Narrative:

During an autoplt descent through 12500 ft (or so, approximately) for 11000 ft (preselect) at about 2500 FPM in glaring sunlight with the panel lights on high, the panel went dead. All the gauges and lights went down including the electric encoding altimeter. My first officer asked me what happened, and I said I didn't know. Center then crackled on and said air carrier X say altitude to which I looked down and replied 10000 ft, which is what I thought I saw in the sunlight. Center then said climb to 11000 ft, to which I looked down and saw us smoothly descending through 11500 ft. I leveled off at 11000 ft and continued the flight. The aircraft did not lurch down like in a thunderstorm, nor did it suddenly climb. My thoughts are the spike in voltage brief as it was (4 or 5 seconds) affected the electric altimeter in ways I am unfamiliar with, not being a mechanic. I believe what I said may have been wrong because the lack of aircraft motion, indicating 12500 ft one second, 10000 ft the next, then finally 11500 ft descending normally. Callback conversation with reporter revealed the following information: the reporter stated the power loss was not caused by a static discharge or lightning strike and only appeared from 4-5 seconds. The reporter said the aircraft was maintenance ferried to the overhaul base in ZZZ and the electrical system was thoroughly checked but the report could not be duplicated. The reporter said the aircraft was returned to service with no subsequent reports of power problems.

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Original NASA ASRS Text

Title: A LEARJET 35 IN DSCNT FROM 12000 FT LOST ALL ELECTRICAL PWR FOR 4-5 SECONDS THEN PWR WAS RESTORED.

Narrative: DURING AN AUTOPLT DSCNT THROUGH 12500 FT (OR SO, APPROX) FOR 11000 FT (PRESELECT) AT ABOUT 2500 FPM IN GLARING SUNLIGHT WITH THE PANEL LIGHTS ON HIGH, THE PANEL WENT DEAD. ALL THE GAUGES AND LIGHTS WENT DOWN INCLUDING THE ELECTRIC ENCODING ALTIMETER. MY FO ASKED ME WHAT HAPPENED, AND I SAID I DIDN'T KNOW. CTR THEN CRACKLED ON AND SAID ACR X SAY ALT TO WHICH I LOOKED DOWN AND REPLIED 10000 FT, WHICH IS WHAT I THOUGHT I SAW IN THE SUNLIGHT. CTR THEN SAID CLB TO 11000 FT, TO WHICH I LOOKED DOWN AND SAW US SMOOTHLY DSNDING THROUGH 11500 FT. I LEVELED OFF AT 11000 FT AND CONTINUED THE FLT. THE ACFT DID NOT LURCH DOWN LIKE IN A TSTM, NOR DID IT SUDDENLY CLB. MY THOUGHTS ARE THE SPIKE IN VOLTAGE BRIEF AS IT WAS (4 OR 5 SECONDS) AFFECTED THE ELECTRIC ALTIMETER IN WAYS I AM UNFAMILIAR WITH, NOT BEING A MECH. I BELIEVE WHAT I SAID MAY HAVE BEEN WRONG BECAUSE THE LACK OF ACFT MOTION, INDICATING 12500 FT ONE SECOND, 10000 FT THE NEXT, THEN FINALLY 11500 FT DSNDING NORMALLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PWR LOSS WAS NOT CAUSED BY A STATIC DISCHARGE OR LIGHTNING STRIKE AND ONLY APPEARED FROM 4-5 SECONDS. THE RPTR SAID THE ACFT WAS MAINT FERRIED TO THE OVERHAUL BASE IN ZZZ AND THE ELECTRICAL SYS WAS THOROUGHLY CHKED BUT THE RPT COULD NOT BE DUPLICATED. THE RPTR SAID THE ACFT WAS RETURNED TO SVC WITH NO SUBSEQUENT RPTS OF PWR PROBS.

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.