Accident Overview
An aircraft carrying a pilot and a passenger crashed into trees on snow-covered terrain while flying through canyons at altitudes between 8,000 and 10,000 feet MSL. The flight was intended for property observation and moose spotting.
Sequence of Events
According to the pilot, the aircraft flew up and down several canyons. Shortly after entering a 45-degree bank turn for a second pass over an area, the pilot heard a "muffled pop" from the forward part of the aircraft. Noting a fluctuation in manifold pressure, the pilot suspected an engine problem. At about that time, the aircraft struck trees and crashed.
The rear-seat passenger, who sustained only minor injuries, reported that the aircraft was circling at low altitude. She did not hear any change in engine sound but heard the stall warning just before impact. After the crash, she walked 6 miles to seek help.
Investigation Findings
Examination revealed that the initial impact occurred when the right horizontal stabilizer struck a tree at approximately 35 feet AGL, 460 feet from the aircraft's final resting place. The aircraft then flew about 300 feet before the left wing tip hit a second tree. Beyond that tree, the propeller severed numerous tree branches. The density altitude at the time was approximately 11,000 feet. Investigators found no preimpact part failure or malfunction.
Conclusion
The investigation did not assign a probable cause, noting the absence of any mechanical failure or malfunction before the impact.