Is it legal to use retractable broadheads during wild turkey seasons?

Yes. Turkeys are classified as game birds, and retractable broadheads are allowed for game birds in Washington. However, retractable broadheads cannot be used for big game in Washington.
Use caution, however, when the turkey season is overlapped with big game seasons, such as during the spring bear season or the fall turkey seasons. You should not be hunting with a mechanical broadhead while hunting with a spring bear permit, or while hunting for deer and elk during the fall turkey season.