Narrative:

While approaching ocf (via direct) at 7000 ft, radio communication was lost. All avionics on board failed, including transponder. An attempt was made to transmit in the blind to jax approach and 7600 was set in the transponder in case any 1-WAY communication was available. Subsequent attempts to recycle the avionics failed and the decision was made to land VFR at ocf (ocala). While descending to approach ocf, there was no indication of landing gear lights, which directed my attention to a larger system-wide electrical problem. I noticed that my left knee had apparently bumped the switch for the alternators (located at the bottom left of the electrical panel on the left fuselage wall), moving them to the off position and forcing a drain of reserve power from the battery. (Note: operation of each alternator was confirmed during runup.) when the alternator switch was reactivated, sufficient electrical power was available to again operate all system. At that time, because there appeared to be no mechanical or electrical problem other than a switch being inadvertently turned off, the decision was made to recontact jax approach and radio communication was re-established. After approval from jax approach, we changed squawk code from 7600 back to our assigned code, climbed back to cruise altitude and continued the flight. No further untoward events transpired and the flight was completed safely. More caution when moving about in the pilot's seat during flight with special attention given to knee position is in order. Inclusion of a bus voltage indicator or an alternator warning light would also have been helpful, since the present ammeter indicates system draw, not output. More careful pilot attention to the electrical status is always a positive attribute. Callback conversation with reporter revealed the following information: the reporter was wearing a noise suppressing headset, one that requires a battery pack. Since he did not want the pack on the floor, subject to moving under the rudder pedals, he clipped it to his left pants leg. There are 3 switches for the alternator, 1 master switch and 1 for each alternator. The 3 switches are located in a recessed housing to the left of the pilot's station. The battery pack, in swinging on its attachment cord, had entered this cavity and tripped the master switch, rendering all electrical equipment inoperative. The electrical monitoring instrumentation on the panel consists of an ammeter that reads from zero on up, showing current flow only. It does not indicate the source of the current flow, reading only the bus voltage available. This was a rental aircraft. The pilot has 200 hours in type and has never heard of this happening before. He said that, '...an incident like this probably would not happen again in 20000 flts....' reporter stated that he is going to send this information to his pilot organization for publication as an anecdotal story of interest to other PA44 pilots.

Related reports:

Google
 

Original NASA ASRS Text

Title: PRIMARY ELECTRICAL SUPPLY PROB OCCURS WHEN THE PLT OF PA44 SEMINOLE ACCIDENTALLY TRIPS THE MASTER ALTERNATOR SWITCH TO THE OFF POS 15 MI NE OF OCF, FL.

Narrative: WHILE APCHING OCF (VIA DIRECT) AT 7000 FT, RADIO COM WAS LOST. ALL AVIONICS ON BOARD FAILED, INCLUDING XPONDER. AN ATTEMPT WAS MADE TO XMIT IN THE BLIND TO JAX APCH AND 7600 WAS SET IN THE XPONDER IN CASE ANY 1-WAY COM WAS AVAILABLE. SUBSEQUENT ATTEMPTS TO RECYCLE THE AVIONICS FAILED AND THE DECISION WAS MADE TO LAND VFR AT OCF (OCALA). WHILE DSNDING TO APCH OCF, THERE WAS NO INDICATION OF LNDG GEAR LIGHTS, WHICH DIRECTED MY ATTN TO A LARGER SYS-WIDE ELECTRICAL PROB. I NOTICED THAT MY L KNEE HAD APPARENTLY BUMPED THE SWITCH FOR THE ALTERNATORS (LOCATED AT THE BOTTOM L OF THE ELECTRICAL PANEL ON THE L FUSELAGE WALL), MOVING THEM TO THE OFF POS AND FORCING A DRAIN OF RESERVE PWR FROM THE BATTERY. (NOTE: OP OF EACH ALTERNATOR WAS CONFIRMED DURING RUNUP.) WHEN THE ALTERNATOR SWITCH WAS REACTIVATED, SUFFICIENT ELECTRICAL PWR WAS AVAILABLE TO AGAIN OPERATE ALL SYS. AT THAT TIME, BECAUSE THERE APPEARED TO BE NO MECHANICAL OR ELECTRICAL PROB OTHER THAN A SWITCH BEING INADVERTENTLY TURNED OFF, THE DECISION WAS MADE TO RECONTACT JAX APCH AND RADIO COM WAS RE-ESTABLISHED. AFTER APPROVAL FROM JAX APCH, WE CHANGED SQUAWK CODE FROM 7600 BACK TO OUR ASSIGNED CODE, CLBED BACK TO CRUISE ALT AND CONTINUED THE FLT. NO FURTHER UNTOWARD EVENTS TRANSPIRED AND THE FLT WAS COMPLETED SAFELY. MORE CAUTION WHEN MOVING ABOUT IN THE PLT'S SEAT DURING FLT WITH SPECIAL ATTN GIVEN TO KNEE POS IS IN ORDER. INCLUSION OF A BUS VOLTAGE INDICATOR OR AN ALTERNATOR WARNING LIGHT WOULD ALSO HAVE BEEN HELPFUL, SINCE THE PRESENT AMMETER INDICATES SYS DRAW, NOT OUTPUT. MORE CAREFUL PLT ATTN TO THE ELECTRICAL STATUS IS ALWAYS A POSITIVE ATTRIBUTE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS WEARING A NOISE SUPPRESSING HEADSET, ONE THAT REQUIRES A BATTERY PACK. SINCE HE DID NOT WANT THE PACK ON THE FLOOR, SUBJECT TO MOVING UNDER THE RUDDER PEDALS, HE CLIPPED IT TO HIS L PANTS LEG. THERE ARE 3 SWITCHES FOR THE ALTERNATOR, 1 MASTER SWITCH AND 1 FOR EACH ALTERNATOR. THE 3 SWITCHES ARE LOCATED IN A RECESSED HOUSING TO THE L OF THE PLT'S STATION. THE BATTERY PACK, IN SWINGING ON ITS ATTACHMENT CORD, HAD ENTERED THIS CAVITY AND TRIPPED THE MASTER SWITCH, RENDERING ALL ELECTRICAL EQUIP INOP. THE ELECTRICAL MONITORING INSTRUMENTATION ON THE PANEL CONSISTS OF AN AMMETER THAT READS FROM ZERO ON UP, SHOWING CURRENT FLOW ONLY. IT DOES NOT INDICATE THE SOURCE OF THE CURRENT FLOW, READING ONLY THE BUS VOLTAGE AVAILABLE. THIS WAS A RENTAL ACFT. THE PLT HAS 200 HRS IN TYPE AND HAS NEVER HEARD OF THIS HAPPENING BEFORE. HE SAID THAT, '...AN INCIDENT LIKE THIS PROBABLY WOULD NOT HAPPEN AGAIN IN 20000 FLTS....' RPTR STATED THAT HE IS GOING TO SEND THIS INFO TO HIS PLT ORGANIZATION FOR PUB AS AN ANECDOTAL STORY OF INTEREST TO OTHER PA44 PLTS.

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.