Type Certification: TC, TCDS and Changes
EASA Part-21 type certification: how a type certificate is issued, what the TCDS records, the holder’s obligations, minor and major changes, and the STC.
Dionysis Kefalas7 min readFor Part-21 and CAMO staff
Part 3 of 6 in EASA Part-21 Initial Airworthiness Show parts
Quotes checked on against EASA Easy Access Rules for Initial Airworthiness and Environmental Protection (Regulation (EU) No 748/2012, Part-21) — 27 Nov 2025 revision.
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Certifying a design
The type certificate is the approval of a design. Aircraft built afterwards depend on it. This guide is how that certificate is issued, what the data sheet is, what the holder keeps doing, and how the approved design is changed.
How a type certificate is issued
(a)In order to be issued with a product or a CMU type certificate, or with an aircraft restricted type certificate for the aircraft that does not meet the essential requirements laid down in Annex II to Regulation (EU) 2018/1139,, the applicant shall:
1.demonstrate its capability in accordance with point 21.A.14;
2.demonstrate compliance in accordance with point 21.A.20;
[…]
(b)By way of derogation from point (a)(2), at the applicant’s request included in the declaration referred to in point 21.A.20(d), the applicant is entitled to have the aircraft type certificate or restricted type certificate issued before the applicant has demonstrated compliance with the applicable operational suitability data certification basis, provided that the applicant demonstrates such compliance before the date on which this data is to be actually used.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
Point (a) begins with capability in accordance with point 21.A.14, and compliance in accordance with point 21.A.20, before a product or CMU type certificate, or an aircraft restricted type certificate, is issued. The quote keeps the double comma after 2018/1139.
(a)Following the acceptance of the certification programme by the Agency, the applicant shall demonstrate compliance with the type certification basis, operational suitability data certification basis and environmental protection requirements, as established and notified to the applicant by the Agency in accordance with points 21.B.80, 21.B.82, 21.B.85, and shall provide the Agency with the means by which such compliance has been demonstrated.
[…]
(d)After completion of all demonstrations of compliance in accordance with the certification programme, including any inspections and tests in accordance with point 21.A.33, and after all flight tests in accordance with point 21.A.35, the applicant shall declare that:
1.it has demonstrated compliance with the type-certification basis, operational suitability data certification basis and environmental protection requirements, as established and notified by the Agency, following the certification programme as accepted by the Agency; and
2.no feature or characteristic has been identified that may make the product, the UAS or the CMU unsafe for the uses for which certification is requested.
(e)The applicant shall submit to the Agency the declaration of compliance provided for in point (d). Where the applicant holds an appropriate design organisation approval, the declaration of compliance shall be made in accordance with Subpart J and submitted to the Agency.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
Point (a) is the demonstration of compliance after the Agency has accepted the certification programme. Point (e) is the submission of that declaration to the Agency. The certification specifications in the basis are the subject of the certification-specifications guide.
What the certificate records
The type-certificate and restricted type-certificate shall include the type design, the operating limitations, the instructions for continued airworthiness, the type-certificate data sheet for airworthiness and emissions, the applicable type-certification basis and environmental protection requirements with which the Agency records compliance, and any other conditions or limitations prescribed for the product, the UAS orthe CMU in the applicable certification specifications and environmental protection requirements. The aircraft type-certificate and restricted type-certificate shall include in addition the applicable operational suitability data certification basis, the operational suitability data and the type-certificate data sheet for noise. The aircraft type-certificate and restricted type-certificate data sheet shall include the record of CO2 emissions compliance, and the engine type-certificate data sheet shall include the record of exhaust emissions compliance.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
The first sentence includes the instructions for continued airworthiness and the type-certificate data sheet for airworthiness and emissions. For an aircraft type-certificate or restricted type-certificate, the text adds the operational suitability data and the type-certificate data sheet for noise. The same sentence still runs the words UAS orthe together. The quote keeps that spelling. The lifecycle guide walks the same sentence.
The holder's continuing obligations
Each holder of a type-certificate or restricted type-certificate shall:
(a)undertake the obligations laid down in points 21.A.3A, 21.A.3B, 21.A.4, 21.A.5, 21.A.6, 21.A.7, 21.A.9, 21.A.62 and 21.A.65, and, for this purpose, shall continue to meet the qualification requirements for eligibility under point 21.A.13; and
(b)specify the marking in accordance with Subpart Q.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
Point (b) is the marking in accordance with Subpart Q.
Changing an approved type
Changes to a type certificate shall be classified as “minor” and “major”. A “minor change” has no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics, certified noise or emissions levels, operational suitability data, or other characteristics affecting the airworthiness or the environmental compatibility of the product or of the UAS, or no appreciable effect on the reliability, operational characteristics, or other characteristics affecting the airworthiness of the CMU. Without prejudice to point 21.A.19, all other changes shall be considered “major changes” under this Subpart. Major and minor changes shall be approved in accordance with points 21.A.95 or 21.A.97, as appropriate, and shall be adequately identified.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
A minor change has no appreciable effect on the characteristics that sentence lists.
(a)Minor changes to a type-certificate shall be classified and approved by:
1.the Agency; or
2.an approved design organisation within the scope of its privileges provided for in points (1) and (2) of point 21.A.263(c), as recorded in the terms of approval.
[…]
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
(a)Major changes to a type-certificate shall be classified and approved by:
1.the Agency; or
2.an approved design organisation within the scope of its privileges provided for in points (1) and (8) of point 21.A.263(c), as recorded in the terms of approval.
[…]
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
Point 21.A.95(a) classifies and approves minor changes, by the Agency or by an approved design organisation within the privileges that point names. Point 21.A.97(a) classifies and approves major changes, by the Agency or by an approved design organisation within the privileges that point names.
Supplemental type certificates
This Subpart establishes the procedure for the approval of major changes to the type-certificate under supplemental type-certificate procedures, and establishes the rights and obligations of the applicants for, and holders of, those certificates. In this Subpart, the references to type-certificates include type-certificates and restricted type-certificates.
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
A supplemental type certificate is this procedure for the approval of major changes to the type certificate. The point does not say the applicant is someone other than the type-certificate holder.
(a)An application for a supplemental type-certificate shall be made in a form and manner established by the Agency.
(b)When applying for a supplemental type-certificate, the applicant shall:
(i)include in the application the information required by point 21.A.93(b);
(ii)specify whether the certification data has been or will be prepared completely by the applicant or on the basis of an arrangement with the owner of the type-certification data.
[…]
Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision.
Where to read it yourself
The points quoted above are in the EASA Easy Access Rules for Initial Airworthiness and Environmental Protection, Regulation (EU) No 748/2012. Every citation in this guide was checked against the 2025-11-27 revision.
Educational content, not regulatory compliance advice. Verify against the current regulation text before relying on it.
In this series
Related
- The Airworthiness Lifecycle: From Design to ServiceGuide · 4 min
- Certification Specifications (CS) and ETSO AuthorisationsGuide · 4 min
- Design and Production Organisations (DOA and POA)Guide · 6 min
- Certificates of Airworthiness and Permits to FlyGuide · 8 min
- Parts, Appliances and the EASA Form 1Guide · 7 min
Written by Dionysis Kefalas. Retired Hellenic Air Force Captain and founder of Avioverse. About the author
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