# NTSB ATL90LA042: Bell TH-1, N106SR, Creola, AL, December 20, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: December 20, 1989, 08:20 local (14:20 UTC)
- Place: Creola, AL
- Coordinates: 30.889352, -88.000442 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.8894&lon=-88.0004&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report October 7, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 8191
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL90LA042
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8191/pdf
- Page: https://openairdocs.org/ntsb/ATL90LA042

## Probable cause

THE LOSS OF ENGINE POWER DUE TO A #21 BEARING FAILURE. THE BEARING FAILED AS A RESULT OF INADEQUATE MAINTENANCE. A FACTOR IN THE ACCIDENT WAS THE PILOT OPERATING THE HELICOPTER WITHIN THE AVOID OPERATING ENVELOPE.

## 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
  - turbine assembly,shaft bearing - contamination (cause)
  - turbine assembly,shaft bearing - seized (cause)
  - maintenance - inadequate, other maintenance personnel (cause)
- Forced landing, landing - flare/touchdown
  - autorotation - performed, pilot in command
- In flight collision with terrain/water, landing - flare/touchdown
  - proper altitude - not maintained, pilot in command (contributing factor)

## Analysis

THE ENGINE FAILED WHILE THE PILOT WAS HOVERING AT 110 FT DURING AN EXTERNAL LOAD OPERATION. THE PILOT RELEASED THE LOAD AND AUTOROTATED INTO A SWAMPY AREA. ENGINE TEARDOWN SHOWED EVIDENCE OF SEIZURE AND HEAVY WEAR AT THE #21 BEARING ASSEMBLY ROLLER/SHAFT INTERFACE. METALLURGICAL EXAM REVEALED A BREAKDOWN OF THE TUNGSTEN CARBIDE AND COBALT COATING REPAIR. THE DETONATION GUN (DGUN) REPAIR BUILDUP ON THE BEARING/SEAL JOURNAL, SEO T53-LO-R0035, WAS USED IN 1969, AND CANCELED IN 1970. THE PROCEDURE WAS NOT APPROVED OR PRACTICED BY LYCOMING, AND THE MANUFACTURER RECOMMENDED THAT PARTS REPAIRED IAW THE SEO NOT BE INSTALLED IN ENGINES. THE PILOT WAS OPERATING WITHIN THE 'AVOID OPERATION' AREA OF THE AIRSPEED VELOCITY CHART.

## Aircraft

- Registration: N106SR (not matched to a registry record)
- Reported make and model: BELL TH-1
- Category: Helicopter
- Serial number: 157806
- Airframe hours: 8403
- Engines: LYCOMING T53-L13B 1100 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Other work use, Part 91
- Registered owner: Scott Paper Company
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, November 29, 1989, 80 hours before
- Departed: MT VERNON, AL
- Destination: MOBILE, AL

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 1, valid medical--no waivers/lim.; flight hours: 15,534 total, 3,629 in this make and model, 296 in the last 90 days, 56 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 10 knots
- Visibility: 10 statute miles
- Lowest ceiling: 3,000 ft overcast
- Temperature: 39 °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 19891220052119A](https://openairdocs.org/incident/19891220052119A), Dec 20, 1989: Bell TH1L, Creola, AL, Destroyed. Engine seized in long line hover. Crash landed. Engine operated in high stress mode. Military repair not approved.

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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