Bell 206B N60EA accident near Groom, Texas

Probable cause

The total loss of engine power due to fuel starvation. Contributing to the accident was the pilot’s decision to operate the helicopter with minimum fuel on board.

NTSB analysis

The commercial pilot of the helicopter stated that there were 20 gallons of fuel on board when he departed on the aerial application flight. He flew to a 43-acre field and made steep turns while spraying the field. After dispensing the chemical, he made a steep, "hard right turn" en route to the operator's base, which was located about 3/4 mile west of the field. About 40 seconds after making the hard right turn and with the fuel gauge indicating 10 gallons remaining, the helicopter was on approach for landing. While on a right base leg to the landing zone and about 40 ft above ground level with about 35 kts airspeed, the pilot felt the "tail wag," and the engine stopped producing power. He performed an autorotation, but the tail impacted the ground during the landing flare, which resulted in substantial damage to the helicopter.

During the examination of the helicopter, 2 spoons full of fuel were drained from the airframe fuel filter assembly. When the fuel boost pumps were turned on, they initially sounded as though they were cavitating. With the fuel boost pumps running, 7 gallons of fuel were drained from the fuel tank through the airframe fuel filter assembly. The engine was removed from the airframe and placed on a test cell, where it operated normally.

The helicopter flight manual stated that, if installed, the FUEL LOW light would illuminate with about 20 gallons of fuel remaining. It stated that, if this light illuminated, the pilot should, "Land as soon as practical." The flight manual also contained a warning that, "Operation with both fuel boost pumps inoperative is not authorized. Due to possible fuel sloshing in unusual attitudes or out of trim conditions and one or both fuel boost pumps inoperative, the unusable fuel is 10 gallons."

It is likely that the engine experienced a total loss of power due to fuel starvation; however, the reason for the fuel starvation was not determined. The pilot decided to operate the helicopter with less than 20 gallons of fuel, and 7 gallons of fuel were found in the helicopter after the accident occurred. The final, steep right turn likely was uncoordinated, and it might have caused the fuel pickup in the tank to become unported, allowing air into the fuel line. However, the pilot reported that the boost pump circuit breakers were in, and they should have been able to deliver fuel to the fuel filter assembly.

Text from the NTSB. Open the NTSB docket for CEN18LA020 for the full record.