This document covers the recommended practice for determining the acceptability of the dendrite arm spacing (DAS) of D357-T6 aluminum alloy castings required to have tensile strength not lower than 50 ksi (345 MPa). To apply this method, at least two coupons used for DAS measurement and two tensile specimens shall be attached in locations defined by the cognizant engineering organization. Areas of the casting that require DAS control must be accessible for surface DAS measurements, or if internal locations are to be tested, such locations shall be defined by the cognizant engineering organization.