What happened
On 1 March 2006, a Eurocopter AS 350 B3 helicopter, registration SE-JHD, was performing a utility flight over Södra Åsjön in Blekinge county, Sweden. The mission involved spreading powdered limestone over a partially ice-covered lake. After the pilot completed engine warm-up and took off with a low power setting, the aircraft climbed to approximately 40 meters (1/8 of a nautical mile) at a speed of just over 50 knots.
During the climb, the engine stopped abruptly without warning. Ground personnel observed a momentary flash of light from the engine exhaust at the time of the failure. The pilot immediately initiated an autorotation and attempted a steep right turn toward the shore to avoid landing on the uncertain ice. However, the aircraft struck the ice about 20 meters from the shoreline with a high rate of descent. The impact caused the tail boom to detach, and the helicopter slid into trees on the shore. The pilot escaped the wreckage without injury.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the wreckage and the engine components. While no mechanical malfunctions were found in the engine's control systems, investigators identified damage to three compressor blades. The nature of the damage—a forward curving of the blades without sharp edges—indicated the presence of Foreign Object Damage (FOD) from a "soft" object, such as ice or packed snow.
Investigators also examined the engine air intake cover used while the aircraft was parked overnight. They found that the tarpaulin used to cover the intake could absorb significant amounts of water. Given that it had snowed heavily the previous night, the investigation focused on how frozen moisture could have entered the engine.
Findings
- The helicopter had been parked outdoors during heavy snowfall.
- Three compressor blades showed damage consistent with being struck by a soft object.
- The engine is highly sensitive to water or ice ingress; the manufacturer notes that as little as 40 grams of such material can trigger a flameout.
- Undetected ice build-up likely occurred while the aircraft was parked, which was subsequently drawn into the engine during takeoff, causing the flameout.
- The aircraft was not equipped with an Auto Ignition System, which could have helped mitigate the failure.
Safety action
The SHK recommended that the Swedish Civil Aviation Authority advise operators of this helicopter type on the critical importance of preventing ice, snow, or water from entering the engine. Additionally, the authority recommended efforts to make Auto Ignition Systems a standard feature for this aircraft type to improve safety during such incidents.