On February 19, 1982, a Bell 47G2 (registration N4021A) operated by Mar Aviation was involved in an aviation accident near Brawley, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot visually estimated 1/4 tank fuel, loaded 60 gallons of water for calibration, then experienced engine failure while moving to spray remaining water; autorotated from 7 feet.
Pre-Flight and Spray Calibration
Prior to the flight, the pilot visually checked the gas tank and estimated there was about one-quarter tank of fuel. After starting the engine, the pilot hovered to a water tanker and loaded 60 gallons of water into the spray tank to calibrate the gallons per acre that the rig sprayed. The pilot then sprayed some water on the ground.
Refueling Attempt and Relocation
The pilot asked the tanker operator to refuel the helicopter but was told that would be impossible because the pump was inoperable. A mechanic looked into the gas tank and told the pilot it was acceptable to move the helicopter to the gas pump. The pilot lifted the helicopter and moved to an adjacent wheat field to spray out the remaining water.
Engine Failure and Autorotation
During the spraying of the remaining water, the engine failed to produce power. The pilot performed an autorotation from an estimated height of 7 feet.
Investigation Findings
The investigation did not state a probable cause for the engine failure.