Bell 47G-3B, N47AH, registered to and operated by Scott's Helicopter Services Inc: Accident occurred July 24, 2017 in Toeterville, Mitchell County, Iowa

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Des Moines, Iowa

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

http://registry.faa.gov/N47AH

Location: Toeterville, IA
Accident Number: GAA17CA436
Date & Time: 07/24/2017, 1600 CDT
Registration: N47AH
Aircraft: BELL 47G 3B
Aircraft Damage: Substantial
Defining Event: Loss of control in flight
Injuries: 1 None
Flight Conducted Under: Part 137: Agricultural 

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.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot's failure to maintain rotor rpm while maneuvering at low altitude with low airspeed and a tailwind. 

Findings

Aircraft
Prop/rotor parameters - Not attained/maintained (Cause)
Airspeed - Not attained/maintained (Cause)
Altitude - Attain/maintain not possible (Cause)

Personnel issues
Aircraft control - Pilot (Cause)

Environmental issues
Tailwind - Effect on operation (Cause)


Factual Information

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 powerline wires, 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 the horizontal stabilizer.

The nearest METAR was 15 nautical miles south-southeast and 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. 

Pilot Information

Certificate: Private
Age: 33, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): Helicopter
Restraint Used: 4-point
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 05/05/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent: 04/13/2017
Flight Time: (Estimated) 389 hours (Total, all aircraft), 1 hours (Total, this make and model), 150 hours (Last 90 days, all aircraft), 100 hours (Last 30 days, all aircraft), 10 hours (Last 24 hours, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Manufacturer: BELL
Registration: N47AH
Model/Series: 47G 3B 3B
Aircraft Category: Helicopter
Year of Manufacture: 1961
Amateur Built: No
Airworthiness Certificate: Restricted; Normal
Serial Number: 2645
Landing Gear Type: Skid;
Seats: 1
Date/Type of Last Inspection: 05/01/2017, Annual
Certified Max Gross Wt.: 2850 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 14259 Hours at time of accident
Engine Manufacturer: LYCOMING
ELT: Not installed
Engine Model/Series: TV0-435 SER
Registered Owner: SCOTTS HELICOPTER SERVICE INC
Rated Power: 250 hp
Operator: SCOTTS HELICOPTER SERVICE INC
Operating Certificate(s) Held: Agricultural Aircraft (137) 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KAUM, 1233 ft msl
Observation Time: 0814 UTC
Distance from Accident Site: 15 Nautical Miles
Direction from Accident Site: 334°
Lowest Cloud Condition: Clear
Temperature/Dew Point: 14°C / 13°C
Lowest Ceiling: None
Visibility: 7 Miles
Wind Speed/Gusts, Direction: Calm
Visibility (RVR):
Altimeter Setting: 30.03 inches Hg
Visibility (RVV):
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Toeterville, IA
Type of Flight Plan Filed: None
Destination: Toeterville, IA
Type of Clearance: None
Departure Time: 0150 CDT
Type of Airspace: Class G

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude:  43.438889, -92.782222 (est)