What happened
The pilot was flying an aircraft when he encountered thunderstorm activity at approximately 1900 hours. During this time, the left fuel gauge became inoperative, and the aircraft had no communication equipment installed. Only one navigation receiver was operative, and there were no instrument lights or a slaved directional gyro available for use.
As conditions darkened, the pilot was unable to see the instrument panel. He noticed that the 10-amp circuit breaker had popped, indicating a loss of electrical power. Consequently, he was unable to activate the runway lights at Lincoln County Airport because he lacked a radio transmitter to trigger them. Without electrical power, the landing light could not be used either.
The pilot made a first approach attempt from north to south. He then made his last approach attempt from the south to the north. During this final attempt, the aircraft struck rolling terrain approximately one mile south of the runway.
The investigation
A laboratory evaluation was conducted on both voltage regulators found in the aircraft. The results showed that both units operated within the manufacturer's rated performance specifications, indicating they were not the source of the electrical failure.
Findings
The pilot had no electrical power during the critical phase of the approach. This failure prevented the use of instrument lights, landing lights, and runway activation systems. The lack of visibility due to darkness and the absence of functional navigation aids contributed significantly to the inability to complete the safe landing.
Safety message
Pilots should ensure that essential electrical components are functioning correctly before flight, especially when planning to operate in weather conditions that may require instrument approaches or night operations. Redundancy in communication and navigation equipment is critical for safety.