NTSB Identification: CEN12CA031
14 CFR Part 91: General Aviation
Accident occurred Friday, October 14, 2011 in Fort Worth, TX
Probable Cause Approval Date: 12/27/2011
Aircraft: HUGHES 269A, registration: N10375
Injuries: 2 Uninjured.
NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.
The certified flight instructor (CFI) and pilot receiving instruction were practicing hovering autorotations on a taxiway. With the skids on the ground for about 20 seconds after completing a hovering autorotation and with the engine at 2,000 rpm, the helicopter began to vibrate and violently shake, consistent with ground resonance. The vibrations and shaking continued to increase and lasted about 15 to 30 seconds. After the shaking stopped, the CFI shut down the helicopter. A postaccident examination of the helicopter revealed that the tail rotor and gearbox separated, and the fuselage was bent and deformed. No preimpact mechanical malfunctions or failures with the helicopter were noted that would have precluded normal operation.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The inadvertent entry into ground resonance after a hovering autorotation. Full narrative available
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