Richards Heavylift Helo Inc UH-1H N567VF accident near Oakdale, Illinois

Probable cause

An in-flight loss of control for undetermined reasons.

NTSB analysis

The pilot was flying an aerial application flight in a pattern consisting of north-south passes starting on the western edge of the field with turns to the east to work the field. ADS-B and on-board GPS devices that recorded the accident flight showed that before the accident, for undetermined reasons, the helicopter turned to the west, descended, and impacted terrain.

An examination of the helicopter and its engine did not detect any preimpact anomalies that would have contributed to a loss of control. A visual examination of the nearby power lines did not show evidence of arcing or damage to the lines or power pole.

The pilot’s severe coronary artery disease increased his risk of experiencing a sudden impairing or incapacitating cardiac event, such as arrhythmia, chest pain, or heart attack. The autopsy does not provide evidence that such an event occurred; however, such an event does not leave reliable autopsy evidence if it occurs shortly before death. Even severe coronary artery disease may not cause major symptoms.

Toxicology results indicate that the pilot had used the medication cetirizine. The cetirizine levels in his cavity blood and tissue indicate a possibility that the pilot may have been experiencing some associated impairing effects, such as mild sedation, at the time of the accident. However, it is also possible that the pilot was not experiencing any impairing effects of his cetirizine use.

Text from the NTSB. Open the NTSB docket for CEN23FA340 for the full record.