What happened
On 28 June 2003, a modified Rotorway Executive 90, registration G-BUJZ, was performing private flight exercises near the Street Farm Helipad in Essex. Following a completed flight to Andrewsfield Aerodrome, the pilot decided to conduct additional hovering practice in the local area. After refueling, the pilot and one passenger departed to practice maneuvers near a small woodland area.
During the exercises, the pilot attempted to transition the aircraft into a low, downwind hover at an altitude of approximately 20 feet. As the pilot slowed the aircraft and raised the collective lever, the engine power proved insufficient to maintain the hover. This caused the rotor RPM to decay, leading to a continued descent over a sloping field. The right-hand skid made contact with the ground while the aircraft was moving sideways, resulting in a rollover onto its right side. The impact caused the engine to stop, though the pilot successfully performed the emergency shutdown procedure. Both the pilot and the passenger exited the aircraft through the left-hand door without sustaining any injuries.
The investigation
The AAIB examined the flight conditions and the aircraft's weight at the time of the accident. The helicopter weighed approximately 1,429 lb, which was 71 lb below its maximum takeoff weight, though this remained a relatively high weight for the maneuver. Weather conditions were described as warm with a 10-knot wind.
Findings
- The pilot was flying downwind in blustery conditions, which caused the aircraft to fly into its own vortices.
- The combination of the aircraft's weight and the flight profile created the ideal conditions for the helicopter to enter a vortex ring state.
- The resulting loss of effective lift at a low altitude made recovery impossible, leading to the ground impact.