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NTSB investigation record

GAA19CA238

Completed

Aerospatiale As350· N350DL

Date
April 30, 2019
Location
Sula, MT
Conditions
VMC
Record
Published September 26, 2020

Primary finding

Probable cause

The pilot's failure to maintain adequate clearance from ground equipment, which resulted in a tail rotor blade impact.

Investigator assessment

Analysis narrative

The helicopter pilot reported that, after an agricultural application flight, he set the bucket down in a predetermined operations zone near a semi-truck loading hopper to be refilled. He added that another truck arrived to top off the semi-truck hopper, which emitted fertilizer dust and led to the pilot being concerned that it would deteriorate visibility. He advised the ground crew that he was going to temporarily move out of the operations zone. The pilot reported that he set the bucket in the new temporary operations zone. As the skid steer approached, he eased the helicopter backward to keep the other ground equipment in his view. The pilot heard a "bang," disconnected the helicopter from the long-line, and then landed the helicopter without further incident. Postaccident examination revealed that the auger from the semi-truck hopper was fully extended behind the helicopter and that a tail rotor blade had sustained substantial damage. The pilot reported that he might have backed the helicopter into the extended auger. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.

Source record

Factual narrative

The helicopter pilot reported that, after an aerial application flight, he set the bucket down in a pre-determined operations zone near a semi-truck loading hopper to be refilled. He added that another truck arrived to top off the semi-truck hopper, which emitted fertilizer dust that caused the pilot concerns for his deteriorating visibility. He advised the ground crew that he was going to move out of the operations zone temporarily. The pilot reported that he set the bucket in the new temporary operations zone. As the skid steer approached, he eased the helicopter backward to keep the other ground equipment in his view. The pilot heard a "bang", disconnected from his long-line, and landed the helicopter without further incident. Postaccident examination revealed that the auger from the semi-truck hopper was fully extended behind the helicopter and tail rotor blade sustained substantial damage. The pilot suspected that he backed the helicopter into the extended auger. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.

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