The Design Delegation Holders Seminars held by the Aircraft and Product Certification Unit bring together participants from the industry, CAA, and other National Airworthiness Authorities (CASA, FAA, etc).

The seminars provide a forum for Design Delegation Holders and Part 146 Design Organisations' staff to discuss technical and professional topics, and network with other members of the industry.

Presentations from recent seminars

2021 Part 146 design delegation holders seminar

2020 Part 146/148/DDH seminar

2019 Design Delegation Holders and Part 148 seminar

2018 Design Delegation Holders Seminar Presentations

2017 Design Delegation Holders Seminar Presentations

If you wish to see presentations from earlier seminars, please email

Advice to CAA Design Delegates and Part 146s

Where appropriate, CAA provides advice, clarification or guidance to Design Delegation Holders and Part 146 Design Organisations. The following are relevant documents that have been issued in the past and remain current.

Schedule One [PDF 760 KB] – Guidance on what constitutes a major design change

Major Design Change Effectivity Changes (21 May 2021) [PDF 305 KB] – Clarification on aircraft effectivity changes

14 CFR 23 Amendment 64 (21 Oct 2020) [PDF 271 KB] – Expectations relating to Part 23 certification basis

Guidance regarding modifications using “Belly-Bands for Human External Cargo" (23 Dec 2016) [PDF 1.5 MB]

Guidance regarding modifications to aircraft seats (15 Sep 2016) [PDF 2.4 MB]

Composite safety and certification meeting – 2016 seminar on the safe use and certification of composite materials

 Ask us about airworthiness

If you have any questions about this topic, use our contact form, or email