Amateur-built MK-4 accident near Harnett, North Carolina, August 30, 2018

The NTSB's narrative final · quoted from the NTSB record

The pilot departed on a 35-nautical-mile flight with 9 gallons of fuel onboard. While en route, he noticed that the fuel quantity was decreasing faster than normal, and he elected to stop for fuel. During the descent toward the airport, the engine lost total power and the pilot subsequently performed a forced landing in a field. After touchdown, the airplane nosed over and came to rest inverted, resulting in substantial damage to the wings and fuselage. Examination of the airplane and engine revealed no evidence of preimpact mechanical anomalies that would have prevented normal engine operation. About 1/2 gallon of fuel was drained from the fuel tank after the accident; however, an unquantified amount spilled onto the ground during recovery, and the amount of fuel onboard at the time of the accident could not be determined. The right wing fuel tank was vented by a modified fuel cap. Holes were drilled in the top of the cap to allow air in the tank as fuel is consumed. The pilot recommended that a forward-facing tube vent be installed per a service letter issue by the kit manufacturer of a similar experimental, amateur-built airplane; however, the reason for loss of engine power and whether the modified fuel cap contributed to the accident could not be determined based on the available information.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.