What happened
On October 29, 2011, a Eurocopter AS3 350-B2 helicopter, registration N165EH, crashed approximately 7 miles southwest of Iliamna, Alaska. The flight, operated by ERA Helicopters LLC, was a VFR on-demand charter flight. The aircraft had originated in Nome, Alaska, and had completed fuel stops in Unalakleet and Bethel, Alaska, en route to its destination of Iliamna.
At approximately 2008 Alaska daylight time, the Sky Connect satellite tracking system signal was lost while the helicopter was flying near the northern shore of Iliamna Lake. The following morning, a crew from a Bell 212 helicopter located the fragmented wreckage in a marshy, tundra-covered area. The pilot, the sole occupant, sustained 1 fatal injury.
During the flight, fuel vendors in Unalakleet and Bethel noted that the pilot appeared rushed and expressed a desire to reach Iliamna before nightfall. At the time of the accident, the weather at Iliamna Airport was characterized by visual meteorological conditions, though light snow and reduced visibility were reported in the area around the time of the crash.
The investigation
Investigators examined the wreckage and the Turbomeca Arriel 1D1 turboshaft engine. The engine examination revealed circumferential scoring on internal rotating components, which is consistent with the engine producing power at the time of impact. No pre-accident mechanical anomalies were found that would have prevented normal operation.
The debris path was approximately 195 feet long, with the main wreckage site containing all major components. The tail boom had separated from the fuselage at the forward attachment point. The investigation also included a review of the pilot's medical records and a postmortem examination.
Findings
An autopsy of the pilot revealed significant heart abnormalities, including an enlarged heart, severe calcifying atherosclerosis of all three coronary arteries, and a 99 percent occlusion of the right coronary artery. Additionally, the aortic valve was found to be severely calcified and stenotic. These conditions presented a high risk for a sudden cardiac event, such as an arrhythmia or myocardial infarction, which could lead to incapacitation.
While the pilot was attempting to reach his destination before dark following a four-day weather delay, the physical evidence and medical findings suggest that the pilot's medical condition likely led to the loss of control.