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 did not cite a suspected cause of the crash, and noted that “a review of the U.S. Air Force’s Avian Hazard Advisory System found the probability of bird activity ‘low’ in the vicinity of the accident.” It also noted that the carcasses of several geese were found at the debris field, with one carcass found embedded in the helicopter’s flight control system. Samples of the geese feathers were collected so that officials can work to identify them, the report said.

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