On September 25, 1985, a Hughes 369D (registration N29707) operated by Michael G. Dawson was involved in an aviation accident near Porterville, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot and passenger survived for two and a half days after a crash in the Sierra Nevada mountains. The aircraft experienced a rapid vibration, then descended, lost directional control, and made an uncontrolled forced landing at 9,000 feet elevation.
Accident Flight
A helicopter pilot climbing to a cruise altitude of 13,500 feet MSL to cross the Sierra Nevada mountains south of Mount Whitney entered cruise flight at an indicated airspeed of approximately 120 to 130 knots. The pilot's flight manual listed 110 knots as the velocity never to exceed (VNE) at that pressure altitude and temperature.
While in cruise, the pilot first felt a rapid vibration in the anti-torque pedals. He then entered a descent. As the aircraft descended to approximately 300 feet AGL, it was jolted and directional control was lost.
Forced Landing
The pilot stated that he made an uncontrolled forced landing and crashed on a mountain at an elevation of 9,000 feet.
Survival
Both the pilot and his passenger survived the crash and remained at the site for two and a half days before being found by hunters.