# NTSB LAX91LA405: Bell 47G2, N6708D, Keaau, HI, September 14, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: September 14, 1991, 11:30 local (21:30 UTC)
- Place: Keaau, HI
- Coordinates: 19.690706, -155.080947 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=19.6907&lon=-155.0809&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 2 minor, 1 uninjured
- Status: Completed, report March 24, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27367
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA405
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27367/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA405

## Probable cause

THE PILOT'S LANDING HARD.  A CONTRIBUTING FACTOR IN THIS ACCIDENT WAS THE AIRCRAFT EMITTING A VIBRATION FROM AN UNKNOWN SOURCE.

## Sequence of events

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

- Hard landing, landing - flare/touchdown
  - aircraft performance - vibration (contributing factor)
  - precautionary landing - performed, pilot in command (cause)

## Analysis

WHILE FLYING, THE PILOT FELT A VIBRATION AND HE PERFORMED A PRECAUTIONARY LANDING.  THE PILOT LANDED THE AIRCRAFT HARD.  THE AIRCRAFT WAS REMOVED WITHOUT NTSB AUTHORIZATION AND CONSEQUENTLY IT COULD NOT BE EXAMINED.  THE PILOT DID NOT PROVIDE THE NTSB A COMPLETED 'AIRCRAFT ACCIDENT REPORT' FORM 6120.1.  THE ORIGIN OF THE REPORTED VIBRATION WAS NOT DETERMINED.

## Aircraft

- Registration: [N6708D](https://openairdocs.org/deregistered/N6708D-1994-12-08), registration cancelled 1994-12-08, S/N 2189 (OpenAirDocs)
- Reported make and model: BELL 47G2
- Registry model: [Bell 47G-2](https://openairdocs.org/model/bell-47g-2) (registry code 1181008) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2189
- Engines: LYCOMING VO-540-B1B 240 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Operator: Koinoa Aviation
- Last inspection: Unknown, January 2, 2000
- Departed: ITO, HILO, HI
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 30; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; flight hours: 6,400 total

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 7 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Observed at: ITO, 1 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 19910914042799A](https://openairdocs.org/incident/19910914042799A), Sep 14, 1991: Bell 47G2, Keaau, HI, Substantial damage. Reported vibration on sightseeing flight. Elected to land. Impacted hard on landing. Chopped tail. Cause unknown.

## Other investigations on N6708D (5)

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 FTW74FQG36](https://openairdocs.org/ntsb/FTW74FQG36), Dec 30, 1973: Bell 47G-2 (N6708D), Stratford, TX, substantial damage
- [NTSB ANC70A0023](https://openairdocs.org/ntsb/ANC70A0023), Aug 27, 1969: Bell 47G-2 (N6708D), Prudhoe Bay, AK, substantial damage
- [NTSB ANC69A0041](https://openairdocs.org/ntsb/ANC69A0041), Mar 4, 1969: Bell 47G-2 (N6708D), Chugiak, AK, substantial damage
- [NTSB ANC69A0003](https://openairdocs.org/ntsb/ANC69A0003), Jul 25, 1968: Bell 47G-2 (N6708D), Minchumina, AK, substantial damage
- [NTSB UNK65X0317](https://openairdocs.org/ntsb/UNK65X0317), Oct 18, 1964: Bell 47G2 (N6708D), King Salmon, AK, 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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