Introduction
On 4 June 2001, at 1500 UTC, a Robinson R22 Alpha helicopter (registration G-VMSL), powered by a single Lycoming O-320-B2C piston engine, sustained extensive damage during a training flight adjacent to Turweston Airfield, Northants. The aircraft was manufactured in 1985 and operated with one crew member, a 43-year-old student pilot with 56 hours of flying experience on type. No passengers were on board.
Sequence of Events
The student pilot was conducting the second leg of a qualifying cross-country navigation exercise from Sywell to Turweston. Approaching Turweston, the pilot assessed that the helicopter was too high for a direct approach to the helicopter landing area and began a left turn to reposition. Weather conditions were good, with surface wind from 300° at 10 knots.
During the orbit at approximately 700 feet above ground level with cruise power set, the pilot lost sight of the airfield and referred to a map to confirm position, about 1 nautical mile south of the landing area. The pilot then noticed the helicopter shuddering; airspeed had decreased to 20 knots or less and cyclic control became ineffective, leading to a rapid descent. The pilot lowered the collective lever fully and entered autorotation, regaining airspeed to about 50 knots. After selecting a landing area, flaring, and touching down with residual forward speed in a rough crop field, the helicopter rolled over onto its side during the ground slide.
Post-accident
There was no fire. The pilot, uninjured, vacated the helicopter through the broken canopy. The pilot assessed that distraction from the primary handling task led the helicopter to enter the early stages of a vortex ring condition, resulting from inadvertent loss of forward speed in the turn while power was applied.