On August 5, 1987, a Bell 47D-1 (registration N917B) was involved in an aviation accident near Taft, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced engine power loss at low altitude due to fuel exhaustion. During autorotation, the main rotor blades contacted and severed the tail boom. Post-accident inspection revealed an empty fuel tank and a discrepancy in fuel capacity markings.
Accident Narrative
The pilot reported that the engine lost power at approximately 300 feet above ground level after the helicopter had flown for about 2.7 hours without refueling. The pilot initiated an autorotative landing; however, before touchdown, the main rotor blades contacted and severed the tail boom.
Engine and Fuel Information
An examination revealed that the fuel tank was empty, and no signs of fuel leakage were found. The helicopter was equipped with a 210 horsepower Franklin engine in accordance with a supplemental type certificate. No factory data on fuel consumption rates for this configuration were available. Other operators who operated this make and model of helicopter estimated the fuel consumption at approximately 12 gallons per hour.
Fuel Capacity Discrepancy
After the accident, the pilot measured the fuel capacity of the helicopter's fuel cell. He stated that the cell would hold only 26.5 gallons of fuel, instead of 29 gallons as indicated by a stick-on marker that had been installed on a previously painted placard.