On June 11, 1983, a Bell 47G-2 (registration N41721) was involved in an aviation accident near Zillah, WA. Investigators recorded the probable cause as: The power loss was due to fuel exhaustion. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter made a hard landing after striking trees during an autorotation following an engine failure caused by fuel exhaustion. The pilot was uninjured, but the aircraft sustained substantial damage.
Incident Overview
A helicopter experienced an engine failure while on a repositioning flight between aerial application operations, forcing the pilot to execute an autorotational landing. The rotorcraft was flown into an orchard and contacted trees, resulting in substantial damage to the skids, main rotor blades, and tail boom. The pilot was uninjured. The flight originated from a temporary site a few minutes before the mishap.
Fuel System Examination
Investigation revealed that the power loss was due to fuel exhaustion. The fuel cells were found empty, but the fuel gauges indicated fuel remaining. The aircraft had been fueled with 22 gallons of fuel. After the incident, when the system was drained, the fuel gauges read one-quarter on the left and one-half on the right. Following complete drainage, the gauges read one-eighth on the left and one-quarter on the right, indicating inaccuracies in the fuel indication system.