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.
What happened in the 30 Jun 1999 Hiller UH-12ET accident near Williams, CA?
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.
What aircraft was involved and where did it happen?
The accident on 30 Jun 1999 involved a Hiller UH-12ET, registration N7173F, operated by Pacific Valley Aviation, at Williams, CA.
What was the probable cause of the accident?
The pilot's inadequate preflight planning and verification that fuel was available for the intended flight. A factor was the fuel quantity false indication.
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…