A flight is fraught with danger when the PIC surrenders authority.
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Investigators from the , , American and USA began operations the next morning. On Feb. 18, they were joined by representatives of the German Federal Bureau of Aircraft Accident Investigation (BFU) and Eurocopter Deutschland.
The linear debris path — consisting primarily of pieces of yellow main rotor blade and the left horizontal endplate — extended north from the main wreckage about 2,000 ft. All major aircraft components were accounted for near the wreckage or along the flightpath. There was no evidence of an inflight fire.
Impact forces and the post-crash fire destroyed the cockpit and cabin areas. The cockpit floor structure exhibited accordion compression in the aft direction. The twist grip throttles were both found past the neutral detent and in the high range. The anti-torque pedals were found in the near-neutral position. All flight controls were accounted for, and all flight control tube fractures appeared angular and consistent with overload. Those flight control components not damaged by impact forces were found attached and secured. The airspeed indicator had frozen at 103 kt., the rotor rpm gauge indicated 95%, the engine No. 1 gauge indicated 92%, and the engine No. 2 gauge indicated 90%.
The first identified piece of debris along the flightpath leading to the wreckage site was a piece of ribbon from the helicopter's left vertical endplate. An area of main rotor blade debris that included foam, honeycomb and paint chips was then identified extending from the initial point of the debris field south for about 1,050 ft. A large piece of the yellow main rotor blade was located about 750 ft. north of the main wreckage site. A fragment of the helicopter's tail-rotor driveshaft flex coupling was found about 695 ft. north of the wreckage. A lower piece of the left vertical fin was located about 450 ft. north of the main wreckage.
A further survey of the area revealed that a piece of the yellow blade tip was found about 400 ft. northwest of the main wreckage, with myriad small fragmented pieces of the helicopter observed between the blade tip and the wreckage site. The main rotor blades and hub were located about 25 ft. north of the primary wreckage site. The tail boom fenestron was lying on its right side at the main wreckage site and oriented in a north-to-south direction. Its ring frame exhibited heat damage and the fracture surfaces were consistent with overload.
No obvious preimpact mechanical anomalies were observed on any of the hydraulic system components. All main transmission gear/component damage was consistent with impact and/or overload. The main transmission anti-resonance isolation system mounts were examined on site, with no evidence of preimpact damage. The damage to the main transmission torque strut was consistent with impact and overload.
The engines were removed for detailed study. No evidence of preimpact failure was observed. In addition, the helicopter's gross weight fell within the flight envelope and below the helicopter's maximum certified gross weight at the time of the accident.
In the end, it seemed clear that the main rotor disc had moved from its normal plane, allowing the yellow blade to strike the tail.