The pilot reported that, prior to departure, he was told the Bell UH 1H helicopter was topped off with fuel for the multi-stop flight. He added that he did not verify the fuel quantity.
During the last leg, he departed about 60 miles from the destination airport with just below 600 pounds of fuel and he decided to fly at 120 knots with a tailwind. He added that about three miles from the destination airport, the engine lost power. He performed an autorotation, but landed hard near Bethel, Alaska. The helicopter sustained substantial damage to the tailboom and transmission mounts.
He reported that after landing, the fuel quantity gauge read about 225 pounds of fuel remaining and that the 20-minute fuel light, which did not illuminate during the flight, illuminated once on the ground.
The pilot was unsure if anyone had verified the fuel quantity remaining after landing, but they added about 50 gallons of fuel and continued to the destination airport. He estimated that the helicopter’s fuel burn was about 75 to 80 gallons an hour.
The chief pilot and owner reported that he had refueled the helicopter, which was on uneven terrain, before the flight. He filled the tank to the bottom of the filler cap on the left side, which he estimated was about 10 to 15 gallons less than total fuel capacity of 210 gallon tank. He estimated that the helicopter burned about 90 gallons an hour. He added that there were no open mechanical squawks on the helicopter and that he was not aware of any mechanical issues.
The FAA inspector, who examined the helicopter at the accident site, reported that the fuel quantity gauge had been serviced and calibrated earlier in the year, but continued to indicate fuel after the helicopter ran out of fuel. The 20-minute low fuel light appeared to be functioning normally.
The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.
Probable Cause: The pilot’s improper fuel planning, which resulted in fuel exhaustion and a total loss of engine power, and his improper landing flare during a forced autorotation, which resulted in a hard landing. Contributing to the accident were the inoperative fuel gauge, which was not accurately calibrated, and the pilot’s reliance on the gauge.
This June 2019 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.