Bell 206BII accident near Newhalem, Washington, August 24, 2000
On August 24, 2000 at about 1:00 am local time, a Bell 206BII (helicopter), registered N90307, was substantially damaged in an accident near Newhalem, Washington. It was a business flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
Debonding between the elastomeric material and the center plate of the transmission isolation mount.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 24, 2000 · about 1:00 am local time
- Place
- Newhalem, Washington · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206BII · all 206BIIs on the register
- Registration
- N90307 · registry record · serial 1747
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that after landing the helicopter and reducing the engine to idle power, he heard a 'snap' or 'click' above and behind him. The main rotor immediately pitched back and to the left. This violent gyration resulted in the toe of the skids to lift off the ground and the helicopter moved backwards with each pitch up. The pilot shut the engine down. The main rotors windmilled to a stop and the mast came to rest back and to the left about 30 degrees off of vertical. Inspection of the helicopter found that the pylon isolation mount failed. Examination of the mount found that the failure occurred over a long period of time and was probably due to inadequate surface preparation of the center plate to the elastomeric blocks, which resulted in the debonding of the material and allowing the center plate more movement than normal.
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: multi-engine land; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane; rotorcraft: helicopter
- Flight time: 28,711 hours in all; 386 in this make and model; 119 in the last 90 days; 26 in the last 30 days; 6,594 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Last inspection: annual inspection, May 31, 2000
- Maximum gross weight: 3,000 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20 (turboshaft); 0 hours total
The flight
- Departed from: S97 Brewster WA
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
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.
Other NTSB records under N90307 the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number SEA00LA197.