On July 25, 2023, about 0733 central daylight time, a Heath V-Strut, N9549, was substantially damaged when it was involved in an accident at Wittman Regional Airport (OSH), Oshkosh, Wisconsin. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to one witness, after an extensive taxi, the airplane used about 200 ft of the runway to raise the tail of the airplane and about 1,000 ft of runway to become airborne. The witness stated that the airplane “looked sluggish” after takeoff, with the nose of the airplane high. The airplane started a left turn and then the left wing dipped, and the airplane descended below the tree line. Security video showed the airplane descend in a relatively flat pitch attitude. The left wing dropped, and the airplane impacted the ground in a left-wing-low attitude. The airplane continued forward onto the engine and propeller, nosed over, and came to rest inverted.

According to the pilot he had just departed runway 36L and the climb rate was as expected. He turned the airplane 150° as instructed during his briefing to avoid runway 9/27. During the turn, the airplane stopped climbing and exhibited a decrease in performance. The pilot reported that he aimed the airplane toward a clearing past the trees and attempted a landing to the field.

The airplane impacted a field adjacent to a commercial building about 1,000 ft east of runway 36L. The initial impact point contained fragmented wood consistent with the wing tip. The main wreckage was located just east of the initial impact point and included both wings, the empennage, fuselage, and engine (see Figure 1).

Figure 1. Airplane wreckage.

Aileron cable continuity was confirmed for both the right and left aileron, from the respective aileron inboard to the flight control stick. Control continuity was confirmed from the rudder inboard to the rudder pedals and from the elevator inboard to the flight control stick.

The engine and propeller assembly remained attached to the fuselage at the firewall. The wooden Watson propeller blade was splintered consistent with impact on each side of the blade and contained grass and vegetation imbedded within the fracture. The splintered pieces of the propeller blade were found forward of the main wreckage. The gascolator and bowl remained attached at the firewall and contained fuel. Nothing mechanical was noted with the engine or related systems that would have precluded normal engine function.

A review of the icing probability chart contained within FAA Special Airworthiness Information Bulletin CE-09-35 showed that the atmospheric conditions at the time of the accident were conducive for icing at glide power.