Incident Overview
On 17 October 1998 at 1600 hrs, a Cessna 340, registration N340YP, operated a private training flight from Biggin Hill Airport, Kent, with two crew members on board. After takeoff, the pilot was unable to raise the landing gear and immediately returned to the airport. The subsequent landing was uneventful until the aircraft turned off the runway, at which point the pilot felt a jarring sensation from the left side. The pilot stopped the aircraft clear of the runway and shut down the engines.
Inspection Findings
Ground inspection revealed that the left main landing gear torque link knuckle joint had separated. This allowed the wheel to caster, causing minor damage to the mainwheel door. No injuries were reported.
Cause of Separation
Investigation determined that the torque link knuckle joint had separated as a result of an insufficiently substantial washer having been fitted under the head of the knuckle bolt at some time. In service, the washer became sufficiently worn and distorted such that the bolt head migrated through the bore of the associated scissor link, carrying the knuckle bush with it, until the joint between the two halves of the scissor link separated.