On July 13, 1990, a Hughes 369D (registration N58239) was involved in an aviation accident near Toutle, WA. Investigators recorded the probable cause as: THE PILOT'S IMPROPER PLANNING/DECISION BY OPERATING AND MANEUVERING THE HELIOCPTER IN A REGIME WHERE HE COULD NOT MAINTAIN ROTOR RPM. THE HIGH DENSITY ALTITUDE AND ROUGH TERRAIN WERE RELATED FACTORS. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A Hughes 369D helicopter collided with terrain after maneuvering within the crater of Mount St. Helens. The pilot reported an engine-out warning and initiated an autorotation. Passengers observed volcanic ash entering the cabin before the crash.
Incident Overview
A Hughes 369D helicopter collided with terrain after maneuvering within the crater at Mount St. Helens. According to the pilot, an engine-out warning indication occurred, prompting an autorotation. The aircraft sustained damage during the landing, and the powerplant required shutdown after the crash.
Passenger Accounts
Both rear seat passengers reported seeing volcanic ash entering their windows just prior to the impact. A third passenger, along with the two rear-seat occupants, stated that the pilot had been planning to land inside the crater at the request of the fourth passenger.
Post-Accident Inspection
During a subsequent post-accident check, the engine operated satisfactorily, with no anomalies detected. The powerplant had been shut down following the crash landing.