Overview
On 19 November 1997, a Sikorsky S61N helicopter, registration G-BCLC, was conducting a search and rescue (SAR) mission for the motor vessel MV Green Lily, which had suffered an engine failure and was drifting near Bressay, Shetland Islands. The helicopter, operated by a crew of four, was tasked with winching the ship's crew to safety. During the operation, the winchman was washed overboard and later lost. The helicopter's cable cutting mechanism failed to operate correctly, delaying any potential recovery.
History of Flight
The SAR crew at Sumburgh was placed on standby at 0836 UTC after the MV Green Lily reported an engine failure. The vessel, with a crew of fifteen, was drifting 10 nm southeast of Bard Head. By 1218 UTC, a tow was established, but it broke at 1239 UTC. At 1258 UTC, the helicopter was scrambled and became airborne at 1309 UTC, arriving on scene at 1319 UTC. The Marine Accident Investigation Branch conducted a separate inquiry; this report focuses on helicopter-related events.
Winching Operations
Upon arrival, the helicopter encountered severe conditions: surface wind estimated at 150°/50–70 kt, sea state 8, and visibility 5,000 meters. The vessel was rolling heavily. Initial attempts to winch injured crewmen were aborted due to the ship's instability. After the tug Tystie failed to stabilize the vessel, the Lerwick Lifeboat rescued five crewmen. The helicopter resumed winching at about 1441 UTC. By 1444 UTC, the ship had started drifting stern-first toward the coast after its anchor cable parted. The commander struggled to maintain position, with radio height varying between 40 and 90 feet and wind gusts exceeding 50 kt.
During the third and fourth lifts, the situation became critical. As the vessel grounded at 1450 UTC, the decision was made to winch the remaining three people—the master, one crewman, and the winchman—together. However, the winchman did not attach himself to the hook. At 1456 UTC, while the cable was being winched out, the Hi-line became snagged. The winchman was no longer on deck; he had been washed overboard. The winch operator activated the cable shear system, but the cable did not cut. The Hi-line later became free, and the hook was raised. The winchman was seen in the sea with his lifejacket inflated, but there was no sign of life. The helicopter then flew the ten rescued crewmen to Gilbert Bain Hospital and returned to Sumburgh for a replacement winch.
Failure of the Cable Cutting Mechanism
Examination of the Lucas Air Equipment Hoist revealed that the cable cutting mechanism had been assembled incorrectly. The shearing pin was inserted through the gas exhaust holes in the shearing knife holder rather than the correct horizontal drilling; this caused the chisel blade to align with the cable axis and only partially sever the cable when the squib fired. An across-the-fleet inspection found one other hoist with the same misassembly and another where the pin bypassed the chisel entirely. The maintenance manual lacked specific instructions on blade orientation and correct pin insertion. The company's hoist worksheets also omitted such instructions. The manual's layout separated text and illustrations, making it difficult to use, and one copy had been unofficially rearranged.