Bell 47G3B2A accident near Tremonton, Utah, September 23, 1999
On September 23, 1999 at about 3:00 pm local time, a Bell 47G3B2A (helicopter), registered N83246, was substantially damaged in an accident near Tremonton, Utah. It was a ferry flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 23, 1999 · about 3:00 pm local time
- Place
- Tremonton, Utah · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47G3B2A · all 47G3B2As on the register
- Registration
- N83246 · no longer on the register · serial 6858
- Damage
- Substantial damage
- Flight
- Ferry flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
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.'
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: single-engine land; rotorcraft: helicopter
- Flight time: 17,000 hours in all; 17,000 in this make and model; 85 in the last 90 days; 22 in the last 30 days
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 9,912 hours
- Last inspection: 100-hour inspection, August 11, 1999; 13 hours since
- Maximum gross weight: 2,950 lb
- Seats: 3
- Landing gear: fixed
- Engine: Lycoming TVO-435-F1A (piston); 0 hours total
The flight
- Departed from: U27 UT at 2:55 pm
- Destination: NONE Coalville UT
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 52°F (11°C), dew point 43°F (6°C)
- Altimeter: 30.00 inHg
- Observation at 2:51 pm from LGU, 16 miles away
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.
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.