Page 91 - UK Regulation Part 21 Initial Airworthiness Annex I (consolidated) March 2022

PART 21 - INITIAL AIRWORTHINESS (ANNEX I)

classification of the intended product change will not be evaluated solely on
the basis of the first application, but rather on the basis of all the required
changes needed to accomplish the intended product change. If the CAA
determines that the current application is a part of a sequence of related
changes, then the CAA will re-evaluate the determination of significance and
the resulting certification basis as a group of related changes.
5.13.2 Example: Cumulative effects - advancing the certification basis.
The type certificate for aeroplane model X lists three models, namely X300,
X200, and X100. The X300 is derived from the X200, which is derived from the
original X100 model. An applicant proposes a change to the X300 aeroplane
model. During the review of the X300 certification basis and the certification
specifications affected by the proposed change, it was identified that one
certification specification, CS 25.571 (damage tolerance requirements),
remained at the same amendment level as the X100 original certification
basis (exception granted on the X200). Since the amendment level for this
particular certification specification was not changed for the two subsequent
aeroplane models (X200 and X300), the applicant must now examine the
cumulative effects of these two previous changes that are related to the
proposed change and the damage tolerance requirements to determine
whether the amendment level needs to advance.
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¹ This example is taken from the FAA experience gained prior to the CAA’s start, therefore the
references to the FAA sections and amendments are kept.

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