Amateur-built ARION LIGHTNING LS-1 N6688S accident near Mountain City, Tennessee

Probable cause

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 takeoff, after the initial loss of engine power, which resulted in a collision with terrain.

NTSB analysis

The amateur-built airplane was assembled from a kit about 10 years prior to the accident and had only been flown about 250 hours during those 10 years. After performing a preflight inspection and noting no anomalies, the pilot proceeded to take off from a 4,498-ft-long asphalt runway. During takeoff, 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 airplane subsequently landed hard in the field and collided with a creek bed. The pilot stated that, in retrospect, he should have rejected the takeoff during the initial partial loss of engine power.

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. When the wire was reconnected, the spade connector had to be wiggled to get the pump to activate. Once activated, it pumped normally. Given this information, it is likely neither fuel pump was able to provide adequate fuel flow to the engine to sustain normal operation during the takeoff.

Text from the NTSB. Open the NTSB docket for ERA22LA186 for the full record.