B787 Dreamliner Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Total 27000
Time Pressure; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Weight And Balance
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Weather
Air interrupt; returned to departure station. Lost both Left and Right radar systems. All [Company] procedures were followed. SAT COM was initiated to Dispatch to discuss continuing or diverting. Maintenance was brought up on frequency as possible resource by Dispatcher. Maintenance pinged the aircraft and confirmed the loss of both radars. Dispatcher was asked to confirm thunderstorm activities along our route. Dispatcher confirmed there was substantial activity forecast for the [subsequent] part of our route. ZZZ had also experienced substantial storm activity earlier in the day and we were headed east. Dispatcher informed us he was uncomfortable with us continuing to ZZZZ. We agreed. We agreed to return to ZZZ and initiated the diversion. Into the diversion we were briefed by the Purser of strange electrical activities in the cabin. These activities included loss of forward galley power to ovens and coffee makers. Intermittent loss of aft galley power and dimmable cabin windows stuck in dark mode. This non normal activity and the timing of it was relayed to Dispatch. Conversation occurred about landing overweight. With this additional unexplained electrical activity it was agreed with the Dispatcher that we would [advise ATC] and land overweight. All [Company] checks were completed including Overweight Landing and Non-Routine landing. [Priority handling was requested] with ZZZ. Landing on Runway XXR was accomplished. Touched down store data was retrieved. It showed 184 FPM. All appropriate log book entries were entered in log book.
B787 Captain reported electrical failures and loss of both radar systems; resulting in a return to the departure airport.