NTSB Factual Report

On August 29, 2016, about 0930 central daylight time, a North American Navion airplane, N91488, departed off the side of the runway at the Monett Regional Airport (KHFJ), Monett, Missouri. The pilot was not injured and the airplane was substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The flight originated from the Gimlin Airport (18MO), Ozark, Missouri, and was landing at KHFJ.

According to the pilot, he landed the airplane on runway 18 at KHFJ about 0930. Weather was clear and he estimated the wind at 120° at 4 knots. Following a normal approached and landing, he noticed the airplane's right wing was lower than the left wing, and the airplane began a pull to the right. The airplane departed the right side of the runway, went down an embankment and run through a barbed wire fence. When the pilot inspected the airplane, he noted that the right main landing gear (MLG) had collapsed. During recovery of the airplane, the airplane was lifted and the right MLG was extended manually and locked.

The airplane was examined by inspectors from the Federal Aviation Administration. A landing gear swing test was conducted and the landing gear had been improperly rigged. A review of the airplane's history revealed that several weeks prior to the accident, the airplane's right MLG scissor was damaged during a high speed turn.

A review of maintenance records revealed that on July 22, 2016, the airplane's right MLG scissor was replaced with a serviceable unit. A gear retraction test was conducted and described as satisfactory.

NTSB Probable Cause

Maintenance personnel’s failure to properly rig the right main landing gear locking mechanism, which resulted in a gear collapse during landing.