What happened
On September 23, 2000, a Bell 407 helicopter was conducting a local flight departing from the private helipad of the pilot, who was also the aircraft owner. Witnesses observed the helicopter flying at a low altitude near the landing site, moving east, and then approaching the landing area from the south on a northerly heading.
Approximately 250 meters before reaching the landing site, the helicopter entered a right-hand turn at an altitude of about 50 meters. During this maneuver, the aircraft began to descend sharply and struck a rapeseed field at 16:45 CEST. The helicopter impacted the ground in a horizontal attitude with almost no forward velocity. Upon impact, the aircraft tilted to the left, causing the main rotor to strike the ground, the tail boom to detach, and a rotor blade to be thrown approximately 100 meters away. The pilot sustained one serious injury, and the aircraft was destroyed. Damage to the surrounding terrain was also recorded.
The investigation
The investigation was conducted by the BFU, with a representative from the helicopter manufacturer also present at the site. Because the pilot could not recall the events leading to the crash, his testimony was unavailable for the investigation. The pilot had approximately 700 hours of helicopter flight experience, primarily on the Bell 206 L4 "Long Ranger," and had obtained his type rating for the Bell 407 one year prior. Having not flown this specific model recently, he had completed 1 hour and 50 minutes of refresher training with an instructor a few days before the accident.
Technical examinations of the wreckage showed no abnormalities in the flight controls or the powertrain; all observed damage was consistent with the impact. The Rolls-Royce Allison 250 C47 engine showed no signs of malfunction. While significant foreign object damage was found on the compressor inlet, the N1 and N2 shafts were free to rotate, and no oil leaks or metal particles were found in the oil system. Data from the Full Authority Digital Engine Control (FADEC) was analyzed in the United States, alongside an investigator from the NTSB. The presence of "spray metal" on the turbine blades confirmed that the engine was still operating at the moment of ground impact.
Findings
- The engine was functioning normally at the time of the crash, as evidenced by FADEC data and the presence of spray metal on the turbine blades.
- No mechanical or structural failures in the flight controls or engine were identified.
- Weather conditions at the time of the accident were good, with light gusts from the east/southeast averaging 15 knots.
- The exact cause of the accident could not be determined.