The National Transportation Safety Board has concluded the probable cause of a helicopter crash that killed the pilot on July 16, 2013 near Dove Creek was a hydraulic fluid leak.
The Tamarack UH-1H helicopter was part of a seismic survey operation conducted by Kinder Morgan for mapping out underground CO2 reserves.
The NTSB report states the helicopter was carrying equipment suspended from a cable, and overshot the intended drop site when the load hit the ground. The cable detached from the helicopter, which then began a series of abrupt maneuvers and crashed while banking steeply to the left.
The pilot, A.J. Blain, of Billings, Mont., was fatally injured in the crash, which shot debris throughout a worksite near a ground crew off of County Road 15.
Blain was the only one on board, and no one else was injured. The helicopter was owned by Billings Flying Service, a subcontractor on the seismic project.
An NTSB accident report states an examination revealed evidence that there was a loss of hydraulic fluid from the flight-control system because of a leak at a check-valve fitting near the tail rotor servo.
According to the report, “As the pilot approached the survey location, the loss of hydraulic pressure most likely resulted in a very high collective-control forces and pilot induced oscillations.”
The director of maintenance stated that the pilot and mechanic were aware of the hydraulic fluid leak and had ordered replacement parts, however they had not yet been installed, and they did not expect the leak to cause a significant issue, according to the NTSB report.
The final NTSB report, released May 8, concludes that the probable cause of the accident to be: “Pilot-induced oscillations caused by the loss of hydraulic assist of the flight controls due to an excessive loss of hydraulic fluid during a critical phase of flight, which resulted in ground impact.”