A B767-300 flight crew opted to declare an emergency and divert to the nearest suitable airport when the right generator drive failed shortly after coast out on a transcontinental flight. They later canceled the emergency and returned uneventfully to their departure airport.

Narrative

While in cruise flight at FL350 I observed a RT GEN DRIVE message on EICAS. I started the APU and asked for the QRH checklist. An emergency was declared with Center radio on HF and Mayday was broadcast because a turn back off route of 180 degrees was required to get to the nearest suitable airport as ETOPS flight could not be continued. QRH checklist items were completed and a lateral track offset 15 NM right of course was established. Also a descent was initiated to FL345 from FL350 per QRH Contingencies guidance.After a discussion with Dispatch and Maintenance via SATCOM we determined that landing at the nearest suitable airport was not required. Our departure airport was chosen as the return airport. All were agreed that if the APU generator failed enroute to the airport we would land at the nearest suitable airport. Center was informed of our new destination and we received routing to the airport and terminated our emergency with the concurrence of Dispatch and Maintenance Control. Landing data and conditions were verified and we made a normal landing at about 317;000 LBS.