Narrative:

Descending through 13000 ft in IMC we experienced total electrical failure. Attempted to reset essential bus on copilot's side. Got us all power back for 10-15 seconds. We had been cleared to descend to 10000 ft, bases were about 10500 ft so at leveloff we were VMC. We discussed options. After attempting to reset essential bus on copilot's side several times, we ran the emergency checklist as we descended toward mdw. This time, checking copilot's breaker panel, the essential bus tie breaker was also popped (I had tried 4-5 times to reset right essential bus to make blind xmissions to approach to keep them informed what we planned). Captain reset his left essential bus and we got power to his side. We didn't try to 'fix' it any further as we were inside a 5 or 6 mi final. The problem turned out to be a chaffed power cable from the recently replaced right generator. If we had had more time we could have done a more thorough job of troubleshooting. One saving grace was the immediate availability of a pocket sized flashlight by which we flew the airplane, ran checklist, and looked at breaker. Obviously more care should have been used by the out base maintenance in routing the power cable. I am also curious as to why the busses could not be pwred separately (ie, the breaker pulled) in normal flight. We had both 40 amp essential bus breakers pop from the dead short on the right generator, but the 20 amp breaker on the tie stayed in for several reset attempts of the right essential bus. Had we not had the busses tied we would have only lost the right bus and had a better idea what the problem was. One thing that later bothered us a great deal was that too much time was spent worrying about legalities instead of dealing with the more immediate problem at hand. It is too easy to be second guessed after the fact and that knowledge diminishes focus that may be critical during an emergency. Supplemental information from acn 385927: the lear 35 can have a complete electrical failure (both essential busses blew before they took out the lower ampere (20) bus tie). The emergency checklist ignores this possibility can exist. Why not leave this bus tie pulled out during normal operations to prevent both essentials from ever possibly blowing? Callback conversation with reporter acn 386084 revealed the following information: the reporter was the first officer on a lear 35 cargo aircraft. He said that when the flight crew first lost their electrical power they were confused about the situation since both essential bus circuit breakers opened, but the bus tie breaker did not. This breaker did not open until the first officer made several attempts to reset the right essential bus circuit. After the bus tie breaker opened the captain was able to reset the left essential bus breaker and they recovered the left instruments and the radio. He also said that the company has reviewed with an outside maintenance contractor the work that was done on the right generator. He thinks that a report was made to the FAA on this matter.

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Original NASA ASRS Text

Title: AN ATX FREIGHTER FLC IN A LR35 HAD A COMPLETE ELECTRICAL FAILURE DURING DSCNT IN NIGHT WX CONDITIONS. THE FLC WAS ABLE TO FLY THE ACFT USING STANDBY INSTS AND A SMALL FLASHLIGHT. THEY WERE ABLE TO PWR THE L ESSENTIAL BUS AFTER SEVERAL ATTEMPTS. MAINT DISCOVERED THAT THE PWR CABLE FROM THE R GENERATOR HAD BEEN DAMAGED WHEN THE GENERATOR HAD BEEN REPLACED BY AN OUTSIDE MAINT ORGANIZATION.

Narrative: DSNDING THROUGH 13000 FT IN IMC WE EXPERIENCED TOTAL ELECTRICAL FAILURE. ATTEMPTED TO RESET ESSENTIAL BUS ON COPLT'S SIDE. GOT US ALL PWR BACK FOR 10-15 SECONDS. WE HAD BEEN CLRED TO DSND TO 10000 FT, BASES WERE ABOUT 10500 FT SO AT LEVELOFF WE WERE VMC. WE DISCUSSED OPTIONS. AFTER ATTEMPTING TO RESET ESSENTIAL BUS ON COPLT'S SIDE SEVERAL TIMES, WE RAN THE EMER CHKLIST AS WE DSNDED TOWARD MDW. THIS TIME, CHKING COPLT'S BREAKER PANEL, THE ESSENTIAL BUS TIE BREAKER WAS ALSO POPPED (I HAD TRIED 4-5 TIMES TO RESET R ESSENTIAL BUS TO MAKE BLIND XMISSIONS TO APCH TO KEEP THEM INFORMED WHAT WE PLANNED). CAPT RESET HIS L ESSENTIAL BUS AND WE GOT PWR TO HIS SIDE. WE DIDN'T TRY TO 'FIX' IT ANY FURTHER AS WE WERE INSIDE A 5 OR 6 MI FINAL. THE PROB TURNED OUT TO BE A CHAFFED PWR CABLE FROM THE RECENTLY REPLACED R GENERATOR. IF WE HAD HAD MORE TIME WE COULD HAVE DONE A MORE THOROUGH JOB OF TROUBLESHOOTING. ONE SAVING GRACE WAS THE IMMEDIATE AVAILABILITY OF A POCKET SIZED FLASHLIGHT BY WHICH WE FLEW THE AIRPLANE, RAN CHKLIST, AND LOOKED AT BREAKER. OBVIOUSLY MORE CARE SHOULD HAVE BEEN USED BY THE OUT BASE MAINT IN ROUTING THE PWR CABLE. I AM ALSO CURIOUS AS TO WHY THE BUSSES COULD NOT BE PWRED SEPARATELY (IE, THE BREAKER PULLED) IN NORMAL FLT. WE HAD BOTH 40 AMP ESSENTIAL BUS BREAKERS POP FROM THE DEAD SHORT ON THE R GENERATOR, BUT THE 20 AMP BREAKER ON THE TIE STAYED IN FOR SEVERAL RESET ATTEMPTS OF THE R ESSENTIAL BUS. HAD WE NOT HAD THE BUSSES TIED WE WOULD HAVE ONLY LOST THE R BUS AND HAD A BETTER IDEA WHAT THE PROB WAS. ONE THING THAT LATER BOTHERED US A GREAT DEAL WAS THAT TOO MUCH TIME WAS SPENT WORRYING ABOUT LEGALITIES INSTEAD OF DEALING WITH THE MORE IMMEDIATE PROB AT HAND. IT IS TOO EASY TO BE SECOND GUESSED AFTER THE FACT AND THAT KNOWLEDGE DIMINISHES FOCUS THAT MAY BE CRITICAL DURING AN EMER. SUPPLEMENTAL INFO FROM ACN 385927: THE LEAR 35 CAN HAVE A COMPLETE ELECTRICAL FAILURE (BOTH ESSENTIAL BUSSES BLEW BEFORE THEY TOOK OUT THE LOWER AMPERE (20) BUS TIE). THE EMER CHKLIST IGNORES THIS POSSIBILITY CAN EXIST. WHY NOT LEAVE THIS BUS TIE PULLED OUT DURING NORMAL OPS TO PREVENT BOTH ESSENTIALS FROM EVER POSSIBLY BLOWING? CALLBACK CONVERSATION WITH RPTR ACN 386084 REVEALED THE FOLLOWING INFO: THE RPTR WAS THE FO ON A LEAR 35 CARGO ACFT. HE SAID THAT WHEN THE FLC FIRST LOST THEIR ELECTRICAL PWR THEY WERE CONFUSED ABOUT THE SIT SINCE BOTH ESSENTIAL BUS CIRCUIT BREAKERS OPENED, BUT THE BUS TIE BREAKER DID NOT. THIS BREAKER DID NOT OPEN UNTIL THE FO MADE SEVERAL ATTEMPTS TO RESET THE R ESSENTIAL BUS CIRCUIT. AFTER THE BUS TIE BREAKER OPENED THE CAPT WAS ABLE TO RESET THE L ESSENTIAL BUS BREAKER AND THEY RECOVERED THE L INSTS AND THE RADIO. HE ALSO SAID THAT THE COMPANY HAS REVIEWED WITH AN OUTSIDE MAINT CONTRACTOR THE WORK THAT WAS DONE ON THE R GENERATOR. HE THINKS THAT A RPT WAS MADE TO THE FAA ON THIS MATTER.

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.