Narrative:

Descending through 10000' into yul, we lost electrical power. The cockpit went almost completely dark and I had red flags on all of my INS on the captain's side. Both blue gen off buss lights were on. However, the amber buss off lights were not. I tried to reset both gens and nothing happened. I told my first officer to start the APU. I went to the bat position on standby power. We told approach control that we had an electrical failure. At this time, it appeared to be a complete electrical failure and I declared an emergency. The APU was now up to speed and we put the right buss on the APU. Some lights came back and the first officer's INS appeared to be working normally. We used standby and first officer's INS to land. My INS never came back and flags remained in view. All lights worked normally in passenger cabin. We did smell an electrical odor. The landing was normal, and after we arrived at the gate, we found the #1 normal buss xfer circuit breaker popped (located low and behind the first officer's seat). All pertinent checklists were used and completed. Callback conversation with reporter revealed the following: reporter cites 2 other cases of this #1 normal buss xfer circuit breaker popping out and creating this partial loss of electrical power. Reporter claims that this circuit breaker is not referenced on the electrical failure checklist and that manufacturer of aircraft has been checking into the cause of these failures. Company was notified of the event, but not specifically told of the 'hidden bkr.' reporter thought, by the symptoms exhibited, that he had experienced a complete electrical failure. One might wonder what is presented to flight crews in their simulator training to give them exposure to this experience.

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Original NASA ASRS Text

Title: MLG ACR FLT CREW EXPERIENCES DARKENED COCKPIT AND LOSS OF FLT INSTRUMENTS. LOSS OF PRIMARY ELECTRICAL POWER SOURCE SUSPECTED. POSSIBLE PUBLICATION DEFICIENCY.

Narrative: DSNDING THROUGH 10000' INTO YUL, WE LOST ELECTRICAL PWR. THE COCKPIT WENT ALMOST COMPLETELY DARK AND I HAD RED FLAGS ON ALL OF MY INS ON THE CAPT'S SIDE. BOTH BLUE GEN OFF BUSS LIGHTS WERE ON. HOWEVER, THE AMBER BUSS OFF LIGHTS WERE NOT. I TRIED TO RESET BOTH GENS AND NOTHING HAPPENED. I TOLD MY F/O TO START THE APU. I WENT TO THE BAT POS ON STANDBY PWR. WE TOLD APCH CTL THAT WE HAD AN ELECTRICAL FAILURE. AT THIS TIME, IT APPEARED TO BE A COMPLETE ELECTRICAL FAILURE AND I DECLARED AN EMER. THE APU WAS NOW UP TO SPD AND WE PUT THE RIGHT BUSS ON THE APU. SOME LIGHTS CAME BACK AND THE F/O'S INS APPEARED TO BE WORKING NORMALLY. WE USED STANDBY AND F/O'S INS TO LAND. MY INS NEVER CAME BACK AND FLAGS REMAINED IN VIEW. ALL LIGHTS WORKED NORMALLY IN PAX CABIN. WE DID SMELL AN ELECTRICAL ODOR. THE LNDG WAS NORMAL, AND AFTER WE ARRIVED AT THE GATE, WE FOUND THE #1 NORMAL BUSS XFER CB POPPED (LOCATED LOW AND BEHIND THE F/O'S SEAT). ALL PERTINENT CHKLISTS WERE USED AND COMPLETED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR CITES 2 OTHER CASES OF THIS #1 NORMAL BUSS XFER CB POPPING OUT AND CREATING THIS PARTIAL LOSS OF ELECTRICAL PWR. RPTR CLAIMS THAT THIS CB IS NOT REFERENCED ON THE ELECTRICAL FAILURE CHKLIST AND THAT MANUFACTURER OF ACFT HAS BEEN CHKING INTO THE CAUSE OF THESE FAILURES. COMPANY WAS NOTIFIED OF THE EVENT, BUT NOT SPECIFICALLY TOLD OF THE 'HIDDEN BKR.' RPTR THOUGHT, BY THE SYMPTOMS EXHIBITED, THAT HE HAD EXPERIENCED A COMPLETE ELECTRICAL FAILURE. ONE MIGHT WONDER WHAT IS PRESENTED TO FLT CREWS IN THEIR SIMULATOR TRNING TO GIVE THEM EXPOSURE TO THIS EXPERIENCE.

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.