# NTSB LAX85LA336: Bell 206 B3, N90328, Arroyo Grande, CA, August 1, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 1, 1985, 10:15 local (17:15 UTC)
- Place: Arroyo Grande, CA
- Coordinates: 35.159149, -120.429969 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.1591&lon=-120.4300&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 24787
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX85LA336
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/24787/pdf
- Page: https://openairdocs.org/ntsb/LAX85LA336

## 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, hover
  - lubricating system,oil tubing - blocked(partial) (contributing factor)
  - maintenance,service of aircraft/equipment - inadequate, company maintenance personnel (cause)
  - turbine assembly,shaft bearing - blocked(partial) (contributing factor)
  - turbine assembly,shaft - failure,partial (contributing factor)
- Forced landing, descent
  - emergency procedure - performed, pilot in command (cause)
  - autorotation - performed, pilot in command (cause)
- Hard landing, landing - flare/touchdown
  - airport facilities,runway/landing area condition - none suitable

## Analysis

WHILE HOVERING AND SLINGING AN EXTERNAL LOAD OVER ROUGH TERRAIN THE ENG CHIP LIGHT ILLUMINATED. THE PLT IMMEDIATELY POSITIONED THE ACFT TO RELEASE THE LOAD AND THE ENG BEGAN MAKING A 'WHINING' NOISE. SEVERAL SECONDS LATER ALL ENG POWER WAS LOST. THE PLT AUTOROTATED TO A FIRM LANDING AND UPON TOUCHDOWN THE MAIN ROTOR BLADES FLEXED DOWNWARD AND SEVERED THE TAIL BOOM. EXAM OF THE ENG'S TURBINE COMPONENTS REVEALED THE PRESENCE OF A 'SLUDGE' MATERIAL IN THE SCAVENGE OIL LINE FROM THE NO. 8 BEARING AND ALSO THE PRESENCE OF A HEAVY BUILD UP OF CARBON ON THE ENGINE ROTOR 'PEASHOOTER' DRIVE SHAFT. THE ACCUMULATED MATERIAL CAUSED SHAFT RUB AND FAILURE OF THE POWER TURBINE'S INNER SHAFT. THE OPERATOR REPORTED THAT AN EARLY INSPECTION OF THE N1/N2 DRIVE SHAFT AREA COULD HAVE DETECTED THE PROBLEM AND PREVENTED THE ACCIDENT.

## Aircraft

- Registration: N90328 (not matched to a registry record)
- Reported make and model: BELL 206 B3
- Category: Helicopter
- Serial number: 1853
- Airframe hours: 4096
- Engines: ALLISON 250 SER 400HP 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Other work use, Part 133
- Operator: Western Helicopters
- Registered owner: Gatx Leasing Corp.
- Airworthiness certificate: Standard, Normal

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 33; commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 5,959 total, 1,600 in this make and model, 170 in the last 90 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 225° at 15 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 64 °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 19850801035509A](https://openairdocs.org/incident/19850801035509A), Aug 1, 1985: Bell 206B, Arroyo Grande, CA, Substantial damage. Carbon in engine rotor drive shafting caused rubbing,failure of power turbine inner shaft. Hard landing on terrain.

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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