Bell 206B accident near Hilo, Hawaii, September 30, 2001
On September 30, 2001, a Bell 206B (helicopter), registered N206KS, was destroyed in an accident near Hilo, Hawaii. It was flown under charter and air-taxi rules (Part 135). 2 people had minor injuries; 3 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of the mechanic to secure the No. 8 bearing thrust nut during maintenance work, which resulted in the total failure of the first stage turbine wheel shaft. Also causal was his misjudgment of his height during the flare resulting in a hard landing. A contributing factor was the high vegetation in the forced landing field, which resulted in a hard landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 30, 2001
- Place
- Hilo, Hawaii · map
- Type
- Accident
- Injuries
- 2 people had minor injuries; 3 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206B · all 206Bs on the register
- Registration
- N206KS · registry record · serial 2457
- Damage
- Destroyed
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The pilot made a mayday call, shut off the fuel valve, and performed an autorotation into high grass after the single engine helicopter experienced a loss of engine power shortly after takeoff. The pilot had heard a bang followed by illumination of the engine out warning light, and the engine began smoking. During the terminal phase of the autorotation, the pilot assumed the grass height was 3 feet and flared accordingly; however, the grass was at least 6 feet tall. Post-accident examination of the engine revealed that the No. 1 turbine wheel was missing. The No. 8 bearing thrust nut exhibited a locking indentation and a notch on its inside surface. Additionally, indentations were on the threads of the threaded end of the first stage turbine wheel shaft. These marks suggest that the thrust nut was not fully engaged on the first stage turbine shaft. The location of the notch suggests that the edge of the nut protruded beyond the end of the turbine shaft. There were no indications of contact by the shaft threads on the inner surface of the deformed area to suggest that it had been displaced into a groove on the first stage turbine shaft. Review of the maintenance records and interviews with the mechanic, who performed the most recent maintenance work, revealed that the turbine section had been replaced approximately 30 hours prior to the accident. Due to excessive oil consumption, maintenance personnel removed the turbine and replaced the No. 5 carbon seal approximately 14 hours prior to the accident. The maintenance records indicated that the day before the accident, the sump cover had been removed for trouble shooting oil consumption. Though it is not detailed in the maintenance entry, it is interpreted that the "sump cover" referred to is the No. 8 Bearing sump nut since the thrust nut was loose.
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: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 2,955 hours in all; 1,255 in this make and model; 186 in the last 90 days; 30 in the last 30 days; 2,650 as pilot in command; 826 on instruments
- Last flight review: June 29, 2001
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 5,456.5 hours
- Last inspection: 100-hour inspection, September 20, 2001; 5,441.5 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison C20B (turboshaft); 0 hours total
- Fire on the ground
The flight
- Departed from: ITO Hilo HI
Weather at the time
- Light: daylight
- Wind: from 010° at 9 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 2,900 ft
- Temperature: 82°F (28°C), dew point 68°F (20°C)
- Altimeter: 29.97 inHg
- Observation at 11:53 pm from PHTO, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 | 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.