What happened
On 5 June 2019, a B737-400 cargo aircraft, registration HS-KMC, landed at Singapore Changi Airport from Bangkok. During the landing roll on Runway 20R, the flight crew experienced intense vibrations immediately after deploying the thrust reversers. These vibrations caused the aircraft to deviate toward the left of the runway centerline, forcing the pilot to apply significant right rudder input to maintain control. The captain eventually took over the controls and applied braking to slow the aircraft.
Upon reaching the parking bay, a post-flight inspection by a maintenance engineer revealed substantial damage to the right-hand main landing gear. The upper torsion link was broken, and the damper manifold was missing. Furthermore, a hydraulic leak was identified due to a disconnected return line. During the subsequent inspection of the taxi route, airport personnel recovered the missing damper manifold and a hydraulic line guide from a nearby taxiway, which had been left as foreign object debris (FOD) on the ground.
The investigation
The investigation focused on the recent maintenance history of the aircraft's landing gear. The gear set had been recently replaced by a maintenance organization in Jakarta, Indonesia, just days prior to the incident. Investigators examined the flight data recorder, which showed no hydraulic pressure anomalies or low sink rates prior to touchdown, suggesting the leak was not present before landing.
Technical examinations of the damaged components, including the broken torsion links and the bent damper piston, were conducted by the aircraft manufacturer. The investigation also tracked the movement of the detached components, which were found on taxiway NC2, posing a potential hazard to other aircraft.