Appendix F F-2
• Modifications,
• Flight hours/cycles for fleet leader and total fleet,
• World airline accident summary data,
• Service difficulty reports,
• National Transportation Safety Board reports, and
• Warranty, repair, and parts usage data.
F.2.5.2 Show that the data presented represent all relevant service experience for the product, including the results of any operator surveys, and is comprehensive enough to be representative.
F.2.5.3 Show that the service experience is relevant to the hazard.
F.2.5.4 Identification and evaluation of each of the main areas of concern with regard to—
• Recurring and/or common failure modes,
• Cause,
• Probability by qualitative reasoning, and
• Measures already taken and their effects.
F.2.5.5 Relevant data pertaining to aircraft of similar design and construction may be included.
F.2.5.6 Evaluation of failure modes and consequences through analytical processes. The analytical processes should be supported by—
• A review of previous test results,
• Additional detailed testing as required, or
• A review of aircraft functional hazard assessments (FHA) and any applicable system safety assessments (SSA) as required.
F.2.6 A conclusion that draws together the data and the rationale.
F.2.7 These guidelines are not intended to be limiting, either in setting the required minimum elements or in precluding alternative forms of submission. Each case may be different, based on the particulars of the system being examined and the requirement to be addressed.
Appendix F F-3 F.3 Example: § 25.1141(f) for Transport Category Airplanes.
F.3.1 The following example, for transport category airplanes (§ 25.1141(f), APU Fuel Valve Position Indication System), illustrates the typical process an applicant follows. The process will be the same for all product types.
F.3.2 This example comes from a derived model transport airplane where significant changes were made to the main airframe components, engines and systems, and APU. The baseline airplane has an extensive service history. The example shows how the use of service experience supports a finding that compliance with the latest regulation would not contribute materially to the level of safety and that application of the existing certification basis (or earlier amendment) would be appropriate. The example is for significant derived models of transport airplanes with extensive service history. It illustrates the process, following the guidelines in this appendix, but does not include the level of detail normally required.
F.3.2.1 Determine the differences between the regulation in the existing certification basis and the regulation as amended, and the effect of the change in the regulation. The existing certification basis of the airplane that is being changed is the initial release of part 25. Amendment 25-40 added requirement § 25.1141(f), which mandates that power-assisted valves must have a means to indicate to the flightcrew when the valve is in the fully open or closed position, or is moving between these positions.
The addressed hazard would be risk of APU fire due to fuel accumulation caused by excessive unsuccessful APU start attempts.
F.3.2.2 What aspect of the proposed changed product would not meet the latest regulations? The proposed APU fuel valve position indication system does not provide the flightcrew with fuel valve position or transition indication and, therefore, does not comply with the requirements of § 25.1141(f).
F.3.2.3 The applicant provides evidence that the proposed certification basis for the changed product, together with applicable service experience of the existing design, provide a level of safety that approaches yet is not fully compliant with the latest regulations. The APU fuel shut-off valve and actuator are unchanged from those used on the current family of airplanes, and have been found to comply with the earlier Amendment 25-11 of § 25.1141. The existing fleet has achieved approximately (#) flights during which service experience of the existing design has been found to be acceptable. If one assumes a complete APU cycle, i.e., start-up and shutdown for each flight, the number of APU fuel shut-off valve operations would be over 108 cycles, which demonstrates that the valve successfully meets its intended function and complies with the intent of the regulation.
F.3.2.4 The applicant provides a description of the design feature and its intended function. The fuel shut-off valve, actuator design, and operation is
Appendix F F-4 essentially unchanged with the system design ensuring that the valve is monitored for proper cycling from closed to open at start. If the valve is not in the appropriate position (i.e., closed), then the APU start is terminated, an indication is displayed on the flightdeck, and any further APU starts are prevented. Design improvements using the capability of the APU electronic control unit (ECU) have been incorporated in this proposed product change. These design changes ensure that the fuel valve indication system will indicate failure of proper valve operation to the flightcrew, these features increase the level of functionality and safety, but the system does not indicate valve position as required by § 25.1141(f).
F.3.2.5 The FAA and applicant record this in an issue paper. The FAA can use the G-1 or a technical issue paper for this purpose. An issue paper was coordinated, included data, or referenced reports documenting relevant service experience compiled from incident reports, fleet flight hour/cycle data, and maintenance records. The issue paper also discussed existing and proposed design details, failure modes, and analyses showing to what extent the proposed airplane complies with the latest amendment of § 25.1141. Information is presented to support the applicant’s argument that compliance with the latest amendment would not materially increase the level of safety. Comparative data pertaining to aircraft of similar design and construction are also presented.
F.3.2.6 The conclusion, drawing together the data and rationale, is documented in the G-1 issue paper. The additional features incorporated in the APU fuel shut-off valve will provide a significant increase in safety to an existing design with satisfactory service experience. The applicant proposes that compliance with the latest amendment would not materially increase the level of safety and that compliance with § 25.1141 at Amendment 25-11 would provide an acceptable level of safety for the proposed product change.
Appendix G G-1 APPENDIX G. CHANGED PRODUCT RULE DECISION RECORD
CHANGED PRODUCT RULE (CPR) DECISION RECORD TC/STC No.: Click here to enter text. Project Number: Click here to enter text.
Step 1: Identify the proposed type design changes to the aeronautical product.
(See paragraph 3.2 of AC 21.101-1B) The proposed type design changes are identified here or in the following document(s):
Click here to enter text.
Note: The Issue Paper process is used to track/document the decisions at Step 2 and Steps 5 through 8 as required.
Step 2: Is the proposed type design change substantial?
(See paragraph 3.3 of AC 21.101-1B) ☐ Yes New Type Certificate: Proceed to § 21.19. Section 21.101 does not apply. A G -1 issue paper will be used to establish and document the certification basis.
☐ No Proceed to Step 3.
Step 3: Will you use the latest standards?
(See paragraph 3.4 of AC 21.101-1B) ☐ Yes Latest Requirements: Propose a certification basis using the standards in effect at the date of application. Proceed to Step 8.
☐ No Proceed to Step 4.
Step 4: Arrange changes into related and unrelated groups.
(See paragraph 3.5 of AC 21.101-1B) Note: For multiple groupings, continuation of this process should be split into separate decision records. Groupings may be rationalized and recorded in separate documents:
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Step 5: Is each related or unrelated group a significant change?
(See paragraph 3.6 of AC 21.101-1B) ☐ Yes Proceed to Step 6.
☐ No Earlier Requirements: Propose a certification basis using the standards in effect before the date of application but not earlier than the existing certification basis.
Certification basis to be defined and documented as indicated (below). Proceed to Step 8.
Step 6: Prepare your Certification Basis List.
(See paragraph 3.9 of AC 21.101-1B) Affected Areas:
The Affected Area(s) are detailed here or in the following Certification Basis List document number(s):
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Process and propose each applicable requirement individually. Proceed to Step 7.
Not Affected Areas: Existing Requirements: You may continue using the existing certification basis.
Step 7: Do the latest requirements contribute materially to the level of safety and are they practical?
(See paragraph 3.10 of AC 21.101-1B) ☐ Yes Latest Requirements: Propose a certification basis using the standards in effect on the date of application.
☐ No Earlier Requirements: You may propose a certification basis using the standards in effect before the date of application but not earlier than the existing certification basis. Certification basis defined or documented as indicated below.
☐ Continuation Sheet(s) Attached Note: Several standards may apply to each affected area , and the assessment may differ from standard to standard. Indicate “Yes” if compliance with any latest standard(s) is required.
Indicate “No” only if earlier standards are proposed.
Note: You may submit a proposal for the decision in Step 7; however, the FAA will make the final certification basis determination.
Step 8: Ensure the proposed certification basis is adequate .
(See paragraph 3.11 of AC 21.101-1B) If you deem that the certification basis is adequate , submit proposed certification basis to the FAA.
If not, consult the FAA. A G -1 issue paper may be needed to document the certification basis.
Certification Basis: The certification basis is detailed here or in the following document(s):
Click here to enter text.
Based on the information provided above, I am proposing the certification basis with the following classification for the type design change.
(check one) ☐ Significant, pursuant to § 21.101. ☐ Not significant, pursuant to § 21.101.
Click here to enter text. Click here to enter text.
Printed Name/Title Signature Date
Appendix H H-1 APPENDIX H. EXAMPLES OF DOCUMENTING THE PROPOSED
CERTIFICATION BASIS LIST H.1 Example 1.
H.1.1 This optional tool may be used to establish the applicable airworthiness regulations that will be the certification basis. For a significant change, the applicant must show compliance for the change and the area affected by the change to the airworthiness requirements that were in effect at the date of application. However, in some cases earlier requirements can be used, as allowed in § 21.101.
H.1.2 In order to efficiently determine and agree upon a certification basis with the FAA, the following information is useful to understand your position:
H.1.2.1 The scope of the change. This includes a high level description of the physical and functional changes and performance/functional characteristics, which are changed as a result of the physical or functional change, and the regulations for which showing compliance is required as a result of the change.
H.1.2.2 The amendment level of all the applicable airworthiness requirements at the date of application.
H.1.2.3 Your proposed certification basis, including amendment levels.
H.1.2.4 If you propose a certification basis that includes amendment levels earlier than what was in effect at the date of application, include the exception as outlined in § 21.101 and your justification if needed.
H.1.3 Exceptions.
H.1.3.1 Unrelated changes that are not significant (§ 21.101(b)(1)).
H.1.3.2 Not affected by the change (§ 21.101(b)(2)).
H.1.3.3 Compliance to the regulation would not contribute materially to the level of safety (§ 21.101(b)(3)).
H.1.3.4 Compliance to the regulation would be impractical (§ 21.101(b)(3)).
H.1.4 One easy way to document the proposed certification basis is using a tabular form as shown in table H-1 below.
Appendix H H-2 Table H-1. Tabular Form for Documenting a Proposed Certification Basis 14 CFR Section Amendment Levels Applicant Justification for Lower Amendment Level and Comments Affected Area Existing TCDS Amendment Amendment at Date of Application Proposed Amendment Level Subpart A – General
Subpart B – Flight
H.1.5 Best Practices.
H.1.5.1 Account for all regulations, even if they are not applicable.
H.1.5.2 Mark regulations that are not applicable as N/A.
H.1.5.3 If more than one amendment level is used depending on the area of the aircraft, list all areas and amendment levels at each area with proper justification.
H.1.5.4 If the justification is long, provide the justification below the table and only place the regulatory reference and note in the comment field.
H.1.5.5 Include airworthiness regulations required by other 14 CFR parts
(e.g., parts 91, 121, 125, 135) of affected areas.
H.2 Example 2.
Pages H-3 through H-9 of this appendix contain another example for documenting a proposed certification basis.
Appendix H H-3 Title of Design Change Product Name or Change to Type Certificate [XXXX] Proposed Certification Basis Pursuant to 14 CFR 21.101
Appendix H H-4
1. I NTRODUCTION.
1.1 R EFERENCE DOCUMENTS.
Reference Title [1] Section 21.101 Designation of applicable regulations [2] AC 21.101-1B Establishing the Certification Basis of Changed Aeronautical Products [3] XXXX Application letter [4] Type Certificate YYYY Product type certification basis [5] Document ZZZZ Certification plan [6] <The above referenced documents are examples. Each applicant should reference documents appropriate to their products and procedures.>
1.2 A CRONYMS.
Acronym Meaning AC Advisory Circular AFM Airplane Flight Manual ELOS Equivalent Level of Safety IP Issue Paper MOC Means of Compliance SC Special Condition TC Type Certificate <This section constitutes a representative list of acronyms. Each applicant should provide an acronym list appropriate for their product and document.>
1.3 P URPOSE OF THE DOCUMENT.
The purpose of this document is to propose the certification basis applicable to [Product Design Change] in accordance with 14 CFR 21.101.
<Note that this optional document is intended to be used for changes to type certificated products for which the change or a portion of the change is significant at the product level pursuant to § 21.101. Not significant changes being accomplished concurrently with significant changes(s) would also be identified in this document.>
Appendix H H-5
1.4 P URPOSE OF THE CHANGE.
High-level description of the project (e.g., Airplane Model 123 is being modified from a passenger configuration to an all-cargo configuration).
2. D ESIGN DEFINITION.
2.1 BASELINE PRODUCT.
The type design to be changed, which is also known as the “baseline product,” is the Model Series___ (this should be a specific product configuration, such as a specific serial number or line number).
The reference product certification basis is TCDS No. [XXXX], issued on [DATE].
2.2 DESIGN CHANGE AND BASELINE PRODUCT COMPARISON SUMMARY.
<Example table where the product is an airplane. This is a representative set of data that may be provided by the applicant.> Specification Model Series X Model Series Y Max Taxi Weight – MTW (lbs) A1 A2 Max Takeoff Weight – MTOW (lbs) B1 B2 Max Landing Weight – MLW (lbs) C1 C2 Max Zero Fuel Weight – MZFW (lbs) D1 D2 Max Length (ft, in) E1 E2 Max Height (ft, in) F1 F2 Wing Span (ft, in) G1 G2 Horizontal Tail Span (ft, in) H1 H2 Fuel Capacity (gal) I1 I2 Total Cargo Volume (ft3) J1 J2 Max Passenger Limit – one class seating (occupants) K1 K2 Engine Types L1 & M1 L2 Maximum Engine Thrust T1 T2
Appendix H H-6
2.3 DESCRIPTION OF DESIGN CHANGE, GROUPING AND CLASSIFICATION.
2.3.1 SIGNIFICANT CHANGE(S).
<Describe here the stand-alone change(s) and/or change grouping(s) that are part of the proposed changed product and are proposed as significant. Include with each stand-alone change or change grouping the relevant accumulated change(s) and the applicable physical and/or functional effects. Note, the description should be detailed enough to identify why the change or change grouping is proposed as significant.> The following group of changes is proposed as significant based on [AC 21.101-1, Appendix A, “[Description of Change in Appendix A]] or [the general configuration is not retained, principles of construction are not retained, or assumptions for certification of the product to be changed do not remain valid].
Changes Related to [Title of Significant Change X]:
[Title of High-Level Change C1] The areas of physical change are:
• [design change xx]
• [design change yy]
• [design change zz] The areas unchanged but affected by the change are:
• [affected area aaa]
• [affected area bbb]
• [affected area ccc] [Title of High-Level Change C2]…..
2.3.2 UNRELATED NOT-SIGNIFICANT CHANGES.
<Describe here the stand-alone changes or change groupings that are part of the modification but are unrelated to any of the significant changes described in paragraph 2.3.1.> [Title of High-Level Change D1]. [Description].
<The description must be just detailed enough to serve its purpose, which is to identify why each of those changes is not-significant and unrelated.> [Title of High-Level Change D2]. [Description]…..
3. IDENTIFICATION OF APPLICABLE REQUIREMENTS.
3.1 PROPOSED CERTIFICATION BASIS.
Based on the effective application date, [date], under the provisions of § 21.101, the applicable type certification standards for the [Title of Design Change] are proposed as
Appendix H H-7 follows. The proposed certification basis includes exceptions to earlier amendments, exemptions, special conditions, and equivalent level of safety findings.
3.1.1 Requirements Effective at the Date of Application.
Applicable requirements in effect on the date of the application are:
<List the applicable parts and amendment levels here.> Example for FAA transport airplane:
• 14 CFR 25 through Amendment 25-138.
• 14 CFR 26 through Amendment 26-6.
• 14 CFR 34 through Amendment 34-5A.
• 14 CFR 36 through Amendment 36-29.
3.1.2 Section 21.101 Exception Rationale.
The completed rationale for each does not contribute materially to the level of safety (DCMLS) or impractical exception is provided in this section.
Exception 1:
Exception 2: ….
3.1.3 Optional Requirements Applicable requirements in effect on the date of the application are:
<List the applicable parts and amendment levels here.> Example for FAA transport airplane:
• 14 CFR 25.1419, Ice protection, Amendment 25-129.
• 14 CFR 25.1535, ETOPS approval, Amendment 25-120.
3.1.4 Requirements in Other 14 CFR Parts Applicable requirements in effect on the date of the application are:
<List the applicable parts and amendment levels here.> Example for FAA transport airplane:
• 14 CFR 121.215, Cabin interiors, Amendment 121-84.
• 14 CFR 121.316, Fuel tanks, Amendment 121-293.
3.1.5 Proposed Special Conditions.
Special Condition (or TBD) Title Effective Date (or TBD)
Appendix H H-8
3.1.6 Equivalent Level of Safety.
ELOS Memo No.
(or TBD) Title Applicable Regulation
3.1.7 Exemptions.
Exemption No.
(or TBD) Title Applicable Regulation Date Issued (or TBD)