Boeing 737-59D, G-BVKC, 21 February 2004
Boeing 737-59D, G-BVKC
Summary:
The left main landing gear (MLG) began a violent shimmy (yaw oscillation) when the wheelbrakes were applied after a normal landing touchdown, probably damaging the MLG lower torsion link. The shimmying stopped when braking was reduced but restarted when braking was increased, causing the torsion link to fracture. Further higher amplitude shimmying of the left MLG ensued, resulting in severe MLG tyre, wheel and brake damage and substantial oscillatory loads on the aircraft structure. Steering difficulties were experienced during both shimmying episodes. It was likely that the shimmying resulted from excessive wear of the torsion link apex joint that reduced the effectiveness of the shimmy damper. Maintenance records indicated that the MLG had been maintained in accordance with the manufacturer’s recommendations, but it was considered that relevant Aircraft Maintenance Manual (AMM) procedures could be difficult to follow. Similar failures had occurred over a number of years, which had been attributed by the aircraft manufacturer to excessive apex joint wear that had not been detected or adequately rectified during maintenance. One safety recommendation has been made.
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