Background
The accident aircraft was a Robinson R44 Raven, registration G-EKKO, manufactured in 2000 and equipped with one Lycoming O-540-F1B5 piston engine. The owner of the aircraft held a private pilot's licence for fixed-wing aircraft (since 1991) and helicopters (since 1993), with his only helicopter rating on the R22, which had lapsed about three years prior to the accident. He had previously owned an R22 and accumulated about 600 hours on type. The owner had recently purchased G-EKKO and intended to become rated on the R44. On the day of the accident, he planned a local flight with a friend, a qualified private pilot with valid ratings on both R22 and R44 helicopters.
History of the Flight
The pilot and owner were seen completing a walk-round check of the aircraft, which was positioned on the airport apron. They then boarded the aircraft, with the pilot occupying the front right seat and the owner the front left. Shortly afterwards, the aircraft was heard to start, and with the rotors running, the owner requested departure instructions over the radio for a VFR flight to the west. The weather at the time was reported as good with a wind of 160 degrees at 8 knots.
The owner then called "LIFTING." The engine noise was heard to increase, and with the aircraft still on the ground, it began to rotate to the left. It continued to rotate at an increasingly rapid rate, completing approximately five rotations. The aircraft then pitched forward until the main rotor blades came into contact with the tarmac, and the aircraft rolled onto its left side, the tail rotor and empennage separating from the fuselage.
The pilot was able to climb out through his door and assisted the owner out through the broken windscreen. Both men were injured; the owner received serious injuries. The airfield fire and rescue service quickly attended and spread foam on leaked fuel. During the accident sequence, pieces of the rotor blades were projected over 100 metres from the main wreckage. No third party was injured.
Aircraft Information
The Robinson R44 is a four-seat, single-engined helicopter. It can be fitted with dual controls, including dual sets of yaw pedals, dual collective sticks, and a T-bar cyclic stick with left and right grips. The T-bar cyclic has a removable grip assembly for the left-hand pilot, marked with a decal "Solo from right seat only." The left collective lever and yaw pedals are also removable. The R44 Pilot's Operating Handbook includes a note in the daily or preflight checks stating: "CAUTION: Remove left seat controls if person in that seat is not a rated helicopter pilot."
Engineering Examination
The aircraft was inspected with particular attention to the yaw controls, tail rotor, and tail rotor drive systems. The inboard end-plate on the left rudder pedals for the left-hand seat was bent, almost certainly as a result of the impact sequence. The deformation was such that the pedals were stuck in a left pedal input position, consistent with the yaw pedals being in the left pedal forward position when the damage occurred, which might have been a result of action by either one, or both, of the occupants. All damage to the yaw controls, tail rotor, and tail rotor drive systems was consistent with overload from the impact sequence, and nothing significant was found with these and other aircraft systems that might have contributed to the accident. All removable left seat flying controls were found fitted to the aircraft, with the "Solo from right seat only" decal in place and clearly legible.
Comment
Neither the pilot nor the owner had any recollection of the events leading to the accident. The existing evidence indicates that the accident was caused by either one, or both, of the occupants applying excessive left yaw, probably as the aircraft became light on its skids, when attempting to takeoff. Accidents to helicopters such as this can be particularly dangerous as a consequence of flying aircraft debris. A recent accident to a Robinson R44 at Goodwood Airfield (AAIB Report EW/G2009/05/26) resulted in a member of the public losing part of a leg; they had been struck by a piece of the aircraft's main rotor which became detached when the aircraft rolled onto its side on the airfield apron.