On August 17, 1988, a Hiller UH-12E (registration N65120) operated by West Farm Air, Inc was involved in an aviation accident near Thermal, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Shortly after refueling and reloading the hopper, a helicopter lost engine power while starting to spray a field. The helicopter touched down upright but skidded into a berm, rolled over, and came to rest in a muddy, flooded field. Mud and water were found in the fuel system.
Accident Sequence
Shortly after the helicopter was refueled and the hopper was reloaded, the pilot took off and began spraying a field. During this operation, the engine suddenly lost power. The pilot reported that the helicopter was descending from about 30 feet when the power loss occurred, leaving barely enough time to take corrective action. The helicopter touched down in an upright attitude, but it skidded into a one-foot-high berm, rolled over, and came to rest in a muddy, flooded field.
Fuel Contamination Investigation
Mud and water were found in the aircraft's fuel system. Evidence indicated that the fuel contamination was not a result of impact and inversion. An examination of the mobile refueling unit revealed that it contained cracks, which allowed moisture and other contaminants to enter the fuel. Additionally, the mobile unit's fuel filter was improperly installed and was not removing contaminants from the fuel.