What happened
On 27 August 2016, at approximately 1545LT, a MASwings DHC6-400 (registration 9M-SSB) was performing a scheduled landing at Marudi Airfield, Sarawak. Operating as flight MH3568, the aircraft was cleared to land on Runway 10 under wind conditions reported by Air Traffic Control as 290 degrees at 04 knots.
The aircraft's main wheels made contact with the runway 300 meters from the threshold. The nose wheel subsequently touched down 179 meters further down the runway, remaining relatively centered on the runway centerline. However, shortly after the nose wheel contact, the aircraft began to deviate from its path. Tire marks on the runway indicate that the aircraft started to veer to the left approximately 18 meters after the nose wheel touchdown. Following this deviation, the aircraft skidded for 72 meters before exiting the runway onto the grass. The aircraft eventually came to a stop 28 meters from the runway centerline, with the tail section extending 3 meters beyond the airport perimeter fence, though it did not strike the structure.
The investigation
Investigators examined the runway surface and analyzed tire marks left by the aircraft during the excursion. The inspection revealed a distinct line of tire marks from the nose wheel touchdown point, which included seven dark spots spaced at uniform intervals of 2.2 meters. The investigation focused on the sequence of the aircraft's movement from the point of touchdown to its final position on the grass.
Findings
- The aircraft initially maintained the centerline during the main wheel touchdown.
- A deviation to the left occurred 18 meters after the nose wheel made contact with the runway.
- The aircraft underwent a 72-meter skid on the grass after leaving the runway surface.
- The final resting position was 28 meters from the runway centerline.
- The exact cause of the directional deviation remains undetermined.
Safety action
Following the investigation, the following recommendations were made:
- Implement the use of colors other than white for nose wheel centering markings on the control column to help the pilot better assess the position of the nose-wheel tiller.
- Conduct a technical review of the assembly and mechanical components of the nose-wheel centering mechanism.