Zenith CH701 N56553 accident near Okeechobee, Florida

Probable cause

An in-flight structural failure due to a severely corroded wing strut, which resulted in a loss of airplane control.

NTSB analysis

The private pilot was repositioning the experimental light-sport airplane that had neither been flown nor received a condition inspection in about 4 years. Witnesses near the accident site reported that the airplane was rocking back and forth when one or both wings folded up and back. The airplane entered an uncontrolled descent, impacted the ground in a residential area, and was destroyed by a postcrash fire. Two windscreen fragments, including one that was about 18 inches by 11.5 inches, were found on the ground about 150 ft northeast of the initial ground scar, opposite the airplane's direction of travel.

Examination of the engine did not reveal any preimpact mechanical malfunctions; however, impact and fire damage precluded a functional check of the engine and its fuel and ignition systems.

Metallurgical examination of the wings' front and rear struts revealed severe internal corrosion in all the struts and multiple separations. Lack of bending deformation suggested that the initial failure of the wing struts occurred in the left wing forward strut, likely as a result of normal operational loads applied to a severely corroded strut with a severely reduced cross-sectional area.

The airplane was manufactured about 8 years before the accident and purchased by the current owner about 7 years before the accident. The pilot was operating the airplane without a current condition inspection or ferry permit authorization. Witness statements, the discovery of the windscreen fragments about 150 ft before the airplane's first contact with ground, and metallurgical examination of the wing struts suggest that the airplane experienced an in-flight structural failure due to corrosion of the wing struts, which resulted in a loss of airplane control.

Text from the NTSB. Open the NTSB docket for ERA16FA033 for the full record.