On June 16, 1997, a Bell 47G-3B-1 (registration N1335X) operated by U.s. Dept. OF The Interior was involved in an aviation accident near Fallon, NV. Investigators recorded the probable cause as: exhaustion of the aircraft's fuel supply, due to improper planning and/or decision. A factor related to the accident was the high density altitude which made a successful autorotative landing unlikely. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.
A helicopter experienced an engine power loss after approximately three hours of flight. An autorotative descent to 6,500 feet density altitude ended in a hard landing that damaged the aircraft.
Incident Summary
A helicopter lost engine power after about three hours of flight. The pilot executed an autorotative descent to a landing site at 6,500 feet density altitude. The helicopter sustained damage during the landing.
Examination Findings
Following the accident, investigators drained 1.9 gallons of fuel from the entire fuel system. The helicopter's unusable fuel quantity is specified as 2.5 gallons. An examination of the helicopter found no evidence of a preaccident mechanical malfunction or failure. The engine carburetor flow tested within the manufacturer's specifications.
Official Comment
A representative from the helicopter manufacturer opined that an autorotative landing at 6,500 feet density altitude would likely result in a hard landing.