# NTSB SEA90LA148: Bell BH-214, N314RM, Thompson Falls, MT, July 28, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 27, 1990, 19:05 local (Jul 28, 1990, 01:05 UTC)
- Place: Thompson Falls, MT
- Coordinates: 47.559371, -115.439727 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.5594&lon=-115.4397&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 4 uninjured
- Status: Completed, report November 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 41251
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA90LA148
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41251/pdf
- Page: https://openairdocs.org/ntsb/SEA90LA148

## Probable cause

CREW'S ENCOUNTER WITH SOFT TERRAIN WHILE ATTEMPTING AN AUTOROTATION LANDING AFTER THE FAILURE OF THE MAIN ROTOR DRIVE SYSTEM.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, cruise
  - rotor drive system,engine to transmission drive - sheared (contributing factor)
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command
- On ground/water encounter with terrain/water, landing - flare/touchdown
  - terrain condition - soft (contributing factor)
  - unsuitable terrain or takeoff/landing/taxi area - encountered (cause)

## Analysis

THE CREW OF THE BELL 214B-1 HELICOPTER ATTEMPTED A FORCED LANDING AFTER THE FAILURE OF THE MAIN DRIVESHAFT ASSEMBLY WHILE THEY WERE IN CRUISE FLIGHT. THE SKIDS DUG INTO SOFT GROUND, CAUSING THE NOSE TO PITCH FORWARD. THE SKIDS LEFT THE AIRFRAME AND THE TAILBOOM WAS STRUCK BY A MAIN ROTOR BLADE. A PINCHED O-RING HAD PERMITTED MOST OF THE LUBRICANT TO BE EVACUATED FROM PART OF THE MAIN DRIVE ASSEMBLY.

## Aircraft

- Registration: [N314RM](https://openairdocs.org/deregistered/N314RM-1992-06-19), registration cancelled 1992-06-19, S/N 28041 (OpenAirDocs)
- Reported make and model: BELL BH-214
- Registry model: [Bell 214B-1](https://openairdocs.org/model/bell-214b-1) (registry code 1182105) (OpenAirDocs)
- Category: Helicopter
- Serial number: 28041
- Engines: LYCOMING T5508D 2250 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Positioning, Part 91
- Registered owner: Rocky Mountain Helicopters,Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, July 24, 1990
- Departed: SANDPOINT, ID
- Destination: MSO, MISSOULA, MT
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; commercial; medical: class 2, valid medical--no waivers/lim.; flight hours: 16,661 total, 5,297 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 4 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 57 °F, dew point -0 °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 19900727028959A](https://openairdocs.org/incident/19900727028959A), Jul 27, 1990: Bell 214B1, Thompson Fall, MT, Substantial damage. Loud bang autorotated. Skids dug in. Rotors chopped tailboom. Driveshaft overheated lacked lube due pinched o ring.

## Other investigations on N314RM (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 ANC92FA044](https://openairdocs.org/ntsb/ANC92FA044), Mar 6, 1992: Bell 214B-1 (N314RM), Hobart Bay, AK, substantial damage. Probable cause: FATIGUE FAILURE OF THE COMPRESSOR ASSEMBLY IMPELLER, AND INADEQUATE QUALITY CONTROL BY THE MANUFACTURER. A FACTOR WHICH CONTRIBUTED TO THE ACCIDENT WAS THE MOUNTAINOUS/HILLY TERRAIN.
- [NTSB SEA85LA060](https://openairdocs.org/ntsb/SEA85LA060), Feb 19, 1985: Bell 214B1 (N314RM), Lowell, OR, 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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