What happened
On October 29, 2018, at approximately 13:45 CDT, a Eurocopter AS350 B3 (present designation Airbus H125) crashed near Odanah, Wisconsin. The aircraft, registration N910S, was being operated by Enbridge Energy Company, Inc. for a scheduled pipeline patrol flight.
The helicopter departed Gogebic-Iron County Airport (IWD) in Ironwood, Michigan, at approximately 13:00, en route to Madison, Wisconsin. During the flight, two pipeline employees working roughly 2 to 3 miles from the crash site observed the helicopter flying overhead. They reported that the aircraft appeared and sounded normal.
No distress call was received, and the pilot did not establish contact with air traffic control. After the helicopter failed to arrive at its destination, an alert notice was issued. The wreckage was later located about 22 miles west of I/WD in a remote wooded area, approximately 200 yards north of the pipeline. The pilot sustained 1 fatal injury, and the helicopter was destroyed.
The investigation
The investigation was significantly hindered by a post-crash fire that consumed much of the cabin and destroyed the cockpit image and flight data monitoring system. Additionally, the digital engine control unit and engine data recorder could not be accessed due to thermal damage.
Despite the fire, investigators examined the engine and airframe. The engine's intake axial compressor blades showed damage at the outer tips, and a torque nut slippage was found that was consistent with the engine producing power at the time of impact. The tail rotor blades were broken but remained attached, with impact marks consistent with hitting the stabilizer. No preimpact abnormalities were identified in the airframe or engine during the examination.
An autopsy of the pilot revealed moderate-to-severe coronary artery disease, heart muscle scarring from a previous heart attack, and indicators of congestive heart failure. Toxicology results were negative for drugs and alcohol.