Narrative:

I was in cruise flight in IMC at 6000 ft. I had just transitioned from V408 (swbound) to V143 (swbound) at robrt intersection near martinsburg. Because of turbulence at 6000 ft, I decided to call the controller (dulles approach) to request 8000 ft. I pressed the microphone button and began my request. After 4 or 5 words, everything on the panel seemed to go blank. I was taken completely by surprise and I was startled. I quickly realized that the engine was fine and all my flight instruments were ok, but all radios, transponder, intercom, navigation instruments, LORAN, DME and even my yoke mounted GPS were off, and I didn't know why. I realized I had a lost communication situation and thought of squawking 7600 but then remembered the transponder was off, too. During this time I was trying to hold altitude and heading ('fly the plane') but headings did wander +/-15-20 degrees. Then I realized it was not just lost communication, but also lost navigation. Both vors, the LORAN and GPS (neither were IFR certified) were inoperative and I was not far from the dulles class B airspace. I even thought of squawking 7700, but again the transponder was off. I knew cloud bases were about 4500 ft and I decided to use emergency authority/authorized to descend to VFR conditions and land at the nearest airport. At this point, I still didn't know what the problem was and was concerned that it might lead to a total electrical failure. I descended to about 4000 ft, determined my position from the sectional chart, and decided that martinsburg, wv, was the nearest airport, and headed toward it in VFR conditions. Once established toward martinsburg, I was able to think about the problem some more and realized that if the master avionics switch was off, I would have these symptoms. The switch is hidden from view by the control column, but when I felt it, I could tell it was off. I switched it back on and everything returned to normal. I called dulles approach and advised him of my altitude and approximately position. He cleared me to mrb VOR and to climb to 5000 ft (later to 8000 ft) and told me to tell him next time before I changed altitude. I would have been glad to but had no way to do that. In retrospect, I wish I had thought of the avionics master earlier, but I was scared and did what I thought was prudent. Callback conversation with reporter revealed the following information: the avionics switch, which is a switch type circuit breaker, was found to be rated to 20 amps. The draw when all the equipment being used was 70 amps. The system was checked and a new switch installed. No similar problems since.

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Original NASA ASRS Text

Title: C182 LOSES ALL COM AND NAV RADIOS IN IMC WX. PLT ELECTS TO DSND BELOW KNOWN CEILING AND DIVERT VFR. SUBSEQUENTLY FINDS AVIONICS SWITCH OFF ALLOWING RESOLUTION OF PROB. FLT IS CONTINUED.

Narrative: I WAS IN CRUISE FLT IN IMC AT 6000 FT. I HAD JUST TRANSITIONED FROM V408 (SWBOUND) TO V143 (SWBOUND) AT ROBRT INTXN NEAR MARTINSBURG. BECAUSE OF TURB AT 6000 FT, I DECIDED TO CALL THE CTLR (DULLES APCH) TO REQUEST 8000 FT. I PRESSED THE MIKE BUTTON AND BEGAN MY REQUEST. AFTER 4 OR 5 WORDS, EVERYTHING ON THE PANEL SEEMED TO GO BLANK. I WAS TAKEN COMPLETELY BY SURPRISE AND I WAS STARTLED. I QUICKLY REALIZED THAT THE ENG WAS FINE AND ALL MY FLT INSTS WERE OK, BUT ALL RADIOS, XPONDER, INTERCOM, NAV INSTS, LORAN, DME AND EVEN MY YOKE MOUNTED GPS WERE OFF, AND I DIDN'T KNOW WHY. I REALIZED I HAD A LOST COM SIT AND THOUGHT OF SQUAWKING 7600 BUT THEN REMEMBERED THE XPONDER WAS OFF, TOO. DURING THIS TIME I WAS TRYING TO HOLD ALT AND HDG ('FLY THE PLANE') BUT HDGS DID WANDER +/-15-20 DEGS. THEN I REALIZED IT WAS NOT JUST LOST COM, BUT ALSO LOST NAV. BOTH VORS, THE LORAN AND GPS (NEITHER WERE IFR CERTIFIED) WERE INOP AND I WAS NOT FAR FROM THE DULLES CLASS B AIRSPACE. I EVEN THOUGHT OF SQUAWKING 7700, BUT AGAIN THE XPONDER WAS OFF. I KNEW CLOUD BASES WERE ABOUT 4500 FT AND I DECIDED TO USE EMER AUTH TO DSND TO VFR CONDITIONS AND LAND AT THE NEAREST ARPT. AT THIS POINT, I STILL DIDN'T KNOW WHAT THE PROB WAS AND WAS CONCERNED THAT IT MIGHT LEAD TO A TOTAL ELECTRICAL FAILURE. I DSNDED TO ABOUT 4000 FT, DETERMINED MY POS FROM THE SECTIONAL CHART, AND DECIDED THAT MARTINSBURG, WV, WAS THE NEAREST ARPT, AND HEADED TOWARD IT IN VFR CONDITIONS. ONCE ESTABLISHED TOWARD MARTINSBURG, I WAS ABLE TO THINK ABOUT THE PROB SOME MORE AND REALIZED THAT IF THE MASTER AVIONICS SWITCH WAS OFF, I WOULD HAVE THESE SYMPTOMS. THE SWITCH IS HIDDEN FROM VIEW BY THE CTL COLUMN, BUT WHEN I FELT IT, I COULD TELL IT WAS OFF. I SWITCHED IT BACK ON AND EVERYTHING RETURNED TO NORMAL. I CALLED DULLES APCH AND ADVISED HIM OF MY ALT AND APPROX POS. HE CLRED ME TO MRB VOR AND TO CLB TO 5000 FT (LATER TO 8000 FT) AND TOLD ME TO TELL HIM NEXT TIME BEFORE I CHANGED ALT. I WOULD HAVE BEEN GLAD TO BUT HAD NO WAY TO DO THAT. IN RETROSPECT, I WISH I HAD THOUGHT OF THE AVIONICS MASTER EARLIER, BUT I WAS SCARED AND DID WHAT I THOUGHT WAS PRUDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE AVIONICS SWITCH, WHICH IS A SWITCH TYPE CIRCUIT BREAKER, WAS FOUND TO BE RATED TO 20 AMPS. THE DRAW WHEN ALL THE EQUIP BEING USED WAS 70 AMPS. THE SYS WAS CHKED AND A NEW SWITCH INSTALLED. NO SIMILAR PROBS SINCE.

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.