What happened
On 25 June 2013, a Pitts S-1E Special, registration G-OKAY, was performing a private flight at Knettishall Airfield in Suffolk. The weather conditions at the time were favorable, with a light and variable wind and a westerly surface wind of approximately 10 knots. After completing a low approach and a subsequent go-around, the pilot attempted a landing on the grass runway 23.
As the aircraft made contact with the ground, it experienced a sudden yaw to the right. The pilot attempted to correct this movement, but the aircraft's main wheels became entangled in a wheat crop situated adjacent to the runway, which was approximately one metre in height. This entanglement caused the aircraft to somersault before coming to a halt. The pilot sustained minor injuries and was able to exit the wreckage without help.
The investigation
Investigators examined the aircraft's landing gear and components following the accident. An inspection of the right main landing gear revealed no evidence of binding within the wheel bearing or the brake. The wheel spats had been recently refitted the previous weekend and were confirmed to be free of debris prior to the flight. However, following the incident, a dense mass of soil and grass was discovered inside the spat. The pilot indicated that this material had likely been collected during the landing roll, subsequently jamming the tyre and triggering the rightward yaw.