NTSB Identification: WPR09LA253
14 CFR Part 91: General Aviation
Accident occurred Friday, May 22, 2009 in Rock Springs, AZ
Probable Cause Approval Date: 06/27/2011
Aircraft: GAUCHAT SAFARI, registration: N147MD
Injuries: 2 Fatal.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

During a personal flight the experimental helicopter experienced an in-flight separation of the main rotor head. Both main rotor blades were located in opposite directions from the main wreckage. The helicopter was substantially damaged by the impact forces and the postimpact fire. Postaccident examination of the main rotor head assembly and the main rotor spindle revealed that the main rotor spindle had failed due to cyclic fatigue. The origin area was located near distinct circumferential machining marks. The manufacturer subsequently issued a mandatory inspection bulletin requiring inspection of all main rotor spindles.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The separation of the main rotor head during cruise flight as a result of cyclic fatigue of the main rotor head spindle. The fatigue crack was due to an inadequate manufacturing process.

Full narrative available

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