Page 26 - UK Regulation Part 21 Initial Airworthiness Annex I (consolidated) March 2022

PART 21 - INITIAL AIRWORTHINESS (ANNEX I)

See AMC 21.A.15(b)(5) for the determination of the compliance demonstration items (CDIs).
21.A.15(b)(6) on information relevant for the determination of the level of involvement (LoI)
The applicant should provide sufficient detailed information about the novelty, complexity, and criticality
aspects of each proposed CDI.
It is recommended to provide this information at the level of each CAA panel or discipline affected by a
proposed CDI. Further interpretative material on the necessary level of details is provided in AMC
21.B.100(a) and 21.A.15(b)(6).
The applicant should provide detailed information about the proposed means of compliance with the
applicable requirements identified under 21.A.15(b)(4). The information provided should be sufficient
for the CAA to determine its (initial) LoI. This should include the following, as far as this information is
available at the time of submission to the CAA:
33. a compliance checklist addressing each requirement, the proposed means of compliance
(see Appendix A to AMC 21.A.15(b) below for the relevant codes), and the related
compliance document(s);
34. identification of industry standards (Society of Automotive Engineers (SAE), American
Society for Testing and Materials (ASTM), European Organisation for Civil Aviation
Equipment (EUROCAE), AeroSpace and Defence Industries Association of Europe (ASD),
etc.), methodology documents, handbooks, technical procedures, technical documents
and specifications specified in the type certificate data sheet, certification memoranda,
policy statements, guidance material, etc., that should be followed in the demonstration of
compliance;
35. when the compliance demonstration involves testing, a description of the ground and flight
test article(s), test method(s), test location(s), test schedule, test house(s), test conditions
(e.g. limit load, ultimate load), as well as of the intent/objective(s) of the testing; and
36. when the compliance demonstration involves analyses/calculations, a
description/identification of the tools (e.g. name and version/release of the software
programs) and methods used, the associated assumptions, limitations and/or conditions,
programs) and methods used, the associated assumptions, limitations and/or conditions,
as well as of the intended use and purpose; furthermore, the validation and verification of
such tools and methods should be addressed.
For every aspect mentioned above, the applicant should clearly identify whether the demonstration of
compliance involves any method (analysis or test) which is novel or unusual for the applicant. This
should include any deviations from the published AMC to the relevant CS.
21.A.15(b) APPA to AMC Appendix A to AMC 21.A.15(b) Means of compliance codes

21.A.15(b)(5) AMC Breakdown of the certification programme into compliance demonstration items (CDIs)
1. What is a CDI?
A CDI is a meaningful group of compliance demonstration activities and data identified in
the certification programme which can be considered in isolation for the purpose of
performing the risk assessment that allows the CAA to determine its level of involvement
(LoI) using a riskbased approach.
The possibility to create this grouping of compliance demonstration activities and data is
intended to facilitate the risk assessment. However, there may be cases in which the risk
assessment may also be performed at the level of the compliance demonstration activity
or data, or at the level of the whole certification project.
The chosen breakdown into CDIs may affect the resulting risk classes (please refer to
AMC 21.B.100(a) and 21.A.15(b)(6)), but should not have any effect on the compliance
demonstration itself or on the CAA’s LoI.
2. The grouping of compliance demonstration activities and data
The compliance demonstration activities and data grouped in a CDI may demonstrate
compliance with a requirement, a group of requirements, or even a part of a requirement.
In this context, ‘requirement’ means any element of the typecertification basis or
operational suitability data (OSD) certification basis as specified in 21.B.80 and 21.B.82, or
the environmental protection requirements as specified in 21.B.85.
A CDI may comprise any of the means of compliance listed in Appendix A to AMC
21.A.15(b).
CDIs may be tailored to the scope and size of the project. On simple projects, a CDI may
address all the compliance demonstration activities within a given technical area (e.g.
avionics, flight, structures, hydromechanical systems, OSDcabin crew data (CCD), etc.)
or of the whole project.
A CDI should not be too large, by combining completely unrelated compliance
demonstration activities or data, so that it becomes meaningless, but neither should it be
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