Background
The pilot refueled a Piper Cub and departed without incident. The flight was engaged in patrolling pipelines. During the westbound segment of the route over 8,000-foot mountainous terrain, the pilot was positioning the airplane between segments.
Accident Sequence
No witnesses observed the crash, and the pilot did not establish contact with air traffic control. The airplane crashed approximately 9 miles west of the departure airport. When located, the aircraft was in a near-vertical attitude, facing east, with its engine about 4 feet beneath ground level.
Investigation Findings
Examination of the airframe and engine revealed continuity of the flight control system, fuel present in the engine, and no evidence of any preimpact mechanical failures. Medical records indicated the pilot had experienced chest pain. Family members reported that the pilot had recently experienced chest pains severe enough to cause him to interrupt his activity. During the autopsy, the pathologist performed a microscopic examination of the heart and found nuclear pleomorphism and hyperchromatism; no acute changes were present.
Probable Cause
Not stated in the source.