Page 51 - UK Regulation Part 21 Initial Airworthiness Annex I (consolidated) March 2022

PART 21 - INITIAL AIRWORTHINESS (ANNEX I)

000 lb) or less maximum weight, the change and areas affected by the change shall
comply with the type-certification basis incorporated by reference in the type-certificate.
However, if the CAA finds that the change is significant in an area, the CAA may require
that the change and areas affected by the change comply with an amendment to a
certification specification of the type-certification basis incorporated by reference in the
type-certificate and with any other certification specification which is directly related,
unless the CAA also finds that compliance with that amendment does not contribute
materially to the level of safety of the changed product or is impractical.
(d) If the CAA finds that the certification specifications applicable on the date of the application
for the change do not provide adequate standards with respect to the proposed change,
the change and areas affected by the change shall also comply with any special
conditions, and amendments to those special conditions, prescribed by the CAA in
accordance with point 21.B.75, to provide a level of safety equivalent to that established by
the certification specifications applicable on the date of the application for the change.
(e) By derogation from points (a), (b) and (c), the change and areas affected by the change
may comply with an alternative to a certification specification designated by the CAA if
proposed by the applicant, provided that the CAA finds that the alternative provides a level
of safety which is:
1. in the case of a type-certificate:
(i) equivalent to that of the certification specifications designated by the CAA
under (a), (b) or (c) above; or
(ii) compliant with the essential requirements of Annex II to Regulation (EU)
2018/1139;
2. in the case of a restricted type-certificate, adequate with regard to the intended use.
(f) If an applicant chooses to comply with a certification specification set out in an
amendment that becomes applicable after submitting the application for a change to a
type-certificate, the change and areas affected by the change shall also comply with any
other certification specification which is directly related.
(g) When the application for a change to a type-certificate for an aircraft includes, or is
supplemented after the initial application to include, changes to the operational suitability
data, the operational suitability data certification basis shall be established in accordance
with points (a)-(f).
21.A.101 APPA to GM Appendix A to GM 21.A.101 Classification of design changes
The following tables of ‘substantial’, ‘significant’, and ‘not significant’ changes are adopted by the FAA,
Agência Nacional de Aviação Civil (ANAC), the CAA, and Transport Canada Civil Aviation (TCCA)
through international collaboration. The classification may change due to cumulative effects and/or
combinations of individual changes.
A.1 Examples of Substantial, Significant, and Not Significant Changes for Small Aeroplanes
(CS-23).
A.1.1 Table A-1 contains examples of changes that are ‘substantial’ for small aeroplanes
(CS-23).

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