During the takeoff roll, about the time of rotation, the airplane yawed right and would not maintain altitude. The airplane cleared one ravine, and the pilot retarded the throttles to abort the takeoff. The airplane touched down in a grass area and came to rest at the bottom of a larger ravine. Examination of the wreckage revealed that a stud, which attached to the pitch change link in one of the left propeller blades, had separated. The last annual inspection of the airplane was performed about 4 years and 5 months prior to the accident.