EASA Part 21 commonly refers to the European aviation rules for certification of aircraft and related products, parts, and appliances, including requirements for design and production organizations. In manufacturing, it is relevant to how aerospace parts and assemblies are produced, controlled, documented, and released within an approved airworthiness framework.
Part 21 is associated with activities such as type certification, design organization approval, production organization approval, conformity demonstration, configuration control, and airworthiness release documentation. For shopfloor and quality systems, the operational impact is usually seen in controlled work instructions, traceable build records, approved design data, inspection evidence, nonconformance handling, and release documents such as an EASA Form 1 where applicable.
EASA Part 21 should not be confused with AS9100 or AS9102. AS9100 is a quality management system standard, and AS9102 addresses first article inspection reporting. EASA Part 21 is a regulatory framework for aviation design, production, and certification activities. It is also distinct from EASA Part 145, which applies to maintenance organization approval.