# NTSB DEN83FA122: Bell 206B, N16937, Billings, MT, May 27, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: May 26, 1983, 20:00 local (May 27, 1983, 02:00 UTC)
- Place: Billings, MT
- Coordinates: 45.650287, -108.380477 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.6503&lon=-108.3805&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 5 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 15988
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN83FA122
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15988/pdf
- Page: https://openairdocs.org/ntsb/DEN83FA122

## Sequence of events

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

- Fire/explosion, takeoff - initial climb
  - turbine assembly,turbine wheel - failure,total (cause)
  - inadequate quality control, manufacturer (cause)
  - turbine assembly,turbine wheel - fatigue (cause)
- Loss of engine power(total) - mech failure/malf, takeoff - initial climb
- Forced landing, landing - flare/touchdown

## Analysis

THE HELICOPTER MADE A HARD AUTOROTATIVE LANDING AFTER TAKEOFF FROM AN OFF ARPT LANDING STIE. THE PLT WAS ON A PERSONAL FLT WITH FAMILY AND FRIENDS WHEN A ENGINE FIRE/EXPLOSION FORCED HIM TO LAND. THE FIRE WAS EXTINGUISHED BY THE PLT AFTER LANDING. POST ACCIDENT INVESTIGATION REVEALED THAT THE FAILURE WAS DUE TO ERROR IN THE MANUFACTURE OF THE 1ST STAGE TURBINE WHEEL. ACCORDING TO AN ALLISON SPOKESMAN THE ERROR IN PROPER WEB THICKNESS WAS MADE DURING THE MANUFACTURING PROCESS AND ESCAPED DETECTION.

## Aircraft

- Registration: N16937 (not matched to a registry record)
- Reported make and model: BELL 206B
- Category: Helicopter
- Serial number: 2322
- Airframe hours: 3145
- Engines: ALLISON 250-C20B 317 horsepower turbo shaft
- Damage: Substantial damage
- Fire: Both
- Flight: Personal, Part 91
- Operator: Beartooth Helicopters
- Registered owner: Blain Helicopter Sales & Servi
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, May 16, 1983, 3,130 hours before
- Departed: BIL, BILLINGS, MT
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; airline transport, commercial; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 27,000 total, 3,000 in this make and model, 27,000 as pilot in command

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 150° at 7 knots
- Visibility: 50 statute miles
- Lowest ceiling: 20,000 ft overcast
- Temperature: 73 °F, dew point 36 °F
- Altimeter: 29.00 inHg
- Observed at: BIL, 39 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 19830526025409A](https://openairdocs.org/incident/19830526025409A), May 26, 1983: Bell 206B, Billings, MT, Substantial damage. Helicopter was transitioning to forward flight when explosion in engine compartment occurred.

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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