Robinson Helicopter Company R44 II accident near Dimmitt, Texas, June 3, 2017

The NTSB's narrative final · quoted from the NTSB record

The private pilot, who did not hold a rotorcraft rating, departed in the helicopter on a routine flight to check and observe crop fields, business facilities, and other business-related assets. A search was initiated when the pilot did not return from the flight, and the accident site was located in a field the following morning. There were no witnesses to the accident. Data obtained from an onboard GPS showed the helicopter making a series of turns at a low altitude above the field in which the wreckage was located. Examination of the helicopter did not reveal any preimpact mechanical malfunctions and there was no damage to nearby obstructions to suggest an in-flight collision. The pilot's autopsy revealed scarring in heart muscle from previous heart attacks and severe left ventricular hypertrophy. Each of these findings significantly increased his risk for a sudden arrhythmia. Such an arrhythmia would likely cause sudden symptoms such as palpitations or altered/decreased consciousness as a result of diminished blood pressure. It is likely that scarring from previous heart attacks and severe hypertrophy of the left ventricular wall caused arrhythmia which resulted in incapacitation and a loss of control at low altitude. Although the pilot did not hold a rating for rotorcraft, his recent flight experience in the accident helicopter performing similar flight profiles make it unlikely that he simply lost helicopter control.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.