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2 and 3, applicants may use earlier requirements for significant changes to areas not affected by the change, or for cases where compliance to the latest requirements would not contribute

2 materially to the level of safety or would be impractical. Earlier amendments may not precede the corresponding regulation listed in the existing certification basis. Under § 21.101(c), special conditions apply when the regulations do not provide adequate standards for the proposed change because of a novel or unusual design feature. § 21.101(c) applies to significant and not significant design changes. § 21.101(d) explains how long an application remains valid for a change to a TC, including STCs. An application for a change to a TC for a transport category aircraft is effective for five years, and an application for a change to any other category aircraft is effective for three years. 5. Roles and Responsibilities The following information identifies the roles and responsibilities for both the applicant and Aircraft Certification Service during certification projects: a. Applicants: (1) Identify and evaluate the proposed change. In assessing the change, define the affected areas and include previous relevant design changes along with the related, appropriate regulations. The evaluation should be comprehensive enough to fully understand the scope of the change. (2) Identify if the change is significant or not significant at the product level using the information in AC-21-AA-2014-36. The determination of significance must include a review of any previous relevant design changes. (3) Apply the latest regulations for significant changes, unless a proposal is presented to apply earlier regulations. The applicant may propose to use one of the exceptions of §21.101(b)

2 or 3, that is, not affected area, does not contribute materially to the level of safety, and/or impracticality. (4) Propose a certification basis with appropriate amendment levels. b. Aircraft Certification Service: (1) Guides the applicant on how to apply the rule. (2) Uses the delegation system to streamline implementation. Aircraft Certification Service must work closely with its applicants to establish an effective delegation system.

3 (3) Approves or disapproves the latest amendment exceptions as proposed by the applicant. When the applicant proposes exceptions, the CAAC engineer must review data submitted and make a finding. Many times the Administrator will have predetermined if the change is not significant. The table in Appendix A of AC-21-AA-2014-36 contains examples C predetermined by the Administrator C of substantial, significant, and not significant design changes. (6) Uses the G-1 issue paper to record issues and resolution for changes to the certification basis. The G-1 issue paper would normally be used to document: significant changes where earlier regulations are applied per § 21.101(b) 2,

3 (unaffected area, contribution to the level of safety, and impracticality);

not significant changes, due to an inadequate certification basis, requiring the use of later regulations;

and the application of special conditions per §21.101(c). (5) Determines the certification basis. To establish the certification basis for validation programs, the procedures in the appropriate BASA IPA should be consult. 6. Determining the Applicability of § 21.101 for Changed Products a. A change to a type certificate as stated in § 21.101 refers to changes in type design. Minor changes (as classified by §21.93 and approved §21.95) are by definition considered to be not significant. Therefore, they can be approved per the existing certification basis. b. Substantial changes (§21.19) to a product that are so extensive that they require a complete investigation of compliance require a new TC. The Administrator weighs the magnitude of the proposed design change against the degree of investigation needed to establish compliance with the regulations. New type certificates require the use of the regulations in effect on the date of application for the change. The following table outlines the certification process for substantial and not substantial changes: If the Administrator finds that the proposed design change … Then the applicant must … And … Is substantial. Submit an application for a new TC. Establish the certification basis (§21.17), using the regulations in effect on the date of application for the change.