Narrative:

I deviated at suggestion of approach between thunderstorms on RNAV direct route from new dgr tlm. The radios failed (high pitch tone on both communications) after approach requested I reset transponder because they were not receiving. I determined source of problem appeared to be low voltage and discharge on ammeter. I contacted gpt on hand held radio and requested vectors to nearest airport. Gpt handed me over to mob approach. Mob was breaking up on my hand held and they were having problems understanding me. To avoid IMC conditions, I changed altitude to a lower altitude before authorized. All lights on panel were about out and by turning off all equipment and lights, I salvaged use of LORAN for navigation (including turning off transponder that probably wasn't operating because of low voltage). I did not know this area and had difficulty using IFR map for VFR navigation. I maintained, as I got closer to mobile, a broken conversation with mobile, but deviated altitude to maintain VMC when I could not understand approach. Landed mob without lights in heavy rain without further incident. Conditions were dark at landing, I do not know if I interfered with other traffic, but may have flown through a military traffic pattern on way to mobile. Vors wouldn't function. Ceiling lowered to below 1200 near airport. The next day a mechanic determined voltage regulator failed. Apparently I was distraction by WX and did not see any alternative than unauthorized change in altitude to maintain VMC condition with marginal at best navigation instruments. The operating instruments would not have likely supported an instrument approach. The plane is well maintained but this did not prevent a failure of the total electrical system. I need to practice emergency procedures.

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Original NASA ASRS Text

Title: AN SMA PVT PLT HAD A PARTIAL ELECTRICAL FAILURE IN IMC. HE DEVIATED FROM HIS ASSIGNED ALT AND COURSE TO LAND ENRTE.

Narrative: I DEVIATED AT SUGGESTION OF APCH BTWN TSTMS ON RNAV DIRECT RTE FROM NEW DGR TLM. THE RADIOS FAILED (HIGH PITCH TONE ON BOTH COMS) AFTER APCH REQUESTED I RESET TRANSPONDER BECAUSE THEY WERE NOT RECEIVING. I DETERMINED SOURCE OF PROBLEM APPEARED TO BE LOW VOLTAGE AND DISCHARGE ON AMMETER. I CONTACTED GPT ON HAND HELD RADIO AND REQUESTED VECTORS TO NEAREST ARPT. GPT HANDED ME OVER TO MOB APCH. MOB WAS BREAKING UP ON MY HAND HELD AND THEY WERE HAVING PROBLEMS UNDERSTANDING ME. TO AVOID IMC CONDITIONS, I CHANGED ALT TO A LOWER ALT BEFORE AUTHORIZED. ALL LIGHTS ON PANEL WERE ABOUT OUT AND BY TURNING OFF ALL EQUIP AND LIGHTS, I SALVAGED USE OF LORAN FOR NAV (INCLUDING TURNING OFF TRANSPONDER THAT PROBABLY WASN'T OPERATING BECAUSE OF LOW VOLTAGE). I DID NOT KNOW THIS AREA AND HAD DIFFICULTY USING IFR MAP FOR VFR NAV. I MAINTAINED, AS I GOT CLOSER TO MOBILE, A BROKEN CONVERSATION WITH MOBILE, BUT DEVIATED ALT TO MAINTAIN VMC WHEN I COULD NOT UNDERSTAND APCH. LANDED MOB WITHOUT LIGHTS IN HVY RAIN WITHOUT FURTHER INCIDENT. CONDITIONS WERE DARK AT LNDG, I DO NOT KNOW IF I INTERFERED WITH OTHER TFC, BUT MAY HAVE FLOWN THROUGH A MIL TFC PATTERN ON WAY TO MOBILE. VORS WOULDN'T FUNCTION. CEILING LOWERED TO BELOW 1200 NEAR ARPT. THE NEXT DAY A MECH DETERMINED VOLTAGE REGULATOR FAILED. APPARENTLY I WAS DISTR BY WX AND DID NOT SEE ANY ALTERNATIVE THAN UNAUTHORIZED CHANGE IN ALT TO MAINTAIN VMC CONDITION WITH MARGINAL AT BEST NAV INSTS. THE OPERATING INSTS WOULD NOT HAVE LIKELY SUPPORTED AN INST APCH. THE PLANE IS WELL MAINTAINED BUT THIS DID NOT PREVENT A FAILURE OF THE TOTAL ELECTRICAL SYS. I NEED TO PRACTICE EMER PROCS.

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.