Accident Overview
An accident occurred when an aircraft entered a box canyon at an altitude below the tops of the surrounding ridges. The purpose of the flight was for the pilot to examine water drainage in the canyon.
Witness Observations
Witnesses observed the aircraft in level flight within the canyon. The engine power sounds were reported as normal. Shortly after the aircraft disappeared behind a ridge, the witnesses saw black smoke rising from the canyon floor.
Canyon and Accident Site
The area of the canyon where the accident occurred is relatively narrow, with steep sides and a floor that rises abruptly to the mountains behind.
Wreckage Examination
Examination of the accident site revealed that the aircraft impacted nose down in a near-vertical descent. No preimpact mechanical malfunctions or failures were identified during the wreckage examination.
Summary
The aircraft entered a box canyon at a low altitude, witnesses reported normal engine sounds, and the aircraft subsequently impacted the canyon floor without any identified mechanical issues.