No person may import a TSO article for civil aviation use unless properly certificated. The holder of the TSO article shall use the procedures in Attachment 18 for the validation of imported TSO articles, unless otherwise prescribed in a treaty or an agreement.Airworthiness approvals that were issued by the airworthiness authority of the exporting country shall be attached with the imported TSO articles.Attachment 18 Appliance Design Validation Procedure.odt