U.S. Department Advisory of Transportation Circular Federal Aviation Administration Subject: Establishing the Certification Basis of Date: March 11, 2016 AC No: 21.101-1B Changed Aeronautical Products Initiated By: AIR-100 This advisory circular (AC) provides guidance for the application of theiChanged Product Rule (CPR)," pursuant to Title 14 of the Code of Federal Regulations (14 CFR) 21.101, Designation of applicable regulations, and 21.19, Changes requiring a new type certificate, for changes made to type certificated aeronautical products.
If you have suggestions for improving this AC, you may use the feedback form at the end of this Susan AM Cabler Susan J. M. Cabler Acting Manager, Design, Manufacturing & Airworthiness Division Aircraft Certification Service
CONTENTS Paragraph Page ii
Chapter 1. Introduction1-1
1.1 Purpose1-1
1.2 Applicability1-1
1.3 Cancellation1-1
1.4 AC Content1-1
1.5 Terms Used in this AC1-3
Chapter 2. Overview of §§ 21.19 and 21.1012-1
2.1 Section 21.192-1
2.2 Section 21.1012-1
Chapter 3. Process for Establishing the Certification Basis for Changed Products3-1
3.1 Overview3-1
3.2 Step 1. Identify the Proposed Type Design Changes to an Aeronautical Product3-3
3.3 Step 2. Verify the Proposed Type Design Change is Not Substantial3-4
3.4 Step 3. Will you Use the Latest Standards?3-4
3.5 Step 4. Arrange Changes into Related and Unrelated Groups3-5
3.6 Step 5. Is Each Related or Unrelated Group a Significant Change?3-6
3.7 Proposing an Amendment Level for a Significant Change3-9
3.8 Proposing an Amendment Level for a Not Significant Change3-9
3.9 Step 6. Prepare your Proposed Certification Basis List3-9
3.10 Step 7. Do the Latest Requirements Contribute Materially to the Level of Safety and are
They Practical?3-11
3.11 Step 8. Ensure Proposed Certification Basis is Adequate3-17
Chapter 4. Excepted Products under § 21.101(c)4-1
4.1 Excepted Products4-1
Chapter 5. Other Considerations5-1
5.1 Design-Related Operating Requirements5-1
5.2 FAA Policy5-1
5.3 A Baseline Product Consists of One Unique Type Design Configuration5-1
5.4 Predecessor Regulations5-2
CONTENTS (CONTINUED) Paragraph Page iii
5.5 Special Conditions, § 21.101(d)5-2
5.6 Effective Period for an Application to Change a Type Certificate, § 21.101(e)5-2
5.7 Other Category Aircraft, § 21.101(f)5-3
5.8 Clarification of § 21.101(g), Part 26 Requirements5-5
5.9 Documentation5-5
5.10 Incorporation of STCs into the Type Design5-6
5.11 Removing Design Changes5-6
5.12 The Certification Basis is Part of the Design Change5-7
5.13 Sequential Design Changes—Cumulative Effects5-7
Appendix A. Classification of Design ChangesA-1
Appendix B. Application Charts for Changed Product RuleB-1
Appendix C. A Method to Determine the Changed and Affected AreasC-1
Appendix D. Other Guidance for Affected AreasD-1
Appendix E. Procedure for Evaluating Material Contribution to Safety or Impracticality of
Applying Latest Requirements to a Changed ProductE-1
Appendix F. The Use of Service Experience in the Exception ProcessF-1
Appendix G. Changed Product Rule Decision RecordG-1
Appendix H. Examples of Documenting the Proposed Certification Basis ListH-1
Appendix I. Related DocumentsI-1
Appendix J. Definitions and TerminologyJ-1
CONTENTS (CONTINUED) iv
FIGURES Number Page Figure 3-1. Developing a Proposed Certification Basis for a Changed Product Pursuant to
§ 21.1013-2
Figure 3-2. Related and Unrelated Changes for Example of Increasing the Maximum Number of
Passengers3-6
Figure 3-3. Affected Areas versus Not Affected Areas3-10
Figure 3-4. Design Change Affected Areas with Secondary Changes3-14
Figure C-1. Method to Determine the Changed and Affected AreasC-1
Figure E-1. Safety Benefits versus ResourcesE-2
TABLES Number Page
Table A-1. Examples of Substantial Changes for Small Airplanes (Part 23)A-1
Table A-2. Examples of Significant Changes for Small Airplanes (Part 23)A-3
Table A-3. Examples of Not Significant Changes for Small Airplanes (Part 23)A-14
Table A-4. Examples of Substantial Changes for Transport Airplanes (Part 25)A-25
Table A-5. Examples of Significant Changes for Transport Airplanes (Part 25)A-26
Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25)A-38
Table A-7. Examples of Substantial Changes for Rotorcraft (Parts 27 and 29)A-49
Table A-8. Examples of Significant Changes for Rotorcraft (Parts 27 and 29)A-50
Table A-9. Examples of Not Significant Changes for Rotorcraft (Parts 27 and 29)A-56
Table A-10. Examples of Substantial Changes for Engines (Part 33)A-64
Table A-11. Examples of Significant Changes for Engines (Part 33)A-65
Table A-12. Examples of Not Significant Changes for Engines (Part 33)A-72
Table A-13. Example of a Substantial Change for Propellers (Part 35)A-80
Table A-14. Examples of Significant Changes for Propellers (Part 35)A-80
Table A-15. Examples of Not Significant Changes for Propellers (Part 35)A-84
Table B-1. Application Chart for § 21.101(a) and (b) and § 21.19B-1
Table B-2. Application Chart for § 21.101(c) Excepted ProductsB-2
CONTENTS (CONTINUED)
TABLES (CONTINUED) Number Page v Table C-1. Example of Associating a Physical Change with the Applicable
Airworthiness RequirementsC-2
Table C-2. Example of a Functional Change, Affected Areas, and Associated EffectsC-3
Table C-3. Example of Associating Affected Areas with the Applicable
Airworthiness RequirementsC-4
Table C-4. Example of a Combined List of Physical and Functional Changes with Applicable
Airworthiness RequirementsC-5
Table H-1. Tabular Form for Documenting a Proposed Certification BasisH-2
1-1 CHAPTER 1. INTRODUCTION
1.1 Purpose.
T his AC provides guidance for establishing the certification basis for changed aeronautical products pursuant to Title 14 of the Code of Federal Regulations (14 CFR)
21.101, Designation of the applicable regulations. The guidance is intended to help applicants and delegated organizations determine if it will be necessary to apply for a new type certificate (TC) under § 21.19, Changes requiring a new type certificate. The guidance describes the process for establishing the certification basis for an amended TC, supplemental type certificate (STC), and amended STC, detailing the requirements (evaluations, classifications, and decisions) throughout the process.
1.2 Applicability.
1.2.1 This AC is for applicants and holders of delegated organizations applying for amended TCs, STCs, or amended STCs.
1.2.2 This AC applies to major type design changes under § 21.101 for aeronautical products certificated under 14 CFR parts 21, 23, 25, 27, 29, 31, 33, and 35. References to “design change” include the design change and areas affected by the design change pursuant to § 21.101.
1.2.3 Minor type design changes are automatically considered not significant under the “does not contribute materially to the level of safety” provision of § 21.101(b).
1.2.4 This AC also applies to aircraft certificated under §§ 21.17(b), 21.19, 21.24, 21.25, and
21.27.
1.2.5 The term aeronautical product, or product, means a type certificated aircraft, aircraft engine, or propeller.
1.2.6 This AC is not intended to be used to determine the applicable aircraft noise, fuel venting, and exhaust emission requirements for changed products.
1.2.7 This AC is not mandatory and is not a regulation. This AC describes an acceptable means, but not the only means, to comply with § 21.101. However, if you use the means described in this AC, you must follow it entirely.
1.3 Cancellation.
This AC cancels AC 21.101-1A, dated September 3, 2010.
1.4 AC Content.
This AC contains 5 chapters and 10 appendices.
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1.4.1 This chapter clarifies the purpose of this AC, describes its content, specifies the intended audience affected by this AC, clarifies which changes are within the scope of this AC, and references the definitions and terminology used in this AC.
1.4.2 Chapter 2 provides a general overview of §§ 21.101 and 21.19, clarifies the main principles and safety objectives, and directs applicants to the applicable guidance contained in subsequent chapters of this AC.
1.4.3 Chapter 3 contains guidance for implementation of § 21.101(b) to establish the type certification basis for changed aeronautical products. It describes in detail the various steps for developing the certification basis, a process that applies to all major design changes to aeronautical products. Chapter 3 also addresses § 21.19 considerations for identifying conditions under which an applicant for a type design change is required to submit an application for a new TC and provides guidance at which stage of the process this assessment is performed.
1.4.4 Chapter 4 provides guidance about products excepted from the requirement of § 21.101.
1.4.5 Chapter 5 contains considerations for—
• Design-related operating requirements,
• Determining which policy to apply to a design change,
• Defining a baseline product,
• Predecessor regulations,
• Using special conditions under § 21.101(d),
• The effective period of application for a change to a TC under § 21.101(e),
• Other category aircraft under § 21.101(f),
• Clarification of § 21.101(g) regarding 14 CFR part 26 requirements,
• Documenting revisions to the TC basis,
• Incorporating STCs into the type design,
• Removing design changes,
• Determining a certification basis after removing an approved design change, and
• Sequential design changes.
1.4.6 Appendix A contains examples of typical type design changes for small airplanes, transport airplanes, rotorcraft, engines, and propellers. The Federal Aviation Administration (FAA) has categorized these examples into individual tables according to the classifications of design change—“substantial,” “significant,” and “not significant.”
1.4.7 Appendix B contains application charts for applying the § 21.101 process, including the excepted process.
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1.4.8 Appendix C contains one method for determining the changed and affected areas of a product.
1.4.9 Appendix D contains additional guidance on affected areas not discussed in other parts of this AC.
1.4.10 Appendix E provides detailed guidance with examples for evaluating the “impracticality” exception in the rule.
1.4.11 Appendix F provides guidance with examples on the use of relevant service experience in the certification process as one way to show that a later amendment may not contribute materially to the level of safety, allowing the use of earlier requirements.
1.4.12 Appendix G provides an example CPR decision record.
1.4.13 Appendix H provides examples of documenting a proposed certification basis list.
1.4.14 Appendix I lists the FAA regulations and orders related to this AC.
1.4.15 Appendix J lists the definitions and terminology applicable for application of the rule.
1.5 Terms Used in this AC.
1.5.1 The following terms are used interchangeably and have the same meaning:
requirements, regulations, standards, and airworthiness standards.
1.5.2 The terms certification basis, type certification basis, and amendment are used interchangeably to refer to the groups of requirements defined above.
2-1 CHAPTER 2. OVERVIEW OF §§ 21.19 AND 21.101
2.1 Section 21.19.
2.1.1 Section 21.19 requires an applicant to apply for a new TC for a changed product if the FAA finds that the change in design, power, thrust, or weight is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
2.1.2 Changes that require a substantial re-evaluation of the product’s compliance findings are referred to as “substantial changes.” For guidance, see paragraph 3.3 in chapter 3 of this AC. Appendix A of this AC provides examples of type design changes that will require a new TC.
2.1.3 If the FAA determines through § 21.19 that your proposed design change does not require a new TC, see § 21.101 for the applicable requirements to develop the certification basis for your proposed design change. For guidance, see chapter 3 and the examples in appendix A of this AC.
2.2 Section 21.101.
2.2.1 Section 21.101(a).
Section 21.101(a) requires a change to a TC and the area affected by the change to comply with the latest requirements, unless the change meets the criteria for the exceptions identified in § 21.101(b) or (c). The intent of § 21.101 is to enhance safety by incorporating the latest requirements into the type certification basis for the changed product to the greatest extent practicable.
2.2.2 Section 21.101(b).
2.2.2.1 Section 21.101(b) pertains to when an applicant may show that a changed product complies with an earlier amendment of a regulation, provided that the earlier amendment is considered adequate and meets the criteria in § 21.101(b)(1), (2), or (3). When design changes involve features or characteristics that are novel and unusual as compared to the airworthiness standard at the proposed amendment, more recent airworthiness standards and/or special conditions will be applied for these features.
2.2.2.2 You can comply with the earlier requirements consistent with § 21.101(b), when—
2.2.2.2.1 A change is not significant (see § 21.101(b)(1));
2.2.2.2.2 An area, system, component, equipment, or appliance is not affected by the change (see § 21.101(b)(2));
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2.2.2.2.3 Compliance with a later amendment for a significant change does not contribute materially to the level of safety (see § 21.101(b)(3)); or
2.2.2.2.4 Compliance with the latest amendment would be impractical (see § 21.101(b)(3)).
2.2.2.3 Earlier amendments may not precede the regulatory amendment level of the identified baseline product’s type certification basis and any requirement found in 14 CFR 23.2, 25.2, 27.2, and 29.2 or the applicable provision of part 26 related to the change.
2.2.2.4 Section 21.101(b)(1)(i) and (ii) pertain to design changes that meet the automatic criteria where the change is significant.
2.2.3 Section 21.101(c).
Section 21.101(c) provides an exception from the requirements of § 21.101(a) for a change to certain aircraft with less than the specified maximum weight. If you apply for a type design change to an aircraft (other than rotorcraft) of 6,000 pounds or less maximum weight, or to a non-turbine powered rotorcraft of 3,000 pounds or less maximum weight, you can show that the changed product complies with the regulations incorporated by reference in the type certificate. You can also elect to comply or may be required to comply with the later regulations. See paragraph 4.1 of this AC for specific guidance on this provision.
2.2.4 Section 21.101(d).
Section 21.101(d) provides for the use of special conditions, under § 21.16, when the proposed certification basis and any later regulations do not provide adequate standards to the proposed change because of a novel or unusual design feature.
2.2.5 Section 21.101(e).
Section 21.101(e) prescribes the effective period that an application will remain valid for a change.
2.2.6 Section 21.101(f).
Section 21.101(f) pertains to aircraft certificated in certain categories and special classes
(e.g., gliders, airships, other nonconventional aircraft, and balloons certificated under 14 CFR part 31), including the engines and propellers installed on them, under the requirements of §§ 21.17(b), 21.24, 21.25, and 21.27 airworthiness requirements.
2.2.7 Section 21.101(g).
Section 21.101(g) pertains to regulatory compliance of transport category airplanes with the applicable provisions of part 26 and/or corresponding later amendments to part 25.
See paragraph 5.8 of this AC for additional details.
3-1 CHAPTER 3. PROCESS FOR ESTABLISHING THE CERTIFICATION BASIS FOR
CHANGED PRODUCTS
3.1 Overview.
3.1.1 The applicant and the FAA each have a responsibility under § 21.101(a) and (b). As an applicant for the certification of a type design change, you must show that the change and areas affected by the change comply with the latest applicable airworthiness requirements unless you propose exception(s) under § 21.101(b). If you are proposing exception(s), you should make a preliminary classification whether the change is “significant” or “not significant,” and propose an appropriate certification basis. The FAA is responsible for determining whether your classification of the change, and proposal for the certification basis, are consistent with the applicable rules and their interpretation. The FAA determination does not depend on whether the TC holder or applicant for an STC is originating the change. The certification basis can vary depending on the magnitude and scope of the change. The steps below present a streamlined approach for making this determination.
3.1.2 The tables in appendix A of this AC are examples of classifications of typical type design changes. See paragraph 3.6.3 of this chapter for instructions on how to use those tables.
3.1.3 If your proposed change is not in the examples provided in appendix A, you may use the following steps in conjunction with the flowchart in figure 3-1 of this AC to develop the appropriate certification basis for the type design change. For clarification, the design change discussed in the flowchart also includes areas affected by the design change pursuant to § 21.101. See paragraph 3.9.1 of this AC for guidance about affected areas.
Figure 3-1. Developing a Proposed Certification Basis for a Changed Product Pursuant to § 21.101 Step 1: Identify the Proposed Type Design Changes to an Aeronautical Product.
Step 2: Verify the Proposed Type Design Change is Not Substantial. See Note 1.
Step 3:
Will you Use the YES Latest Standards?
§ 21.101(a) NO Step 4: Arrange Changes into Related and Unrelated Groups.
Step 5:
Not Significant NO Is Each Related or Unrelated Group a Significant Change?
§ 21.101(b)(1) YES Step 6: Prepare your Proposed Certification Basis List. See Note 2.
Not Affected Areas Affected Areas § 21.101(b)(2) Step 7:
Do the Latest Requirements Contribute Materially to YES Existing Requirements the Level of Safety and are they Practical?
§ 21.101(b)(3) See Note 2/ NO Earlier Requirements Latest Requirements Step 8: Ensure Proposed Certification Basis is Adequate.
Submit Proposed Certification Basis to the FAA Notes:
1. Changed products that are substantially changed do not follow this flowchart. Refer to § 21.19.
2. Process and propose each applicable requirement individually. If requirements are linked together, then they should be assessed together.
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