N186GCCessna 208B · 2009

**This report was modified on December 5, 2024. Please see the docket for this accident to view the original report.**

The pilot reported that, during the landing ground roll, the airplane started to veer left. He applied right rudder input, but the airplane continued to “drag” left. As the pilot repositioned his feet to apply the brakes, the airplane “turned harder to the left,” exited the runway, and impacted terrain. The right wing was substantially damaged. The pilot thought that “a left main tire malfunction on or before landing” had occurred.

An examination of the left wheel and tire assembly (by the Federal Aviation Administration) found that the valve stem to the tire inner tube had completely sheared off and was located inside the tire. No other damage to the inner tube was noted, and no other anomalies were observed within the assembly. The operator’s director of maintenance reported no preimpact mechanical malfunctions or failures that would have precluded normal operation.

A video recording of the accident landing (taken by a passenger in the first row of passenger seats) indicated that, based on the sound recorded, the left main landing gear tire became flat immediately after main gear touchdown. The left flat tire would have increased the drag between the tire and the runway surface, resulting in a left-turning tendency and a loss of directional control.

In addition, a photograph taken during the on-scene investigation showed a double track on the runway starting near the location where the left main tire touched down. The double track was likely caused by the rubber in the left and right sidewalls of the tire contacting the runway after the center of the tire deflated.

The left main landing gear tire was installed on the airplane 3 days before the accident. The tire could have become flat if it had been improperly installed or had a material defect. It is also possible that the tire became flat because it hit something not heard or seen on the video of the landing. In addition, another photograph taken during the on-scene investigation showed that the valve stem of the tire inner tube was sheared, indicating that the tire could have become flat because the valve (within the valve stem) had failed.

The failure mode for the left main landing gear tire could not be determined based on the available evidence. Nevertheless, the evidence was sufficient to show that the reason for the airplane’s loss of lateral directional control was the flat left main tire.