B777 Undifferentiated or Other Model
Flight Crew Total 12018; Flight Crew Type 7798
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport
Aircraft
We were climbing out and I was sitting up front awaiting another pilot to return from using the lavatory before starting my break. Climbing through FL250; I noticed the left generator OFF and DRIVE lights both on simultaneously. [The other pilot] and I performed the electronic checklist which included starting the APU and we both decided to continue towards [destination]. Leveling at FL320; I looked up and now saw the right generator OFF and DRIVE lights on simultaneously. We performed the checklist and this time; with 2 main generators inoperative and their drives disconnected per the checklist; we elected to return to jettison fuel and return to [departure airport]. Jettison was performed and [we] landed without incident. No emergency was declared and no special handling was requested. Upon landing; the mechanics pulled up the Electrical Page in the Maintenance Log and found that the left GENERATOR Oil level showed 'Service' and the right GENERATOR Oil level showed 'Normal'. Further; the Left GENERATOR Filter showed 'Blocked'. The Right GENERATOR Filter also showed 'Blocked'.
A B777 Captain reported returning to their international departure airport after losing both main generators in flight.