Appendix A A-78 Table A-12. Examples of Not Significant Changes for Engines (Part 33) (continued) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes Piston Engines
24. Subsystem change produces no changes in base engine input parameters, and previous analysis can be reliably extended. For example, a change in turbocharger where induction system inlet conditions remain unchanged, or if changed, the effects can be reliably extrapolated.
No No No
25. Change in material of secondary structure or not highly loaded component.
For example, a change from metal to composite material in a non-highly loaded component, such as an oil pan that is not used as a mount pad.
No No No Component level change.
Appendix A A-79 Table A-12. Examples of Not Significant Changes for Engines (Part 33) (continued) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes Piston Engines
26. Change in material that retains the physical properties and mechanics of load transfer. For example, a change in trace elements in a metal casting for ease of pouring or to update to a newer or more readily available alloy with similar mechanical properties.
No No No Component level change.
Appendix A A-80 A.5 Examples of Substantial, Significant, and Not Significant Changes for Propellers (Parts 35).
A.5.1 Table A-13 contains an example of a change that is “substantial” for propellers (part 35).
Table A-13. Example of a Substantial Change for Propellers (Part 35) Example Description of change Notes
1. Change in the number of blades. Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
A.5.2 Table A-14 contains examples of changes that are “significant” for propellers (part 35).
Table A-14. Examples of Significant Changes for Propellers (Part 35) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes
1. Principle of pitch change such as a change from single acting to dual acting.
Yes Yes Yes Requires extensive modification of the pitch change system with the introduction of back-up systems.
The inherent control system requires re-evaluation.
Appendix A A-81 Table A-14. Examples of Significant Changes for Propellers (Part 35) (continued) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes
2. Introduction of a different principle of blade retention such as a single row to a dual row bearing.
Yes Yes No Requires extensive modification of the propeller hub and blade structure.
The inherent strength requires re-evaluation.
3. A hub configuration change such as a split hub to a one-piece hub.
Yes Yes No Requires extensive modification of the propeller hub structure.
The inherent strength requires re-evaluation.
4. Changing the method of mounting the propeller to the engine such as a spline to a flange mount.
Yes Yes No Requires extensive modification of the propeller hub structure.
The inherent strength requires re-evaluation.
Appendix A A-82 Table A-14. Examples of Significant Changes for Propellers (Part 35) (continued) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes
5. Change in hub material from steel to aluminum.
Yes Yes No Requires extensive modification of the propeller hub structure and change to method of blade retention.
The inherent strength requires re-evaluation.
6. Change in blade material from metal to composite.
Yes Yes Yes Requires extensive modification of the propeller blade structure and change to method of blade retention.
Composite construction methods required.
The inherent strength requires re-evaluation.
Appendix A A-83 Table A-14. Examples of Significant Changes for Propellers (Part 35) (continued) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes
7. Change from hydro-mechanical to electronic control.
Yes Yes Yes Electronic manufacturing and design methods required.
Assumptions used for certification are no longer valid or not addressed in the original certification, i.e., HIRF and lightning protection, fault tolerance, software certification, and other aspects.
Appendix A A-84 A.5.3 Table A-15 contains examples of changes that are “not significant” for propellers (part 35).
Table A-15. Examples of Not Significant Changes for Propellers (Part 35) Example Description of change Is there a change to the general configuration?
§ 21.101(b)(1)(i) Is there a change to the principles of construction?
§ 21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
§ 21.101(b)(1)(ii) Notes
1. Change in the material of a blade bearing.
No No No Component level change.
2. Change to a component in the control system.
No No No Component level change.
3. Change to a propeller de-icer boot.
No No No Component level change.
4. Changes to the operational design envelope such as increase in power.
No No No Propeller’s operating characteristics and inherent strength require re-evaluation.
5. Change to the intended usage such as normal to acrobatic category.
No No No Propeller’s operating characteristics and inherent strength require re-evaluation.
Appendix B B-1 APPENDIX B. APPLICATION CHARTS FOR CHANGED PRODUCT RULE Table B-1. Application Chart for § 21.101(a) and (b) and § 21.19 Substantial (§ 21.19) (§ Significant
21.101(a) and (b)) Not Significant (§ 21.101)(b)(1)) Substantially changed product Compliance to all latest regulatory standards required for product certification.
Previously approved type design and compliance data may be allowed if valid for the changed product.
Affected area (Changed and/or affected areas) New showing of compliance is required Unaffected area No new showing of compliance is required.
Unaffected area continues to comply with the existing certification basis.
Affected area (Changed and/or affected areas) New showing of compliance is required.
The applicant may propose a certification basis using an earlier amendment but not earlier than in the existing TC basis.
Unaffected area No new showing of compliance is required.
Unaffected area continues to comply with the existing certification basis.
Compliance with the latest amendment materially contributes to safety No material contribution to safety Practical Impractical The applicant may propose a certification basis using earlier regulatory requirement(s), but not earlier than the existing TC basis.
The applicant may propose a certification basis using earlier regulatory requirement(s), but not earlier than the existing TC basis.
Certification Basis Proposed by Applicant New certification basis using standards.
latest regulatory Latest regulatory standards, with earlier amendments with supporting rationale.
Existing certification basis.
Existing certification basis including elect to comply.
Existing certification basis.
FAA Resultant Type Certification Basis New certification basis using the latest New certification basis using the latest Existing certification Existing certification Existing certification regulatory standards, and special conditions if regulatory standards with earlier approved basis. basis (if adequate); if basis.
required. amendments, and special conditions if required. not, first appropriate later amendment(s) and/or special condition including elect to comply.
Appendix B B-2 Table B-2. Application Chart for § 21.101(c) Excepted Products Affected Area (Changed areas and/or unchanged New showing of compliance is but affected) required.
Unaffected Area No new showing of compliance is required.
Unaffected area continues to be compliant with the existing TC basis.
Type Certification Basis Proposed by Applicant The existing TC basis, including “elects to comply.” The existing TC basis.
Found by the FAA to be “significant in an area.” Not significant in an area.
Compliance with a later amendment materially contributes to safety. No material contribution safety.
to Practical Impractical FAA Resultant Type Certification Basis The latest amendment designated by the FAA including special conditions and including elect to comply.
The existing TC basis. If inadequate, the first special conditions, appropriate later amendment.
including elect to comply.
If not appropriate, add The existing TC basis.
Appendix C C-1 APPENDIX C. A METHOD TO DETERMINE THE CHANGED AND AFFECTED AREAS C.1 Overview.
C.1.1 When you make a change to a product, some areas you change physically, while others you change functionally. The FAA refers to this combination as changed and affected areas. For example, if you extend the wing of a fixed wing aircraft, you 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., carry greater load, but it would not change physically. These areas have associated airworthiness requirements, which become part of the certification basis for the change.
C.1.2 Figure C-1 below provides an overview of one method you can use to determine the changed and affected areas and the applicable airworthiness requirements.
Figure C-1. Method to Determine the Changed and Affected Areas
Appendix C C-2 C.2 Physical Changes.
C.2.1 Steps.
• Step 1. Make a list of the physical changes.
• Step 2. List the corresponding airworthiness requirements 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, you modify an electrically driven slat actuator 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. You would list airworthiness requirements applicable to the actuator. You would not list the airworthiness requirements 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 airworthiness requirements.
Table C-1. Example of Associating a Physical Change with the Applicable Airworthiness Requirements Physical Change Applicable Regulations* Amendment of Existing Certification Basis Amendment on Application Date Structural change to slat actuator § 25.xxx 25-aaa 25-ddd § 25.yyy 25-bbb 25-eee § 25.zzz 25-ccc 25-fff * These would be airworthiness requirements 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, system, component, and appliance that are affected by that effect.
Appendix C C-3
• Step 4. List the airworthiness requirements associated with the effect for each area, system, component, 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 airworthiness requirements (steps 4 and 5 above).
Table C-2. Example of a Functional Change, Affected Areas, and Associated Effects Description of Change Effects Affected Areas Installation of winglet Increased loads in wing structure Wing spars Wing skins Effect 2* Area 1 Area 2 Effect 3* Area 3 * There may be other effects as well.