What happened
On 4 June 2006, an MD 900 helicopter, registration G-EHMS, was performing a commercial air transport mission to attend a road traffic accident in South London. The crew, consisting of two pilots, a doctor, and a paramedic, arrived at the Walworth Road site to assist a pedestrian with life-threatening injuries.
To ensure the access road remained clear, the crew selected a garage forecourt near a petrol station as a landing site. During the final stages of the landing, as the aircraft was establishing a hover, a loud impact was heard. The helicopter's main rotor blades struck metal debris that had been pulled from a garage wall. The commander immediately performed a controlled landing, and the engines were shut down. No injuries were sustained by the crew or any members of the public.
The investigation
Investigators examined the wreckage and found significant damage to the main rotor blades, the rotor head, the gearbox, and the left vertical stabiliser. A piece of metal debris, measuring approximately one foot by 10 inches, was identified as part of an advertising sign from the garage.
Examination of the garage structure revealed that the metal bracket connecting the fascia board to the brick wall had been dislodged. Evidence suggested the base of the wall had been previously struck by a heavy goods vehicle. The investigation also reviewed the aircraft's flight data, which showed no mechanical faults or exceedances prior to the impact.
Findings
- The metal sign became detached from the garage wall due to the downwash from the helicopter's rotors.
- The detached sign was drawn into the rotor disc, causing multiple impacts and shredding the metal.
- The garage wall may have been structurally weakened by a previous collision with a heavy goods vehicle.
- While the crew correctly assessed the landing site as meeting minimum size requirements, the presence of a vehicle in the forecourt reduced the available clearance.