Aviation Accident Summaries

Aviation Accident Summary CHI07CA028

Moline, IL, USA

Aircraft #1

N471BW

Cessna 421C

Analysis

The right main landing gear collapsed during landing flare/touchdown. The pilot reported that the airplane initially touched down on the left main landing gear, followed by the nose and right main landing gears. The pilot stated that when the right main landing gear touched it "didn't feel right or usual." The pilot reported that he advanced engine power, and the airplane became airborne for about 50 feet. The pilot stated that the airplane "bounced onto runway" and the right propeller impacted the runway. The airplane became airborne again, and then "landed hard" for the final time. Inspection of the right main landing gear showed that the upper and lower torque links had separated at the common pivot-point, which allowed the lower strut to rotate within the upper strut. The two torque links are connected by a bolt, nut, bushing, and several washers. The washer that prevents the bolt head and pressed bushing from pulling through the common pivot-point was not installed. The as-installed stack-up remained together, and was attached to the upper torque link. The pressed bushing from the lower torque link was found with the as-installed stack-up. The torque links for the left main landing gear were found correctly assembled.

Factual Information

The right main landing gear collapsed during landing flare/touchdown. The pilot reported that the airplane initially touched down on the left main landing gear first, followed by the nose and right main landing gears. The pilot stated that when the right main landing gear touched it "didn't feel right or usual." The pilot reported that he advanced engine power and the airplane became airborne for about 50 feet. The pilot stated that the aircraft "bounced onto runway" and the right propeller impacted the runway. The pilot reported that the airplane became airborne again and then "landed hard" for the final time. Inspection of the right main landing gear showed that the upper and lower torque links had separated at the common pivot-point, which allowed the lower strut to rotate within the upper strut. The two torque links are connected by a bolt, nut, bushing, and several washers. The washer that prevents the bolt head and pressed bushing from pulling through the common pivot-point was not installed. The as installed stack-up remained together and was attached to the upper torque link. The pressed bushing from the lower torque link was found with the as installed stack-up. The torque links for the left main landing gear were found correctly assembled.

Probable Cause and Findings

The incorrect installation of the torque link scissor assembly by maintenance personnel, which resulted in the collapse of the right main landing gear during landing.

 

Source: NTSB Aviation Accident Database

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