# NTSB CHI05CA267: West Revolution Mini 500, N20925, Ida, MI, September 3, 2005

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: September 3, 2005, 13:15 local (17:15 UTC)
- Place: Ida, MI
- Coordinates: 41.854999, -83.591392
- Nearby events: https://openairdocs.org/map.md?lat=41.8550&lon=-83.5914&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 28, 2006
- Report: Approved by Office Director
- Parties: FAA-Detroit FSDO
- NTSB case key (mKey): 62633
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI05CA267
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/62633/pdf
- Page: https://openairdocs.org/ntsb/CHI05CA267

## Probable cause

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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, cruise
  - engine instruments,tachometer - false indication (contributing factor)
- Abrupt maneuver, cruise
  - rotorcraft flight controls - improper use of, pilot in command (cause)
  - planning/decision - improper, pilot in command (contributing factor)
  - misc rotorcraft,main rotor/tail boom contact (cause)
  - autorotation - initiated, pilot in command
- In flight collision with terrain/water, emergency descent/landing
  - terrain condition - crop (contributing factor)

## Analysis

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.

## Factual narrative

This report is based on information received by the NTSB.  Additional details may be found in the NTSB's public docket for this case.  For further information, please contact the NTSB Office of Public Inquiries.

## Aircraft

- Registration: [N20925](https://openairdocs.org/deregistered/N20925-2011-06-22), registration cancelled 2011-06-22, S/N 0176 (OpenAirDocs)
- Reported make and model: West Revolution Mini 500
- Registry model: [West Kenneth Gary MINI 500](https://openairdocs.org/model/west-kenneth-gary-mini-500) (registry code 05615XE) (OpenAirDocs)
- Category: Helicopter, amateur-built
- Serial number: 0176
- Airframe hours: 69.3
- Engines: Rotax 582 65 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Condition, June 1, 2005, 65.3 hours before
- Departed: 86G, Petersburg, MI
- Airport: 86G, Lada

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 60; injuries: none; seat: center; flight hours: 103 total, 54 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: 7,000 ft broken
- Temperature: 79 °F, dew point 54 °F
- Altimeter: 30.18 inHg
- Observed at: TTF, 8 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20050903027209A](https://openairdocs.org/incident/20050903027209A), Sep 3, 2005: Amtr MINI500, Ida Township, MI, Substantial damage. (-23) Pilot was in cruise flight at about 1750 ft when he experienced a loss of rotor speed and increased engine RPM. He auto rotated the aircraft and had a…

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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