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Appendix C to GM 21.A.101 A method to determine the changed and affected areas

Available versions for ERULES-1963177438-3717

ED Decision 2012/020/R found in: Initial Airworthiness and Environmental Protection (No 748/2012) Part-21 Part-21L (Jul 2024)

Version Text

Appendix C to GM 21.A.101 A method to determine the changed and affected areas

ED
Decision 2017/024/R

C.1     Overview.

C.1.1  When a product is changed, some areas may
change physically, while others may change functionally. EASA refers to this
combination as changed and affected areas. For example, an extension to the
wing of a fixed-wing aircraft would physically change the wing tip and likely
other wing structure. Some areas of the airframe may have sufficient strength
for the increase in load and would change functionally, i.e. they would carry
greater load, but they would not change physically. These areas have
associated certification specifications, which become part of the
certification basis for the change.

C.1.2  Figure C-1 below provides an overview of
one method that applicants may use to determine the changed and affected areas
and the applicable certification specifications.

Figure C-1. Method to Determine the Changed and Affected
Areas

![Aviation.Bot AI suggestion, not from EASA source: [Image caption skipped for debugging]](/static/files/file_ocz75zUMmy4/image019.jpg)

**C.2     Physical
Changes.**

C.2.1  Steps*.*

—
Step 1. Make a list of the
physical changes.

—
Step 2. List the corresponding
certification specifications applicable to the physical changes.

—
Step 3. List the amendment
level recorded on the existing certification basis of the baseline product and
the amendments on the date of application.

C.2.2  Example*.*

The change is adding a winglet to a
fixed-wing aircraft and a change to the leading-edge slats for a performance
increase. As part of the change, an electrically driven slat actuator is
modified by changing the mounting structure of the actuator used to connect
the actuator to the slat. The actuator structure is changed. The electrical
system in the actuator is not affected. The applicant would list certification
specifications applicable to the actuator. The applicant would not list the
certification specifications applicable to the electrical system of the
actuator. See Table C-1 below for an example of how to chart a physical
change and the associated certification specifications.

Table
C-1. Example of Associating a Physical Change with the Applicable
Certification Specifications

<table border="1" cellpadding="0" cellspacing="0">
<thead>
<tr>
<td width="150">
Physical Change
</td>
<td width="150">
Applicable Certification
 Specifications*
</td>
<td width="150">
Amendment of Existing
 Certification Basis
</td>
<td width="150">
Amendment on Application
 Date
</td>
</tr>
</thead>
<tr>
<td rowspan="3" valign="top" width="150">
Structural
 change to slat actuator
</td>
<td valign="top" width="150">
25.xxx
</td>
<td valign="top" width="150">
25-aaa
</td>
<td valign="top" width="150">
25-ddd
</td>
</tr>
<tr>
<td valign="top" width="150">
25.yyy
</td>
<td valign="top" width="150">
25-bbb
</td>
<td valign="top" width="150">
25-eee
</td>
</tr>
<tr>
<td valign="top" width="150">
25.zzz
</td>
<td valign="top" width="150">
25-ccc
</td>
<td valign="top" width="150">
25-fff
</td>
</tr>
</table>

\* These would be certification
specifications related to structural aspects only.

**C.3     Functional
Changes.**

C.3.1  Steps*.*

—
Step 1. Describe each change.

—
Step 2. Describe the effects
of the change (e.g. structural, performance, electrical, etc.).

—
Step 3. List the areas,
systems, parts, and appliances that are affected by those effects.

—
Step 4. List the certification
specifications associated with the effects for each area, system, part, or
appliance.

—
Step 5. List the amendment
level recorded on the existing certification basis of the baseline product and
the amendments on the date of application.

C.3.2  Example.

The change is adding a winglet to a
fixed-wing aircraft and a change to the leading-edge slats for a performance
increase. The wing root bending moment has increased. The loads in the wing
box are increased but the wing box has sufficient structural margins to carry
the higher loads. Thus, the wing box is not physically changed but its
function has changed because it carries greater loads. See Table C-2
below for an example of how to chart a functional change, its effects, and the
affected areas (steps 1 through 3 above). See Table C-3 below for an
example of how to chart an area affected by a functional change and the
associated certification specifications (steps 4 and 5 above).

Table
C-2. Example of a Functional Change, Affected Areas, and Associated Effects

<table border="1" cellpadding="0" cellspacing="0">
<thead>
<tr>
<td width="200">
Description
 of Change
</td>
<td width="200">
Effects
</td>
<td width="200">
Affected
 Areas
</td>
</tr>
</thead>
<tr>
<td rowspan="5" valign="top" width="200">
Installation
 of winglet
</td>
<td rowspan="2" valign="top" width="200">
Increased
 loads in wing structure
</td>
<td valign="top" width="200">
Wing
 spars
</td>
</tr>
<tr>
<td valign="top" width="200">
Wing
 skins
</td>
</tr>
<tr>
<td rowspan="2" valign="top" width="200">
Effect
 2*
</td>
<td valign="top" width="200">
Area
 1
</td>
</tr>
<tr>
<td valign="top" width="200">
Area
 2
</td>
</tr>
<tr>
<td valign="top" width="200">
Effect
 3*
</td>
<td valign="top" width="200">
Area
 3
</td>
</tr>
</table>

\* There may be other effects as well.

Table C-3. Example of Associating Affected Areas
with the Applicable Certification Specifications

<table border="1" cellpadding="0" cellspacing="0">
<thead>
<tr>
<td width="151">
Impacted
 Area
</td>
<td width="150">
Applicable
 Certification Specifications*
</td>
<td width="150">
Amendment
 of Existing Certification Basis
</td>
<td width="150">
Amendment
 on Application Date
</td>
</tr>
</thead>
<tr>
<td rowspan="3" valign="top" width="151">
Wing
 spar
</td>
<td valign="top" width="150">
25.xxx
</td>
<td valign="top" width="150">
25-aaa
</td>
<td valign="top" width="150">
25-ddd
</td>
</tr>
<tr>
<td valign="top" width="150">
25.yyy
</td>
<td valign="top" width="150">
25-bbb
</td>
<td valign="top" width="150">
25-eee
</td>
</tr>
<tr>
<td valign="top" width="150">
25.zzz
</td>
<td valign="top" width="150">
25-ccc
</td>
<td valign="top" width="150">
25-fff
</td>
</tr>
</table>

\* These would be structural
certification specifications only. There could be other certification
specifications applicable to the wing box. But since the effect is structural,
then only the structural certification specifications are applicable.

**C.4     Combine
the Lists.**

C.4.1  EASA
typically presents the certification basis for a product by certification
specification and not by area. The next step is to combine these two lists.
However, since only a portion of the product is being changed, the changed and
affected areas of the new certification basis need to be identified. The unchanged
area is not required to comply with the certification specifications in effect
at the date of application. (See point [21.A.101](#_DxCrossRefBm1649096998)(b)(2))

C.4.2  When
the change is quite extensive, applicants will save time by listing all the
certification specifications applicable to the category of product they are
certifying*.* They can use Table C-4 below in the next step where
they will identify any other exceptions that they would like EASA to consider.

C.4.3  Example.
If we use the examples above for the combined list for the actuator structural
changes and the wing box functional change, then the certification basis would
be listed as shown in Table C-4 below.

Table
C-4. Example of a Combined List of Physical and Functional Changes with
Applicable Certification Specifications

<table border="1" cellpadding="0" cellspacing="0">
<thead>
<tr>
<td rowspan="2" width="124">
Certification
 Specification
</td>
<td colspan="2" width="293">
Amendment Levels
</td>
<td rowspan="2" width="184">
Changed and
 Affected Area
</td>
</tr>
<tr>
<td width="147">
Amendment of
 Existing Certification Basis
</td>
<td width="146">
Amendment on
 Application Date
</td>
</tr>
</thead>
<tr>
<td valign="top" width="124">
25.xxx*
</td>
<td valign="top" width="147">
25-aaa
</td>
<td valign="top" width="146">
25-ddd
</td>
<td rowspan="3" valign="top" width="184">
-       Wing spar
-       Leading-edge actuator
-       Wing loads
</td>
</tr>
<tr>
<td valign="top" width="124">
25.yyy*
</td>
<td valign="top" width="147">
25-bbb
</td>
<td valign="top" width="146">
25-eee
</td>
</tr>
<tr>
<td valign="top" width="124">
25.zzz*
</td>
<td valign="top" width="147">
25-ccc
</td>
<td valign="top" width="146">
25-fff
</td>
</tr>
</table>

\* These represent structural
certification specifications.