# NTSB DEN87DTG02: Bell 47G-4A, N2238W, Minot, ND, September 8, 1987

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: September 8, 1987, 15:30 local (20:30 UTC)
- Place: Minot, ND
- Coordinates: 47.260036, -101.770217 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.2600&lon=-101.7702&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 2, 1988
- Report: Approved by Office Director
- NTSB case key (mKey): 17069
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN87DTG02
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17069/pdf
- Page: https://openairdocs.org/ntsb/DEN87DTG02

## Sequence of events

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

- Vortex turbulence encountered, maneuvering - aerial application
  - in-flight planning/decision - improper, pilot in command (cause)
  - weather condition - unfavorable wind
- Altitude deviation,uncontrolled, maneuvering - aerial application
  - terrain condition - mountainous/hilly (contributing factor)
  - weather condition - downdraft (contributing factor)
  - spray/dusting equipment - corroded (contributing factor)
  - load jettison - not possible
  - descent - not corrected
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - downhill (contributing factor)
- On ground/water collision with object, other
  - object - tree(s) (contributing factor)

## Analysis

THE PLT RPRTD THAT WHEN HE TOOK OFF FM A NRBY NURSE TRUCK, THE WIND WAS FM THE NE AT 5 TO 7 MPH. HE MADE AN OBSERVATION PASS ACROSS THE AREA TO BE TREATED, THEN BGN A DSCNDG RGT TURN TO MAKE A SWATH RUN IN THE OPPOSITE DRCTN. HE STATED HE WAS UNAWARE OF A WIND-SHIFT TO THE NW. SUBSEQUENTLY, THE HELICOPTER ENCOUNTERED WHAT THE PLT THOUGHT WAS WAKE TURBC FM THE OBSERVATION PASS. THE ACFT BGN TO SETTLE & THE PLT INCREASED THE COLLECTIVE IN AN EFFORT TO STOP THE DSCNT. THE PLT SAID THE 'RECOVERY ENDED IN A DEEP CANYON APPROX 150 TO 200 FT DEEP. EMERGENCY TRIP DOOR SOLENOID TO RELEASE LOAD FAILEDTO WORK. WAS ONLY ABLE TO SUSTAIN HOVER FOR APPROX 2 MIN BEFORE A/C SETTLED ON A 30 TO 40 (DEGREE) EMBANKMENT & SLID DOWN 40 FT TO TREES, TAIL FIRST.'  RPRTDLY THE DUMP VLV FAILED TO OPERATE DUE TO CORROSION FM CHEMICALS CARRIED ON THE PREVIOUS FLT.

## Aircraft

- Registration: [N2238W](https://openairdocs.org/deregistered/N2238W-2012-08-30), registration cancelled 2012-08-30, S/N 7704, built 1970 (OpenAirDocs)
- Reported make and model: BELL 47G-4A
- Registry model: [Bell 47G-4A](https://openairdocs.org/model/bell-47g-4a) (registry code 1181031) (OpenAirDocs)
- Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 7704
- Engines: LYCOMING VO-540-B1B3 280 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: James H Morten
- Registered owner: Larimore Air Service, Inc.
- Airworthiness certificate: Standard, Normal; Special, Restricted (Special)
- Last inspection: 100 hour, July 25, 1987, 60 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 16,488 total, 1,850 in this make and model, 16,400 as pilot in command, 265 in the last 90 days, 87 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 0° at 6 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 72 °F
- Altimeter: 29.00 inHg
- Observed at: MOT, 12 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 19870908050469A](https://openairdocs.org/incident/19870908050469A), Sep 8, 1987: Bell 47G4A, Minot, ND, Substantial damage. The helicopter lost rotor speed after encountering its own wake during spraying. Valve failure prevented load dump.

## Other investigations on N2238W (2)

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 FTW90DPJ05](https://openairdocs.org/ntsb/FTW90DPJ05), Apr 14, 1990: Bell 47G-4A (N2238W), Bixby, OK, destroyed. Probable cause: LOSS OF CONTROL DUE TO UNDETERMINED MECHANICAL FAILURE.
- [NTSB NYC73FHM18](https://openairdocs.org/ntsb/NYC73FHM18), Dec 28, 1972: Bell 47G-4A (N2238W), Suffern, NY, substantial damage

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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