The Dayton Daily News reports that the crash of the Wright "B'' Flyer probably happened because of a failed propeller shaft weld that resulted in a loss of engine thrust during the test flight.

Two experienced pilots died when the plane, dubbed "Silver Bird," crashed about 3 miles from an airport in Springfield, where they had taken off on July 30, 2011. Springfield is about 45 miles west of Columbus.

A probable cause report released this week by the National Transportation Safety Board said the left propeller shaft had a broken weld, which would have prevented the left propeller from being driven by the engine.