Incorrect assembly of landing gear hardware caused a Cessna 402C twin to veer off a runway on landing, said the FAA in a special airworthiness information bulletin that alerts owners, operators, and maintenance personnel to two new caution statements to be included as supplements to the aircraft maintenance manual.
The caution statements “stress the criticality” of proper handling of washers (part number 5045018) that are part of the torque link center pivot attaching hardware during assembly.
“The loss of control was due to the right main landing gear (MLG) torque links detaching at a center pivot point. The detachment of the torque links allowed the lower strut and wheel assembly to rotate 90 degrees perpendicular to the runway, which caused the tire and wheel assembly to lock up. The locking up and dragging of the tire and wheel assembly during landing inhibited the controllability of the aircraft and caused it to veer off the runway into the grass, where it came to rest,” said the bulletin.
The FAA determined that the detachment was caused by incorrect assembly of the torque link center pivot attaching hardware. Recommended corrective measures include tagging the washers during removal to ensure proper placement during reinstallation, and a cautionary reminder to maintenance personnel that the washers “must be properly located under the bolt head and the nut.”
The FAA recommends that the caution statements be added as supplements to the aircraft maintenance manual until a revised manual is released, probably in the third quarter of 2011.
