Bell 47G 5 N7089J accident near Mansfield, Illinois

Probable cause

The pilot's failure to maintain clearance from power lines during low-altitude flight in gusting wind conditions following his use of a sedating medication.

NTSB analysis

The commercial pilot was conducting an agricultural application flight in the helicopter and had just completed spraying a field. A witness near the accident site reported that he saw the helicopter flying low and then pass a tree line when a wind gust lifted the helicopter up and to the left directly into power lines. Weather conditions reported at an airport in the area included wind at 16 knots gusting to 21 knots at the time of the accident.

Separated power lines were observed near the accident site, and a witness mark was melted into the leading edged of a main rotor blade, consistent with it contacting a power line. Recorded GPS data were consistent with low-altitude operations near the accident site. Based on the evidence, it is likely that, while the pilot was flying low-altitude operations in gusting wind conditions, he failed to maintain adequate clearance from power lines.

Toxicology testing detected the sedating antihistamine diphenhydramine in the pilot's urine and in his heart blood. Although some degree of impairment from diphenhydramine cannot be completely ruled out, the pilot's behavior on the day of the accident, as evidenced by GPS data that shows he flew straight lines and made good coverage of the fields during the spraying, was consistent with his level of skill and experience. Therefore, it is unlikely that the pilot's impairment from diphenhydramine contributed to the accident.

Text from the NTSB. Open the NTSB docket for CEN14LA423 for the full record.