Narrative:

At FL270, in cruise, autoplt on, captain's leg, we heard a loud thump with immediate right yaw and a very loud buzzing as the air-driven generator deployed and the autoplt kicked off with associated warning sound. All EFIS screens went blank, so we didn't have an immediate indication of why we had lost electrical power. All EFIS screens recovered shortly, and the EICAS caution messages displayed #1 generator off, AC #1 automatic-xfer, and other messages associated with electrical power interruption. As captain hand-flew aircraft and first officer got out QRH, both pilots smelled acrid odor, like burning wire insulation and observed smoke coming from glare shield in front of captain and around captain's feet. Captain ordered oxygen masks on and told first officer to tell ATC we needed to divert to closest airfield for emergency. First officer declared emergency for smoke in cockpit and electrical problems and called for immediate descent with ZTL while changing squawk to 7700. Captain directed first officer to run QRH checklists while captain descended aircraft and proceeded on vectors to rdu. First officer communicated to flight attendant that we were diverting and ensured that there were no problems or smoke in cabin. Communication with flight attendant was difficult due to noise level from air driven generator. Smoke dissipated quickly, so captain elected not to depressurize cabin, although captain and first officer kept masks on in case of further smoke problems. #1 generator would not reset. Aircraft synoptic page showed #1 generator offline, #1 AC bus unpowered, #1 utility bus shed, #2 generator online and pwring #2 AC bus and essential bus. Dc electric synoptic page showed tru (transformer rectifier) #1 unpowered. Started APU for generator redundancy. Ran descent, approach and before landing checklists. First officer informed flight attendant that we were 5 mins out and landing would be normal. Uneventful landing and rollout, cleared runway and asked crash fire rescue equipment to check aircraft before proceeding to gate. Common tower/crash fire rescue equipment/ground frequency had worked in air, but could not communicate with crash fire rescue equipment on ground, and had to relay through tower. Contacted station personnel, who told us they were expecting us (our company had been informed by another company flight who had heard us on center frequency) and were already planning passenger handling. While taxiing to gate, first officer informed passenger that we had diverted to rdu because a backup system had operated when it wasn't supposed to. Burnt insulation smell was still very evident in flight deck compartment, appeared not to have penetrated to cabin. Deplaned passenger at gate, met with maintenance personnel on ground, relayed to company maintenance that we had called operations center chief pilot, scheduling, and conferred with ramp personnel about securing aircraft. Postflt inspection with maintenance indicated an electrical component, possibly a relay, in the avionics bay under the flight deck compartment, had caught fire and melted, and scorched wiring bundles and the immediate surrounding area.

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Original NASA ASRS Text

Title: CL65 CREW HAD AN ELECTRIC RELAY ASSOCIATED WITH #1 GENERATOR CATCH FIRE. THE APPROPRIATE BUSSES WERE NOT ABLE TO BE PWRED. THE CREW DECLARED AN EMER AND LANDED AT THE NEAREST SUITABLE ARPT.

Narrative: AT FL270, IN CRUISE, AUTOPLT ON, CAPT'S LEG, WE HEARD A LOUD THUMP WITH IMMEDIATE R YAW AND A VERY LOUD BUZZING AS THE AIR-DRIVEN GENERATOR DEPLOYED AND THE AUTOPLT KICKED OFF WITH ASSOCIATED WARNING SOUND. ALL EFIS SCREENS WENT BLANK, SO WE DIDN'T HAVE AN IMMEDIATE INDICATION OF WHY WE HAD LOST ELECTRICAL PWR. ALL EFIS SCREENS RECOVERED SHORTLY, AND THE EICAS CAUTION MESSAGES DISPLAYED #1 GENERATOR OFF, AC #1 AUTO-XFER, AND OTHER MESSAGES ASSOCIATED WITH ELECTRICAL PWR INTERRUPTION. AS CAPT HAND-FLEW ACFT AND FO GOT OUT QRH, BOTH PLTS SMELLED ACRID ODOR, LIKE BURNING WIRE INSULATION AND OBSERVED SMOKE COMING FROM GLARE SHIELD IN FRONT OF CAPT AND AROUND CAPT'S FEET. CAPT ORDERED OXYGEN MASKS ON AND TOLD FO TO TELL ATC WE NEEDED TO DIVERT TO CLOSEST AIRFIELD FOR EMER. FO DECLARED EMER FOR SMOKE IN COCKPIT AND ELECTRICAL PROBS AND CALLED FOR IMMEDIATE DSCNT WITH ZTL WHILE CHANGING SQUAWK TO 7700. CAPT DIRECTED FO TO RUN QRH CHKLISTS WHILE CAPT DSNDED ACFT AND PROCEEDED ON VECTORS TO RDU. FO COMMUNICATED TO FLT ATTENDANT THAT WE WERE DIVERTING AND ENSURED THAT THERE WERE NO PROBS OR SMOKE IN CABIN. COM WITH FLT ATTENDANT WAS DIFFICULT DUE TO NOISE LEVEL FROM ADG. SMOKE DISSIPATED QUICKLY, SO CAPT ELECTED NOT TO DEPRESSURIZE CABIN, ALTHOUGH CAPT AND FO KEPT MASKS ON IN CASE OF FURTHER SMOKE PROBS. #1 GENERATOR WOULD NOT RESET. ACFT SYNOPTIC PAGE SHOWED #1 GENERATOR OFFLINE, #1 AC BUS UNPOWERED, #1 UTILITY BUS SHED, #2 GENERATOR ONLINE AND PWRING #2 AC BUS AND ESSENTIAL BUS. DC ELECTRIC SYNOPTIC PAGE SHOWED TRU (TRANSFORMER RECTIFIER) #1 UNPOWERED. STARTED APU FOR GENERATOR REDUNDANCY. RAN DSCNT, APCH AND BEFORE LNDG CHKLISTS. FO INFORMED FLT ATTENDANT THAT WE WERE 5 MINS OUT AND LNDG WOULD BE NORMAL. UNEVENTFUL LNDG AND ROLLOUT, CLRED RWY AND ASKED CFR TO CHK ACFT BEFORE PROCEEDING TO GATE. COMMON TWR/CFR/GND FREQ HAD WORKED IN AIR, BUT COULD NOT COMMUNICATE WITH CFR ON GND, AND HAD TO RELAY THROUGH TWR. CONTACTED STATION PERSONNEL, WHO TOLD US THEY WERE EXPECTING US (OUR COMPANY HAD BEEN INFORMED BY ANOTHER COMPANY FLT WHO HAD HEARD US ON CTR FREQ) AND WERE ALREADY PLANNING PAX HANDLING. WHILE TAXIING TO GATE, FO INFORMED PAX THAT WE HAD DIVERTED TO RDU BECAUSE A BACKUP SYS HAD OPERATED WHEN IT WASN'T SUPPOSED TO. BURNT INSULATION SMELL WAS STILL VERY EVIDENT IN FLT DECK COMPARTMENT, APPEARED NOT TO HAVE PENETRATED TO CABIN. DEPLANED PAX AT GATE, MET WITH MAINT PERSONNEL ON GND, RELAYED TO COMPANY MAINT THAT WE HAD CALLED OPS CTR CHIEF PLT, SCHEDULING, AND CONFERRED WITH RAMP PERSONNEL ABOUT SECURING ACFT. POSTFLT INSPECTION WITH MAINT INDICATED AN ELECTRICAL COMPONENT, POSSIBLY A RELAY, IN THE AVIONICS BAY UNDER THE FLT DECK COMPARTMENT, HAD CAUGHT FIRE AND MELTED, AND SCORCHED WIRING BUNDLES AND THE IMMEDIATE SURROUNDING AREA.

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.