Casualties unknown

2006-11-26: Cessna 421C (N471BW) — Moline, IL

Moline, IL, US

On November 26, 2006, a Cessna 421C (registration N471BW) was involved in an aviation accident near Moline, IL. Investigators recorded the probable cause as: The washer that prevents the bolt head and pressed bushing from pulling through the common pivot-point was not installed. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

During landing, the right main landing gear collapsed due to separation of the upper and lower torque links at the common pivot-point, caused by a missing washer in the assembly.

Event Description

The incident occurred during the landing flare and touchdown. The pilot reported that the airplane initially touched down on the left main landing gear, followed by the nose gear and then the right main landing gear. When the right main landing gear made contact, the pilot stated it "didn't feel right or usual."

Pilot Actions

In response, the pilot advanced engine power, and the airplane became airborne for approximately 50 feet. Subsequently, the airplane "bounced onto runway," and the right propeller struck the runway. The airplane became airborne again before performing a final "hard landing."

Inspection Findings

Post-incident inspection of the right main landing gear revealed that the upper and lower torque links had separated at the common pivot-point. This separation allowed the lower strut to rotate within the upper strut. The 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. Despite this, 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 correctly assembled.

The missing washer allowed the torque links to separate during touchdown, leading to the collapse of the right main landing gear.

Probable cause

The washer that prevents the bolt head and pressed bushing from pulling through the common pivot-point was not installed.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20070109X00026. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.