FTW02LA177 · Bell 47G-3B-1
Bell 47G-3B-1 · Accident: in flight encounter with weather en route
From Nederland, CO (no airport) to an unrecorded destination
Event
- NTSB case
- FTW02LA177
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Bell 47G-3B-1
- Aircraft type
- Bell 47
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N999DW
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Nederland, CO (no airport)To not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- In flight encounter with weather
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Pilot in command › Flight into adverse weather, inadvertent
- Weather condition › Turbulence
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
Prior to the flight in mountainous terrain, the pilot obtained a weather forecast that called for winds from the southwest at 30 mph, with gusts up to 40 mph. The flight departed and was in cruise flight at 9,000 feet (700 feet agl) with a 20-25 knot headwind and experiencing light turbulence, when the flight encountered "severe turbulence." The pilot stated that the helicopter went "up and down violently for a period of 2-3 seconds." The tailrotor drive shaft was severed by the main rotor blades, and the helicopter then experienced "a right yaw that full application of left pedal would not correct." The pilot stated that during the event the engine and rotor rpm increased past their upper limits. He was able to bring the engine and rotor rpm within limits and regained control of the helicopter. Subsequently, the pilot performed an autorotation to sloping terrain without further incident. According to a witness, who was fishing on a lake 4 miles from the accident site, he observed water spouts between 2 and 8 feet tall and high swirling winds near the time of the accident.
Probable cause
the pilot's inadvertent in-flight encounter with severe turbulence, which resulted in main rotor-tailboom contact and the separation of the tailrotor drive shaft.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW02LA177
- Event ID
- 20020612X00856
- Case number
- FTW02LA177
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: e1aa0eb45c7ea3da7a29565720fa9d026c346b4b08b1ba4585096b5b7c505c61; retrieved 2026-09-22T10:51:48.169Z.