Narrative:

Flight plan was (pwm) portland, me, to (iad) washington, dulles. After departure, while at FL240, right generator failed on a ba-4100. Shortly thereafter vibration and noise were noted coming from right engine. Checklist was completed for the generator failure and flight was continued. Approximately 30 min after generator failed, vibrations became continuous and torque began to rise and fall. The erratic engine memory items were accomplished and engine was shut down. We declared the emergency and diverted into providence landing without further incident. Callback conversation with reporter revealed the following information: reporter stated that the normal means of shutting down a failed generator is to comply with the checklist and actuate the electrical contactor switch which turns the generator off. This should allow the shaft to automatic shear from the engine. That did not happen. First officer feels that this design is marginal at best and felt that the only reason the captain had initially elected to continue the flight (up to the point of engine vibrations) was that the en route WX was so clear. He stated that this aircraft has marginal levels of electrical generation.

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Original NASA ASRS Text

Title: INFLT ENG SHUTDOWN REQUIRES A DIVERSION TO ALTERNATE. PRIMARY ELECTRICAL SUPPLY PROB PRECEDED THE ENG SHUTDOWN.

Narrative: FLT PLAN WAS (PWM) PORTLAND, ME, TO (IAD) WASHINGTON, DULLES. AFTER DEP, WHILE AT FL240, RIGHT GENERATOR FAILED ON A BA-4100. SHORTLY THEREAFTER VIBRATION AND NOISE WERE NOTED COMING FROM R ENG. CHKLIST WAS COMPLETED FOR THE GENERATOR FAILURE AND FLT WAS CONTINUED. APPROX 30 MIN AFTER GENERATOR FAILED, VIBRATIONS BECAME CONTINUOUS AND TORQUE BEGAN TO RISE AND FALL. THE ERRATIC ENG MEMORY ITEMS WERE ACCOMPLISHED AND ENG WAS SHUT DOWN. WE DECLARED THE EMER AND DIVERTED INTO PROVIDENCE LNDG WITHOUT FURTHER INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE NORMAL MEANS OF SHUTTING DOWN A FAILED GENERATOR IS TO COMPLY WITH THE CHKLIST AND ACTUATE THE ELECTRICAL CONTACTOR SWITCH WHICH TURNS THE GENERATOR OFF. THIS SHOULD ALLOW THE SHAFT TO AUTO SHEAR FROM THE ENG. THAT DID NOT HAPPEN. FO FEELS THAT THIS DESIGN IS MARGINAL AT BEST AND FELT THAT THE ONLY REASON THE CAPT HAD INITIALLY ELECTED TO CONTINUE THE FLT (UP TO THE POINT OF ENG VIBRATIONS) WAS THAT THE ENRTE WX WAS SO CLR. HE STATED THAT THIS ACFT HAS MARGINAL LEVELS OF ELECTRICAL GENERATION.

Data retrieved from NASA's ASRS site as of July 2007 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.