What happened
On 7 October 2005, a BAe 146, registration EI-CPJ, was performing a passenger flight when it experienced a significant technical issue during its landing roll on Runway 10 at London City Airport. Following a smooth touchdown, the nose wheel began to vibrate as it contacted the runway. As the crew applied braking to the main wheels, the vibration intensified into a violent shimmy. To maintain directional control and mitigate the severity of the oscillation, the pilot utilized moderate differential braking, eventually bringing the aircraft to a halt. The crew declared a PAN call to Air Traffic Control, and airport emergency services attended the scene.
The investigation
Following the incident, an engineer inspected the nose landing gear and discovered that a bolt from the torque link assembly was missing. The aircraft was subsequently moved to a maintenance facility for a more thorough examination. While the missing bolt was not recovered from the airport or the departure airfield, inspections by both the operator's engineering staff and the landing gear manufacturer confirmed the loss of the central pivot bolt in the torque link assembly.
Detailed analysis revealed that once the bolt detached, the upper half of the torque link pivoted downward, making contact with a shoulder on the lower part of the landing gear. This movement effectively turned the assembly into a solid strut, preventing the oleo from compressing under the 2.5-tonne weight of the nose. This mechanical restriction caused localized damage to the torque link components and the landing gear housing. Furthermore, testing showed that the breakout torque of the steering/castering friction damper was significantly lower than specified, and the oleo inflation pressure was approximately 28% above the required level, likely due to oil leakage past the seals.
Findings
- The nose wheel steering/braking was inoperative due to the failure of the torque link assembly.
- The loss of the central pivot bolt caused the torque link to pivot into a position that prevented the oleo strut from compressing.
- The missing torque link bolt was a primary factor, though investigators could not determine if its loss caused the shimmy or was a result of it.
- The nose landing gear experienced internal oil leakage, leading to an inflation pressure 28% above the specified limit.
- The breakout torque for the steering/castering friction damper was only about 34-40% of the required value.