Date: 201408
Local time of day: 1201-1800
Location: ZZZZ.ARTCC, FO
Flight conditions: VMC
Light: Daylight
Aircraft: A330
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Generator Drive
Component problem: Design; Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Troubleshooting; Human-Machine Interface; Distraction; Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Aircraft Automation Overrode Flight Crew; Flight Crew FLC complied w / Automation / Advisory
Contributing factors: Aircraft; Procedure; Company Policy; Chart Or Publication
Primary problem: Aircraft

Narrative: Aircraft was MEL'd with Number 2 Engine Generator IDG inoperative/disconnected. However; once at cruise FL360; long before we would start our Atlantic Track crossing we received an Advisory ECAM; indicating that the Number 2 IDG temperature was rising above 152 degrees C. The MEL states that it was possible to see these temperatures rise; but did not have a maximum temperature to use as a precaution or a guidance to decide if there are other abnormalities to be concerned or a potential for 'Fire.' The IDG is supposed to be disconnected and all indications on the electrical page indicated it was disconnected including the overhead switch (IDG PB) was off along with GEN 2. We contacted Maintenance via SAT-COMM and they informed us of this possibility; but we did not received what 'if' the temperature would rise and what were the limits. A Chief Pilot had placed a crew message back on 2011 mentioning these potential issues and indications with a disconnected IDG. Dispatcher went back on history of other events like this and found one where the temperature reached 211 degrees C. We could not find as to what the maximum was and what the conditions to this temperature rise were. Very disconcerting when you have an impending Track/Atlantic crossing. However; we checked Alternate's weather; we had a 120 minute diversion time; we obtained FL400 as our final Altitude and it was daytime; in the event we felt an impending engine shutdown was necessary.Do not know; but would like to know and we NEED to know what causes these anomalies so as to be better prepared mentally and understand what the systems are doing and how CRITICAL it is. We need to find the reason for these indications; not just that it can go above 151 degrees C or receive a secondary advisory if goes above 185 degrees C and that it has been known to reach 211 degrees C. If this were to happen during an Atlantic Eastbound crossing at NIGHT; I would have diverted to an alternate or return to our departure point. At night in a moonless weather crossing with number two IDG/GEN on MEL with an IDG temperature rising; even if the books says it may rise above 151 degrees C; is not the place to be without knowing WHY?My better judgment and 40+ years of experience tell me that it is time to fix the problem; not to take the problem elsewhere and drop it in the laps of another crew with same lack of knowledge on this system.




Synopsis: An A330 Number 2 Engine IDG was disconnected and MEL'ed prior to departure but in flight the temperature was rising above 152 degrees C with no written or verbal guidance about crew actions should it rise to unsafe limits.