On 7 April 2022, at 1630 Universal Standard Time, an experimental Arion Lightning LS-1, registered N6688S, was departing Johnson County Airport, Mountain City, Tennessee, United States. During take-off, the engine experienced a partial loss of power at 70 knots, about midfield. The pilot was not sure that he could land on the remaining runway and immediately turned the right fuel tank to on and the engine rpm increased significantly. Within seconds, the engine lost total power, and the pilot elected to keep the airplane on the runway heading to clear several obstacles at the end of the runway. The pilot attempted a forced landing in a field but pulled up to clear a fence. The pilot was seriously injured.
Examination of the wreckage revealed that the diaphragm return spring on the engine side of the diaphragm was corroded. Additionally, the electric boost pump’s electrical wire was disconnected from the cockpit pump switch and the pump switch’s spade connector was loose. It is likely neither fuel pump was able to provide adequate fuel flow to the engine to sustain normal operation during the take-off.
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
A total loss of engine power due to intermittent operation of both the engine-driven fuel pump and the electric boost pump. Contributing was the pilot’s delay in rejecting the take-off, after the initial loss of engine power, which resulted in a collision with terrain.