Amateur-built CH750 N750GZ accident near Savannah, Tennessee

Probable cause

The total loss of engine power due to a loss of all electrical power. Contributing to the accident was the inaccessible placement of the alternator circuit breaker and the construction of the airplane without a backup electrical source.

NTSB analysis

The pilot was conducting a personal flight in the experimental amateur-built airplane, and after departing the local area, noticed the DC electrical bus voltage decrease from 13.6 volts to 12.5 volts. He initiated a turn back to the airport and about 2 minutes later, the DC bus voltage decreased to 0 volts and the engine stopped producing power. The pilot performed a forced landing to an open field, during which the airplane sustained substantial damage.

The airplane was constructed such that the engine was electrically dependent on a single alternator and a single battery to provide required electrical power to operate the fuel pump and ignition systems. Examination of the airplane revealed that the alternator circuit breaker, which was located behind the instrument panel and out of view of and inaccessible to the pilot, was tripped. Based on the pilot's description of events, it is likely that an electrical load drew an excessive current through the alternator circuit breaker, which resulted in it tripping and interrupting the electrical power supplied by the alternator. The engine's electrically-operated fuel and ignition systems continued to function on battery power for about 2 minutes before the engine stopped running. The pilot's reported inability to restore electrical power (and subsequently, engine power) at a low altitude resulted in the forced landing.

Text from the NTSB. Open the NTSB docket for ERA19LA177 for the full record.