Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 210; Flight Crew Total 8805; Flight Crew Type 6084
Confusion; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Human Factors; MEL
During climb out; aircraft's right generator and associated IDG (Integrated Drive Generator) failed. The right IDG was disconnected. Associated checklist item. 'APU selector if available start'. APU was started. If APU were to be used for the remainder of the flight; a diversion would be required. After all checklists were completed and situation stabilized; myself and the other [relief pilot] proceeded to crew rest.Upon return; we were briefed on the resolution to this problem. Captain; Dispatch; [Maintenance Control] and fleet managers were conferenced into satcom discussions. As reference; MEL required the use of the APU for the entire flight. However the MEL was disregarded due to it being a dispatch requirement. Crew guidance of this problem was therefore the checklist; 2.XX.X. Eng gen off L. The question arose as to the interpretation of 'APU selector if available start'. This statement appears to give discretion to the crew. If the APU was required for flight; I believe the checklist would be written; 'APU start. If not available; consider divert.' What is the meaning of 'if available'? Does this allow for operational considerations? Checklists rarely state 'if available' to any item.Via conference call; it was agreed by Captain; Dispatch; [Maintenance Control] and fleet managers that the APU was not required for the remainder of the flight. I believe we used excellent CRM and all available resources to reach this conclusion. However the vagueness of the checklist was enough to warrant writing this [ASRS Report].
A Boeing 777 pilot reported an electrical system anomaly that was successfully managed despite ambiguous Flight Manual and MEL guidance.