non-normal checklist was complete and the situation stabilized we contacted Dispatch along with a patch to [maintenance control]. [Maintenance] ran an airplane diagnostic and informed us that a circuit breaker had tripped and no solution could be attempted to reconcile the situation and get the #10 spoiler back. Dispatch along with the [operations] and [maintenance] suggested that we could continue to [the destination] where an attempted fix or deferral could be made.At this point as a complete crew we once again reviewed the non-normal 'Spoiler' checklist to bring up to speed the IRO's regarding that checklist.It was clear that we would have to divert so as a crew we referenced the 'Diversion Planning Guide' for guidance. We also referenced the 'Emergencies/Non-Normal' section in the FOM. As a crew we now entered into discussion as to where to divert. ZZZ was discussed as recommended by Dispatch. However; all four of us crew members felt very uncomfortable with continuing in airspace [further North] as diversion options become more challenging and possibly less safe.There was also an increase in fuel burn because of the drag created by our flight control issue. Dispatch and [maintenance] were not able to give us a fuel burn analysis with the #10 spoiler deployed. As a crew we all agreed a turn back was the safest option. Not knowing what caused a circuit breaker to open and cause a flight control to fail caught our attention and a turn back with lots of diversion airport options was the safest and most logical conclusion.Taken all input from Dispatch; [maintenance]; [operations]; Diversion Guide; Emergency/Non-Normal chapter; Weather and Pilot Crew member input; the Captain with the support of all pilot Crew Members made the decision to divert to ZZZ1.As a crew we felt that this was the safest plan while considering the needs of the company to recover the operation with the capabilities of ZZZ1. A normal approach and landing was made in ZZZ1. We landed with approx. 40.0 pounds of fuel. We had approx. 7.0 pounds over burn from the revised flight plan showing the diversion. We credit this do to the increased drag from the flight control failure.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.