What happened
The private pilot, who also served as an Alaska hunting guide, was transporting supplies to clients located in a remote field. Upon completing the delivery, the pilot landed the aircraft on a stretch of remote snow-covered tundra. Immediately after touchdown, the right landing gear bolt attachment fitting failed structurally. This failure caused the aircraft to ground loop violently upon impact with the surface.
The investigation
Post-accident examination of the aircraft revealed significant mechanical issues contributing to the incident. Inspectors noted preexisting fatigue on the right landing gear bolt attachment fitting. A critical factor in the undetected nature of this defect was that the fitting is normally enclosed within fabric, rendering it inaccessible for routine visual inspection by maintenance crews or pilots.
Findings
The structural failure of the right landing gear bolt attachment fitting due to preexisting fatigue was the primary mechanical cause. The design of the aircraft, which hides this critical component inside fabric, prevented earlier detection of the wear. The pilot managed to land on remote snow covered tundra, but the compromised gear integrity led to the loss of directional control and subsequent ground loop.
Safety message
This incident highlights the importance of inspecting components that are difficult to access during standard maintenance. Regular checks should include methods to verify the integrity of fittings enclosed in fabric or other coverings to prevent fatigue-related failures from going unnoticed until catastrophic failure occurs.