21.B.135 Maintenance of the letter of agreement

• Regulation (EU) No 748/2012 found in: Initial Airworthiness and Environmental Protection (748/2012) Part-21 Part-21L (Jul 2024)
• Regulation (EU) 2024/1110 found in: Initial Airworthiness and Environmental Protection (748/2012) (Nov 2025)

21.B.135 Maintenance of the letter of agreement Regulation (EU) No 748/2012 The competent authority shall maintain the letter of agreement as long as: (a)     the manufacturer is properly using the EASA Form 52 (see [Appendix VIII](#_DxCrossRefBm1649096923)) as a statement of conformity for complete aircraft, and the EASA Form 1 (see [Appendix I](#_DxCrossRefBm1649096870)) for products other than complete aircraft, parts and appliances; and (b)     inspections performed by the competent authority of the Member State before validation of the EASA Form 52 (see [Appendix VIII](#_DxCrossRefBm1649096923)) or the EASA Form 1 (see [Appendix I](#_DxCrossRefBm1649096870)), as per point [21.A.130](#_DxCrossRefBm1649096912)(c) did not reveal any findings of non-compliance with the requirements or the procedures as contained in the manual provided by the manufacturer, or any non‑conformity of the respective products, parts or appliances. These inspections shall check at least that: 1.       the agreement covers the product, part or appliance being validated, and remains valid; 2.       the manual described in point [21.A.125A](#_DxCrossRefBm1649096929)(b) and its change status referred in the letter of agreement is used as basic working document by the manufacturer. Otherwise, the inspection shall not continue and therefore the release certificates shall not be validated; 3.       production has been carried out under the conditions prescribed in the letter of agreement and satisfactorily performed; 4.       inspections and tests (including flight tests, if appropriate), as per points [(b)(2)](#_DxCrossRefBm1649096912) and/or (b)(3), have been carried out under the condition prescribed in the letter of agreement and satisfactorily performed; 5.       the inspections by the competent authority described or addressed in the letter of agreement have been performed and found acceptable; 6.       the statement of conformity complies with point [21.A.130](#_DxCrossRefBm1649096912), and the information provided by it does not prevent its validation; and (c)      any termination date for the letter of agreement has not been reached. #### 21.B.135 Maintenance of the letter of agreement *Regulation (EU) 2024/1110* The competent authority shall maintain the letter of agreement for as long as: (a) the manufacturer properly uses the EASA Form 52 (see [Appendix VIII](#_DxCrossRefBm485230414)) as a statement of conformity for complete aircraft, and the EASA Form 1 (see [Appendix I](#_DxCrossRefBm485230360)) for products other than complete aircraft, parts, appliances, control and monitoring units (CMUs) and CMU components; and (b) inspections performed by the competent authority of the Member State before validation of the EASA Form 52 (see [Appendix VIII](#_DxCrossRefBm485230414)) or the EASA Form 1 (see [Appendix I](#_DxCrossRefBm485230360)), as per point [21.A.130](#_DxCrossRefBm485230403)(c) did not reveal any findings of non-compliance with the requirements or the procedures as contained in the manual provided by the manufacturer, or any non‑conformity of the respective products, parts or appliances. These inspections shall check at least that: 1. the agreement covers the product, part, appliance, control and monitoring unit (CMU) or CMU component to be validated, and remains valid; 2. the manual described in point [21.A.125A](#_DxCrossRefBm485230420)(b) and its change status referred in the letter of agreement is used as basic working document by the manufacturer. Otherwise, the inspection shall not continue and therefore the release certificates shall not be validated; 3. production has been carried out under the conditions prescribed in the letter of agreement and satisfactorily performed; 4. inspections and tests (including flight tests, if appropriate), as per points [(b)(2)](#_DxCrossRefBm485230403) and/or (b)(3), have been carried out under the condition prescribed in the letter of agreement and satisfactorily performed; 5. the inspections by the competent authority described or addressed in the letter of agreement have been performed and found acceptable; 6. the statement of conformity complies with point [21.A.130](#_DxCrossRefBm485230403), and the information provided by it does not prevent its validation; and (c) any termination date for the letter of agreement has not been reached.