NTSB Identification: CEN12LA247
14 CFR Part 91: General Aviation
Accident occurred Tuesday, April 17, 2012 in Grinnell, IA
Probable Cause Approval Date: 08/13/2013
Aircraft: HUGHES 269A, registration: N69HJ
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The helicopter began to vibrate as the pilot raised the collective for liftoff. The pilot lowered the collective and closed the throttle when the vibration began; however, he was too late in recognizing the onset of ground resonance, which resulted in a violent, uncontrollable oscillation and separation of the tail boom from the fuselage. Examination of the helicopter revealed no anomalies that would have precluded normal operation.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's improper liftoff technique, which resulted in ground resonance, and the pilot's delayed recognition of the ground resonance. Full narrative available
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