What happened
On September 28, 2014, at approximately 09:54 LMT, a training flight involving a SZD-9bis Bocian 1E glider ended in an incident at Kruszyn airport (EPWK). The flight was being conducted by an instructor and a student pilot as part of a formal training program for a Single Pilot License (SPL), specifically practicing landing with a tailwind.
After the crew successfully completed a landing with the wind, the aircraft was in the final phase of its landing roll when a mechanical failure occurred. A securing bolt used to fasten the main landing gear axle to the leg fractured, leading to the incident.
The investigation
The investigation, conducted by the aircraft operator's commission, examined the mechanical state of the landing gear and the circumstances of the landing. The investigators analyzed the airfield surface, the crew's actions, and the prevailing meteorological conditions, finding that none of these factors contributed to the failure. The investigation focused on the physical properties of the fractured bolt, looking for evidence of fatigue or corrosion.
Findings
The primary cause of the incident was the fracture of the bolt securing the main landing gear axle to the leg. The investigation could not determine the specific reason for the bolt's failure, as no evidence of fatigue or corrosion was found on the component.
Several contributing factors were identified that may have placed additional stress on the landing gear:
- The aircraft's use in flight training, which involves a high frequency of landings.
- The specific nature of the maneuver, which involved landing with a higher ground speed due to the tailwind component.