What happened
On August 21, 2015, an AS350 B3 helicopter, registration I-GBVD, was engaged in aerial firefighting operations near Arzana, Italy. The aircraft, operated by an aerial work company, had taken off from the San Cosimo helisurface to combat an active wildfire. After refilling its water supply from a nearby basin, the crew proceeded to the fire site to discharge the load.
During the release of the water from a Bambi Bucket, the crew experienced a loud impact and intense vibrations originating from the rear of the aircraft. Witnesses on the ground observed the bucket striking the tail rotor immediately following the water release. Following the collision, the helicopter lost control, entered a descending rotation, and crashed near a municipal landfill in the Orgiola Onniga area. The pilot sustained serious injuries, while the co-pilot remained uninjured. The aircraft was destroyed.
The investigation
The ANSV investigation focused on the mechanical interaction between the firefighting equipment and the aircraft. Investigators examined the flight history, the technical condition of the AS350 B3, and the operational procedures of the operator. The inquiry reviewed the maintenance logs, which showed no recent malfunctions, though the pilot noted a previous unrecorded repair to the bucket's pump.
Technical analysis of the wreckage and witness accounts confirmed that the collision between the Bambi Bucket and the tail rotor was the immediate trigger for the loss of control. The investigation also scrutinized the operator's manuals, finding a lack of specific procedures for managing the unique risks associated with specialized firefighting missions and the use of external loads.
Findings
- The primary cause of the accident was the collision between the firefighting bucket and the tail rotor.
- The pilot failed to execute the emergency procedures for tail rotor failure as outlined in the aircraft's Flight Manual.
- The specific type of bucket being used was not suitable for this helicopter model, and there was a lack of certified configurations for the use of such equipment on most AS350 models.
- The operator's manual lacked detailed procedures for firefighting operations, including risk mitigation strategies for the high-pressure environment of aerial firefighting.
- There was an absence of standardized national or EU-wide training requirements specifically for firefighting qualifications.