Probable cause
The pilot’s failure to maintain rotor rpm while maneuvering at low altitude with low airspeed and a tailwind.
NTSB analysis
According to the helicopter pilot, during an agricultural flight, he made a downwind turn to spray the intended field. During the low airspeed right turn, he increased the engine power, and the rotor rpm decreased. He reported that he leveled the helicopter to clear power lines, but the rotor rpm remained low. The helicopter descended, and the pilot landed the helicopter in a corn field.
The helicopter sustained substantial damage to the tailboom and horizontal stabilizer.
The nearest METAR located 15 nautical miles south-southeast from the accident site reported that, about the time of the accident, the wind was calm.
The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Text from the NTSB. Open the NTSB docket for GAA17CA436 for the full record.
Event
- Date
- Jul 24, 2017
- Type
- Accident
- Place
- Toterville, Iowa
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Bell 47G 3B
- N-number
- N47AH
- Category
- Helicopter
- Year built
- 1961
- Damage
- Substantial
- Operating rule
- Part 137 (agricultural)
- Purpose of flight
- Aerial application
Other records under this N-number
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.