Mountain City, TN, USA
N6688S
HENRY L BERRIER JR ARION LIGHTNING LS-1
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.
On April 7, 2022, about 1310 eastern daylight time, an experimental amateur-built Arion Lightning LS-1, N6688S, was substantially damaged when it was involved in an accident near Mountain City, Tennessee. The commercial pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot/owner stated that prior to flight, the airplane was completely filled with fuel, and he performed a preflight inspection with no anomalies noted. The airplane departed on runway 24 at Johnson County Airport (6A4), Mountain City, Tennessee. Runway 24 is a 4,498 ft long asphalt runway. The engine was at full power and the pilot lifted off at 53 knots, but the engine experienced a partial loss of power several seconds later 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 he 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 had to pull-up to clear a fence. The airplane subsequently landed hard in the field and collided with a creek bed, resulting in substantial damage to the forward fuselage. The pilot added that in retrospect, he should have rejected the takeoff during the first loss of engine power. Additionally, the airplane had experienced one other total loss of engine power a few months prior to the accident. At that time, the pilot was in cruise flight when the engine lost power; however, the propeller kept windmilling and he was able to restore power. He does not remember everything that he did to restore power, but he remembered switching fuel tanks He immediately brought the airplane to the kit manufacturer for troubleshooting; however, the cause of the power loss was never determined. Examination of the wreckage by a Federal Aviation Administration inspector revealed substantial damage to the right wing and fuselage. Adequate fuel remained onboard and was drained by first responders due to a potential environmental hazard. The inspector observed that the fuel bowl was about three-fourths full of fuel and the fuel was absent of visible contamination. He checked the air intake, and it was free of obstructions. Additionally, the propeller rotated without any binding. The wreckage was further examined following its recovery to the airport, by the airport manager and a mechanic with an inspection authorization. The electric boost pump switch in the cockpit was noted in the off position; however, the pilot stated that it was on for takeoff and after impact, he moved the fuel selector, master switch, and fuel pump switch to off. Disassembly of the engine driven fuel pump revealed that the diaphragm return spring on the engine side of the diaphragm was corroded. One end of the spring, where it sat against the steel plate on the diaphragm, was rusted completely away leaving an abrupt sharp point. Examination of the electric boost pump revealed its 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 the pump activated, it pumped 4 psi, which was in the range for normal engine operation. The airplane was assembled from a kit in 2012. Its most recent annual condition inspection was completed on August 16, 2021. At that time, the airframe and engine had accumulated 233 hours since new. The airplane flew an additional 15 hours from the time of the most recent inspection until the accident. The previous owner also built the airplane. The accident pilot stated that he was never able to get the fuel pressure sensor connected properly to the Dynon primary flight display (PFD). As such, fuel pressure was not displayed to the pilot. Additionally, fuel pressure data recorded by the Dynon was erroneous. Data from the PFD were successfully downloaded and plotted; however, the fuel pressure parameter was considered unreliable. Many of the recorded values during the accident flight and previous flight ranged from 0.1 to 0.9 psi, which would not support engine operation. The engine manufacturer published a 3.0 psi as nominal for normal engine operation.
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.
Source: NTSB Aviation Accident Database
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