Bell 47G N473TT accident near Atoka, Tennessee

Probable cause

A total loss of engine power due to a blocked fuel line; the reason for the blockage could not be determined based on the available evidence.

NTSB analysis

The pilot had conducted eight brief (7- to 8-minute) nonrevenue passenger flights uneventfully on the day of the accident. The helicopter was fueled before the eighth flight. During the ninth flight, the helicopter’s engine lost total power when the helicopter was about 1.5 miles north of the heliport and was descending through an altitude of 900 ft mean sea level. The pilot executed an autorotation and landed in a field. On touchdown, the main rotor blade struck the tailboom.

Postaccident examination of the airframe and engine revealed no evidence of any preimpact malfunctions except for the fuel line to the carburetor, which had collapsed. A borsescope inspection revealed that light could not be observed through the fuel line. The borescope was then pushed through the fuel line, and no contaminates were found. A subsequent metallurgical examination of the fuel line revealed no blockages; no damage to the interior of the hose; and no evidence of kinks, creases, or material creep. The blocked fuel line likely resulted in the loss of engine power; however, the reason for the blockage could not be determined.

Text from the NTSB. Open the NTSB docket for ERA20LA216 for the full record.