Appendix A A-33 The following examples are for NOT SIGNIFICANT changes for Transport Airplanes (Part 25):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Redesign floor structure No No No By itself, not a significant product change. It is significant if part of a cargo conversion of a passenger airplane.
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. New and novel 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.
A rearrangement of an interior (e.g. seats, galleys, lavatories, closets, etc)
No No No Rearrangement requires the use of the existing floor structure.
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.
Appendix A A-34 The following examples are for NOT SIGNIFICANT changes for Transport Airplanes (Part 25):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Initial installation of a non-essential auxiliary power unit (APU) No No No A stand-alone initial APU installation on an airplane originally designed to use ground/airport supplied electricity, and airconditioning. In this case, the APU would be an option to be independent of airport power.
A rearrangement of an interior (e.g. seats, galleys, lavatories, closets, etc)
No No No Requires the use of the existing mounting structure.
Appendix A A-35 Table 3. Examples of Changes for Rotorcraft (Parts 27 and 29)
The following examples are for SUBSTANTIAL changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Change from the number and or configuration of rotors (e.g., main & tail rotor system to two main rotors) NA NA NA Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
Change from an all metal rotorcraft to all composite rotorcraft NA NA NA Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
Appendix A A-36
The following examples are for SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Comprehensive flight deck upgrade, such as conversion from entirely federated, independent electromechanical 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.
Certification for flight into known icing conditions No No Yes (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-37 The following examples are for SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes 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 May be a substantial change depending upon project details.
A change of rotor drive system primary gearbox splash type lubrication system to a pressure lubricated system due to an increase in horsepower of an engine or changing a piston engine to a turbine engine
No
Yes
Yes
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-38 The following examples are for SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes 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 Extensive primary structure changes from metallic material to composite material No Yes Yes Change in principles of construction and assumptions used for certification for the product level change. Changes of a few individual elements from metal to composite are not typically considered a significant change.
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.
Skid landing gear to wheel landing gear or wheel landing to skid Yes No Yes
Appendix A A-39 The following examples are for SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Change of the number of rotor blades Yes No Yes Change tail anti-torque device (e.g., tail rotor, ducted fan or other technology) Yes Yes No Passenger configured helicopter to a Firefighting equipment configured helicopter Yes No Yes Depends on the firefighting configuration.
Passenger configured helicopter to a agricultural configured helicopter Yes No Yes Depends on the agricultural configuration.
A new Category A certification approval to an existing configuration No No Yes Instrument flight rules (IFR) upgrades involving installation of upgraded components for new IFR configuration
No No Yes
Appendix A A-40 The following examples are for SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Human external cargo (HEC) certification approval No No Yes Must comply with the latest HEC certification requirements in order to obtain operational approval. HEC include fatigue, quick release systems, high intensity radio frequency (HIRF), one engine inoperative (OEI) performance and OEI procedures.
Reducing the number of pilots for instrument flight rules (IFR) from 2 to 1 No No Yes
Appendix A A-41
The following examples are for NOT SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Emergency floats No No No Must comply with the specific applicable requirements for emergency floats. This installation, in itself, does not change the rotorcraft configuration, overall performance, or operational capability.
Expanding an operating envelope (such as operating altitude and temperature) and mission profile (such as passenger carrying operations to external load operations, or flight over water, or operations in snow conditions) are not by themselves so different that the original certification assumptions are no longer valid at the type certificated product level.
FLIR or surveillance camera installation No No No Additional flight or structural evaluation may be necessary but the change does not alter the basic rotorcraft certification.
Helicopter terrain awareness warning system (HTAWS) for operational credit No No No Certificated per rotorcraft HTAWS AC guidance material and FAA TSO-C194.
Health usage monitoring system (HUMS) for maintenance credit.
No No No Certificated per rotorcraft HUMS AC guidance material.
Appendix A A-42 The following examples are for NOT SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Expanded limitations with minimal or no design changes, following further tests/justifications or different mix of limitations (center of gravity (CG) limits, oil temperatures, altitude, minimum/maximum weight, minimum/max external temperatures, speed, ratings structure).
No No No Expanding an operating envelope (such as operating altitude and temperature) and mission profile (such as passenger carrying operations to external load operations, or flight over water, or operations in snow conditions) are not by themselves so different that the original certification assumptions are no longer valid at the type certificated product level.
Installation of a new engine type, equivalent to the former one;
leaving aircraft installation and limitations substantially unchanged No No No Refer to AC 27-1 or AC 29-2 for guidance Windscreen installation No No No Does not change the rotorcraft overall product configuration.
Snow skis, “Bear Paws” No No No Must comply with specific requirements associated with the change. Expanding an operating envelope (such as operating altitude and temperature) and mission profile (such as passenger carrying operations to external load operations, or flight over water, or operations in snow conditions) are not by themselves so different that the original certification assumptions are no longer valid at the type certificated product level.
Appendix A A-43 The following examples are for NOT SIGNIFICANT changes for Rotorcraft (Parts 27 and 29):
Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes External cargo hoist No No No Must comply with the specific applicable requirements for external loads. This installation, in itself, does not change the rotorcraft configuration, overall performance, or operational capability. Expanding an operating envelope (such as operating altitude and temperature) and mission profile (such as passenger carrying operations to external load operations, excluding human external cargo (HEC), or flight over water, or operations in snow conditions) are not by themselves so different that the original certification assumptions are no longer valid at the type certificated product level.
Instrument flight rules (IFR) upgrades involving installation of upgraded components to replace existing components No No No Not a rotorcraft level change.
Appendix A A-44 Table 4. Examples of Changes for Engines (Parts 33)
The following are examples of SUBSTANTIAL changes for Engines (Parts 33 ) Description of change Is there a change to the general configuration?
14 CFR §
21.101(b)(1)(i) Is there a change to the principles of construction?
14 CFR §
21.101(b)(1)(i) Have the assumptions used for certification been invalidated?
14 CFR §
21.101(b)(1)(ii) Notes Turbine Engines Traditional turbofan to geared-fan engine NA NA NA Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required Note: There may be certain circumstances where this change would be significant.
Low bypass ratio engine to high bypass ratio engine with an increased inlet area NA NA NA Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
Note: There may be certain circumstances where this change would be significant.
Turbojet to Turbofan NA NA NA Proposed change in design is so extensive that a substantially complete investigation of compliance with the applicable regulations is required.
Note: There may be certain circumstances where this change would be significant.