Narrative:

I departed for a night VFR flight. An IFR flight plan at 10;000 feet had been filed for the flight but prior to departure; I requested the IFR clearance be changed to VFR flight following with a cruising altitude of 10;500 feet. The flight was anticipated to be around a 30 minute flight and there was approximately 3 hours of fuel on board. There were 3 souls on board; the pilot and two passengers. Takeoff and climb out were normal. While enroute at 10;500 feet; the low voltage light flickered once; there was a brief buzzing sound in the headsets and the right generator tripped offline. I did not attempt to reset the generator. I checked the load on the remaining (left) generator and it was under 100 amps. As a precaution; I turned off the pitot static heat and made sure the AC compressor was offline (it was). Approximately 5 minutes later; I began a descent from 10;500 to 3;500. At this point I was approximately 40 miles from [destination]. As I was descending through approximately 8;500 feet; the passenger in the rear of the plane alerted us that there were sparks coming out of the generator vents of the engine cowling. It appeared that there was a mechanical issue with the generator as well as electrical. I elected to shut down the right engine as a precaution and [advised ATC]. At this point I was approximately 10 minutes from [destination]. I elected to continue. [After landing] the emergency equipment followed the airplane to the ramp. I shutdown the engines and all of the occupants exited the airplane normally through the door on the left side of the plane. The firefighters inquired as to the situation and I informed them that it all appeared to be normal. There was no evidence of smoke or fire; so the fire equipment returned to their base and I put the plane in the hangar. I then notified the chief pilot of the situation so repairs could be initiated.

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Original NASA ASRS Text

Title: AC90 pilot reported shutting down the right engine after a passenger noticed sparks coming from the cowling following a generator failure.

Narrative: I departed for a night VFR flight. An IFR flight plan at 10;000 feet had been filed for the flight but prior to departure; I requested the IFR clearance be changed to VFR flight following with a cruising altitude of 10;500 feet. The flight was anticipated to be around a 30 minute flight and there was approximately 3 hours of fuel on board. There were 3 souls on board; the pilot and two passengers. Takeoff and climb out were normal. While enroute at 10;500 feet; the low voltage light flickered once; there was a brief buzzing sound in the headsets and the right generator tripped offline. I did not attempt to reset the generator. I checked the load on the remaining (left) generator and it was under 100 amps. As a precaution; I turned off the pitot static heat and made sure the AC compressor was offline (it was). Approximately 5 minutes later; I began a descent from 10;500 to 3;500. At this point I was approximately 40 miles from [destination]. As I was descending through approximately 8;500 feet; the passenger in the rear of the plane alerted us that there were sparks coming out of the generator vents of the engine cowling. It appeared that there was a mechanical issue with the generator as well as electrical. I elected to shut down the right engine as a precaution and [advised ATC]. At this point I was approximately 10 minutes from [destination]. I elected to continue. [After landing] the emergency equipment followed the airplane to the ramp. I shutdown the engines and all of the occupants exited the airplane normally through the door on the left side of the plane. The firefighters inquired as to the situation and I informed them that it all appeared to be normal. There was no evidence of smoke or fire; so the fire equipment returned to their base and I put the plane in the hangar. I then notified the chief pilot of the situation so repairs could be initiated.

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.