NTSB Identification: CHI05CA267.
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Accident occurred Saturday, September 03, 2005 in Ida, MI
Probable Cause Approval Date: 06/28/2006
Aircraft: West Revolution Mini 500, registration: N20925
Injuries: 1 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 pilot reported that the amateur-built helicopter was in cruise flight at 1,750 feet mean sea level when the main rotor contacted the tail boom. He stated that the engine tachometer began indicating near the high operating limit. At the same time the rotor tachometer was indicating near the low operating limit. His attempt to correct the condition was not successful. The pilot stated that he lowered the collective and the helicopter pitched forward. He reported that when he compensated for the forward pitch the main rotor blades struck the tail boom. He then turned into the wind and entered an autorotation. The pilot stated that a post accident examination revealed that the engine tachometer was providing false indications and improperly indicated an engine overspeed condition.

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

The pilot's abrupt (improper) control action which resulted in the main rotor contacting the tail boom. Contributing factors were the false indication provided by the engine tachometer, the pilot's decision to immediately initiate an autorotation instead of performing a precautionary landing, and the corn field encountered during landing.

Full narrative available

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