21L.A.227 Compliance activities for declaring compliance of a major repair design

VOLUNTARY INVOLVEMENT OF EASA PRIOR TO THE SUBMISSION OF DECLARATION The declarant may choose to involve EASA prior to submitting the declaration of design compliance for a major repair design. This would allow EASA to:

(a)check the scope of the product is still within the scope of Subpart C;

(b)provide guidance on the completeness of the compliance-demonstration plan and the selection of means of compliance;

(c)advise on the selection of the applicable detailed technical specifications and applicable noise requirements;

(d)provide guidance about noise tests (if applicable) and witness them;

(e)avoid any issues or delays during the first-article inspection (after submission of the declaration of design compliance and if considered necessary under point 21L.B.221(b)). The initiation of the project may occur before starting the compliance activities or during those activities. The assignment of a dedicated project number would facilitate any subsequent communication with EASA. This will facilitate the provision of compliance documentation required by point 21L.A.226(d) which may be provided by the declarant to EASA at key stages in the compliance demonstration prior to the submission of the declaration of design compliance for the major repair design.

COMPLIANCE-DEMONSTRATION PLAN FOR A MAJOR REPAIR The compliance-demonstration plan for a major repair is a document that allows the declarant to manage and control the design of the major repair, as well as the process of compliance demonstration, and that enables EASA to investigate the root cause(s) in the event of a safety issue being discovered. The description of the repair should include an explanation of the purpose of the repair, the pre-repair and post-repair configuration(s) of the aircraft, schematics/pictures, and any other detailed features and boundaries of the physical change (this may be supplemented by drawings or outlines of the design, if this helps to understand the design change), as well as the identification of the areas of the aircraft that are affected by the repair, and the identification of any changes to the approved manuals. The items of the declaration of aircraft design compliance made in accordance with Subpart C that are affected by the repair and for which a new demonstration of compliance is necessary should be identified together with the means (e.g. calculation, test or analysis) by which it is proposed to demonstrate compliance. The compliance demonstration should include the analysis for the classification of the change in accordance with GM1 21L.A.223. In particular, the following information should typically be expected: identification of the relevant personnel that make decisions affecting airworthiness and environmental compatibility, and that will interface with EASA during any physical inspection and assessment of the repaired aircraft if required under point 21L.B.221(b); subcontracting arrangements for design, environmental compatibility and/or production (if applicable). Point 21L.A.226(d)(1) ‘Description of the major repair’ An overview of the nature and type of repair that is required should be provided that describes the changes to the previously declared design. Point 21L.A.226(d)(2) ‘Operating characteristics, design features and limitations’ The declarant should consider whether there are any affects to the operating characteristics and limitations as a result of the repair, including: operating speed limitations; service ceiling, maximum airfield elevation; cabin pressure; limit load factors; number of passengers, minimum crew, payload, range; weight and centre-of-gravity (CG) envelope and fuel loading; performance; environmental envelope; runway surface conditions; other items, if considered to be more appropriate, which address the specific aeronautical product. The declarant should provide detailed information about the means of compliance with the applicable requirements identified under point 21L.A.226(a). This should include the following: a compliance checklist addressing each requirement, the proposed means of compliance (see Appendix A to AMC1 21L.A.227(a) below for the relevant codes), and the related compliance document(s); identification of industry standards, methodology documents, handbooks and any other acceptable means of compliance, specified in the airworthiness or noise data sheet, which have been followed in the demonstration of compliance; when the compliance demonstration involves testing, a description of the ground- and flight-test article(s), test method(s), test location(s), test schedule, test house(s), test conditions (e.g. limit load, ultimate load), as well as of the intent/objective(s) of the testing; and when the compliance demonstration involves analyses/calculations, a description/ identification of the tools (e.g. name and version/release of the software programs) and methods used, the associated assumptions, limitations and/or conditions, as well as of the intended use and purpose. For every aspect mentioned above, the declarant should clearly identify whether the demonstration of compliance involves different means than those contained in the published AMC to the relevant CSs and any method (analysis or test) which is novel or unusual for the declarant. For every aspect related to compliance with the applicable environmental protection requirements mentioned above, the declarant should clearly identify whether the demonstration of compliance involves means that are described in ICAO Doc 9501 ‘Environmental Technical Manual’.

COMPLIANCE DOCUMENTATION

(a)Compliance documentation comprises one or more test or inspection programmes/plans, reports, drawings, design data, specifications, calculations, analyses, etc., and provides a record of the means by which compliance with the applicable detailed technical specifications and environmental protection requirements has been demonstrated.

(b)Each compliance document should typically contain: the reference of the detailed technical specifications or environmental protection requirements addressed by the document; substantiation data demonstrating compliance (except test or inspection programmes/plans); a statement by the declarant declaring that the document provides the proof of compliance for which it has been created; and the declarant’s signature.

(c)Each compliance document should be unequivocally identified by its reference and issue date. The various issues of a document should be controlled and comply with point 21L.A.7.

INSPECTIONS AND TESTS In accordance with point 21L.A.227(d), the declarant must address the conformity of the test specimen, as well as of the test and measuring equipment. Conformity of the test specimen The recorded justification of the conformity of the test articles is intended to ensure that the manufactured test specimen adequately represents the declared applicable design data. Possible types of non-conformity may be the following: Non-conformity between the design of the test specimen and the originally intended design data at the time of the test. These are typically identified in the early stage of the test planning, and should be addressed as early as possible (e.g. in the test plan). There may be several reasons for such a non-conformity: to account for interfaces with the test equipment, to conservatively cover several or future design configurations, etc. Non-conformity between the manufactured test specimen and the design of the test specimen. Such a non-conformity may be the result of the manufacturing of the test specimen. While it is convenient to define any possible non-conformity as early as possible, the declarant does not need to make the distinction between the two types of non-conformity above as long as they are explicitly addressed and justified by cross reference to the test plan or other documents. However, testing for the demonstration compliance with the applicable environmental protection requirements may be conducted in the final design of the product having incorporated the repair design. Compliance demonstration is typically an iterative process in which the design is under continuous evolution. If the aircraft design evolves after the time of the inspection or test, then the final major change design should be checked against the originally intended design (as it was at the time of the inspection or test), and the differences (if any) should be analysed to ensure that the inspection or test results are representative of the final configuration. However, such changes made to the design may lead to the invalidation of the inspection or test results and the need to repeat the inspection or test. It is recommended that the declarant should have a thorough configuration management process to track the evolving design of the major repair. Conformity of the test and measuring equipment: the configuration of the test and measuring equipment should be defined in the test plan and include the following: definition/design of the test equipment (relevant tools, mechanical parts, electronic components used to execute the test); and definition of the measuring equipment: type/model of sensors, together with their technical characteristics; position and orientation of exciters and sensors; and electronic measuring equipment (in some cases, this may also include the acquisition and post-processing of data). The configuration of the test and measuring equipment should be defined and controlled through test plans and supporting documentation. The test plan should also include the following elements: the test cases, methods, and procedures for test execution; the pass–fail criteria; and pre-, during- and post-test inspections. The declarant should confirm that the test and measuring equipment conform to its definition in the test plan, and that the sensors and measuring system are appropriately calibrated. Any non-conformity should be assessed, and it should be justified that it will not compromise the test purpose and results. This may be done either in the recorded justification of the conformity of the test articles and equipment or by cross reference to other documents (test minutes of meetings, test notes, etc.). Use of the term ‘adequate’: the test and measuring equipment is considered ‘adequate’ as long as the test execution on the manufactured test specimen (including any non-conformity) and the use of the installed test set-up do not compromise the test purpose and results (for example, by providing better performance than the proposed type design, or by masking any potential failure mode or behaviour). Changes that affect the validity of the recorded justification of the conformity of the test articles and equipment: if changes need to be introduced to the test specimen or to the test and measurement equipment after the justification has been recorded (and before the test is undertaken), then it must be updated. Development versus compliance demonstration tests: sometimes, tests of specimens that conform to a preliminary design, but are not intended for demonstration of compliance (known as development tests), are performed as part of a risk control strategy and to develop knowledge of a subject. Problems and failures found during development are part of the process of increasing the understanding of the design, including its failure modes and the potential for optimisation. Such development tests do not need to meet the requirements of point 21L.A.227(d) and (e). Any planned test event should be classified in advance as either a development test or a compliance demonstration test. It is acceptable for a development test to finally form part of the compliance demonstration, and it may be declared afterwards to be a compliance demonstration test as long as it meets the requirements of point 21L.A.227(d) and (e). For this reason, it is important to keep the configuration of such tests under control. If the test specimen used for a compliance-demonstration test has already undergone a series of previous tests that may affect or ultimately invalidate its validity due to potential non-conformity to point 21L.A.227(d) as required by point 21L.A.226(d)(6), this aspect should be considered when justifying the conformity, and specific analyses or inspections may be required to support such a statement. Because of the above aspects, declarants may wish to inform EASA if they intend to conduct a campaign of development tests that may eventually be used as demonstration-of-compliance tests to establish whether EASA would wish to witness the tests.

PHYSICAL INSPECTION OF THE FIRST ARTICLE The declarant should be prepared for any additional investigations as notified by EASA according to point 21L.B.222(b). Refer to AMC 21L.A.47(a) for an explanation of the activities performed under the first-article inspection.

TESTS AND INSPECTIONS PERFORMED BY THE AGENCY The declarant should inform EASA sufficiently in advance about the execution of significant inspections and tests that are used for compliance-demonstration purposes in order to permit EASA the opportunity to perform or witness these inspections or tests in advance of any physical inspection and assessment of the repaired aircraft if required by point 21L.B.221(b). This would be advantageous for the declarant to avoid any issues or delays if a physical inspection and assessment of the repaired product is required. Additionally, the declarant may propose to EASA to perform or witness flight or other tests of particular aspects of the product during its development and before the design of the major repair is fully defined. However, before EASA performs or witnesses any flight test, the declarant should perform these tests and should ensure that no features of the product preclude the safe conduct of the evaluation requested. A recorded justification of the conformity of the test articles and equipment as per point 21L.A.226(d)(6) is required for the above tests.