Amateur-built SEAREY N914WM accident near Polk City, Florida

Probable cause

The improper installation of incorrect attachment hardware by maintenance personnel during an undocumented repair, which resulted in an in-flight structural failure and subsequent loss of aircraft control. Contributing to the accident was the covering of the inspection port during the undocumented repair, which made it impossible for pilots or mechanics to inspect the attachment hardware for problems.

NTSB analysis

The pilot reported that the amateur-built amphibian airplane performed normally during taxi operations and takeoff from the surface of the lake. About 100 feet above the lake, the pilot heard a "loud bang or crashing sound," and the airframe then twisted. The airplane entered an uncontrolled, spiraling descent until it contacted the water. Postaccident examination of the airplane revealed that the right/forward wing strut joint was disconnected from the leading edge and that the attachment bolts were fractured. Further examination revealed that the bolts were installed after the airplane's original assembly and that they were shorter than the prescribed bolts and had been installed opposite the prescribed direction, which likely resulted in fatigue cracking and the eventual shearing of the bolts during the accident flight. Further examination of the wreckage revealed that the inspection port for the right wing strut attachment area had been covered during a previous, undocumented repair, which made it difficult for pilots or maintenance personnel to inspect the attachment hardware.

Text from the NTSB. Open the NTSB docket for ERA13LA199 for the full record.