DEN99LA168 · Bell 47G3B2A
Bell 47G3B2A · Accident: partial loss of engine power (non-mechanical) en route
From U27 · UT to Coalville, UT (no airport)
Event
- NTSB case
- DEN99LA168
- 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
- 0
- 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 47G3B2A
- 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
- N83246
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From U27 · UTTo Coalville, UT (no airport)
- 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 137: Agricultural
- 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
- Partial loss of engine power (non-mechanical)
- 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 › Rotor RPM, not maintained
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot departed the airport en route to a local staging area to perform aerial application work. He departed with 30 gal. of fuel and was planning to pick up a load of chemical spray at his destination. Approximately 2 1/2 miles southeast of the airport, the engine began to miss. He decided to make a precautionary landing in an alfalfa field. When the helicopter was 200 ft. agl, the engine began to run rougher and he initiated an autorotation. He closed the throttle and the engine quit. The helicopter impacted the ground, stopped suddenly and rocked forward. The rotor blades flexed downward, severing the tail boom. The day following the accident, an examination of the engine was performed by an FAA maintenance inspector and no discrepancies were found. When asked what recommendation the pilot could make as to how the accident could have been prevented, he responded that he could have 'performed [a] better autorotation.'
Probable cause
The pilot's failure to maintain rotor rpm while attempting a precautionary autorotation landing. A factor was the loss of engine power for undetermined reasons.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN99LA168
- Event ID
- 20001212X19745
- Case number
- DEN99LA168
- 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. 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: 5a6296dc2dc7e0e9d1404fd370cba80e0caeda59cf14b92790b65f5b67d8be5f; retrieved 2026-09-22T14:02:07.501Z.