What happened
On December 24, 2022, a Cessna 185C was performing a local recreational flight at the Villarrica Aerodrome (SCVI) in the La Araucanía Region of Chile. The aircraft, carrying a pilot and two passengers, departed for a 50-minute flight under clear skies.
Upon returning to land on runway 33, the aircraft made contact with the pavement. During the landing roll, the aircraft drifted to the left. In an attempt to correct the direction, the aircraft exited the paved surface and traveled across a grassy area. During this excursion, the aircraft encountered uneven terrain consisting of 1-to-2-meter wide depressions parallel to the runway. This impact caused the left main landing gear to detach from the airframe. Consequently, the left wing and propeller struck the ground, and the aircraft eventually re-entered the runway, coming to a stop with significant structural damage. All three occupants escaped the aircraft without injury.
The investigation
DGAC Chile investigators examined the aircraft, the site of the occurrence, and the mechanical components involved in the failure. The investigation included a macrographic analysis of the landing gear's attachment bolt performed by a certified aeronautical technical laboratory.
Regarding the aircraft's maintenance, records indicated that the Cessna 185C had undergone its 100-hour and annual inspections on February 2, 2022, and was considered airworthy at the time of the accident. Fuel samples showed no signs of contamination or water. The investigation also reviewed local meteorological data, which noted moderate mountain-induced downdrafts were possible in the area, though the surface winds were relatively light.
Findings
- The primary cause of the accident was the fracture of the left main landing gear attachment bolt due to combined tensile and bending overstress.
- Laboratory analysis of the bolt confirmed a ductile fracture with shear marks, showing evidence of stretching and bending but no signs of fatigue.
- The aircraft's excursion from the runway was exacerbated by the presence of uneven terrain (depressions) located just off the left side of the runway.
- The impact of the detached gear and subsequent ground contact caused extensive damage to the left wing structure, the propeller blades, and the horizontal stabilizer.
- The aircraft's maintenance program and recent inspections were found to be in compliance with regulatory requirements.