Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
On departure from ZZZZ during flap retraction we initially had the EICAS caution message Flaps Primary" which then turned to "Flaps Drive". We continued the climb to FL180 while accomplishing the initial flaps primary then the follow on flaps drive checklists. We informed ATC of our issue and restriction of FL200. I then turned control of the aircraft over to my Check Airman then contacted Dispatch. While on satellite phone the Pilot Flying to match the flap indication which caused a flap overspeed we changed flaps back to up which solve that problem. After conferring with Dispatch; Maintenance Control and the Chief Pilot. Collectively decided to divert to ZZZZ1. When in contact with Center asked for and received FL160 to stall margin versus flap overspeed margin. When in contact with ZZZZ1 we asked for and received permission to dump fuel to bring us closer to max landing (this was in consideration of the max tire speed) due to the speed additive of Vref flaps 30 + 25. After arriving in the ZZZZ1 area we were still too heavy to land and asked for delay vectors to burn down to max landing weight. When we were at weight when we asked for approach and landed without further incident. We could have initially asked for lower altitude to give better stall margin and flap overspeed protection. Dispatch initially suggested an overweight landing but due to tire speed limitation and the speed additive we decided the best course of action was to get the aircraft down to at least max landing weight."
Captain reported a diversion and fuel dumping due to trailing edge flap drive and position sensing/control failure.