N600VSVans Aircraft RV-6A

On December 5, 2023, about 1645 central standard time, an experimental, amateur-built Vans RV6A airplane, N600VS, was substantially damaged when it was involved in an accident near Fordyce, Arkansas. The two pilots received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

A private pilot and a flight instructor had purchased the airplane and planned to fly it to their home airport in Mississippi from Durant Regional Airport (DUA), Durant, Oklahoma. The private pilot stated that the airplane did not have a current regulatory condition inspection. The private pilot stated that he attempted to obtain a ferry permit for the flight, but after being unable to reach the Oklahoma Flight Standards District Office, he decided not to pursue obtaining a ferry permit.

The flight instructor, who was the pilot flying, reported that at 7,500 ft mean sea level (msl), with the autopilot on, the airplane was “running great.” About one minute after the cabin heat was turned on, the engine sound decreased, and the tachometer indication went to zero rpm. They turned the cabin heat off, checked the circuit breakers, and turned on the fuel boost pump. The fuel gauges indicated that both tanks were more than half full. They diverted the flight to Fordyce Municipal Airport (5M4), Fordyce, Arkansas, to attempt a landing on runway 5 (3,183 ft by 60 ft, dry asphalt). With the autopilot disengaged, they descended toward 5M4 at an airspeed of about 65 knots. About 2,000 ft msl, the engine was still sputtering so they reduced the throttle to idle, turned off the fuel boost pump, and turned off the master switch, but the engine continued to sputter. They continued to descend and maneuvered the airplane onto final approach, and then turned the master switch back on. They were unable to extend the electric flaps so they performed a forward slip in an attempt to descend. They discontinued the slip about 1,500 ft down the runway, then landed with about 500 ft of runway remaining and were unable to stop; they overran the runway and nosed over in the grass.

The private pilot reported they were in cruise flight about 7,500 ft msl and about 178 knots indicted airspeed with “no signs of abnormal operation or any indication of faulty systems.” Next, the primary tachometer on the electronic flight instrument system (EFIS) indicated 4,500 rpm and shortly after indicated zero rpm. Then the standby tachometer indicated zero rpm as the airspeed decreased to 160 knots and continued to decrease. They selected the left fuel tank and turned on the fuel pump, which resulted in a slight rpm increase followed by a loss of power. They elected to land at the nearest airport, 5M4, and attempted to shut down the engine, but it continued to sputter with partial power. They turned the electrical power back on in attempt to extend the electric flaps, but they would not extend. They were still too fast, so they completed two S-turns on the base leg, and a forward slip during final approach. The airplane touched down about 2,500 ft down the 3,183 ft runway. The airplane then went off the end of the runway and nosed over.

The Federal Aviation Administration inspector reported that the airplane came to rest inverted about 100 yards from the end of the runway and sustained substantial damage to the fuselage and empennage.

Postaccident examination revealed that the airplane was equipped with an experimental automotive engine. There were two 12-volt car batteries mounted in the engine compartment. The positive cable on the right battery was not tight and could be moved with light finger pressure. There was no independent ignition system installed.

An external power source was used to supply DC voltage to the batteries to facilitate powering the airplane’s electrical system. The electrical panel featured a three-position, momentary up/down toggle switch for the flap position control circuit, with the center position being OFF. The momentary up/down switch would drive the flap motor and when released it automatically returned to the center OFF position. The flap circuit was tested and verified operational, and the flap position switch was actuated in all three positions. In the center position, no voltage was supplied, in the up position there was 12V present, and in the down position, there was 12V present, but the polarity was reversed. The engine-driven automotive alternator charging function could not be verified.

With the avionics master switch on, the fuel quantity indicators were operational. The left tank indicated half full, and the right tank indicated empty. The fuel selector valve was found in the left tank position. The electric fuel pump was tested and verified operational. There was no engine-driven fuel pump installed.

The spark plugs were removed from all cylinders. The engine starter was energized with the ignition switch in the on position, and a spark was verified from each spark plug. All four spark plugs were clean with no oil burning or carbon fouling present.

With external battery power supplied, an engine start was attempted with the ignition on and the fuel pump off. The engine starter cranked the engine, but it would not start. An engine start was then attempted with the fuel pump on and the engine started and operated at an idle setting. A red light labeled “check engine” on the instrument panel was illuminated during the engine operation and through multiple throttle setting changes. A multimeter was used to test for alternator output at the alternator cable; however, only voltage from the external battery was present. With the engine running, the external battery was disconnected from the airplane’s main batteries and the engine stopped immediately.

Additional engine test runs were accomplished to determined how the engine would respond if the fuel pump was turned off during operation. There was a decrease in rpm, but the engine operated more than a minute before all fuel was exhausted and the engine stopped.