Narrative:

Shortly after reaching 12000', cruise altitude on IFR flight slc-sql, I noticed alternator discharge. WX was good VMC all the way to destination airport, approximately 500 NM to west. I turned off all electrical equipment except 1 navigation and 1 communication radio and transponder. This was sufficient for flight conditions, so long us battery power remained. Rather than stop at a remote desert location, I elected to try to complete as much of the flight as I could, due to good WX conditions. Predictably, however, my battery would not power remaining gear and I advised ATC of problem, and got clearance for precautionary landing at rno in VFR conditions. All radio communication lost by 45 mins before landed. I circled down from 8000' MSL and landed west/O incident at rno, though I observed no tower lights (approximately X:40 pm PST). Appeared departing traffic may have been held while I landed on smaller, GA runway at reno cannon field (16L). I obtained assistance in taxiing to a repair facility from rno operations. They were helpful and did not comment on my circumstances, nor was I asked to contact anyone. I was able to obtain repairs and took off all 4 hours later, to complete my trip VFR at night. As soon as I cleared rno airspace, I shut off all nonessential electrical gear to preserve battery power in event of repeat alternator failure (belt problem), and knowing my battery was not well charged. At one point, I mistakenly turned off now lights for a few mins over sparsely populated area. May have gotten off cardinal altitudes a bit. Finished flight avoiding sfo TCA, but I mistakenly encroached on airspace (air traffic area possibly) of moffett air base and pao due to error of orientation at night, trying to preserve electrical power. Landed at sql west/O further incident, completing all phases of trip west/O apparent harm to anyone or anything at any time. I have no specific recommendations or thoughts as to how to avoid incidents of this type. Callback conversation with reporter revealed the following: reporter admits to a certain level of get homeitis on this flight. In retrospect he felt he should not have continued after the failure of his alternator. The failure was caused by the drive belt coming off the pulley drive which the maintenance people feel was caused by the propeller, which was found to be out of balance, creating enough vibration to cause the belt to detach from the pulley. No in-flight vibration was felt during this trip. Reporter stated that more discretion would be shown if this type of event was to happen again.

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Original NASA ASRS Text

Title: SMA PLT CONTINUES HIS IFR FLT EVEN THOUGH HIS ALTERNATOR LIGHT INDICATES A POTENTIAL LOSS OF 2-WAY COM AND LOSS OF ELECTRICAL POWER. AFTER REPAIRS HE REDUCES ELECTRICAL LOADS IN ANTICIPATION OF ELECTRICAL LOSS.

Narrative: SHORTLY AFTER REACHING 12000', CRUISE ALT ON IFR FLT SLC-SQL, I NOTICED ALTERNATOR DISCHARGE. WX WAS GOOD VMC ALL THE WAY TO DEST ARPT, APPROX 500 NM TO W. I TURNED OFF ALL ELECTRICAL EQUIPMENT EXCEPT 1 NAV AND 1 COM RADIO AND XPONDER. THIS WAS SUFFICIENT FOR FLT CONDITIONS, SO LONG US BATTERY PWR REMAINED. RATHER THAN STOP AT A REMOTE DESERT LOCATION, I ELECTED TO TRY TO COMPLETE AS MUCH OF THE FLT AS I COULD, DUE TO GOOD WX CONDITIONS. PREDICTABLY, HOWEVER, MY BATTERY WOULD NOT PWR REMAINING GEAR AND I ADVISED ATC OF PROB, AND GOT CLRNC FOR PRECAUTIONARY LNDG AT RNO IN VFR CONDITIONS. ALL RADIO COM LOST BY 45 MINS BEFORE LANDED. I CIRCLED DOWN FROM 8000' MSL AND LANDED W/O INCIDENT AT RNO, THOUGH I OBSERVED NO TWR LIGHTS (APPROX X:40 PM PST). APPEARED DEPARTING TFC MAY HAVE BEEN HELD WHILE I LANDED ON SMALLER, GA RWY AT RENO CANNON FIELD (16L). I OBTAINED ASSISTANCE IN TAXIING TO A REPAIR FAC FROM RNO OPS. THEY WERE HELPFUL AND DID NOT COMMENT ON MY CIRCUMSTANCES, NOR WAS I ASKED TO CONTACT ANYONE. I WAS ABLE TO OBTAIN REPAIRS AND TOOK OFF ALL 4 HRS LATER, TO COMPLETE MY TRIP VFR AT NIGHT. AS SOON AS I CLRED RNO AIRSPACE, I SHUT OFF ALL NONESSENTIAL ELECTRICAL GEAR TO PRESERVE BATTERY PWR IN EVENT OF REPEAT ALTERNATOR FAILURE (BELT PROB), AND KNOWING MY BATTERY WAS NOT WELL CHARGED. AT ONE POINT, I MISTAKENLY TURNED OFF NOW LIGHTS FOR A FEW MINS OVER SPARSELY POPULATED AREA. MAY HAVE GOTTEN OFF CARDINAL ALTS A BIT. FINISHED FLT AVOIDING SFO TCA, BUT I MISTAKENLY ENCROACHED ON AIRSPACE (ATA POSSIBLY) OF MOFFETT AIR BASE AND PAO DUE TO ERROR OF ORIENTATION AT NIGHT, TRYING TO PRESERVE ELECTRICAL PWR. LANDED AT SQL W/O FURTHER INCIDENT, COMPLETING ALL PHASES OF TRIP W/O APPARENT HARM TO ANYONE OR ANYTHING AT ANY TIME. I HAVE NO SPECIFIC RECOMMENDATIONS OR THOUGHTS AS TO HOW TO AVOID INCIDENTS OF THIS TYPE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR ADMITS TO A CERTAIN LEVEL OF GET HOMEITIS ON THIS FLT. IN RETROSPECT HE FELT HE SHOULD NOT HAVE CONTINUED AFTER THE FAILURE OF HIS ALTERNATOR. THE FAILURE WAS CAUSED BY THE DRIVE BELT COMING OFF THE PULLEY DRIVE WHICH THE MAINT PEOPLE FEEL WAS CAUSED BY THE PROP, WHICH WAS FOUND TO BE OUT OF BALANCE, CREATING ENOUGH VIBRATION TO CAUSE THE BELT TO DETACH FROM THE PULLEY. NO INFLT VIBRATION WAS FELT DURING THIS TRIP. RPTR STATED THAT MORE DISCRETION WOULD BE SHOWN IF THIS TYPE OF EVENT WAS TO HAPPEN AGAIN.

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.