2005 Aeronorte Eurocopter AS 350 B2 accident at Lamas, Valpaços (CS-HES)

Overview and notification On 30 July 2005, the Portuguese accident investigation authority GPIAA was notified around 18:30 UTC of an accident involving a Eurocopter AS 350 B2 helicopter, registration CS-HES. The aircraft was owned by Heliportugal and operated by Aeronorte for the National Fire and Civil Protection Service (SNBPC) during wildfire-fighting operations in the Serra da Padrela, near Lamas in the Valpaços municipality. Because of the late notification, the responsible investigator traveled to the site the following day to begin the investigation. ## Flight history and sequence of events At 17:45 UTC, the helicopter was based at the Chaves heliport and was requested to respond to a wildfire in the Ervões area of Valpaços. The pilot took off with a firefighting team, inspected the terrain, obstacles, fire size and spread, and possible water sources, then dropped the team and began water-dropping operations. Around 18:20 UTC, while preparing for a third water drop and performing a positioning maneuver for the drop pass, the pilot felt the helicopter sink. He maneuvered to recover from the descent, after which the helicopter began rotating counterclockwise. Pedal input did not stop the rotation. ## Impact and damage Without control, the helicopter struck trunks of small trees and bushes with its main rotor blades and tail, then fell to the ground. The aircraft sustained severe damage, including deformation and fractures to the tail cone, tail rotor transmission shaft, main rotor blades and rotor head, tail rotor, right horizontal stabilizer, lower vertical stabilizer, right landing skid, and main transmission supports. The engine was declared unrecoverable due to overheating-related deformation. No third-party damage was reported. ## Personnel, aircraft, and conditions The pilot was the sole occupant. He was a 44-year-old Brazilian national holding a CPL(H) license valid to 30 December 2005, with AS 350 type qualification and no restrictions. He had 2,800 total flight hours and 1,400 hours on type. Before starting wildfire work in Portugal, he completed a theoretical course and a 40-minute training flight with three landings and several water drops under an instructor. The helicopter was a single-turbine, three-blade main rotor aircraft with a tail rotor and skid landing gear. It was fitted with the fixed ventral ISOLAIR water-bombing system, adding 173 kg to basic mass and allowing a maximum takeoff mass of 2,500 kg. The system included a 1,000-liter water tank plus 57 liters of retardant, two hydraulically actuated drop doors, a three-meter intake hose with valve and electric pump capable of 1,500 liters per minute, and an in-cabin control panel. The aircraft had 3,618:45 total airframe hours, 664:40 engine hours, and 3,641:15 rotor hours, with last inspection on 13 July 2005. Weather was normal for the season, with nearly clear skies, moderate southwest wind, and a temperature of about 28°C. At the accident site, the fire had been contained and was about 50 meters ahead, with no significant smoke reducing visibility. The site was rural and mountainous, at about 600 m altitude, with sandy soil, some schist stones, gorse, and small young pines. The helicopter was not equipped with flight recorders, and none were required.