What happened
On 20 April 2020, a Pacific Aerospace FU 24-950 (registration PK-PNZ) was performing agricultural fertilizer spraying operations at Mambruk Airstrip in Lereh, Papua. After completing its 15th flight of the day, the pilot approached runway 36 for landing. The approach and touchdown were initially normal, with the aircraft maintaining a speed of approximately 55 knots.
During the landing roll, the pilot heard an impact from beneath the aircraft, followed by the nose of the plane dipping suddenly. The pilot immediately applied maximum braking and set the propeller to reverse. The aircraft subsequently veered to the left, exiting the runway and coming to a stop on the grass shoulder. Upon inspection, the crew discovered that the nose wheel had collapsed and the propeller blades were bent. A dead boar was later found approximately 120 meters from the start of the runway, with traces of its fur found on the aircraft's nose wheel mudguard.
The investigation
The KNKT investigation focused on the sequence of events leading to the gear failure and the presence of livestock on the airstrip. Investigators examined the wreckage and found that the nose gear cylinder had fractured and the fuselage skin at the lower attachment bracket was cracked. The investigation also looked into the management of the Mambruk Airstrip, which is located adjacent to a conservation area used by local residents for boar farming.
Analysis of the impact indicated that the boar was run over by the nose wheel and became lodged in the aircraft's nose wheel mudguard (fender). This created a significant braking effect on the nose gear, generating enough stress to cause the cylinder to fracture and the gear to collapse.
Findings
- The primary cause of the incident was the collapse of the nose landing gear following an impact with a boar on the runway.
- The aircraft was equipped with a nose wheel mudguard that allowed the animal to become stuck, creating the mechanical braking force that led to the structural failure.
- Existing fencing and gutter conditions at the airstrip were insufficient to prevent livestock from entering the runway area.
- Local residents were utilizing the nearby conservation area for boar farming, which placed animals in close proximity to flight operations.
Safety action
Following the incident, the airstrip operator implemented several measures, including repairing fences, improving gutter depth, and relocating the local farming area 6 km away from the airstrip. Additionally, the operator established 24-hour security posts at the runway ends. The aircraft operator, PT Sinar Mas Super Air, issued a quality notice prohibiting the installation of nose wheel mudguards on their Fletcher fleet to prevent similar mechanical interference in the future.