What happened
On October 9, 2001, an AS 350 B2 helicopter, registration I-LASG, was performing aerial work in the Rebruant-Vallone Rio Freddo area near Vinadio, Italy. The mission involved transporting a metal bucket filled with cement via a long-line sling load to support the installation of an aqueduct pipeline. The operation required the pilot to hover at approximately 1,800 feet to discharge the material, guided by ground personnel via radio.
After completing the first discharge, the pilot began flying back down the mountain slope toward the supply point. At an altitude of approximately 4,500 feet, witnesses observed the aircraft suddenly rotate around its axis with the external load positioned near the tail section. The helicopter then entered a steep dive and struck the ground. The impact caused a massive fire that destroyed over two-thirds of the airframe. The pilot sustained fatal injuries in the crash.
The investigation
The ANSV investigation examined the aircraft's technical condition, the flight history, and the operational environment. Investigators analyzed the wreckage, noting significant damage to the tail rotor and the vertical stabilizer. Evidence showed that the tail rotor blade had detached from its hub, with damage consistent with an impact against the suspended bucket. The investigation also reviewed the pilot's extensive experience, noting over 4,800 total flight hours, including significant time in mountain operations.
Findings
- The primary cause of the accident was the positioning of the external load, which swung into the tail rotor area during flight.
- The pilot likely overestimated their ability to manage the load's movement, leading to a failure to maintain an adequate safety altitude relative to the terrain and the load's oscillation.
- A lack of standardized operational procedures for specialized aerial work in mountainous terrain contributed to the risk, as existing regulations at the time focused more on public transport than on complex sling-load maneuvers.
Safety action
- The ANSV recommended that the Italian Civil Aviation Authority (ENAC) evaluate the implementation of general operational standards for aerial work to standardize pilot training methodologies and procedures.