What happened
On 11 September 2000, a Bolkow BO-105DBS-4, registration G-WMAA, was undergoing ground testing at RAF Cosford. The aircraft was being run to check for hydraulic leaks and perform crossover checks following recent maintenance work. After receiving clearance for flight, the pilot initiated a hover.
During this phase, the pilot noticed that the friction on the collective pitch lever had become looser than intended during the ground checks. To address this, the pilot attempted to move the helicopter away from the taxiway and other parked aircraft to a safer position where the friction could be readjusted. While the aircraft was moving forward, a wasp flew into the cockpit and stung the pilot on the cheek. In a reflexive response to the sting, the pilot moved his left hand away from the collective control to swat the insect.
This sudden movement caused the helicopter to descend from a height of roughly 8 feet. The aircraft struck the ground and rotated onto its left skid before the right skid made contact with the surface. Following the impact, the aircraft was found to be sitting unevenly.
The investigation
Investigators examined the aircraft and the circumstances surrounding the pilot's reaction. The inspection revealed that the landing gear had sustained minor damage to both skid cross tubes, which caused the helicopter to sit low on the right side. Following the incident, engineering support was called to the scene. After a technical inspection, the aircraft was moved to a helipad and shut down without further incident.