Investigators with the National Transportation Safety Board — in a recently released report that outlined the probable causes of the crash — said the helicopter experienced "a loss of engine power due to fuel contamination while maneuvering at a low altitude." The report also cited the pilot’s "inadequate preflight inspection, which failed to detect the contamination" as a contributing factor.
Read more: http://www.deseretnews.com/article/865639729/NTSB-Contaminated-fuel-caused-helicopter-crash-that-killed-2-Utah-men.html?pg=all