Sofema Aviation Services (SAS) www.sassofia.com reviews the guidance material – Ref GM 21.A.91 EASA Classification of changes to a type-certificate (TC) (ED Decision 2019/018/R).
Introduction – Complementary guidance for classification of changes.
- A change to the TC is judged to have an āappreciable effect on the mass, balance, structural strength, reliability, operational characteristics, noise, fuel venting, exhaust emission, operational suitability or other characteristics affecting the airworthiness, environmental protection or operational suitability of the productā and, therefore, should be classified as major, in particular, but not only, when one or more of the following conditions are met:
o Where the change requires an adjustment of the type-certification basis or the OSD certification basis (special conditions or equivalent safety findings) other than electing to comply with later certification specifications;
o Where the applicant proposes a new interpretation of the certification specifications used for the type certification basis or the OSD certification basis that has not been published as AMC material or otherwise agreed with the Agency;
o Where the demonstration of compliance uses methods that have not been previously accepted as appropriate for the nature of the change;
o Where the extent of new substantiation data necessary to comply with the applicable certification specifications and the degree to which the original substantiation data has to be re-assessed and re-evaluated is considerable;
o Where the change alters the airworthiness limitations or the operating limitations;
o Where the change is made mandatory by an airworthiness directive or the change is the terminating action of an airworthiness directive (ref. 21.A.3B), see Note 1; and
o Where the design change introduces or affects functions where the failure effect is classified as catastrophic or hazardous.
Concerning Cabin Safety – changes which introduce a new cabin layout of sufficient change to require a re-assessment of emergency evacuation capability or which adversely affect other aspects of passenger or crew safety.
Items to consider include, but are not limited to:
- changes to or introduction of dynamically tested seats.
- change to the pitch between seat rows.
- change of distance between seat and adjacent obstacle like a divider.
- changes to cabin layouts that affect evacuation path or access to exits.
- installation of new galleys, toilets, wardrobes, etc.
- installation of a new type of electrically powered galley insert.
Note 1: A change previously classified as minor and approved prior to the airworthiness directive issuance decision needs no reclassification. However, EASA retains the right to review the change and reclassify/reapprove it if found necessary.
Note 2: The conditions listed above are a further explanation of the following – Regulation (EU) 2019/897 – Changes to a type-certificate are classified as minor and major. A āminor changeā has no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics, operational suitability data, or other characteristics affecting the airworthiness of the product or its environmental characteristics. Without prejudice to point 21.A.19, all other changes are āmajor changesā under this Subpart.
Major and minor changes shall be approved in accordance with points 21.A.95 or 21.A.97, as appropriate, and shall be adequately identified. (See below for further details)
Complementary guidance on the classification of changes to OSD
- This paragraph provides firstly general guidance on minor OSD change classification, and secondly additional guidance specific to each OSD constituent.
- Changes to OSD are considered minor when they:
o Incorporate optional information (representing improvements/enhancements);
o Provide clarifications, interpretations, definitions, or advisory text; or
o Do not change the intent of the OSD document, e.g. changes to:
– titles, numbering, formatting, applicability;
– order, sequence, pagination; or
– sketches, figures, units of measurement, and correction of editorial mistakes such as:
o spelling; or
o reference numbers.
Given the structure and individual intent of the separate OSD constituents, the interpretation of āappreciableā is also affected by the specific nature of the applicable certification specifications (CS) for that constituent. Therefore, specific guidance on each of the OSD constituents is provided hereafter.
21.A.95 Requirements for approval of a minor change (Regulation (EU) 2019/897)
Minor changes to a type-certificate shall be classified and approved by:
- The Agency; or
- An approved design organisation within the scope of its privileges as recorded in the terms of approval.
Notes: A minor change to a type-certificate shall only be approved:
- When it has been demonstrated that the change and areas affected by the change comply with the type-certification basis and the environmental protection requirements incorporated by reference in the type-certificate;
- In the case of a change affecting the operational suitability data, when it has been demonstrated that the necessary changes to the operational suitability data comply with the operational suitability data certification basis incorporated by reference in the type-certificate;
- When compliance with the type-certification basis that applies in accordance with point (1) has been declared and the justifications of compliance have been recorded in the compliance documents; and
- When no feature or characteristic has been identified that may make the product unsafe for the uses for which certification is requested.
- The applicant shall submit to the Agency the substantiation data for the change and a statement that compliance has been demonstrated.
- An approval of a minor change to a type-certificate shall be limited to the specific configuration(s) in the type-certificate to which the change relates.
21.A.97 Requirements for approval of a major change Regulation (EU) 2019/897
Major changes to a type-certificate shall be classified and approved by:
- The Agency; or
- An approved design organisation within the scope of its privileges.
A major change to a type-certificate shall only be approved:
- When it has been demonstrated that the change and areas affected by the change comply with the type-certification basis and environmental protection requirements, as established by the Agency in accordance with point 21.A.101;
- In the case of a change affecting the operational suitability data, when it has been demonstrated that the necessary changes to the operational suitability data meet the operational suitability data certification basis, as established by the Agency in accordance with point 21.A.101; and
- When compliance has been demonstrated in accordance with point 21.A.20, as applicable to the change.
By derogation, at the applicant’s request included in the declaration referred to in point 21.A.20(d), a major change to an aircraft type-certificate may be approved before compliance with the operational suitability data certification basis has been demonstrated, provided that the applicant demonstrates such compliance before the date at which those data are actually used.
Note: An approval of a major change to a type-certificate shall be limited to the specific configuration(s) in the type-certificate to which the change relates.
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aviation, EASA, OSD, SAS blogs, CS 25, Type Certificate, Aircraft Cabin, TC, Aviatin Training, Part 21 G, Part 21 J, Cabin safety, Ref GM 21.A.91, ED Decision 2019/018/R, Regulation (EU) 2019/897, EASA Classification
