KNIGHT AA Nieuport 28 — Basehor, KS

What happened

On the day of the accident, the pilot intended to fly the airplane for the first time since it had been repaired following a previous hard landing. The pilot, who was the builder of the experimental biplane, was taking off on a personal flight when the airplane veered to the left, lifted off the runway, and flew back toward the runway centerline. A witness noted that the airplane was going “very slow.” When the airplane reached an altitude of about 200 ft above ground level, the airplane started to make a slow left turn. The witness then observed the tail of the airplane drop down and the left wing roll, and the airplane subsequently spun to the ground. A postcrash fire ensued.

About 2 years before the accident, the airplane was involved in a hard landing, which damaged the landing gear. The pilot subsequently repaired the landing gear, which would have included removal and reassembly of the wing struts. Postaccident examination of the airplane found that the left outer interplane strut was not correctly attached to the lower left wing compression strut. The bolt and nut were present through the outer interplane strut but had not been secured to the lower wing compression strut.

The disconnected strut would have resulted in an out-of-rig condition and change the flight characteristics of the upper and lower left wings, potentially inducing drag while in flight. In this case, the upper and lower left wings would have each displayed different flight characteristics because the lower wing angle was pushed down and the upper wing was pushed up during the wire-tensioning process. The faster the airplane flew in the out-of-rig condition, the more pronounced the changed flight characteristics of the upper and lower left wings would have become. During the accident sequence, the pilot likely tried to slow the airplane to improve the changed flight characteristics, but the airplane’s critical angle of attack was exceeded and resulted in the airplane’s subsequent stall and spin to the ground.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.