B767-300 and 300 ER
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Aircraft
The APU was deferred and I was the Pilot Flying on this leg.  While descending through FL180; as Captain activated the exterior lights; I observed numerous fluctuations in my EFIS (Electronic Flight Instrument System) screens followed by a loss of the Flight Director; seed tape and information on my EHSI (Electronic Horizontal Situation Indicator). At that time; I lost my CDU as well as many of the ambient and indicating lights in the flight deck area. The upper EICAS screen began listing numerous amber messages. Captain determined that the aircraft had a Right AC Bus failure. Due to the loss of some indicating information on my flight instruments; I transferred aircraft control to Captain and he called for the R AC BUS OFF Non-normal Checklist. As I worked through the checklist; ATC cleared us for the ILSXXR approach. At the completion of that checklist electrical function had been restored. The upper EICAS screen only displayed an amber R UTIL BUS OFF message. Captain then called for the R UTIL BUS OFF Checklist. While resetting the R Utility Bus switch the Right Bus Tie tripped again and the partial loss of indicating instruments and lighting reoccurred. Per the R AC BUS OFF non-normal checklist; the Right Bus Tie may only be reset once in flight. The Captain and I agreed landing in the current condition was the best option. The flight was completed with no further issues.
B767-300 flight crew reported electrical anomaly in flight.