On February 13, 1998, a Hiller UH-12E (registration N4027Z) was involved in an aviation accident near Chico, CA. Investigators recorded the probable cause as: Fuel exhaustion due to the pilot's failure to ensure that an adequate fuel supply was onboard. A contributing factor was related to the fuel quantity gage's erroneous indication of fuel. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
While conducting an aerial application flight at low altitude, a helicopter experienced total engine power loss due to fuel exhaustion. The pilot made a hard landing in an open field, resulting in substantial damage. The fuel gauge had indicated 12 gallons remaining, but the float had stuck.
Accident Overview
An agricultural helicopter operating at an altitude of 40 feet above ground level over an orchard suffered a complete loss of engine power. The low altitude prevented the pilot from entering an autorotation. The helicopter made a hard landing in an open field, sustaining substantial damage.
Post-Accident Examination
Inspection of the helicopter revealed that it was out of fuel. The pilot reported that before the event, the fuel quantity gauge had indicated 12 gallons remaining. The pilot further stated that the fuel float had become stuck in the tank. An FAA coordinator attempted to duplicate the discrepancy in postimpact testing but could not reproduce the conditions. However, during the examination, when the fuel quantity sender arm was manipulated, the float could be induced to hang up vertically. When the float was lowered to the bottom of the tank, the fuel quantity reading indicated 12 gallons. All other system circuitry and component tests returned negative results. No specific mechanical defect was identified. The helicopter was substantially damaged but no further anomalies were found.