GM1 21L.A.103 Classification of changes to the design of an aircraft for which design compliance has been declared

• ED Decision 2023/013/R found in: Initial Airworthiness and Environmental Protection (748/2012) Part-21 Part-21L (Jul 2024)

GM1 21L.A.103 Classification of changes to the design of an aircraft for which design compliance has been declared ED Decision 2023/013/R Major changes that are classified as being ‘substantial’ should require a new declaration of design compliance to be submitted in accordance with Subpart C of Annex Ib (Part 21 Light). Examples of major changes that are considered substantial may be found in Appendix B to GM1 21L.A.103. (a)     PURPOSE OF CLASSIFICATION The purpose of the classification of changes to the design of an aircraft that was subject to a declaration made in accordance with point [21L.A.63](#_DxCrossRefBm1649097729) of Subpart C is to allow the declarants to determine the route to be followed for the declaration and whether they need to submit the declaration to EASA (major change) or to maintain it in order to make it available to EASA upon request (minor change). Point [21L.A.63](#_DxCrossRefBm1649097729), as referenced by point [21L.A.103](#_DxCrossRefBm1649097879)(a), requires that all changes be classified as either ‘major’ or ‘minor’ using the criteria in point [21L.A.63](#_DxCrossRefBm1649097729). (b)     INTRODUCTION (1)     Point [21L.A.63](#_DxCrossRefBm1649097729)(b) and (c), as referenced by point [21L.A.103](#_DxCrossRefBm1649097879)(a), proposes criteria for the classification of design changes as either ‘minor’ or ‘major’. This GM is intended to provide guidance on the term ‘appreciable effect’ affecting the airworthiness of the product, the declared noise or emissions levels or affecting any of the other characteristics mentioned in point [21L.A.63](#_DxCrossRefBm1649097729), where ‘airworthiness’ is interpreted in the context of a product in conformity with the applicable detailed technical specifications and is in condition for safe operation. It provides complementary guidelines to assess a change to the declared aircraft in order to meet the requirements of point [21L.A.103](#_DxCrossRefBm1649097879) where classification is the first step of a procedure. Characteristics affecting the environmental compatibility of the product are characteristics affecting the compliance of the product with the applicable environmental protection requirements. Note: For classification of repairs, see GM 21L.A.223. Although this GM provides guidance on the classification of major changes, as opposed to minor changes as defined in point [21L.A.103](#_DxCrossRefBm1649097879), the GM and point [21L.A.103](#_DxCrossRefBm1649097879) are deemed entirely compatible. [Appendix A to GM1 21L.A.103](#_DxCrossRefBm1649097948) provides examples of major changes and a classification process. (c)      ASSESSMENT OF A CHANGE FOR CLASSIFICATION (1)     Changes to the declared design Point [21L.A.103](#_DxCrossRefBm1649097879) addresses all changes to any of the aspects of a declaration of design compliance that was submitted under Subpart C. (2)     Reserved (3)     Classification process (see also the flow chart ‘Classification process’ in Appendix A to GM 21L.A.103) Point [21L.A.103](#_DxCrossRefBm1649097879) requires all changes to be classified as either ‘major’ or ‘minor’, using the criteria of point [21L.A.63](#_DxCrossRefBm1649097729). Wherever there is doubt as to the classification of a change, EASA should be consulted for clarification. When the strict application of the point (c)(4) criteria results in a major classification, the declarant may request reclassification by EASA. A simple design change planned to be mandated by an airworthiness directive may be reclassified as minor due to the involvement of EASA in the continued airworthiness process when this is agreed between EASA and the declarant. The reasons for a classification decision should be recorded. (4)     General guidance on the classification of major changes A change that is judged to have an ‘appreciable effect on the mass, balance, structural strength, reliability, declared noise or emissions levels, operational characteristics, or other characteristics affecting the airworthiness or the environmental compatibility’ is classified as major, in particular, but not only, when one or more of the following conditions are met: (i)      where the change requires an adjustment of the detailed technical specifications other than electing to comply with later certification specifications; (ii)     where the declarant proposes a new interpretation of the certification specifications used to define the applicable detailed technical specifications; (iii)     where the demonstration of compliance uses methods that have not been previously determined as appropriate for the nature of the change; (iv)     where the extent of new substantiation data necessary to comply with the applicable detailed technical specifications and the degree to which the original substantiation data has to be reassessed and re-evaluated is considerable; (v)      where the change alters the airworthiness limitations or the operating limitations; (vi      where the change is made mandatory by an airworthiness directive or the change is the terminating action of an airworthiness directive (ref. point [21L.A.4](#_DxCrossRefBm1649097737)), see Note 1; and (vii)    where the design change introduces or affects functions where the failure effect is classified as ‘catastrophic’ or ‘hazardous’. Note 1:        A change previously classified as minor and approved prior to the decision to issue an airworthiness directive needs no reclassification. However, EASA retains the right to review the change and reclassify/reapprove it if found necessary. Note 2:        The conditions listed in points (i) through (vii) above are an explanation of the criteria noted in point [21L.A.63](#_DxCrossRefBm1649097729) as referenced by point [21L.A.103](#_DxCrossRefBm1649097879). For an understanding of how to apply the above conditions, it is useful to take note of the examples given in Appendix A to GM 21L.A.103. (5)     Guidance on the classification of changes to aircraft flight manuals (AFMs) The following changes to the AFM are deemed to be minor: (i)      revisions to the AFM associated with changes to the design that are classified as minor in accordance with point [21L.A.103](#_DxCrossRefBm1649097879); (ii)     revisions to the AFM that are not associated with changes to the design (also identified as stand-alone revisions) which fall into one of the following categories: (A)     changes to limitations or procedures that remain within already declared limits (e.g. weight, structural data, etc.); (B)     consolidation of two or more previously declared and compatible AFMs into one, or the compilation of different parts taken from previously declared and compatible AFMs that are directly applicable to the individual aircraft (customisation); and (C)     the introduction into a given AFM of compatible and previously declared AFM amendments, revisions, appendices or supplements; and (iii)     administrative revisions to the AFM, defined as follows: (A) (a)      editorial revisions or corrections to the AFM; (b)     conversions of previously Federal Aviation Administration (FAA)- or EASA-approved combinations of units of measurement added to the AFM in a previously approved manner; (c)      the addition of aircraft serial numbers to an existing AFM where the aircraft configuration, as related to the AFM, is identical to the configuration of aircraft already covered by that AFM; (d)     the removal of references to aircraft serial numbers no longer applicable to that AFM; and (e)     the translation of an AFM into the official language of the State of design or State of registry. (6)     Guidance on the classification of changes to declared aircraft noise levels (i)      Volume I of ICAO Doc 9501 ‘Environmental Technical Manual’ defines ‘no-acoustical changes’ as changes that would result in very small changes in the declared noise level(s) and provide criteria for their determination. These changes have ‘no appreciable effect’ on the declared noise levels. Consequently, they are classified as minor changes and the declared noise level(s) remain unchanged. (ii)     All other changes to the declared aircraft noise levels are classified as major changes. (iii)     Examples of major changes are provided in [Appendix A to GM1 21L.A.103](#_DxCrossRefBm1649097948). ##### GM1 21L.A.103 Classification of changes to the design of an aircraft for which design compliance has been declared *ED Decision 2023/013/R* Major changes that are classified as being ‘substantial’ should require a new declaration of design compliance to be submitted in accordance with Subpart C of Annex Ib (Part 21 Light). Examples of major changes that are considered substantial may be found in Appendix B to GM1 21L.A.103. (a) PURPOSE OF CLASSIFICATION The purpose of the classification of changes to the design of an aircraft that was subject to a declaration made in accordance with point [21L.A.63](#_DxCrossRefBm485231225) of Subpart C is to allow the declarants to determine the route to be followed for the declaration and whether they need to submit the declaration to EASA (major change) or to maintain it in order to make it available to EASA upon request (minor change). Point [21L.A.63](#_DxCrossRefBm485231225), as referenced by point [21L.A.103](#_DxCrossRefBm485231375)(a), requires that all changes be classified as either ‘major’ or ‘minor’ using the criteria in point [21L.A.63](#_DxCrossRefBm485231225). (b) INTRODUCTION (1) Point [21L.A.63](#_DxCrossRefBm485231225)(b) and (c), as referenced by point [21L.A.103](#_DxCrossRefBm485231375)(a), proposes criteria for the classification of design changes as either ‘minor’ or ‘major’. This GM is intended to provide guidance on the term ‘appreciable effect’ affecting the airworthiness of the product, the declared noise or emissions levels or affecting any of the other characteristics mentioned in point [21L.A.63](#_DxCrossRefBm485231225), where ‘airworthiness’ is interpreted in the context of a product in conformity with the applicable detailed technical specifications and is in condition for safe operation. It provides complementary guidelines to assess a change to the declared aircraft in order to meet the requirements of point [21L.A.103](#_DxCrossRefBm485231375) where classification is the first step of a procedure. Characteristics affecting the environmental compatibility of the product are characteristics affecting the compliance of the product with the applicable environmental protection requirements. *Note*: For classification of repairs, see GM 21L.A.223. Although this GM provides guidance on the classification of major changes, as opposed to minor changes as defined in point [21L.A.103](#_DxCrossRefBm485231375), the GM and point [21L.A.103](#_DxCrossRefBm485231375) are deemed entirely compatible. [Appendix A to GM1 21L.A.103](#_DxCrossRefBm485231444) provides examples of major changes and a classification process. (c) ASSESSMENT OF A CHANGE FOR CLASSIFICATION (1) Changes to the declared design Point [21L.A.103](#_DxCrossRefBm485231375) addresses all changes to any of the aspects of a declaration of design compliance that was submitted under Subpart C. (2) Reserved (3) Classification process (see also the flow chart ‘Classification process’ in Appendix A to GM 21L.A.103) Point [21L.A.103](#_DxCrossRefBm485231375) requires all changes to be classified as either ‘major’ or ‘minor’, using the criteria of point [21L.A.63](#_DxCrossRefBm485231225). Wherever there is doubt as to the classification of a change, EASA should be consulted for clarification. When the strict application of the point (c)(4) criteria results in a major classification, the declarant may request reclassification by EASA. A simple design change planned to be mandated by an airworthiness directive may be reclassified as minor due to the involvement of EASA in the continued airworthiness process when this is agreed between EASA and the declarant. The reasons for a classification decision should be recorded. (4) General guidance on the classification of major changes A change that is judged to have an ‘appreciable effect on the mass, balance, structural strength, reliability, declared noise or emissions levels, operational characteristics, or other characteristics affecting the airworthiness or the environmental compatibility’ is classified as major, in particular, but not only, when one or more of the following conditions are met: (i) where the change requires an adjustment of the detailed technical specifications other than electing to comply with later certification specifications; (ii) where the declarant proposes a new interpretation of the certification specifications used to define the applicable detailed technical specifications; (iii) where the demonstration of compliance uses methods that have not been previously determined as appropriate for the nature of the change; (iv) where the extent of new substantiation data necessary to comply with the applicable detailed technical specifications and the degree to which the original substantiation data has to be reassessed and re-evaluated is considerable; (v) where the change alters the airworthiness limitations or the operating limitations; (vi where the change is made mandatory by an airworthiness directive or the change is the terminating action of an airworthiness directive (ref. point [21L.A.4](#_DxCrossRefBm485231233)), see *Note* 1; and (vii) where the design change introduces or affects functions where the failure effect is classified as ‘catastrophic’ or ‘hazardous’. *Note 1*: A change previously classified as minor and approved prior to the decision to issue an airworthiness directive needs no reclassification. However, EASA retains the right to review the change and reclassify/reapprove it if found necessary. *Note 2*: The conditions listed in points (i) through (vii) above are an explanation of the criteria noted in point [21L.A.63](#_DxCrossRefBm485231225) as referenced by point [21L.A.103](#_DxCrossRefBm485231375). For an understanding of how to apply the above conditions, it is useful to take note of the examples given in Appendix A to GM 21L.A.103. (5) Guidance on the classification of changes to aircraft flight manuals (AFMs) The following changes to the AFM are deemed to be minor: (i) revisions to the AFM associated with changes to the design that are classified as minor in accordance with point [21L.A.103](#_DxCrossRefBm485231375); (ii) revisions to the AFM that are not associated with changes to the design (also identified as stand-alone revisions) which fall into one of the following categories: (A) changes to limitations or procedures that remain within already declared limits (e.g. weight, structural data, etc.); (B) consolidation of two or more previously declared and compatible AFMs into one, or the compilation of different parts taken from previously declared and compatible AFMs that are directly applicable to the individual aircraft (customisation); and (C) the introduction into a given AFM of compatible and previously declared AFM amendments, revisions, appendices or supplements; and (iii) administrative revisions to the AFM, defined as follows: (A) (a) editorial revisions or corrections to the AFM; (b) conversions of previously Federal Aviation Administration (FAA)- or EASA-approved combinations of units of measurement added to the AFM in a previously approved manner; (c) the addition of aircraft serial numbers to an existing AFM where the aircraft configuration, as related to the AFM, is identical to the configuration of aircraft already covered by that AFM; (d) the removal of references to aircraft serial numbers no longer applicable to that AFM; and (e) the translation of an AFM into the official language of the State of design or State of registry. (6) Guidance on the classification of changes to declared aircraft noise levels (i) Volume I of ICAO Doc 9501 ‘Environmental Technical Manual’ defines ‘no-acoustical changes’ as changes that would result in very small changes in the declared noise level(s) and provide criteria for their determination. These changes have ‘no appreciable effect’ on the declared noise levels. Consequently, they are classified as minor changes and the declared noise level(s) remain unchanged. (ii) All other changes to the declared aircraft noise levels are classified as major changes. (iii) Examples of major changes are provided in [Appendix A to GM1 21L.A.103](#_DxCrossRefBm485231444).