NTSB Factual Report

On February 23, 2010, approximately 1500 mountain standard time, a Champion 7KCAB, N5065X,registered to and operated by the private pilot, was substantially damaged when the fabric on the upper right wing tore off while the airplane was being maneuvered near Greeley, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot, the sole occupant, was not injured. The local flight originated at Greeley approximately 1430.

According to the pilot’s accident report, he was practicing steep turns around a point at 7,500 feet msl. During one of the turns, he heard an unusual sound and saw something falling away from the aircraft. He then noticed a piece of fabric “flapping” in the slipstream at the trailing edge of the right aileron. The airplane developed a slight sink rate, but the engine and flight controls operated normally. He returned to Greeley and made an uneventful landing.

Post-flight inspection disclosed that nearly 80 percent of the fabric on the top of the right wing had separated, and several ribs were damaged when the rivets separated with the fabric. Several other ribs were distorted from slipstream.

The airplane had been used for fish spotting in Alaska. According to the maintenance records, the airframe was last recovered on July 21, 2003 at a total time of 3,894.0 hours. Fabric punch tests since that recovering had been satisfactory.

The Denver NTSB was notified of this accident on April 10, 2010. The pilot offered no explanation as to why he didn't report the accident promptly in accordance with Title 49 CFR 830.5(a).

NTSB Probable Cause

An in-flight failure of the wing fabric for undetermined reasons.