Bell 47G2 accident near Keaau, Hawaii, September 14, 1991
On September 14, 1991 at about 9:30 pm local time, a Bell 47G2 (helicopter), registered N6708D, was substantially damaged in an accident near Keaau, Hawaii. It was a business flight under general aviation rules (Part 91). 2 people had minor injuries; 1 other was unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE PILOT'S LANDING HARD. A CONTRIBUTING FACTOR IN THIS ACCIDENT WAS THE AIRCRAFT EMITTING A VIBRATION FROM AN UNKNOWN SOURCE.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 14, 1991 · about 9:30 pm local time
- Place
- Keaau, Hawaii · map
- Type
- Accident
- Injuries
- 2 people had minor injuries; 1 other was unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47G2 · all 47G2s on the register
- Registration
- N6708D · registry record · serial 2189
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 6,400 hours in all
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Last inspection: inspection type not recorded, January 2, 2000
- Maximum gross weight: 2,450 lb
- Landing gear: fixed
- Engine: Lycoming VO-540-B1B (piston); 0 hours total
- Operator: Koinoa Aviation
The flight
- Departed from: ITO Hilo HI at 9:00 pm
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 020° at 7 knots
- Visibility: 15 statute miles
- Sky: scat at 4,000 ft
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
- Observation at 8:54 pm from ITO, 1 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.