Narrative:

We were IFR from dpa to ael. 5 mins after leveling off at 10000 ft, we had just been cleared direct to our destination when we noticed a momentary flash of the panel lights and illumination of the right alternator out light. We reset the alternator and continued. Approximately 5 mins later, the right alternator again went off line. This time, it would not reset. We waited approximately 5 mins and attempted a reset -- no luck. We switched the gauge to check the load on the good alternator -- 50 amps -- well within limits of our 100 amp alternator. Approximately 1 min later, there was a trail of sparks issuing from the cooling louvers on top of the left cowling, with a yellow glow apparent inside the cowling. Fearing an exhaust system fire (famous in 400 series cessna aircraft and the subject of an airworthiness directive) we took appropriate action to secure the engine. We punched the 'closest airport' function on the GPS, and found that rochelle, il, was right below us. We elected to go to rockford as it was attended, had long runways, and fire equipment. We would have to spiral down to rochelle, anyway. (At this time, we had secured the left engine and were headed for rockford, 18 mi away. We had left 10000 ft and were descending at approximately 1500 FPM.) the lights were dimming noticeably. The right alternator was out and the left engine was secured, but it had been only 1 min since the incident. Attempted to shut off unnecessary radios, but the lights continued to dim, indicating an electrical short and explaining why we could not raise rockford approach. A preliminary inspection by raytheon mechanics showed large electrical cables in the rear of the left engine burned through. The cause has not yet been determined. The aircraft has only 70 hours since firewall forward replacement of all components by aircraft, and an extensive annual inspection at the same time. Supplemental information from acn 460137: we wanted to power down the gear as we were indicating 200 KTS -- faster than gear operating speed, and wanted to get a gear down indication before the lights went out. We also needed the drag. The landing went uneventfully with full flaps selected. We exited the taxiway at taxiway D. In reviewing what we might have done differently, we discussed possibly shutting off the master switch had we known it was an electrical problem.

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Original NASA ASRS Text

Title: A C414 CREW PERCEIVED THAT THEY HAD A FIRE IN THE L ENG AND BLEW THE FIRE BOTTLE, DECLARED AN EMER, AND DIVERTED.

Narrative: WE WERE IFR FROM DPA TO AEL. 5 MINS AFTER LEVELING OFF AT 10000 FT, WE HAD JUST BEEN CLRED DIRECT TO OUR DEST WHEN WE NOTICED A MOMENTARY FLASH OF THE PANEL LIGHTS AND ILLUMINATION OF THE R ALTERNATOR OUT LIGHT. WE RESET THE ALTERNATOR AND CONTINUED. APPROX 5 MINS LATER, THE R ALTERNATOR AGAIN WENT OFF LINE. THIS TIME, IT WOULD NOT RESET. WE WAITED APPROX 5 MINS AND ATTEMPTED A RESET -- NO LUCK. WE SWITCHED THE GAUGE TO CHK THE LOAD ON THE GOOD ALTERNATOR -- 50 AMPS -- WELL WITHIN LIMITS OF OUR 100 AMP ALTERNATOR. APPROX 1 MIN LATER, THERE WAS A TRAIL OF SPARKS ISSUING FROM THE COOLING LOUVERS ON TOP OF THE L COWLING, WITH A YELLOW GLOW APPARENT INSIDE THE COWLING. FEARING AN EXHAUST SYS FIRE (FAMOUS IN 400 SERIES CESSNA ACFT AND THE SUBJECT OF AN AIRWORTHINESS DIRECTIVE) WE TOOK APPROPRIATE ACTION TO SECURE THE ENG. WE PUNCHED THE 'CLOSEST ARPT' FUNCTION ON THE GPS, AND FOUND THAT ROCHELLE, IL, WAS RIGHT BELOW US. WE ELECTED TO GO TO ROCKFORD AS IT WAS ATTENDED, HAD LONG RWYS, AND FIRE EQUIP. WE WOULD HAVE TO SPIRAL DOWN TO ROCHELLE, ANYWAY. (AT THIS TIME, WE HAD SECURED THE L ENG AND WERE HEADED FOR ROCKFORD, 18 MI AWAY. WE HAD LEFT 10000 FT AND WERE DSNDING AT APPROX 1500 FPM.) THE LIGHTS WERE DIMMING NOTICEABLY. THE R ALTERNATOR WAS OUT AND THE L ENG WAS SECURED, BUT IT HAD BEEN ONLY 1 MIN SINCE THE INCIDENT. ATTEMPTED TO SHUT OFF UNNECESSARY RADIOS, BUT THE LIGHTS CONTINUED TO DIM, INDICATING AN ELECTRICAL SHORT AND EXPLAINING WHY WE COULD NOT RAISE ROCKFORD APCH. A PRELIMINARY INSPECTION BY RAYTHEON MECHS SHOWED LARGE ELECTRICAL CABLES IN THE REAR OF THE L ENG BURNED THROUGH. THE CAUSE HAS NOT YET BEEN DETERMINED. THE ACFT HAS ONLY 70 HRS SINCE FIREWALL FORWARD REPLACEMENT OF ALL COMPONENTS BY ACFT, AND AN EXTENSIVE ANNUAL INSPECTION AT THE SAME TIME. SUPPLEMENTAL INFO FROM ACN 460137: WE WANTED TO PWR DOWN THE GEAR AS WE WERE INDICATING 200 KTS -- FASTER THAN GEAR OPERATING SPD, AND WANTED TO GET A GEAR DOWN INDICATION BEFORE THE LIGHTS WENT OUT. WE ALSO NEEDED THE DRAG. THE LNDG WENT UNEVENTFULLY WITH FULL FLAPS SELECTED. WE EXITED THE TXWY AT TXWY D. IN REVIEWING WHAT WE MIGHT HAVE DONE DIFFERENTLY, WE DISCUSSED POSSIBLY SHUTTING OFF THE MASTER SWITCH HAD WE KNOWN IT WAS AN ELECTRICAL PROB.

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.