# NTSB SEA89LA120: Bell 47G-2, N1161N, Centralia, WA, June 24, 1989

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: June 24, 1989, 08:45 local (15:45 UTC)
- Place: Centralia, WA
- Coordinates: 46.739051, -122.949905 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.7391&lon=-122.9499&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report September 30, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 41038
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA89LA120
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41038/pdf
- Page: https://openairdocs.org/ntsb/SEA89LA120

## Probable cause

THE PILOT MISJUDGED HIS CLEARANCE OVER TREES,  WHICH RESULTED IN AN IN-FLIGHT TAIL ROTOR STRIKE WITH THE TREES AND LOSS OF TAIL ROTOR CONTROL.  THE TREES WERE A RELATED FACTOR.

## Sequence of events

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

- In flight collision with object, maneuvering - aerial application
  - object - tree(s) (contributing factor)
  - clearance - misjudged, pilot in command (cause)
- Loss of control - in flight, maneuvering - aerial application
  - rotor system,tail rotor blade - overload
  - rotor drive system,tail rotor drive shaft - overload
  - directional control - not possible, pilot in command
- Forced landing, descent - uncontrolled
  - autorotation - attempted, pilot in command
- In flight collision with terrain/water, landing
- Roll over, landing

## Analysis

THE PLT WAS MAKING A TURN AROUND MANEUVER OVER TREES BETWEEN SWATH RUNS, WHEN HE HEARD A LOUD 'POP' & LOST TAIL ROTOR CONTROL. THE HELICOPTER BEGAN ROTATING & THE PLT INITIATED AN AUTOROTATION. HOWEVER, THE HELICOPTER IMPACTED WHILE IT WAS ROTATING, THEN IT ROLLED OVER. AN EXAM OF THE TAIL ROTOR DRIVE SYS REVEALED DAMAGE TO THE TAIL ROTOR BLADES, AS WELLAS TORSIONAL FAILURE OF THE TAIL ROTOR DRIVE SHAFT, BUT NO PREIMPACT PART FAILURE WAS FOUND.

## Aircraft

- Registration: [N1161N](https://openairdocs.org/deregistered/N1161N-2017-02-16), registration cancelled 2017-02-16, S/N 42, built 1948 (OpenAirDocs)
- Reported make and model: BELL 47G-2
- Registry model: [Bell 47G-2](https://openairdocs.org/model/bell-47g-2) (registry code 1181008) (OpenAirDocs)
- Registry engine: [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series) (registry code 27033, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 42
- Airframe hours: 9852
- Engines: LYCOMING TVO-435 265 horsepower reciprocating
- Damage: Destroyed
- Flight: Aerial application, Part 137
- Registered owner: Kermit D. Jones
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, January 12, 1989, 130 hours before
- Departed: CENTRAILIA, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; commercial; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 6,000 total, 6,000 in this make and model, 6,000 as pilot in command, 125 in the last 90 days, 50 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 3 knots
- Visibility: 55 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point 55 °F
- Altimeter: 29.00 inHg
- Observed at: OLM, 20 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 19890624017339A](https://openairdocs.org/incident/19890624017339A), Jun 24, 1989: Bell 47G2, Centralia, WA, Destroyed. Lost tail rotor authority on a swath run turn around. Hit ground rotating to the right.

## Other investigations on N1161N (1)

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 UNK64X2935](https://openairdocs.org/ntsb/UNK64X2935), Jul 19, 1964: Bell 47D1 (N1161N), Toppenish, WA, 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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