A dead goose was found in part of the flight control system of a medical helicopter that crashed in western Oklahoma, killing all three people on board, according to a preliminary report by the National Transportation Safety Board.
The report does not cite a suspected cause of the crash, but noted one goose was found in the helicopter's flight control system and others were found in the debris field.
A report on the probable cause could take up to two years to complete, according to the NTSB.
The helicopter crashed Jan. 20 in a pasture near Hydro, about 60 miles (97 kilometers) west of Oklahoma City, as it was returning to Weatherford after taking a patient to an Oklahoma City hospital.
Get top local stories in San Diego delivered to you every morning. Sign up for NBC San Diego's News Headlines newsletter.
The pilot and both Air Evac Lifeteam crew members, a flight nurse and a paramedic, were killed.