Monday, March 09, 2020

Unknown or Undetermined: Eurocopter AS 350B3 AStar, N910S; fatal accident occurred October 29, 2018 in Odanah, Ashland County, Wisconsin

Dean Bass  
Sarnia, Ontario, Canada 
 Dean Bass age 64, passed away suddenly on October 29th, 2018 in a tragic accident while doing what he loved best - flying. Throughout a career that spanned over 40 years and several countries, Dean spent countless hours flying helicopters and living life to its fullest.

Tree knocked down by helicopter

Burnt Helicopter Wreckage

Main Wreckage – Rotor mast

Tree with impact damage

Cell phone, displaying helicopter’s last known position

Engine inlet compressor

Tree cut/slice

Cut tree – likely from the main rotor blade

Module 5, Slippage marks 

Location Overview 

 Photo of damaged Appareo Vision 1000 unit.

Internal memory chips

The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Milwaukee, Wisconsin
Safran helicopter engines; Grand Prairie, Texas
Airbus Helicopters; Grand Prairie, Texas
Enbridge, Superior, Wisconsin

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Odanah, WI
Accident Number: CEN19FA018
Date & Time: 10/29/2018, 1345 CDT
Registration: N910S
Aircraft: EUROCOPTER AS350
Aircraft Damage: Destroyed
Defining Event: Unknown or undetermined
Injuries: 1 Fatal
Flight Conducted Under: Part 91: General Aviation - Aerial Observation 

On October 29, 2018, about 1345 central daylight time, a Eurocopter (Airbus) AS350 B3 helicopter, N910S, impacted terrain near Odanah, Wisconsin. The pilot was fatally injured, and the helicopter was destroyed. The helicopter was registered to and operated by Enbridge Energy Company, Inc., as a Title 14 Code of Federal Regulations Part 91 aerial observation fight. Visual meteorological conditions prevailed at the time of the accident. The flight departed Gogebic-Iron County Airport (IWD), Ironwood, Michigan, about 1300 and was en route to Madison, Wisconsin.

The flight was scheduled as a routine pipeline patrol flight. Two pipeline employees who were working on the pipeline about 2 to 3 miles from the accident site reported seeing the helicopter flying overhead. One of the employees, who had seen pipeline helicopters flying overhead numerous times, stated that he saw "nothing unusual about the helicopter" and heard "no unusual sounds coming from the helicopter."

When the pilot did not arrive at his intended destination, an alert notice was issued for the overdue helicopter. The pilot had not been in contact with air traffic control during the flight, and there was no record of a distress call from the pilot.The helicopter wreckage was subsequently located about 22 miles west of IWD in a remote wooded area and about 200 yards north of the east-west pipeline.


The pilot was a Canadian citizen and held a Canadian commercial pilot certificate with helicopter and instrument ratings. He also held a Canadian private pilot certificate with airplane single-engine land and instrument ratings and a US private pilot certificate with a rotorcraft-helicopter rating (based on the pilot's Canadian license). The pilot held a Canadian category 1 medical certificate that was issued on March 12, 2018.

The operator reported that the pilot had 16,894 hours of total flight experience with 16,535 hours in helicopters, 693 hours of which were in the AS350. The pilot had flown 208 hours in the AS350 during the preceding 90 days before the accident.


The helicopter, a Eurocopter AS350 B3 (present designation: Airbus H125), had a three-bladed main rotor system that rotated in a clockwise direction, with the three main rotor blades attached to a Starflex rotor head. The helicopter was powered by a (Safran) Turbomeca Arriel 2D turboshaft engine. Although the helicopter was equipped with a long-range fuel cell, it was not connected to the helicopter's fuel system. The helicopter received 120 gallons of fuel before departing IWD. The helicopter was also equipped with an Appareo Vision 1000 cockpit image and flight data monitoring system.

The helicopter was maintained under the manufacturer's maintenance inspection program. A review of the maintenance records revealed the helicopter's last inspection was completed on October 26, 2018, with a total airframe time of 2,965.7 hours. At the time of the inspection, the engine had accumulated 2,965.2 total hours and 1,483 cycles. 


At 1356, the automated weather observing system at IWD recorded wind from 300° at 6 knots, 10 miles visibility, overcast sky at 1,600 ft, temperature 41°F, dew point 36°F, and altimeter setting 30.02 inches of mercury. 


The helicopter impacted trees and terrain before it came to rest in an upright position within the trees. Several trees at the crash site showed cuts, and one tree with a diameter of about 10 to 12 inches was completely severed in half. Except for small fragments of plexiglass, the helicopter wreckage was confined to the impact/resting site.The front of the cabin and the cockpit area were mostly destroyed by impact forces and a post-crash fire. The major helicopter components were located at the accident site.

The helicopter was examined on scene by the NTSB investigator-in-charge, and technical representatives from the engine and airframe manufacturers. The flight control continuity inspection was limited due to fire damage, but the bolt connections to the actuators were confirmed. The tail rotor pitch control moved freely: the tail rotor flex cable was attached and ran forward and under the fire-damaged cabin floor. The cyclic and anti-torque pedals were connected to their respective tubes beneath the floor but were destroyed under the cabin area.

The helicopter's Appareo Vision system was located within the wreckage; however, the unit was badly fire damaged, and no data could be retrieved from the unit.

The engine received extensive fire and impact damage. The engine 's intake axial compressor blades exhibited damage near the outer tips, and the module 5 torque nut had a slippage of about 1/16 to 1/8 inch (2 to 4 millimeters), consistent with engine power at the time of impact. The digital engine control unit and engine data recorder were removed and sent to a laboratory for download. However, no data could be extracted from the units because they were badly fire damaged.

The tail rotor blades were broken but remained attached; paint transfer and impact scars were consistent with the tail rotor blades impacting the stabilizer. The three main rotor blades remained with the wreckage and exhibited impact and fire damage.

Though the examination was limited by thermal and impact damage to the helicopter, no preimpact abnormalities were noted during the airframe or engine examinations.


An autopsy on the pilot was performed by the Midwest Medical Examiner's Office, Ramsey, Minnesota. The pilot's cause of death was multiple blunt force injuries. The autopsy noted moderate to severe coronary artery disease scarring of the heart muscle from a previous myocardial infarction (heart attack), and changes in the blood vessels of the liver that were indicative of congestive heart failure

Toxicology testing performed at the Federal Aviation Administration Forensic Sciences Laboratory was negative for carbon monoxide, ethanol and all tested drugs. 
Dean Bass, left, is shown in August 2018 with Evelyn Alemanni and Jim Baird. He took them for a helicopter flight as part of their visit to Sarnia. Bass, a helicopter pilot with Enbridge, died October 29th, 2018 in a helicopter crash in a remote area of Wisconsin during a routine pipeline monitoring and inspection flight.

Pilot Information

Certificate: Commercial; Private
Age: 65, Male
Airplane Rating(s): Single-engine Land
Seat Occupied:
Other Aircraft Rating(s): Helicopter
Restraint Used:
Instrument Rating(s): Helicopter
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: Yes
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 03/12/2018
Occupational Pilot: Yes
Last Flight Review or Equivalent:
Flight Time:  16894 hours (Total, all aircraft), 693 hours (Total, this make and model)

Aircraft and Owner/Operator Information

Aircraft Make: EUROCOPTER
Registration: N910S
Model/Series: AS350 B3
Aircraft Category: Helicopter
Year of Manufacture: 2012
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 7446
Landing Gear Type: High Skid
Date/Type of Last Inspection: 10/26/2018, AAIP
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines: 1 Turbo Shaft
Airframe Total Time: 2965.7 Hours as of last inspection
Engine Manufacturer: Turbomeca (Safran)
Engine Model/Series: Arriel 2D
Registered Owner: Enbridge Energy Co Inc
Rated Power:
Operator: Enbridge Energy Co Inc
Operating Certificate(s) Held: Rotorcraft External Load (133)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: IWD
Distance from Accident Site: 22 Nautical Miles
Observation Time: 1856 UTC
Direction from Accident Site: 90°
Lowest Cloud Condition:
Visibility:  10 Miles
Lowest Ceiling: Overcast / 1600 ft agl
Visibility (RVR):
Wind Speed/Gusts: 6 knots /
Turbulence Type Forecast/Actual:
Wind Direction: 300°
Turbulence Severity Forecast/Actual:
Altimeter Setting: 30.02 inches Hg
Temperature/Dew Point: 5°C / 2°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Ironwood, MI (IWD)
Type of Flight Plan Filed: None
Destination: Madison, WI (MSN)
Type of Clearance: None
Departure Time: 1300 CDT
Type of Airspace:

Wreckage and Impact Information

Crew Injuries: 1 Fatal
Aircraft Damage: Destroyed
Passenger Injuries: N/A
Aircraft Fire: On-Ground
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Fatal
Latitude, Longitude: 46.527222, -90.602500 (est)  

Additional Information

An iPhone and iPad were recovered from the accident site and sent to the NTSB's Vehicle Recorder Division for download of non-volatile memory (NVM). Both units were damaged, and no information could be gleaned from the iPad. Information about text and e-mail messages, photographs, and telephone calls was found on the iPhone. Several photos were recovered from the iPhone that had been taken earlier in the day. The photos indicated the pilot photographed ground activity near the pipeline and of routine engine power checks,but none of the information was pertinent to the accident.

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