Incident Overview
On May 16, 2019, at approximately 1435 central daylight time, an experimental amateur-built Zenith CH750 STOL, registered as N750GZ, sustained substantial damage during a forced landing near Savannah-Hardin County Airport (SNH) in Savannah, Tennessee. The pilot and passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91.
Pilot's Account
According to the pilot, the preflight inspection revealed no anomalies. After engine start, the battery voltage was checked. During flight, the pilot observed a drop in the direct current (DC) electrical bus voltage from a normal value of about 13.6 volts direct current (vdc) to about 12.5 vdc. He initiated a turn back to SNH. Approximately two minutes later, the DC bus voltage dropped to 0 vdc and the engine stopped producing power. The pilot selected an open field and performed a forced landing.
Post-Accident Observations
After the accident, the pilot noted that the alternator in-line circuit breaker, located under the instrument panel, was tripped. An examination by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the firewall, as well as additional damage to the nosewheel and rudder pedals. Inspection of the alternator circuit breaker indicated that its location underneath the instrument panel was not visible or accessible for reset during flight.
Electrical System Configuration
The airplane was constructed with an engine electrically dependent on a single alternator and a single battery to provide required electrical power for the fuel pump and engine ignition systems. Following the accident, the pilot installed a backup battery in the airplane.