NTSB Identification: SEA05FA019.
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Accident occurred Saturday, November 27, 2004 in Arlington, WA
Probable Cause Approval Date: 10/03/2006
Aircraft: Robinson R22 Beta, registration: N4029Q
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
This was the pilot-rated student's first instructional flight in the recently rebuilt helicopter, which he purchased three days prior to the accident flight. About 5 minutes after the helicopter's departure on the accident flight, witnesses reported hearing a loud bang and watching the helicopter fall to the ground. The helicopter impacted terrain in an approximately level attitude, coming to rest in an upright position. There was no postcrash fire. All major components of the helicopter were accounted for and recovered before being moved to a secured storage facility. Both of the helicopter's doors separated from the aircraft in flight. The right door was recovered intact and not damaged, while the left door was accounted for in multiple fragmented pieces, including the door handle and frame, and the door latching mechanism. Both tail rotor blades were located 500 to 600 feet prior to the main impact point, with one blade exhibiting two large impact areas near the tip of the leading edge. One impact area was more rounded than the other, with the other impact area being broader and very flat. Examinations of paint transfers revealed that the material on the leading edge of a piece of main rotor blade and on the door latching mechanism were transferred paint from the tailboom, and that the yellow paint on the main rotor blade was similar to the paint from the tail rotor blade and likely from the same source. The sequence of events preceding the day of the accident flight, as well as the physical evidence examined during the investigation, indicates that the door pins were not installed prior to the flight. Physical evidence consistent with the helicopter's main rotor diverging from its normal plane of rotation and striking the left windscreen was observed in the form of an area of black transfer material, which measured 24 inches by 5 inches on the upper left outboard area of the left windscreen. The initiating event that produced the main rotor divergence could not be determined.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The divergence of the main rotor from its normal plane of rotation for an undetermined reason, resulting in rotor contact with the aircraft's left windscreen. The failure of the door pins to be installed was a factor. Full narrative available
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