Regulatory Framework
How the rules are layered
Maintenance law sits in a hierarchy. At the top are ICAO Standards and Recommended Practices agreed under the 1944 Chicago Convention; they bind States, not individuals. In the EU, the European Commission adopts the Basic Regulation (EU) 2018/1139, which sets objectives and empowers EASA to draft implementing rules. Those appear as Commission Regulations - notably (EU) No 1321/2014 for continuing airworthiness (Part-66, Part-145, Part-M, Part-ML, Part-CAMO, Part-CAO) and (EU) No 748/2012 for design and production (Part-21). National aviation authorities (NAAs) then apply them: issuing licences, approving organisations and performing oversight.
Key concept: regulations are directly applicable in Member States. The NAA - not EASA - normally issues a Part-66 licence or a Part-145 approval. EASA holds design and production approvals and coordinates standardisation.
Traps candidates fall into: confusing Acceptable Means of Compliance (AMC) with the rule itself. AMC and Guidance Material are non-binding; the regulation text binds. Another trap is treating a "Part" (e.g. Part-M) as a separate law - it is an annex to a regulation. A third is assuming EASA certifies individual mechanics; it does not.
Rule of thumb: when a question asks "who issues/approves?", work down the chain - EASA (design, production), NAA (licences, organisation approvals, AMPs), organisation (internal authorisations, work orders, release to service).
Worked example: an aircraft leaves a Part-145 hangar after heavy maintenance. The release to service is signed by that organisation's authorised certifying staff; the NAA only approved the organisation and its MOE. No regulator signature appears on the certificate of release to service.