What happened
On 9 April 1998, a Robinson R22 BII, registration G-BXUJ, was undergoing an acceptance air test at Denham Aerodrome in Middlesex. The flight was being conducted prior to the aircraft being delivered to a new owner. The crew consisted of two pilots: the commander and an instructor representing the new owner.
While the aircraft was stationary on the grass with its rotors running, it was waiting for a taxiing aircraft to pass. During this period, the instructor had taken control of the aircraft. The helicopter lifted into a hover and began a gentle roll to the right. The commander immediately re-established control, repeatedly announcing "I have control," and attempted to maneuver the helicopter back to a level position with the skids on the ground. Despite the commander's efforts, the aircraft continued to roll slowly onto its right side. The crew managed to exit the helicopter through a broken front windscreen and escaped without injury.
The investigation
Investigators examined the circumstances surrounding the loss of control. At the time of the incident, the surface wind was recorded at 045° at 5 knots. The investigation focused on the physical actions of the crew during the transition of control and the subsequent attempt to recover the aircraft from the rolling motion. The investigation also noted the extent of the damage, which included substantial impact to the rotor blades, rotor mast, fuselage, and tail boom.
Findings
- The aircraft experienced a dynamic rollover.
- The rollover was precipitated by interference with the collective control by the second pilot during the commander's attempt to recover the aircraft to a level attitude.