Accident Overview
On December 5, 2023, about 1645 central standard time, an experimental, amateur-built Vans RV6A, registration N600VS, was substantially damaged during an accident near Fordyce, Arkansas. The airplane was operated as a personal flight under Title 14 Code of Federal Regulations Part 91. The two pilots on board sustained minor injuries.
Flight and Power Loss
The airplane was purchased by a private pilot and a flight instructor, who planned to fly it from Durant Regional Airport (DUA) in Durant, Oklahoma, to their home airport in Mississippi. The private pilot noted that the airplane did not have a current regulatory condition inspection and attempted to obtain a ferry permit but was unable to reach the Oklahoma Flight Standards District Office, so he decided not to pursue it.
The flight instructor, acting as pilot flying, reported that at 7,500 ft mean sea level (msl) with the autopilot engaged, the airplane was “running great.” About one minute after the cabin heat was turned on, the engine sound decreased and the tachometer indication dropped to zero rpm. They turned off the cabin heat, checked circuit breakers, and turned on the fuel boost pump. Fuel gauges indicated both tanks were more than half full. They diverted to Fordyce Municipal Airport (5M4) to attempt a landing on runway 5 (3,183 ft by 60 ft, dry asphalt). With the autopilot disengaged, they descended at about 65 knots. At about 2,000 ft msl, the engine was still sputtering, so they reduced throttle to idle, turned off the fuel boost pump and master switch, but the engine continued to sputter. They descended and maneuvered onto final approach, then turned the master switch back on. They were unable to extend the electric flaps, so they performed a forward slip to descend. They discontinued the slip about 1,500 ft down the runway, then landed with about 500 ft of runway remaining, overran the runway, and nosed over in the grass.
The private pilot reported that during cruise at 7,500 ft msl and about 178 knots indicated airspeed, there were no signs of abnormal operation. The primary tachometer on the electronic flight instrument system (EFIS) indicated 4,500 rpm then zero. The standby tachometer then also indicated zero as airspeed decreased. 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 5M4 and attempted to shut down the engine, but it continued to sputter with partial power. They turned electrical power back on to extend the electric flaps, but they would not extend. They performed two S-turns on base leg and a forward slip on final. The airplane touched down about 2,500 ft down the 3,183 ft runway, then went off the end and nosed over.
Postaccident Examination
A 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 the airplane was equipped with an experimental automotive engine. Two 12-volt car batteries were 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. The electrical panel featured a three-position momentary toggle switch for the flap position control circuit (center OFF). The flap circuit was tested and verified operational; in the up position there was 12V, and in the down position 12V with reversed polarity. The engine-driven automotive alternator charging function could not be verified.
With the avionics master switch on, the fuel quantity indicators showed the left tank half full and the right tank 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.
Spark plugs were removed from all cylinders. With the ignition switch on, the engine starter was energized and a spark was verified from each spark plug. All spark plugs were clean with no oil burning or carbon fouling.
With external battery power, an engine start was attempted with ignition on and fuel pump off; the engine cranked but would not start. With the fuel pump on, the engine started and ran at idle. A red “check engine” light on the instrument panel illuminated during operation and through throttle changes. A multimeter tested for alternator output at the alternator cable, but 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 showed that if the fuel pump was turned off during operation, rpm decreased but the engine operated for more than a minute before all fuel was exhausted and the engine stopped.