What happened
On 14 May 2022, a DH82A Tiger Moth, registration G-AXAN, was performing a private flight at a private farm strip near Duxford, Cambridgeshire. During the landing phase on grass Runway 22, the pilot experienced an unusual touchdown that resulted in a bounce. The aircraft subsequently settled into a three-point attitude and came to a sudden halt, causing the aircraft to nose over and come to rest in an inverted position. There were no injuries to the pilot or the single passenger on board, and both occupants were able to exit the aircraft without assistance.
The investigation
Investigators examined the aircraft and the landing site to determine the cause of the structural failure. The inspection of the runway revealed that the left wheel had made contact with a patch of soft ground. A diagram of the accident site showed a depression in the grass where the left wheel struck, followed by a track left by the lower fork end fitting of the compression leg. \nDetailed examination of the aircraft's landing gear showed that the left compression leg top attachment bolt had suffered a shear failure. The stub axle was also found to be slightly bent upwards. While the compression leg lower fork fitting sustained significant mechanical damage upon impact with the ground, there was some evidence of shear failure on the forward lug. The investigation also noted that the aircraft was equipped with wheel brakes, a modification not endorsed by the design approval holder due to the potential for excessive torque loads.
Findings
- The left landing gear failed at the lower fork end fitting of the compression leg.
- The failure occurred because the left wheel touched down in soft ground.
- Evidence from the aircraft's components was consistent with a hard landing, which may have occurred during the accident flight or a previous flight.
- It could not be definitively determined if the ground conditions alone caused the failure or if pre-existing defects, such as those related to braking loads from the fitted wheel brakes, contributed to the structural compromise.