Introduction
A Eurocopter SA342J Gazelle helicopter, registration F-GJSL, was involved in an accident on 8 May 2005 at approximately 1630 hours UTC at Ockington Farm Strip near Dymock, Gloucestershire. The flight was private, carrying the pilot and one passenger. Both occupants sustained serious injuries, and the helicopter was damaged beyond economic repair.
History of the Flight
The pilot, accompanied by his wife, had flown from Warminster to their private landing site. After approaching to a hover, the pilot intended to perform a spot turn to the left, turn through 180°, and hover-taxi back to the pad for an into-wind landing. He initiated the spot turn slowly and stopped after turning through 90°, with the fin approximately side-on to the wind. As he prepared to commence the second half of the turn, but before applying left pedal, the helicopter yawed rapidly to the left. Application of right pedal did not appear to reduce the yaw rate, so the pilot pulled up on the collective lever to gain height and applied aft cyclic to counter a perceived nose-down pitch. The pilot became extremely disorientated and released his grip on the collective lever. The helicopter then struck the roof of an adjacent building, causing the tail boom to detach. The main body fell to the ground. The pilot remained conscious and exited the wreckage, using the onboard fire extinguisher on an engine bay fire. He was unable to extract his wife and called emergency services. Both were airlifted to hospital.
Pilot Information
The pilot, aged 63, held a Private Pilot's Licence. His total flying experience was 600 hours, with only 12 hours on the Gazelle type. The majority of his helicopter experience was on the Bell 206 Jetranger. He had recently acquired F-GJSL, and this was his fourth flight as pilot-in-command on the Gazelle. During conversion training, his instructor recommended that spot turns in the Gazelle be carried out to the right when possible. The pilot indicated confusion regarding the optimum turn direction.
Meteorological Conditions
An aftercast from the Met Office indicated a high pressure area to the west of the UK feeding a light to moderate northerly wind over the accident area. Surface wind was estimated between 320° and 340° at 12–15 knots. There was no low cloud and visibility was excellent. Several local residents reported one or two strong gusts during the late afternoon.
Aircraft Description
The Gazelle is a single-engine helicopter with a three-bladed main rotor and a thirteen-bladed tail rotor housed in a fenestron duct. The cyclic and collective controls are servo-assisted. Yaw pedals alter tail rotor pitch via control rods and cables. The helicopter is equipped with a Stability Augmentation System (SAS) to dampen motion. F-GJSL was manufactured in 1973 as an SA341G, later modified to SA342J specification with optimised blades and an upgraded Turbomeca Astazou XIVG engine. It remained on the French register while based in the UK. The front seats were of the low-back type without upper torso restraints.
Accident Site and Wreckage Examination
The helicopter impacted the pitched roof of the pilot's house, approximately 16 m north of the landing area. The impact attitude was approximately 30° nose-down and right-side low, on a westerly heading. The tail boom and fin separated and remained on the roof. The main rotor blades struck the gable end; one blade was broken. The tail rotor had been rotating at impact. Examination of the flying control system revealed no pre-impact disconnects or failures. The control positions corresponded to a right yaw pedal demand of approximately 75%, right lateral cyclic, and neutral longitudinal cyclic. There was a small engine fire. The fuel tank was intact. No pre-impact defects were found.
Previous Occurrences
The AAIB reported six similar events involving loss of yaw control in the hover with civil Gazelle helicopters. The most recent occurred to Gazelle G-BZOS on 14 July 2002. A common factor in those events was low pilot experience on type. The UK armed services acknowledged that high yaw rates to the left can develop in the Gazelle due to its large fin and weathercock effect. The Ministry of Defence Flight Manual advises that when possible, the first turn should be made to the right to check maximum rotor torque required.