What happened
On the morning of 30 October 2006, a Robinson R44 helicopter, registration SE-JGX, was performing a ferry flight from Västerås/Johannisberg airport toward Hyltebruk. During the flight, the aircraft began a rapid descent at an altitude of approximately 180 meters (590 feet). GPS data and radar imagery indicate that the pilot attempted to maneuver the aircraft toward a clear-cut area, initiating a right turn during the loss of altitude.
The helicopter eventually struck the ground at a steep angle in a woodland area north of Katrineholm. The impact caused the aircraft to be completely destroyed by fire, and the pilot was killed in the accident.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the wreckage, engine, power transmission, and rotors. Technical testing of the engine and transmission systems revealed no mechanical failures or faults that would have directly caused the crash. The investigation also reviewed the pilot's medical history and the meteorological conditions at the time of the accident.
Investigators noted that while the weather was generally good, there was a significant risk of carburetor icing due to the temperature and dew point. Furthermore, the investigation looked into the pilot's medical status, noting discrepancies between clinical records and aviation medical certificates regarding blood pressure.
Findings
- The engine stoppage was likely triggered by carburetor icing, a known risk for this aircraft type under the prevailing conditions.
- The helicopter's automatic governor system may have allowed icing to develop without the pilot noticing the change in engine performance.
- The pilot's medical records indicated untreated hypertension, which could have led to physiological issues such as confusion or loss of consciousness under the extreme stress of an engine failure.
- The aircraft impacted the ground with very low rotor speed, suggesting that the autorotation maneuver was not successfully completed.
- The pilot may have manually disconnected the clutch, possibly due to unusual noises from the coupling.