NTSB Identification: CHI01FA232.
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Accident occurred Saturday, July 21, 2001 in Poplar Grove, IL
Probable Cause Approval Date: 09/20/2002
Aircraft: Smith Kelly-D, registration: N303SM
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The amateur-built experimental biplane was destroyed when it experienced an in-flight separation of the right upper wing and spiraled into the terrain. A witness reported that he saw, "the Kelly-D airplane coming out of a maneuver of some kind. He continued west at approx. 800-1000'. He pulled up, rolled to the left (inverted) and pulled out (1/2 loop). He repeated the same maneuver going east, and as he leveled out I saw what looked like a large piece of fabric and another object leave the airplane. The fabric fell slowly the other object a little faster. The airplane continued for a couple seconds and then rolled over and spiraled into the ground." The witness reported the maneuver was smooth and that it could not have pulled more that 3.5g's during the maneuver. He reported the failure occurred as the airplane was leveling off. He reported the engine was operating during the entire flight and there was no indication of an engine problem. One of the wooden propeller blades was found bent opposite the direction of rotation, broken at the hub, and was splintered. A propeller slash was found in the dirt at the point of propeller impact. The clevis ends of the flying and landing wires were examined. Six of the jam nuts were found loose. The examination of the left front upper spar revealed that the adhesive used on the plywood doubler did not cover the entire area being bonded to the spar. The USDA Forest Products Laboratory report stated, "There was also very little penetration of the adhesive into the spar." The report stated that the right upper front and rear spars exhibited compression and tension failure surfaces.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The right upper wing failed due to overload. A factor was the pilot performing aerobatic manuevers.

Full narrative available

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