What happened
On 21 June 2006, an Agusta A109C, registration G-HBEK, was performing a private flight from Knutsford to a private landing site at High Legh, Cheshire. The flight was intended to position the aircraft for overnight parking. Due to a high volume of planned movements, the pilot intended to refuel the aircraft using a mobile fuel bowser.
Upon arrival, the pilot noted that another helicopter was parked on the taxiway in an obstructive position. To facilitate refueling with the short hoses available on the bowser and to maintain distance from the other aircraft, the pilot attempted a landing close to the bowser. The landing was complicated by strong, gusty crosswinds, with winds recorded at 25 knots gusting to 32 knots.
Following touchdown and the standard two-minute engine shutdown period, the rotor speed began to decrease. As the RPM dropped below 50%, the main rotor blades began to droop. The blades struck the side of the fuel bowser, and despite the pilot's immediate application of the rotor brake, the blades continued to strike the equipment violently. Eventually, one blade became lodged in the bowser, causing the rotors to stop abruptly.
The investigation
The investigation examined the positioning of the aircraft and the equipment at the landing site. It was established that the pilot sought to land as close to the bowser as possible to ensure the refueling hoses could reach the aircraft's connectors. The investigation also looked into the ground conditions and the placement of the fuel bowser, which had been positioned on the edge of the concrete pad.
Findings
- The Agusta A109C sustained extensive damage to the main rotor blades and the rotor head assembly, including a sheared rotor damper.
- Both engines required inspection following the impact.
- The primary cause of the accident was the rotor blades drooping and striking the fuel bowser as rotor speed decreased during shutdown.
- The pilot's decision-making was influenced by the need to facilitate refueling and the obstructive position of another aircraft.
- The fuel bowser sustained only minor damage.