Narrative:

Picked up the aircraft with the AC [generator] bearing right [right] meled. I reviewed the MEL requirements and found that we could continue for 20 flight hours. I briefed the first officer and we continued our planned schedule. After landing in airport ZZZ we deferred the right windshield (ws) heat due to an inflight failure on the previous leg after a right ws fault light illuminated. Maintenance control scheduled a ferry flight to airport ZZZ1 for maintenance. During taxi-out the ground controller reported smoke coming from our right engine. We noticed a high pitched whining sound similar to bearing failure type of noise from the right side as well. We shut down the right engine and requested crash fire rescue equipment to assess the right engine smoke issue. I determined that we would not continue to taxi at this point and shut down the other engine. The crash fire rescue equipment personnel suggested utilizing halon to cool the right AC generator which we had determined was the source of the smoke. They gained access to the generator by lowering the right engine nacelle. There was significant burnt paint and charring around the generator cooling port on the nacelle. After 20-30 minutes; crash fire rescue equipment said we could reposition the aircraft to the FBO ramp which we did via a tug. I contacted an assistant chief pilot (acp); maintenance control; and crew services to advise. We were shut down and sent to the hotel. If this is a reasonably expected outcome from the AC [generator] bearing warning light; then it should not be an MEL item; as the light indicates an eventual bearing failure. If we had gone airborne there is no doubt that it would have been an inflight fire/engine shutdown event.[recommend] the AC bearing light should not be on the MEL. In the future if I am faced with this MEL item; I would refuse to fly with it based on this experience.

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Original NASA ASRS Text

Title: Captain reports that deferral of the Engine AC Generator Bearing Annunciator light with a 20-flight hour continued operation should not be allowed in the MEL for Cessna CE-560XLs. Primary Bearing failure of the Right Engine AC Generator after only three hours operation since deferral caused an electrical fire that burnt and scorched the nacelle; AC Generator; and wires during taxi-out. Pilot suspects the engine fire bottles would not have been sufficient to extinguish that type of fire in flight.

Narrative: Picked up the aircraft with the AC [Generator] bearing R [Right] MELed. I reviewed the MEL requirements and found that we could continue for 20 flight hours. I briefed the First Officer and we continued our planned schedule. After landing in Airport ZZZ we deferred the Right Windshield (WS) Heat due to an inflight failure on the previous leg after a Right WS fault light illuminated. Maintenance Control scheduled a Ferry flight to Airport ZZZ1 for maintenance. During taxi-out the Ground Controller reported smoke coming from our Right engine. We noticed a high pitched whining sound similar to bearing failure type of noise from the right side as well. We shut down the Right engine and requested CFR to assess the Right engine smoke issue. I determined that we would not continue to taxi at this point and shut down the other engine. The CFR personnel suggested utilizing Halon to cool the right AC Generator which we had determined was the source of the smoke. They gained access to the generator by lowering the Right engine nacelle. There was significant burnt paint and charring around the generator cooling port on the nacelle. After 20-30 minutes; CFR said we could reposition the aircraft to the FBO ramp which we did via a tug. I contacted an Assistant Chief Pilot (ACP); Maintenance Control; and Crew services to advise. We were shut down and sent to the hotel. If this is a reasonably expected outcome from the AC [Generator] bearing warning light; then it should not be an MEL item; as the light indicates an eventual bearing failure. If we had gone airborne there is no doubt that it would have been an Inflight Fire/Engine Shutdown event.[Recommend] the AC bearing light should not be on the MEL. In the future if I am faced with this MEL item; I would refuse to fly with it based on this experience.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.