Date: 201509
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Aircraft component: AC Generation
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown
Second reporter function: Pilot Not Flying; Relief Pilot
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Other / Unknown
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: Taxi
Result: General Maintenance Action; General Flight Cancelled / Delayed; General Work Refused
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: We were taxiing out to the runway; single-engine; with the APU off. Near the departure end of the runway; the left engine generator tripped. We followed the non-normal checklist for ELEC GEN OFF L; which allows for only one reset of the generator. We reset the generator. After a few minutes; the generator tripped again; but this time it was accompanied with an automatic left IDG disconnect. We followed the non-normal checklist associated with the IDG disconnect; and backed up the automatic disconnect by pressing the IDG disconnect switch per the checklist. We returned to the gate.Maintenance notified us that they planned on deferring the L engine IDG. Captain said that he was fine flying our Pacific ETOPS flight with an IDG inoperative; making reference to the MEL. I was not comfortable with the decision; and expressed my concern to the Captain. So did the other First Officer. I felt that having a primary source of electrical power unavailable to us would be a degradation of safety; and referred the Captain to the Regional Equipment Guide in the manual; which states: 'The following table lists equipment that is considered operationally sensitive for flights in specific regions. This equipment is deemed highly desirable to maintain the proper level of safety for operations within these challenging areas.......' If one refers to the table it shows; 'Electrical: Two Engine & APU ' with a 'U' in the Pacific column. The 'U' denotes equipment that is; 'highly desirable for flights in the specific region.' Taking an aircraft with an inoperative IDG over a 2;500 mile overwater ETOPS segment with no alternates available along the route did not seem like a prudent path to me.  We would be departing a major maintenance base with an inoperative generator and two First Officers who would be uncomfortable in that situation. After discussing the potential threats of the situation with the Captain and the other First Officer the Captain made it clear that he was going to depart with the inoperative IDG. I then decided to remove myself from the flight. The other First Officer also removed himself from the flight.


Second narrative: I was IRO on a flight to HNL. During single engine taxi out; right engine shut down; the left engine generator tripped. Following the ECL we reset the left engine generator; one reset is allowed. Within a few minutes the left engine generator tripped again. Recalling that only one reset is allowed we coordinated for a return to gate. During the return taxi we noticed the IDG had disconnected and followed that up with the appropriate ECL.After returning to the gate; maintenance informed us of their decision to defer the generator. The crew discussed the situation and the captain informed us of his decision to accept the deferral and operate the flight. FO and I disagreed with the captain and felt the issue should be fixed. It was brought to the Captains attention that the manual states for a 777 crossing the Pacific; it is 'highly desirable' to have both engine generators and APU available. I felt that considering we were leaving a maintenance station; crossing the Pacific with no readily available alternates was not the best option available to us. I did not feel comfortable taking the aircraft over the Pacific with a major system deferred and taking in consideration the guidance provided in the manual. I relayed my concerns to the Captain and he reaffirmed his decision to operate the flight with the deferral. At this time I removed myself from the flight. The other FO also removed himself.


Synopsis: B777 flight crew experienced a generator trip during single engine taxi out and reset the generator. A few minutes later the generator trips again. The flight returns to the gate where Maintenance decided to MEL the IDG. The Captain accepts the aircraft as MEL'd for this ETOPS flight but the First Officers do not and remove themselves from the flight.