Friday, January 10, 2020

Low Altitude Operation/Event: Aerospatiale AS-350B-3 Ecureuil, N350DL; accident occurred April 30, 2019 in Sula, Ravalli County, Montana

Aviation Accident Final Report - National Transportation Safety Board

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Helena, Montana

Investigation Docket - National Transportation Safety Board:

Location: Sula, MT
Accident Number: GAA19CA238
Date & Time: 04/30/2019, 1015 MDT
Registration: N350DL
Aircraft: Aerospatiale AS350
Aircraft Damage: Substantial
Defining Event: Low altitude operation/event
Injuries: 1 None
Flight Conducted Under: Part 137: Agricultural 


The helicopter pilot reported that, after an agricultural application flight, he set the bucket down in a predetermined operations zone near a semi-truck loading hopper to be refilled. He added that another truck arrived to top off the semi-truck hopper, which emitted fertilizer dust and led to the pilot being concerned that it would deteriorate visibility. He advised the ground crew that he was going to temporarily move out of the operations zone.

The pilot reported that he set the bucket in the new temporary operations zone. As the skid steer approached, he eased the helicopter backward to keep the other ground equipment in his view. The pilot heard a "bang," disconnected the helicopter from the long-line, and then landed the helicopter without further incident.

Postaccident examination revealed that the auger from the semi-truck hopper was fully extended behind the helicopter and that a tail rotor blade had sustained substantial damage. The pilot reported that he might have backed the helicopter into the extended auger.

The pilot reported that there were no preaccident mechanical failures or malfunctions 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 adequate clearance from ground equipment, which resulted in a tail rotor blade impact.


Personnel issues Monitoring environment - Pilot
Environmental issues Ground equipment - Effect on operation

Factual Information

History of Flight

Maneuvering-hover Low altitude operation/event (Defining event)
Maneuvering-hover Collision with terr/obj (non-CFIT)

Pilot Information

Certificate: Airline Transport; Flight Instructor; Commercial
Age: 43, Male
Airplane Rating(s): Multi-engine Land; Multi-engine Sea; Single-engine Land; Single-engine Sea
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter
Restraint Used: 3-point
Instrument Rating(s): Airplane; Helicopter
Second Pilot Present: No
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine; Helicopter; Instrument Airplane; Instrument Helicopter
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 01/11/2019
Occupational Pilot: Yes
Last Flight Review or Equivalent: 03/15/2019
Flight Time: (Estimated) 8773 hours (Total, all aircraft), 3125 hours (Total, this make and model), 8700 hours (Pilot In Command, all aircraft), 26 hours (Last 90 days, all aircraft), 11 hours (Last 30 days, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Make: Aerospatiale
Registration: N350DL
Model/Series: AS350 B3
Aircraft Category: Helicopter
Year of Manufacture: 2008
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 4508
Landing Gear Type: Skid
Seats: 6
Date/Type of Last Inspection: 04/24/2019, Annual
Certified Max Gross Wt.: 5225 lbs
Time Since Last Inspection:
Engines: 1 Turbo Shaft
Airframe Total Time: 1103.2 Hours as of last inspection
Engine Manufacturer: Safran
ELT: C126 installed, not activated
Engine Model/Series: Arriel 2B1
Registered Owner: Pj Helicopter Llc
Rated Power: 749 hp
Operator: Mission Mountain Helicopters
Operating Certificate(s) Held:  Agricultural Aircraft (137); Rotorcraft External Load (133); On-demand Air Taxi (135)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation:
Distance from Accident Site:
Observation Time:
Direction from Accident Site:
Lowest Cloud Condition:
Visibility:  10 Miles
Lowest Ceiling: Overcast / 10000 ft agl
Visibility (RVR):
Wind Speed/Gusts: 8 knots /
Turbulence Type Forecast/Actual: None / None
Wind Direction: 200°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting:
Temperature/Dew Point: 2°C
Precipitation and Obscuration: Blowing - Widespread Dust; No Precipitation
Departure Point: Soula, MT
Type of Flight Plan Filed: None
Destination: Soula, MT
Type of Clearance: None
Departure Time: 0700 MDT
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: 45.859444, -113.968056 (est)

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