What happened
On 12 September 2004, a Rotorway Executive 162F, registration G-CBJV, was performing a private flight near Tadcaster, North Yorkshire. As the pilot prepared to land at a private landing site, they observed several loose branches obstructing the concrete landing pad. To avoid these obstacles, the pilot elected to land the aircraft in a nearby field characterized by long grass.
Following the touchdown, the pilot lowered the collective control to its full downward position and commenced the engine shutdown sequence. During this process, the right skid of the helicopter sank into the ground. This sudden movement caused the aircraft to roll over onto its right side. The two occupants, both secured by four-point harnesses, were able to exit the aircraft without sustaining any injuries, though the aircraft sustained damage to the cockpit and tail boom.
The investigation
Investigators examined the circumstances surrounding the loss of stability during the shutdown phase. While the pilot initially suggested that the incident was a result of dynamic rollover caused by the skid entering a rut, the investigation focused on the state of the rotor blades. Because the collective was fully lowered, there was minimal residual lift being produced by the rotors at the time of the event.
Findings
- The investigation established that the rollover was likely caused by a geometric change in the static balance of forces resulting from the right skid sinking into the soft surface.
- The sinking of the skid was a primary factor in the aircraft's instability.
- A 15-knot crosswind from the left may have contributed to the tipping motion.