Module 10.6 — Certification of aircraft, parts and appliances: Part 21 and the CSs

Scope and level

10.6 is level 2 for all categories: a basic understanding of Part 21 (Annex I to Regulation (EU) No 748/2012) and of CS-22, CS-23, CS-25, CS-27, CS-29 and CS-STAN. (Note: the Part 21 Easy Access Rules were not part of the downloaded research pack; the form numbers below were cross-checked against EASA's published form list — verify sub-part letters against the current EAR if needed.)

Part 21 at a glance

Part 21 governs how a design is approved, how products and parts are produced to that design, and how individual aircraft receive airworthiness and noise certificates.

Subpart	Subject
A	General provisions (incl. occurrence reporting by design/production holders, airworthiness directives)
B	Type certificates (TC) and restricted type certificates
D	Changes to type certificates (minor and major changes)
E	Supplemental type certificates (STC)
F	Production without a production organisation approval
G	Production organisation approval (POA)
H	Certificates of airworthiness and restricted CofAs
I	Noise certificates
J	Design organisation approval (DOA)
K	Parts and appliances
M	Repairs
O	ETSO authorisations (European Technical Standard Orders)
P	Permit to fly
Q	Identification of products, parts and appliances (data plates, part marking)

Part 21 Light (Annex Ib, added by Reg. (EU) 2022/1358) provides simpler rules for light sport/ELA aircraft design and production.

Design approvals

• Type certificate (TC): issued by EASA when the applicant shows the type design complies with the type-certification basis (applicable CS plus special conditions) and environmental requirements. Includes the Type Certificate Data Sheet (TCDS).
• Restricted TC: for aircraft that do not meet all CSs but are safe for a specific purpose.
• Changes to type design: classified as minor (no appreciable effect on mass, balance, structural strength, reliability, operational characteristics, noise, emissions or other airworthiness characteristics) or major (all others). Minor changes may be approved by a DOA under its privileges; major by EASA (or DOA with the privilege).
• STC: approval of a major change by someone other than the TC holder.
• Repairs: classified minor/major; repair data must be approved (EASA, DOA or TC holder data such as the SRM).
• ETSO authorisation: approval of design and production of a part/appliance to a European Technical Standard Order (e.g. seats, instruments, ELTs).
• CS-STAN standard changes and repairs: may be embodied on certain light aircraft without a design approval, by following CS-STAN exactly; the person releasing the aircraft takes responsibility that CS-STAN is met.