ERA09FA273 · Explorer Aeronautique Inc. Ecoflyer

The pilot was the designer and manufacturer of the experimental accident airplane, a prototype that he intended to begin producing and selling. He had flown to an aircraft trade show to display the airplane and was returning to his home airport when he encountered turbulent winds. He landed at a nearby airport and then departed again about 2 hours later. Approximately 15 minutes after departure, the left wing separated from the airplane. Postaccident examination of portions of the composite left wing, left wing strut, and tubular metal undercarriage revealed the separation of the left wing likely initiated at the inboard attachments to the fuselage. The structure of the left wing fractured around the aluminum plates connecting the spar to the strut, allowing the strut and wing to separate. At the upper end of the left wing strut, the protruding aluminum bar stock and the two aluminum plates connecting it to the wing spar were bent down and forward. The steel plates connecting the inboard end of the bar stock to the lower fuselage frame had residual deformation showing displacement aft and nose-down twisting, with some cracking in the welds. The bar stock adjacent to the fracture retained residual deformation indicating that the fracture occurred under downward bending at the outboard end. The steel plates connecting the bottom end of the right strut to the lower fuselage frame had residual deformation showing displacement forward and nose-down twisting. Additionally, the construction of the undercarriage displayed several areas susceptible to fatigue cracking, including holes drilled through the metal undercarriage tubes. The foreign airworthiness certification process for the airplane required no inspection, other than self-certification from the pilot/manufacturer, prior to issuance of an airworthiness certificate.

Verbatim NTSB analysis and probable cause from the NTSB dataset