No fatalities

Helicopter Strikes Extended Auger During Temporary Relocation

Sula, MT, United States

On April 30, 2019, an Aerospatiale AS350 B3 operated by Mission Mountain Helicopters was involved in an aviation accident near Sula, MT. No fatalities were reported. Investigators recorded the probable cause as: The pilot's failure to maintain adequate clearance from ground equipment, which resulted in a tail rotor blade impact. This summary draws on records from NTSB; 13 related events involving the same aircraft type or operator are linked below.

SourcesNTSBPrimary reportUpdated 1785761257Data APIEditorial standards

A helicopter pilot moving to avoid fertilizer dust backed into an extended auger, causing tail rotor damage. No injuries reported.

Incident Summary

A helicopter pilot, after completing an aerial application flight, set the bucket down in a pre-determined operations zone near a semi-truck loading hopper for refilling. Another truck arrived to top off the semi-truck hopper, emitting fertilizer dust that reduced visibility. Concerned, the pilot advised ground crew of a temporary move to a new operations zone.

Pilot Actions

In the new zone, as a skid steer approached, the pilot eased the helicopter backward to keep ground equipment in view. A "bang" was heard, prompting the pilot to disconnect from the long-line and land the helicopter without further incident.

Postaccident Findings

Examination revealed the auger from the semi-truck hopper was fully extended behind the helicopter. The tail rotor blade sustained substantial damage. The pilot suspected backing into the extended auger. No preaccident mechanical failures or malfunctions were reported.

Contributing factors

PilotEffect on operation