Incident Overview
On 10 June 2005 at 1900 UTC, a Robinson R44 Clipper II (registration G-SHAN) was involved in a wire strike incident while approaching a field at a private site 2 nm west of Chesham, Buckinghamshire. The helicopter, manufactured in 2005, was powered by one Lycoming IO-540-AE1A5 piston engine. The flight was private, with one pilot and two passengers on board. No injuries were reported, and the only damage was to the main rotor mast fairing.
Aircraft and Crew
The aircraft was a Robinson R44 Clipper II, G-SHAN. The commander held an Airline Transport Pilot's Licence, was 41 years old, and had a total flying experience of 9,000 hours, with 4,500 hours on type. His recent flying included 200 hours in the last 90 days and 70 hours in the last 28 days.
Sequence of Events
The helicopter departed from a private site on a farm. After approximately five minutes of flight, while making a normal approach to a field in another part of the property and at about 100 ft agl, the pilot heard a slight noise. Upon landing, it was discovered that one of a pair of wires traversing the field and valley had been severed by contact with the helicopter's main rotor mast fairing. The wires spanned approximately 900 feet across the valley. The other wire was not struck; it may have sagged differently.
Damage and Injuries
Damage was limited to the main rotor mast fairing. There were no injuries to the crew or passengers.
Circumstances
The pilot, an experienced aviator, concluded that the accident was caused by his inability to see the wires. The wires were green in colour and set against a green background of trees and grass. The telegraph poles supporting the wires were obscured by trees and shrubs. Additionally, the approach was made into the evening sun, and the contrast between the bright sky and darker ground vegetation likely masked the presence of the wires. One wire was reported as being of corroded copper. The weather at the time was good, with less than five knots of wind, visibility in excess of 10 km, and no significant cloud.