Appendix A A-42 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
10. New cabin interior with no fuselage length change.
No No No A new cabin interior includes new ceiling and sidewall panels, stowage, galleys, lavatories, and seats.
Novel or unusual design features in the cabin interior may require special conditions.
Many interior related requirements are incorporated in operational rules. Even though the design approval holder may not be required to comply with these requirements, the operator may be required to comply.
11. A rearrangement of an interior (e.g., seats, galleys, lavatories, closets, etc.).
No No No
Appendix A A-43 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
12. Novel or unusual method of construction of a component.
No No No The component change does not rise to the product level.
Special conditions could be required if there are no existing regulations that adequately address these features.
13. Initial installation of a non-essential APU.
No No No A stand-alone initial APU installation on an airplane originally designed to use ground- or airport-supplied electricity and air conditioning. In this case, the APU would be an option to be independent of airport power.
Appendix A A-44 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
14. Increasing the life limit as § 25.571 fatigue testing progresses for a recently type certificated airplane.
No No No For example, a recently type certificated airplane may undergo fatigue testing as part of compliance with § 25.571.
In this case, the TC holder may specify an initial life limit in the airworthiness limitations section (ALS) and gradually increase that life limit as fatigue testing progresses. Such change to the ALS is considered not significant.
Appendix A A-45 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
15. Extending limit of validity (LOV) pursuant to § 26.23.
No No No Extending an LOV pursuant to § 26.23 without any other change to the airplane is not a significant change. However, if extending the LOV requires a physical design change to the airplane, the design change is evaluated to determine the level of significance of the design change. Note that if design approval holders are developing modifications to support an extended LOV, they must also comply with the requirements of subpart E of part 26.
Appendix A A-46 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
16. Airframe life extension. No No No This does not include changes that involve changes to design loads, such as pressurization or weight increases. Also, this does not include changing from safe life to damage tolerance.
17. Changes in the type or number of emergency exits by de-rating doors or deactivating doors with corresponding reduction in passenger capacity.
No No No The new emergency egress does not exceed that previously substantiated because the certificated number of passengers is reduced.
Appendix A A-47 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
18. Request for ETOPS type design approval for a type design change of a product with an existing ETOPS type design approval.
No No No A change to a product with an existing ETOPS type design approval without a change in diversion capability would normally not be significant.
However, if the existing ETOPS type design approval was based on policy prior to the adoption of transport category ETOPS airworthiness standards, then there is not an adequate certification basis to evaluate the type design change for ETOPS. In this case, the change is still not significant, and the appropriate transport category ETOPS airworthiness standards would apply.
Appendix A A-48 Table A-6. Examples of Not Significant Changes for Transport Airplanes (Part 25) (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
19. An avionics change from federated electro-mechanical displays to federated electronic displays.
No No No Changing an electro-mechanical display to an electronic display is not considered significant.
20. An avionics change replacing an integrated avionics system with another integrated avionics system.
No No No The assumptions used to certify a highly integrated avionics system should be the same for another highly integrated avionics system.
Appendix A A-49 A.3 Examples of Substantial, Significant, and Not Significant Changes for Rotorcraft (Parts 27 and 29).
A.3.1 Table A-7 contains examples of changes that are “substantial” for rotorcraft (parts 27 and 29).
Table A-7. Examples of Substantial Changes for Rotorcraft (Parts 27 and 29) Example Description of change Notes
1. Change from the number and or configuration of rotors
(e.g., main & tail rotor system to two main rotors).
Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
2. Change from an all-metal rotorcraft to all-composite rotorcraft.
Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
Appendix A A-50 A.3.2 Table A-8 contains examples of changes that are “significant” for rotorcraft (parts 27 and 29).
Table A-8. Examples of Significant Changes for Rotorcraft (Parts 27 and 29) 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. Comprehensive flightdeck upgrade, such as conversion from entirely federated, independent electro-mechanical flight instruments to highly integrated and combined electronic display systems with extensive use of software and/or complex electronic hardware.
No No Yes Affects avionics and electrical systems integration and architecture concepts and philosophies.
This drives a reassessment of the human-machine interface, flightcrew workload, and re-evaluation of the original design flightdeck assumptions
2. Certification for flight into known icing conditions.
No No Yes
3. (Fixed) flying controls from mechanical to fly by wire.
No No Yes This drives a complete reassessment of the rotorcraft controllability and flight control failure.
Appendix A A-51 Table A-8. Examples of Significant Changes for Rotorcraft (Parts 27 and 29) (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
4. Addition of an engine;
e.g., from single to twin or reduction of the number of engines; e.g., from twin to single.
Yes Yes Yes
5. A change of the rotor drive primary gearbox from a splash type lubrication system to a pressure lubricated system due to an increase in horsepower of an engine or changing from a piston engine to turbine engine.
No Yes Yes
6. A fuselage or tail boom modification that changes the primary structure, aerodynamics, and operating envelope sufficiently to invalidate the certification assumptions.
Yes No Yes
Appendix A A-52 Table A-8. Examples of Significant Changes for Rotorcraft (Parts 27 and 29) (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. Application of an approved primary structure to a different approved model (e.g., installation on a former model of the main rotor approved on a new model that results in increase performance).
No Yes Yes
8. Emergency medical service (EMS) configuration with primary structural changes sufficient to invalidate the certification assumptions.
No No Yes Many EMS configurations will not be classified as significant. Modifications made for EMS are typically internal, and the general external configuration is normally not affected. These changes should not automatically be classified as significant.
Note: Door addition or enlargement involving structural change would be significant.
Appendix A A-53 Table A-8. Examples of Significant Changes for Rotorcraft (Parts 27 and 29) (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
9. Skid landing gear to wheel landing gear or wheel landing to skid.
Yes No Yes
10. Change of the number of rotor blades.
Yes No Yes
11. Change tail anti-torque device (e.g., tail rotor, ducted fan or other technology).
Yes Yes No
12. Passenger configured helicopter to a Firefighting equipment configured helicopter.
Yes No Yes Depends on the firefighting configuration.
13. Passenger configured helicopter to an agricultural configured helicopter.
Yes No Yes Depends on the agricultural configuration.
14. An initial Category A certification approval to an existing configuration.
No No Yes