# NTSB CHI91DER05: Bell 47G3B1, N73284, Lasalle, MN, June 11, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: June 11, 1991, 14:30 local (20:30 UTC)
- Place: Lasalle, MN
- Coordinates: 44.069213, -94.569038 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.0692&lon=-94.5690&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14851
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91DER05
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14851/pdf
- Page: https://openairdocs.org/ntsb/CHI91DER05

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN ADEQUATE CLEARANCE FROM THE TERRAIN.  A RELATED FACTOR IS THE PILOT'S MISJUDGED ALTITUDE ABOVE THE CROP.

## Sequence of events

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

- In flight collision with terrain/water, maneuvering - aerial application
  - terrain condition - crop
  - terrain condition - ground
  - altitude - misjudged, pilot in command (contributing factor)
  - clearance - not maintained, pilot in command (cause)

## Analysis

THE PILOT STATED THAT HE WAS PERFORMING AERIAL APPLICATION OPERATIONS OVER A WHEAT FIELD WHEN THE ACCIDENT OCCURRED. HE WAS FLYING HIS FIRST SPRAY SWATH ON THE FIELD WHEN THE SPRAY BOOM CONTACTED THE CROP.  THE HELICOPTER IMPACTED THE GROUND AND CAME TO REST INVERTED.  THE PILOT'S RECOMMENDATION WAS TO FLY HIS SPRAY SWATHS AT A HIGHER ALTITUDE.

## Aircraft

- Registration: [N73284](https://openairdocs.org/deregistered/N73284-2013-08-21), registration cancelled 2013-08-21, S/N 2908, built 1964 (OpenAirDocs)
- Reported make and model: BELL 47G3B1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2908
- Airframe hours: 9016
- Engines: ALLISON 250-C20 400 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Tery Jon Aviation
- Registered owner: Tery Jon Aviation
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, April 1, 1991, 68 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 30; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 2,320 total, 50 in this make and model, 2,175 as pilot in command, 68 in the last 90 days, 66 in the last 30 days, 14 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 170° at 2 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 81 °F

## 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 19910611021339A](https://openairdocs.org/incident/19910611021339A), Jun 11, 1991: Bell 47G3B1, Lasalle, MN, Substantial damage. Caught spray boom on crop being sprayed. Caused helicopter to roll over.

## Other investigations on N73284 (5)

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 CHI98LA198](https://openairdocs.org/ntsb/CHI98LA198), Jun 10, 1998: Bell 47G (N73284), Le Center, MN, destroyed. Probable cause: the pilot's failure to maintain clearance with the wire. A factor associated with the accident was the wire which the helicopter contacted.
- [NTSB SEA80FYP34](https://openairdocs.org/ntsb/SEA80FYP34), Aug 23, 1980: Bell 47G-2 (N73284), Sunnyside, WA, substantial damage
- [NTSB SEA73FYG13](https://openairdocs.org/ntsb/SEA73FYG13), Sep 23, 1972: Bell 47-G2A (N73284), Selah, WA, substantial damage, 1 fatal
- [NTSB SEA71DVQ16](https://openairdocs.org/ntsb/SEA71DVQ16), Dec 21, 1970: Bell 47G-2 (N73284), Sixes, OR, substantial damage
- [NTSB SEA68A0074](https://openairdocs.org/ntsb/SEA68A0074-109548), Jun 27, 1968: Bell 47G3B1 (N73284), Lewiston, ID, destroyed

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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