CS 25.603 Materials

The term ‘material’ is differently interpreted, ranging from raw feedstock material to the material state in a final complex part configuration that may have undergone various processes. CS 25.603, CS 25.605, CS 25.613, and AMC 25.613 should therefore be considered together to ensure the coherent and safe design and production of parts and thus maintain occupant and aeroplane safety throughout the aeroplane’s operational life. This is of growing importance as more and more production methods allow the design of complex part configurations for which the characteristics of the materials are defined close to completion of the part production, e.g. castings, composite resin transfer methods, bonding, or additive manufacturing methods. The applicants should therefore discuss with EASA, at an early stage of the certification project, potential details supporting the means of compliance with CS 25.603, CS 25.605, and CS 25.613. Note: organisations engaged in the design and certification of modifications or repairs should also comply with these CSs and consider the related AMC. Appropriately defined tests and analysis pyramids (e.g. as outlined in AMC 20-29 for composite materials) should support the certification of materials, processes, and/or fabrication methods, including the development of the associated design values in more complex part configurations and assemblies.

[Amdt No: 25/27]

The approved material specifications and material process specifications should: be suitable for the application; define material and material process controls; include requirements to assist the applicant in managing raw/feedstock/unfinished materials, as appropriate to the technology (e.g. the feedstock powder used in additive manufacturing, or matrix systems used in pre-impregnated composites). The material strength and other properties that are used in design data (including fatigue and damage tolerance characteristics, when applicable) are governed by, and can be significantly sensitive to, the related variables of the material production process (including raw-material considerations). Furthermore, these properties may also be influenced by other higher-level fabrication processes (manufacturing and assembly), including other post-processing activities (e.g. adhesive material and bonding properties produced in a bonded joint of a complex part may not be the same as those produced in a test coupon). The material specifications, material process specifications, and/or production drawings should identify key characteristics and parameters to be monitored by in-process quality control, including the acceptable limits to the characteristics of materials and processes (e.g. acceptable anomalies or flaws), and should address anisotropy, when applicable. This information may also help applicants identify other defect types and damage modes than the anomalies and flaws that are accepted under the specifications, including those that may occur in service. Such data may be used to help applicants show compliance with other specifications, e.g. CS 25.571. However, showing compliance with CS 25.571 does not relieve from the requirement for material process controls. Note: approved material specifications and approved material process specifications can be, for example, industry or military specifications, or European Technical Standard Orders (ETSOs).

[Amdt No: 25/27]