NTSB Factual Report

On August 21, 1999, about 1940 Eastern Daylight Time, a homebuilt Kolb Mark III, N6268A, was substantially damaged when it impacted terrain near Scott, Ohio. The certificated private pilot and passenger were fatally injured. Visual meteorological conditions prevailed and no flight plan was filed for the local flight conducted under 14 CFR Part 91.

According to a witness, the pilot had departed from an airstrip located on the pilot's property, and circled to the southeast. When the airplane leveled off, the throttle decreased, which the witness described as a "normal" sound; however, he noted that the "plane was not too high."

A second witness heard the airplane flying to the south "at about tree top level," then circled to the left to a northwest heading. The witness recalled that the engine sounded like it was throttling back the entire time that the airplane was turning. The airplane disappeared from the view of the witness, which was followed by the sound of "plastic tearing, and breaking of corn stalks."

A third witness, who noticed the airplane after it passed overhead, stated that the airplane made a "weird sound" and descended nose first toward the ground.

The airplane came to rest in a bean field. Examination of the wreckage by a Federal Aviation Administration (FAA) inspector did not reveal any pre-impact malfunctions with the airframe or engine.

A resident, located about 1/2 mile southwest of the wreckage, found a part of the airplane in a bean field, and turned it over to the local authorities. A FAA inspector later identified the part as a gap seal.

The gap seal was an airfoil shaped piece of plexi-glass used to fill the gap, which remained in-between the wings when they were assembled.

According to a representative of the airplane kit manufacturer, testing had been accomplished with the gap seal removed from the airplane. The test results indicated that performance was reduced due to the "resulting loss of lift." The representative further added, "Some pilots would also forget to properly secure the gap seal before flying, which would be held by 2 springs to the fuselage and a center hold down catch."

A FAA inspector examined the gap seal after the accident. It was observed that the rear left-hand spring was still attached to the gap seal. The spring was not stretched or damaged. The right-hand spring was not recovered after the accident. The center hold down catch was also examined and it did not display any damage.

NTSB Probable Cause

The pilot's failure to maintain airspeed, which resulted in a stall, after he experienced a loss of lift due to an improperly installed gap seal.