What happened
On 26 January 2022, a PAC 750XL, registration P2-BWC, was performing a VFR charter flight from Kiunga Airport to Tekin Airstrip in Sandaun Province. The aircraft, operated by Niugini Aviation Services Limited, was carrying one pilot and six passengers.
During the landing phase, the pilot encountered a downdraft and touched down approximately 3 meters short of the runway threshold. During the landing roll, the left main landing gear assembly collapsed. This failure caused the left wing to drop abruptly, forcing the aircraft to veer toward the eastern edge of the airstrip. The aircraft continued its lateral movement until the left wingtip struck the edge of the extended right-side flap, causing the aircraft to skid across the airstrip boundary as the nose-wheel and right main wheel became bogged in the ground. All seven occupants were able to exit the aircraft without injury.
The investigation
The investigation focused on the structural failure of the landing gear and the operational environment at Tekin Airstrip. Investigators examined the wreckage and found that the left main landing gear attachment bolts had snapped due to significant impact stress. This stress was attributed to a reduced damping effect from either the tyre or the oleo strut during the landing impact.
Additionally, the investigation looked into the aircraft's emergency equipment and the operator's safety management. It was discovered that the aircraft's Emergency Locator Transmitter (ELT) failed to activate because the battery had been expired for eight months, rendering the aircraft unairworthy at the time of dispatch. The investigation also reviewed the operator's maintenance records, tool calibration registers, and risk assessment processes regarding rural airstrip operations.
Findings
- The primary cause of the gear collapse was the impact force transferring through the structure due to insufficient damping in the left main landing gear oleo or tyre.
- The aircraft was not airworthy at the time of departure because the ELT battery was expired.
- The operator had not conducted a specific risk assessment for the previous similar accident at Tekin Airstrip, nor was the pilot specifically checked into this airstrip.
- The operator's equipment calibration records for tyre pressurization tools were incomplete.
- The accident was survivable, and the pilot and passengers egressed the aircraft without external assistance.
Safety action
- The AIC recommended that CASA PNG prohibit fixed-wing flights into Tekin Airstrip until the airstrip is re-evaluated and deemed safe.
- Recommendations were made to the Sandaun Provincial Government to engage agencies like the Rural Airstrips Agency (RAA) to ensure airstrip safety levels are maintained and data is shared with operators.