What happened
On 10 November 2001, an AS332L, registration G-BKZE, was performing a public transport mission to deliver crew members to a drilling vessel located approximately 80 miles west of the Shetland Isles. Weather conditions on the ship prior to arrival included rain, mist, and winds of approximately 260°/25 kts. The helicopter successfully landed on the ship's helideck at 1242 hrs.
Following the landing, the pilot remained in the cockpit with the engines running to facilitate passenger disembarkation and refueling. During this period, the ship's dynamic positioning system experienced a loss of heading control. This caused the vessel to drift slowly to the right, resulting in a starboard list of roughly 1°. As the ship's heading shifted to approximately 330°, the helicopter toppled to the right. The impact of the main rotors against the deck caused them to break up, resulting in one severe injury to the co-pilot caused by flying debris.
The investigation
AAIB inspectors conducted an investigation into the incident, reviewing the aircraft's flight data recorder and the physical wreckage. Analysis of the flight data recorder showed that all Automatic Pilot System channels had been disconnected at the time of touchdown. The data further indicated that the cyclic control remained in a neutral position and the collective lever was down while the aircraft was on the deck. Physical examination of the wreckage confirmed that the parking brake and the nose wheel lock were both engaged during the event.