What happened
On August 10, 2010, a Eurocopter AS-350 B3, registration CS-HFZ, was engaged in aerial firefighting operations near Estreito, in the municipality of Oleiros, Castelo Branco. The aircraft, operated by HTA – Helicópteros, Larga, had been requested by the National Authority for Civil Protection (ANPC) to transport a team of four firefighters to a strategic location near an active wildfire.
During the landing phase, the pilot attempted to land the helicopter in a narrow area close to the fire's perimeter. As the aircraft approached the ground, the main rotor blades struck the branches of a nearby olive tree. While the impact caused damage to the aircraft, there were no injuries to the pilot or the four passengers on board.
The investigation
The GPIAAF investigation examined the aircraft's technical status, the pilot's credentials, and the environmental conditions at the time of the incident. The investigation confirmed that the CS-HFZ was properly maintained according to the manufacturer's program and held all necessary valid documentation. The pilot was fully licensed and authorized for the specific type of aerial work being performed.
Meteorological conditions were found to be favorable, with visibility exceeding 10km, clear skies, and light winds of approximately 5 knots. The investigation also assessed the damage to the aircraft, noting that the primary impact occurred on the main rotor blades. Secondary damage was found on the tail boom, tail rotor blades, and the fuselage, likely caused by debris or fragments from the tree branches being projected during the strike. The only third-party damage recorded was the loss of branches from the olive tree.
Findings
- The main rotor blade strike with tree branches was the primary cause of the incident.
- A contributing factor was the pilot's failure to adequately survey the landing site prior to touchdown, which resulted in the blades making contact with the vegetation.