On June 30, 1999, a Hiller UH-12ET (registration N7173F) operated by Pacific Valley Aviation was involved in an aviation accident near Williams, CA. Investigators recorded the probable cause as: The pilot's inadequate preflight planning and verification that fuel was available for the intended flight. A factor was the fuel quantity false indication. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
While spraying a rice field, a turbine helicopter's engine suddenly quit. The pilot performed a forced landing, causing the tail boom to separate. Examination later revealed a broken wire in the fuel quantity indicating system.
Event Details
A turbine-powered helicopter was engaged in low-level agricultural spraying operations over a rice field when its engine unexpectedly lost power. The pilot performed a forced landing within the field; during the landing, the tail boom was severed. The helicopter had been flown for only 0.5 hours on the day of the accident. The pilot reported that the helicopter had been refueled the previous day, but he did not visually confirm the amount of fuel on board.
Post-Accident Examination
Examination of the helicopter's fuel system revealed a broken wire in the fuel quantity indicating system. According to the maintenance manual for this helicopter model, an open circuit caused by such a wire break will cause the fuel quantity indicator to display 34 gallons, irrespective of the actual fuel level, including when the tank is empty.