# NTSB FTW89LA036: Bell 206B-III, N22704, S.Timbalier 151, January 3, 1989

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: January 3, 1989, 12:50 local (18:50 UTC)
- Place: S.Timbalier 151
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report July 11, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 22825
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW89LA036
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22825/pdf
- Page: https://openairdocs.org/ntsb/FTW89LA036

## Probable cause

A COLLISION BETWEEN THE AIRCRAFT AND THE PLATFORM DURING THE EMERGENCY AUTOROTATION WHICH CAUSED THE LEFT SKID AND FLOAT TO SEPARATE AND DESTABILIZED THE AUTOROTATION. THE COLLISION WAS PROBABLY UNADOIDABLE DUE TO THE MANEUVER THAT WAS BEING CONDUCTED AT THE ONSET OF THE EMERGENCY. THE EMERGENCY LANDING WAS ATTEMPTED FOLLOWING AN ENGINE FAILURE THAT WAS THE RESULT OF A TOTAL COMPRESSOR FAILURE. THE COMPRESSOR FAILURE WAS CAUSED BY A FATIGUE FAILURE OF THE SIXTH STAGE WHEEL WHICH SEPARATED. THE FAILURE WAS INITIATED DUE TO A CASTING INCLUSION IN THE WHEEL WHICH WAS NOT DETECTED DURING THE MANUFACTURING PROCESS.

## 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
  - compressor assembly,rotor disc - failure,total (cause)
  - compressor assembly,casting - fatigue (cause)
  - maintenance,rebuild/remanufacture - improper, manufacturer (cause)
- In flight collision with object, descent - emergency
  - object - building(nonresidential) (cause)
- In flight collision with terrain/water, descent - emergency
  - terrain condition - water

## Analysis

THE ACFT EXPERIENCED AN ENG FAILURE DURING A SLING LOAD PICK UP ON AN OFFSHORE PLATFORM. DURING THE AUTOROTATION, THE LEFT SKID AND FLOAT STRUCK A HANDRAIL ON THE RIG AND SEPARATED. THE ACFT IMPACTED THE WATER, NOSE LOW, AND ROLLED OVER AS A RESULT OF THE SEPARATED FLOAT. INVESTIGATION REVEALED THAT THE ENG FAILURE WAS A RESULT OF A 6TH STAGE COMPRESSOR WHEEL FATIGUE FAILURE. THE WHEEL FATIGUE ORIGINATED AT A CASTING INCLUSION THAT HAD NOT BEEN DETECTED DURING THE MANUFACTURING PROCESS.

## Aircraft

- Registration: [N22704](https://openairdocs.org/deregistered/N22704-2012-11-29), registration cancelled 2012-11-29, S/N 3614, built 1982 (OpenAirDocs)
- Reported make and model: BELL 206B-III
- Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs)
- Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 3614
- Airframe hours: 8213
- Engines: ALLISON 250-C20B 420 horsepower turbo shaft
- Damage: Destroyed
- Flight: Other work use, Part 133
- Registered owner: Petroleum Helicopters, Inc
- Airworthiness certificate: Standard, Utility
- Last inspection: AAIP, December 18, 1988, 45 hours before
- Departed: S.T. 151
- Destination: S.T. 151
- Flight plan: Company VFR
- Airport: 151, S. Tim 151

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; commercial; instrument ratings: helicopter; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 3,522 total, 1,431 in this make and model, 3,143 as pilot in command, 134 in the last 90 days, 55 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 16 knots
- Visibility: 10 statute miles
- Lowest ceiling: 10,000 ft broken
- Temperature: 79 °F, dew point 72 °F
- Altimeter: 30.00 inHg
- Observed at: 300, 15 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 19890103000149A](https://openairdocs.org/incident/19890103000149A), Jan 3, 1989: Bell 206B, South Timbalier, LA, Substantial damage. Engine failed on external load from oil platform. Jettisoned load and crashed in water. Compressor wheel failed.

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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