Hughes 369 N5187S accident near Mcdougal, Arkansas

Probable cause

The pilot's failure to maintain the helicopter's clearance from the powerline structure while hovering in gusty wind conditions, which resulted in an inadvertent collision with the structure and an uncontrolled descent into terrain.

NTSB analysis

The commercial pilot and two crewmembers of the helicopter were performing external load operations to decommission power line structures. The crew reported that, during the first flight after their lunch break, the pilot was hovering the helicopter next to the power line structure when they heard a "loud boom" and "metallic crunch" and the crews' short haul lines were released from the helicopter. The helicopter descended and impacted the ground beneath the structure, fatally injuring the pilot, while the two crewmembers sustained minor injuries.

A postaccident examination of the helicopter revealed no mechanical anomalies that would have precluded normal operation. The power line structure displayed an indentation consistent with impact with the top of the new steel utility pole. There was also a gouge mark to the side of the upper cap plate of the structure, consistent in shape with the indentation mark to the pole. Therefore, it is likely that the pilot failed to maintain clearance from the power line structure while hovering, resulting in contact with the structure.

One lineman stated that before the impact, the pilot did not seem calm and hesitated in responding to the lineman's communications. He said that the helicopter was moving around a lot when he was attaching to the pole, and he could see the helicopter shadow and saw the tail "darting around." Weather data at the time of the accident indicated the winds were 12 knots gusting to 19-25 knots from the southwest with likely unstable air from the surface up to an altitude of 400-500 ft. It is likely the pilot had difficulty maintaining the helicopter's clearance from the utility pole due to the gusty wind conditions.

Toxicology testing performed on the pilot revealed diphenhydramine and tramadol in the pilot's blood and urine. Because both drugs undergo postmortem redistribution, the investigation could not determine whether the pilot was impaired by either drug.

Text from the NTSB. Open the NTSB docket for CEN19FA020 for the full record.