Beech 95-B55 (T42A) N101DC accident near Athens, Georgia

Probable cause

The operator’s and the pilot’s continued operation of the airplane with a known electrical problem, resulting in a loss of electrical power and a gear-up landing.

NTSB analysis

The pilot was at 7,000 ft mean sea level (msl), in cruise flight, when he noticed electrical problems with the airplane. Night, visual meteorological conditions prevailed. He recalled that some of the displays on his navigation system were not functioning, he was hearing air traffic control (ATC) only intermittently, and his transponder was not operating normally. He contacted ATC and was given directions to a nearby airport. As he set up for an approach, he perceived that his engines were losing power and he needed full throttle to maintain safe airspeed. He could not read the engine instruments since it was dark and assumed a loss of engine power based on his tablet computer’s display. He attempted to lower the landing gear with the manual extension handcrank; however, he had difficulty accessing the handcrank and moving it. After landing, the airplane skidded to a stop on the runway with the landing gear retracted, resulting in substantial damage to the lower fuselage.

The manual extension handcrank was used to lower the landing gear after the accident and it operated in a normal manner. After charging the aircraft battery, the engines were started and ran up to 2,100 rpm each. Troubleshooting of the alternators revealed that the 2-amp fuse for the left alternator was blown, preventing that alternator from functioning. Also, the field wire for the right alternator was found disconnected, preventing that alternator from functioning. Once investigators replaced the blown fuse and reattached the field wire, both alternators functioned normally. The postaccident engine test runs did not reveal evidence of a mechanical malfunction or anomaly that would have precluded normal operation.

When interviewed after the accident, the pilot reported that the airplane had been flown for the last 10 days with both alternator warning lights continuously illuminated in the cockpit and with unreliable load meters. When the pilot brought the electrical issues up with his supervisor and with maintenance personnel, he was told to keep flying the airplane because it was being used to transport cargo and there was fear that the operator would lose the contract. He stated that management pressured him to fly the airplane, telling him that there was nothing wrong with it.

Text from the NTSB. Open the NTSB docket for ERA23LA064 for the full record.