A C150 on a training flight at 3000 ft diverted and made an off airport landing due to complete loss...

Attributes
ACN	375722
Time
Date	199707
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : lgc
State Reference	GA
Altitude	agl bound lower : 0 agl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tower : lgb
Operator	general aviation : instructional
Make Model Name	Cessna 150
Operating Under FAR Part	Part 91
Flight Phase	cruise other landing other other
Flight Plan	None
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 12 flight time total : 325 flight time type : 13
ASRS Report	375722
Person 2
Affiliation	Other
Function	instruction : trainee
Qualification	other other : other pilot : student
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

As I was flying with my student on a local flight to practice maneuver, we experienced a complete electrical failure. I therefore decided to head back to the airport and terminate the flight, but on our way back, I heard a noise that sounded like some electrical wires were arcing or shorting. 15 mi away from the airport, I decided to land in a grass field to prevent a possible electrical cabin fire from starting. This landing was therefore a precautionary landing in the interest of our safety and that of the airplane. I didn't want to continue the flight and deal with a possible emergency. After turning off all electrical switches, I made 3 low passes over the field to make sure the area was suitable for landing. I then made a no flap soft field landing after reviewing all checklist items with my student. The FAA and sheriff department were notified, along with the property owner. I believe my decision to make a precautionary landing was the correct one, not knowing what that noise was. There was no damage to the airplane nor to property. Nobody was injured. Callback conversation with reporter revealed the following information: the reporter stated the aircraft was a C150 and the maintenance action taken was to replace the starter relay and the voltage regulator. The reporter advised the starter relay was stuck closed energizing the starter continuously and the voltage regulator had failed electrically.

Original NASA ASRS Text

Title: A C150 ON A TRAINING FLT AT 3000 FT DIVERTED AND MADE AN OFF ARPT LNDG DUE TO COMPLETE LOSS OF ELECTRICAL PWR CAUSED BY A DEFECTIVE STARTER RELAY AND VOLTAGE REGULATOR.

Narrative: AS I WAS FLYING WITH MY STUDENT ON A LCL FLT TO PRACTICE MANEUVER, WE EXPERIENCED A COMPLETE ELECTRICAL FAILURE. I THEREFORE DECIDED TO HEAD BACK TO THE ARPT AND TERMINATE THE FLT, BUT ON OUR WAY BACK, I HEARD A NOISE THAT SOUNDED LIKE SOME ELECTRICAL WIRES WERE ARCING OR SHORTING. 15 MI AWAY FROM THE ARPT, I DECIDED TO LAND IN A GRASS FIELD TO PREVENT A POSSIBLE ELECTRICAL CABIN FIRE FROM STARTING. THIS LNDG WAS THEREFORE A PRECAUTIONARY LNDG IN THE INTEREST OF OUR SAFETY AND THAT OF THE AIRPLANE. I DIDN'T WANT TO CONTINUE THE FLT AND DEAL WITH A POSSIBLE EMER. AFTER TURNING OFF ALL ELECTRICAL SWITCHES, I MADE 3 LOW PASSES OVER THE FIELD TO MAKE SURE THE AREA WAS SUITABLE FOR LNDG. I THEN MADE A NO FLAP SOFT FIELD LNDG AFTER REVIEWING ALL CHKLIST ITEMS WITH MY STUDENT. THE FAA AND SHERIFF DEPT WERE NOTIFIED, ALONG WITH THE PROPERTY OWNER. I BELIEVE MY DECISION TO MAKE A PRECAUTIONARY LNDG WAS THE CORRECT ONE, NOT KNOWING WHAT THAT NOISE WAS. THERE WAS NO DAMAGE TO THE AIRPLANE NOR TO PROPERTY. NOBODY WAS INJURED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS A C150 AND THE MAINT ACTION TAKEN WAS TO REPLACE THE STARTER RELAY AND THE VOLTAGE REGULATOR. THE RPTR ADVISED THE STARTER RELAY WAS STUCK CLOSED ENERGIZING THE STARTER CONTINUOUSLY AND THE VOLTAGE REGULATOR HAD FAILED ELECTRICALLY.

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.

A C150 on a training flight at 3000 ft diverted and made an off airport landing due to complete loss of electrical power caused by a defective starter relay and voltage regulator.