What happened
Two pilots departed for an instructional flight that was intended to serve as a biennial flight review for the aircraft owner. During the course of the flight, the crew navigated to a dirt strip located on a saddleback situated between two mountain peaks in the vicinity of San Marcos.
Evidence indicates that the aircraft performed a low pass over the strip while heading northeasterly. Shortly thereafter, the aircraft struck a large boulder and crashed near the northeast end of the runway. The wreckage came to rest approximately 30 feet northeast of the impact point, sustaining extensive damage. Examination of the propeller blades revealed chordwise scoring along with massive smearing or leading edge damage. An inspection of the runway surface showed no indication that the aircraft had touched down prior to striking the obstacle.
There were no known witnesses to the accident. Investigators found it inconclusive which pilot was manipulating the controls at the time of the crash. For the purposes of this flight, the owner was designated as the pilot-in-command.
The investigation
A mechanical examination of the aircraft revealed no evidence of a pre-impact mechanical problem. The damage to the propeller and airframe was consistent with an impact with a stationary object rather than in-flight failure.