# NTSB CHI90DEP07: Bell 47-G2, N6768D, Hatley, WI, July 10, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: July 9, 1990, 19:05 local (Jul 10, 1990, 00:05 UTC)
- Place: Hatley, WI
- Coordinates: 44.879188, -89.32904 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.8792&lon=-89.3290&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report September 21, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14480
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI90DEP07
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14480/pdf
- Page: https://openairdocs.org/ntsb/CHI90DEP07

## Probable cause

THE PARTIAL LOSS OF POWER DUE TO STICKING INTAKE VALVES.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, takeoff - initial climb
  - engine assembly,valve,intake - seized (cause)
- Forced landing, descent - uncontrolled
  - emergency procedure - initiated, pilot in command
  - altitude - unavailable, pilot in command (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled
  - autorotation - not possible, pilot in command (contributing factor)

## Analysis

THE HELICOPTER WAS LOADED WITH CHEMICALS FOR AGRICULTURE DISPERSAL ON A TRUCK MOUNTED PLATFORM, TEN FEET ABOVE GROUND LEVEL. ON LIFTOFF THE ENGINE SUSTAINED A PARTIAL POWER REDUCTION DUE TO TWO STICKING INTAKE VALVES. THE AIRCRAFT DESCENDED INTO THE TERRAIN WHEN ALTITUDE PROVED INSUFFICIENT TO EFFECT AN AUTOROTATIONAL FORCED LANDING.

## Aircraft

- Registration: [N6768D](https://openairdocs.org/deregistered/N6768D-2018-03-15), registration cancelled 2018-03-15, S/N 2441, built 1959 (OpenAirDocs)
- Reported make and model: BELL 47-G2
- Registry model: [Bell 47G-2](https://openairdocs.org/model/bell-47g-2) (registry code 1181008) (OpenAirDocs)
- Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2441
- Airframe hours: 12331
- Engines: LYCOMING VO-435-A1F 260 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Gitter, Gregory C., doing business as Central Wisconsin Helicopter
- Registered owner: Central Wisconsin
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, June 27, 1990, 40 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 33; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 2,080 total, 375 in this make and model, 1,950 as pilot in command, 120 in the last 90 days, 70 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point 61 °F
- Altimeter: 30.00 inHg
- Observed at: CWA, 20 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 19900709024939A](https://openairdocs.org/incident/19900709024939A), Jul 9, 1990: Bell 47G2A, Hatley, WI, Substantial damage. Engine lost power after liftoff from service truck. Hard impact rotors chopped tailboom. Found sticking valves.

## Other investigations on N6768D (1)

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.

- [NTSB WPR09CA333](https://openairdocs.org/ntsb/WPR09CA333), Jul 8, 2009: Bell 47G-2 (N6768D), Turlock, CA, substantial damage. Probable cause: The pilot's failure to maintain rotor RPM while maneuvering at a low altitude.

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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