Regulations Governing the Certification for Aviation Products, Appliances and Parts Article 23

An applicant for changes to type design, operation limitations, Type Certificate Data Sheets (TCDS) and restrictions relating to the type certified aircraft product, must show that the changed product complies with the airworthiness requirements applicable to the category of the product in effect on the date of the application for the change and/or any other applicable noise, fuel venting and exhaust emission requirements.Except as provided in the first paragraph of this Article, if an applicant shows that the amendment of a regulation and/or that a CAA previously granted equivalence of safety, as in effect on the date of application of original type certificate, brings no significant impact on flight safety, the previously defined requirement may be kept in effect, if approved by CAA, for the changed product.