Narrative:

My family and I were returning to lci from alb. While flying toward concord VOR on an IFR flight plan I was monitoring ZBW. At about 30 mi west of concord VOR I asked center whether they were trying to reach me. Center's voice seemed to be dimming and it sounded as though they were inquiring my call sign. Center said they were not trying to reach me. I told them that their signal seemed strangely weak. Center seemed unimpressed and reiterated that they were not trying to reach me. A short time later center handed me off to mht approach on 134.75. I acknowledged, but when I tried to contact mht approach my radios died, both communication and navigation. Moments later, all electrical power was dead. I checked the ammeter, all circuit breakers and nothing seemed out of place. I could not identify the cause of the loss of electrical power. I then called mht approach on a handheld transceiver and advised them I had a loss of electrical power and requested vectors to mht for an emergency landing. They promptly gave me vectors to the airport and requested that I remain VFR. Obviously, at that point, I was no longer capable of navigating by instruments. I acknowledged and proceeded to the airport. While en route, mht approach inquired about the number aboard, my altitude at various points, and whether my landing gear was operable. I advised them of all this data, including the fact that my landing gear did not operate. They suggested that I try to get the gear down while above 3000 ft MSL, which I did. It was quite difficult to maintain a constant altitude because the emergency gear extension procedure requires slowing to 100 mph and pushing 2 levers forward in succession. These levers require enormous (2 handed) pressure to move into place. The gear came down and mht approach cleared me to land on runway 35. As a precaution, the tower hailed fire apparatus to the runway. The landing and rollout was fine. Fire personnel examined the aircraft before clearing the runway to ensure there was no risk of fire. This problem arose because there was no noticeable indication that both alternators were off line until the radios became weak. By that time, the battery was only moments away from dying. The next day I found that the left alternator field wire broke off causing a momentary voltage surge, which caused the right alternator relay to take the right alternator off line. I never received any signal that this had happened, from the ammeter or the circuit breaker. I believe this is a poor system and defeats the whole purpose of multi-engine aircraft. I believe the electrical system like this should be enhanced so that the pilot will receive a clear warning that electrical problems are afoot. That way the pilot will have an opportunity to correct the problem before total battery failure. In this case my family and I were able to handle the emergency and get ourselves and the aircraft down with a normal safe landing with no injury to us or the aircraft. But for the next pilot, he or she may not be so fortunate. Callback conversation with reporter revealed the following information: reporter states this electrical system defeats the idea of flying a twin, the redundancy, and back up system. Reporter states his aircraft was a PA30, twin comanche. The electrical system is common for piston pwred aircraft with the alternators connected to a control buss. When the second alternator goes off line there is no indication which would help tremendously since you can put the second alternator back on line. Reporter checked the ammeter and there was no indication of any problem. When reporter tried to put the alternator back on line it was probably already too late. New twins have an alternator warning light which comes on when an alternator goes off line. Many new high performance singles have 2 alternators and 2 vacuum pumps each with warning lights so one can manually switch over to the back up system. He believes there should be an airworthiness directive to have such equipment installed in the older aircraft.

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Original NASA ASRS Text

Title: PA30 HAS TOTAL ELECTRICAL FAILURE AT NIGHT ON IFR FLT PLAN.

Narrative: MY FAMILY AND I WERE RETURNING TO LCI FROM ALB. WHILE FLYING TOWARD CONCORD VOR ON AN IFR FLT PLAN I WAS MONITORING ZBW. AT ABOUT 30 MI W OF CONCORD VOR I ASKED CTR WHETHER THEY WERE TRYING TO REACH ME. CTR'S VOICE SEEMED TO BE DIMMING AND IT SOUNDED AS THOUGH THEY WERE INQUIRING MY CALL SIGN. CTR SAID THEY WERE NOT TRYING TO REACH ME. I TOLD THEM THAT THEIR SIGNAL SEEMED STRANGELY WEAK. CTR SEEMED UNIMPRESSED AND REITERATED THAT THEY WERE NOT TRYING TO REACH ME. A SHORT TIME LATER CTR HANDED ME OFF TO MHT APCH ON 134.75. I ACKNOWLEDGED, BUT WHEN I TRIED TO CONTACT MHT APCH MY RADIOS DIED, BOTH COM AND NAV. MOMENTS LATER, ALL ELECTRICAL PWR WAS DEAD. I CHKED THE AMMETER, ALL CIRCUIT BREAKERS AND NOTHING SEEMED OUT OF PLACE. I COULD NOT IDENT THE CAUSE OF THE LOSS OF ELECTRICAL PWR. I THEN CALLED MHT APCH ON A HANDHELD TRANSCEIVER AND ADVISED THEM I HAD A LOSS OF ELECTRICAL PWR AND REQUESTED VECTORS TO MHT FOR AN EMER LNDG. THEY PROMPTLY GAVE ME VECTORS TO THE ARPT AND REQUESTED THAT I REMAIN VFR. OBVIOUSLY, AT THAT POINT, I WAS NO LONGER CAPABLE OF NAVING BY INSTS. I ACKNOWLEDGED AND PROCEEDED TO THE ARPT. WHILE ENRTE, MHT APCH INQUIRED ABOUT THE NUMBER ABOARD, MY ALT AT VARIOUS POINTS, AND WHETHER MY LNDG GEAR WAS OPERABLE. I ADVISED THEM OF ALL THIS DATA, INCLUDING THE FACT THAT MY LNDG GEAR DID NOT OPERATE. THEY SUGGESTED THAT I TRY TO GET THE GEAR DOWN WHILE ABOVE 3000 FT MSL, WHICH I DID. IT WAS QUITE DIFFICULT TO MAINTAIN A CONSTANT ALT BECAUSE THE EMER GEAR EXTENSION PROC REQUIRES SLOWING TO 100 MPH AND PUSHING 2 LEVERS FORWARD IN SUCCESSION. THESE LEVERS REQUIRE ENORMOUS (2 HANDED) PRESSURE TO MOVE INTO PLACE. THE GEAR CAME DOWN AND MHT APCH CLRED ME TO LAND ON RWY 35. AS A PRECAUTION, THE TWR HAILED FIRE APPARATUS TO THE RWY. THE LNDG AND ROLLOUT WAS FINE. FIRE PERSONNEL EXAMINED THE ACFT BEFORE CLRING THE RWY TO ENSURE THERE WAS NO RISK OF FIRE. THIS PROB AROSE BECAUSE THERE WAS NO NOTICEABLE INDICATION THAT BOTH ALTERNATORS WERE OFF LINE UNTIL THE RADIOS BECAME WEAK. BY THAT TIME, THE BATTERY WAS ONLY MOMENTS AWAY FROM DYING. THE NEXT DAY I FOUND THAT THE L ALTERNATOR FIELD WIRE BROKE OFF CAUSING A MOMENTARY VOLTAGE SURGE, WHICH CAUSED THE R ALTERNATOR RELAY TO TAKE THE R ALTERNATOR OFF LINE. I NEVER RECEIVED ANY SIGNAL THAT THIS HAD HAPPENED, FROM THE AMMETER OR THE CIRCUIT BREAKER. I BELIEVE THIS IS A POOR SYS AND DEFEATS THE WHOLE PURPOSE OF MULTI-ENG ACFT. I BELIEVE THE ELECTRICAL SYS LIKE THIS SHOULD BE ENHANCED SO THAT THE PLT WILL RECEIVE A CLR WARNING THAT ELECTRICAL PROBS ARE AFOOT. THAT WAY THE PLT WILL HAVE AN OPPORTUNITY TO CORRECT THE PROB BEFORE TOTAL BATTERY FAILURE. IN THIS CASE MY FAMILY AND I WERE ABLE TO HANDLE THE EMER AND GET OURSELVES AND THE ACFT DOWN WITH A NORMAL SAFE LNDG WITH NO INJURY TO US OR THE ACFT. BUT FOR THE NEXT PLT, HE OR SHE MAY NOT BE SO FORTUNATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THIS ELECTRICAL SYS DEFEATS THE IDEA OF FLYING A TWIN, THE REDUNDANCY, AND BACK UP SYS. RPTR STATES HIS ACFT WAS A PA30, TWIN COMANCHE. THE ELECTRICAL SYS IS COMMON FOR PISTON PWRED ACFT WITH THE ALTERNATORS CONNECTED TO A CTL BUSS. WHEN THE SECOND ALTERNATOR GOES OFF LINE THERE IS NO INDICATION WHICH WOULD HELP TREMENDOUSLY SINCE YOU CAN PUT THE SECOND ALTERNATOR BACK ON LINE. RPTR CHKED THE AMMETER AND THERE WAS NO INDICATION OF ANY PROB. WHEN RPTR TRIED TO PUT THE ALTERNATOR BACK ON LINE IT WAS PROBABLY ALREADY TOO LATE. NEW TWINS HAVE AN ALTERNATOR WARNING LIGHT WHICH COMES ON WHEN AN ALTERNATOR GOES OFF LINE. MANY NEW HIGH PERFORMANCE SINGLES HAVE 2 ALTERNATORS AND 2 VACUUM PUMPS EACH WITH WARNING LIGHTS SO ONE CAN MANUALLY SWITCH OVER TO THE BACK UP SYS. HE BELIEVES THERE SHOULD BE AN AIRWORTHINESS DIRECTIVE TO HAVE SUCH EQUIP INSTALLED IN THE OLDER ACFT.

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.