2023-12416. Decompression Criteria for Interior Compartments

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule.

SUMMARY:

The FAA is amending its standards for pressurized compartment loads such that partitions located adjacent to a decompression hole need not be designed to withstand a certain decompression condition. This rulemaking is necessary because, in some cases, it is not practical to design partitions in certain airplane compartments to withstand this decompression condition if it occurs within that compartment.

DATES:

Effective August 14, 2023.

ADDRESSES:

For information on where to obtain copies of rulemaking documents and other information related to this final rule, see “How to Obtain Additional Information” in the SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT:

For technical questions concerning this action, contact Todd Martin, Airframe Section, AIR–622, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service, Federal Aviation Administration, 2200 South 216th Street, Des Moines, WA 98198; telephone and fax [phone]; email [e-mail].

SUPPLEMENTARY INFORMATION:

I. Authority for This Rulemaking

The FAA's authority to issue rules on aviation safety is found in Title 49 of the United States Code. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the FAA's authority.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General Requirements.” Under that section, the FAA is charged with promoting safe flight of civil aircraft in air commerce by prescribing regulations and minimum standards for the design and performance of aircraft that the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority as it prescribes new safety standards for the design and performance of transport category airplanes.

II. Overview of Final Rule

The FAA is amending § 25.365, “Pressurized compartment loads,” in Title 14, Code of Federal Regulations (14 CFR) part 25, “Airworthiness Standards: Transport Category Airplanes.” Specifically, the FAA is revising § 25.365(g) to allow the failure of partitions that are adjacent to the decompression hole. This allowance only applies to the formula decompression hole specified in § 25.365(e)(2). The ability to withstand a hole of this size is typically the most severe decompression load design requirement for small compartments, such as lavatories, private suites, and crew rest areas. With this revision, partition failure is only allowed if (1) failure of the partition would not interfere with continued safe flight and landing, and (2) meeting the decompression condition in paragraph (e)(2) would be impractical.

This final rule codifies current practice and will not result in additional costs or significant benefits to airplane manufacturers, but will relieve applicants of some administrative burden—see Regulatory Evaluation below.

III. Background

A. Statement of the Problem

The airworthiness standards in § 25.365 address the safety effects of decompression. When the fuselage skin or another part of the pressurized boundary of an airplane fails for any reason, a decompression occurs if the cabin pressure is greater than the outside air pressure. When a decompression occurs, the pressurized air inside the airplane exits the hole, or opening, in the fuselage until equilibrium is reached. This can result in potentially high air loads on floors, partitions, and bulkheads.

Section 25.365(g) requires applicants to design bulkheads, floors, and partitions, in pressurized compartments for occupants, to withstand the sudden decompression conditions specified in paragraph (e). Section 25.365(g) also requires applicants to take reasonable design precautions to minimize the probability of parts becoming detached and injuring seated occupants.

For certain smaller compartments on the airplane, such as lavatories, private suites, and crew rest areas, it has been difficult for applicants to achieve compliance with § 25.365(g), because a large decompression hole, of the size specified in § 25.365(e)(2), occurring in one of these compartments would result in very high air loads on the partitions that form the compartment. Strengthening the partitions to sustain such high loads has been shown to be impractical in many cases for these smaller compartments because doing so could adversely affect the structural integrity of the airplane and its continued safe flight and landing. Further, alternative design strategies may impede the compartment's intended function.

B. History

Amendment 25–54 to § 25.365 (45 FR 60154, Sept. 11, 1980), introduced the requirement, in revised paragraph (e), that bulkheads, floors, and partitions be designed to withstand the decompression conditions specified in the rule.

In amendment 25–71 to § 25.365 (55 FR 13474, Apr. 10, 1990), the specific references to “bulkheads, floors, and partitions” were moved from paragraph (e) to paragraph (g) to provide the required passenger protection criteria related to failure of these structures in occupied compartments, regardless of whether their failure could interfere with safe flight and landing.

Prior to this final rule, § 25.365 required that the applicant consider partition failure in terms of the effects on occupant safety. However, the FAA has long recognized that structural integrity might not be maintained near the decompression hole. The Notice of Proposed Rulemaking (NPRM) for amendment 25–71 (53 FR 8742, Mar. 16, 1988) stated that loss of structural integrity at the opening location, or physiological effects on occupants, were not considerations of that rule. Thus, at that time the FAA was aware of and accepted this risk to an occupant next to the opening location.

The FAA has certified numerous airplane designs for which the partition strength criteria in § 25.365(e) at amendment 25–54 or § 25.365(g) at amendment 25–71 were included in the project's certification basis. Since the issuance of amendment 25–54, the FAA has made several equivalent level of safety (ELOS) findings to § 25.365(e) (at amendment 25–54) or § 25.365(g) (at amendment 25–71, as applicable) in accordance with 14 CFR 21.21.^[1]

C. Summary of the NPRM and Final Rule

The FAA published an NPRM on May 15, 2019 (84 FR 21733), that proposed revisions to the partition failure criteria in § 25.365(g). The NPRM described the decompression criteria in § 25.365 and explained the difficulty of designing certain partitions to withstand a decompression condition. The NPRM proposed changes to § 25.365 that would allow partition failure if it would not interfere with continued safe flight and landing and the applicant shows that designing the partition to meet the decompression load condition of § 25.365(e)(2) would be impractical. This action finalizes the proposal with minor clarifying changes.

D. General Overview of Comments

The FAA received comments from the Boeing Company (Boeing), Airbus, Bombardier Aerospace (Bombardier), the European Union Aviation Safety Agency (EASA), and the General Aviation Manufacturers Association (GAMA). Commenters were generally in favor of the proposal but requested additional flexibility in several aspects of the final rule. All of the commenters requested clarification of terminology used in the proposed rule.

IV. Discussion of Comments and the Final Rule

A. Affected Decompression Conditions

The NPRM proposed to revise § 25.365(g) to allow failure of partitions for the decompression condition specified in § 25.365(e)(2). This decompression condition, referred to as the “formula” hole size, is typically the most severe condition required by § 25.365(e).

Airbus and Boeing commented that partition failure should also be allowed for the decompression condition specified in § 25.365(e)(1): penetration of any pressurized compartment by a portion of an engine following engine disintegration. Airbus suggested that partition failure should also be allowed for the decompression condition specified in § 25.365(e)(3): any other opening caused by failures not shown to be extremely improbable. Both commenters noted that the hole size specified in these other subparagraphs may, in some cases, be greater than the formula hole size specified in § 25.365(e)(2); and therefore, their position is that the same impracticality issues exist for these other decompression conditions.

The FAA disagrees with both suggested changes. The FAA has not seen evidence to suggest that designing partitions to withstand the decompression conditions in § 25.365(e)(1) and (e)(3) is impractical. Unlike the decompression condition specified in § 25.365(e)(2), the FAA has not granted exemptions, or issued equivalent level of safety findings, that allow partition failure for these other two conditions.

With regard to the engine rotor burst example presented by Airbus and Boeing in support of their request for relief from § 25.365(e)(1), the FAA finds that partition failure should not be allowed in this instance. Since a decompression that occurs as a result of a rotor burst would be limited to an area of the fuselage near the engines, affected compartments could be placed outside this area if needed. Also, this condition would likely only result in a hole that is larger than the formula hole if the decompression was the result of a tangential strike to the fuselage. That is, the rotor disk penetrates the fuselage laterally at a tangential angle either towards the top or bottom of the fuselage, resulting in a long narrow decompression hole. By its nature, such a hole would not likely be limited to a single compartment.

The decompression condition suggested for addition by Airbus, and specified in § 25.365(e)(3), covers the maximum opening caused by airplane or equipment failures not shown to be extremely improbable. The FAA concludes that partition failure should not be allowed for this decompression condition. The FAA would not expect any situation in which the size of such an opening would exceed that of the formula hole. If there were such a condition, then the FAA concludes that the rule should require partitions be designed for that condition, or design changes made to reduce the size of the anticipated decompression hole.

B. Use of “Impractical” Standard

The NPRM proposed to allow partition failure only if the applicant could show, in addition to the failure's lack of interference with continued safe flight and landing, that designing the partition to withstand the specified decompression condition (formula hole) of § 25.365(e)(2) is impractical.

GAMA commented that requiring an applicant to show impracticality could lead to inconsistent applications of the regulation, and therefore that this requirement should be removed. GAMA proposed instead that the passenger protection criteria of § 25.365(g), which currently apply to all three of the decompression conditions of paragraph (e), should only apply to the effects of the smaller hole sizes determined under § 25.365(e)(3) (those due to failures not shown to be extremely improbable), and that such partitions would therefore be excepted from (e)(2). The FAA does not agree. To remove the decompression conditions under § 25.365(e)(2) from having to meet the passenger protection criteria of § 25.365(g) would constitute a reduction in safety. To ensure that the required element of impracticality does not lead to inconsistent application of the regulation, the FAA explains the intended meaning of “impractical” later in this discussion.

C. Safety Analysis of Potential Floor Failure

As part of its rationale, the NPRM noted that strengthening a partition, to the extent it would not fail, could increase loads on the floor and thereby the risk of floor failure, thus jeopardizing continued safe flight and landing.

EASA commented that in these cases, reinforcing the floor may be a practical solution, and therefore, partition failure should not be allowed. The FAA partially agrees. To show compliance with the rule, the applicant must show that the floor be designed to withstand the decompression conditions specified in § 25.365(e). If the applicant's analysis shows that the floor could fail if a partition does not fail after decompression, then, in order to obtain the relief provided by this final rule, the applicant could revise their proposed design to increase venting as far as practical within the affected compartment. If the applicant shows that floor failure would still occur with those design changes in place, then the FAA would likely consider reinforcement of the floor to be impractical.

D. Addressing Potential Skin Bay Failure

Airbus asked the FAA to clarify whether a failure of the standard skin bay (the area between two adjacent stringers and two adjacent frames) would be an “opening” within the meaning of § 25.365(e)(3)—the maximum opening not shown to be extremely improbable—and therefore one that the airplane must be designed to withstand. The FAA currently has no guidance as to whether a standard skin bay failure should be assumed under § 25.365(e)(3). Airbus is requesting guidance on compliance with § 25.365(e)(3), which is outside the scope of this rulemaking.

Airbus also asked whether a skin bay failure should be considered as an opening of the maximum size expected to be confined to a small compartment, in accordance with § 25.365(e)(2), and therefore covered under § 25.365(g)(2). The FAA explains the meaning of “small compartments,” as used in § 25.365(e)(2), later in this discussion. No change was made to the final rule as a result of these comments.

E. Required Design Precautions To Protect Occupants

Section 25.365(g) requires that reasonable design precautions be taken to minimize the probability of parts becoming detached and injuring occupants while in their seats. The FAA did not propose any changes to this language in the NPRM.

Boeing commented that these design precautions should no longer apply to partitions that are allowed to fail. Boeing noted that once a partition is allowed to fail, it is structurally difficult to restrain that partition. GAMA noted that there was no practical design standard for this requirement.

As explained in the NPRM, it may not be practical to design the partitions of certain compartments to withstand the decompression condition specified in § 25.365(e)(2) if it occurs within that compartment. The rule would allow partition failure in these cases, if the applicant also shows that such failure would not interfere with continued safe flight and landing. However, even in these cases, “reasonable design precautions” must still be made to protect occupants. Also, this is a performance-based design standard. Accordingly, applicants for type certificates have flexibility to satisfy the standard through a variety of means. For example, an applicant may propose lanyards or other devices to reduce the chance that a failed partition or part will impact an occupant, or may design the partition such that it fails in a direction away from seated occupants.

Boeing also proposed that the FAA remove the discussion in the NPRM that indicated that applicants must add venting, as a reasonable design precaution, to the extent practical to reduce the chance the partition will fail as a result of smaller decompression hole sizes.

The discussion in the NPRM regarding the continuing requirement to take reasonable design precautions to protect occupants remains valid. However, the FAA clarifies that § 25.365(e)(2) requires evaluation of decompression hole sizes “up to” the formula hole size, so new § 25.365(g)(2), which references that requirement, also requires evaluation of decompression hole sizes up to the formula hole size. This includes smaller sizes for which the FAA finds that applicants will be able to add venting to the extent practical to reduce the chance the partition will fail.

F. Need for Additional Guidance Material

EASA and GAMA proposed that the FAA issue an advisory circular (AC) or policy statement to accompany the proposed rule change to clarify terminology and application of the rule. The FAA does not find that an AC or policy statement is necessary. The FAA finds that the discussions in the NPRM and this final rule provide sufficient guidance on how an applicant can comply with the new rule.

G. Crew Rest Compartments

EASA proposed that the FAA provide further guidance to that provided in the NPRM on how to maximize the safety of occupants situated under and within crew rest compartments. EASA reasoned that the lower sections of such compartments are a significant contributor to ensuring all masses and occupants within those compartments are retained. The FAA finds that specific guidance is not needed for crew rest areas. The intent of the rule and the rule change are clear, and specific guidance for every conceivable configuration and compartment type is not possible or necessary.

H. Project-Specific Review

EASA commented that compliance with the proposed requirement should be subject to a project-specific (“case-by-case”) review for each proposed compartment because it may be possible to show compliance without failure of partitions for some larger compartments. The FAA agrees and intends to conduct a project-specific review for each compartment. This final rule does not allow partition failure unless the applicant shows that designing the partition to withstand the condition specified in paragraph (e)(2) of this section is impractical, and that such failure would not interfere with continued safe flight and landing.

I. Clarification of Terms

Several commenters suggested that the FAA clarify terms in § 25.365. Airbus and Bombardier requested clarification of the term “impractical;” Boeing, EASA and GAMA requested clarification of “adjacent;” Bombardier requested clarification of the term “bulkheads;” and Bombardier and EASA requested clarification of “small compartments” as specified in § 25.365(e)(2). Bombardier also requested clarification of the term “seated occupants” as used in the NPRM as compared to “occupants while in their seats” as used in § 25.365(g). The FAA provides the following clarification of these terms:

Impractical. New § 25.365(g)(2) allows partition failure if designing the partition to withstand the specified decompression condition would be “impractical.” As explained in the NPRM, designing a partition to withstand the decompression condition specified in § 25.365(e)(2) would be impractical, in the context of this rule, if (1) doing so would adversely affect the structural integrity of surrounding primary structure, including floors; or (2) the design changes would invalidate the compartment's intended function. The following is an example of the latter. Having a solid door is a fundamental feature for the intended use of some compartments, such as lavatories. While using a curtain in place of a solid door would greatly improve the decompression capability of such a compartment and is physically practical for the purpose of compliance with § 25.365(g), the FAA accepts that changing the lavatory door to a curtain in such cases would be impractical because the resulting design would invalidate the compartment's intended function.

As previously noted, § 25.365(e)(2), which has not been revised in this rulemaking, defines a decompression condition as an opening “up to” the formula hole size defined in that paragraph. Therefore, while partition failure may be accepted as impractical for the maximum hole size specified in § 25.365(e)(2), this regulation means that the applicant must evaluate smaller hole sizes, up to the maximum formula hole size, and where practical, design all partitions to withstand those smaller hole sizes.

Adjacent. Section 25.365(g)(2) allows failure of partitions “adjacent” to the opening specified in § 25.365(e)(2). In this context, adjacent partitions are those that form the compartment exposed to the decompression hole.

Partitions, Floors and Bulkheads. This rule only applies to partitions—meaning, in the context of this rule, any non-structural wall, non-structural floor, or non-structural ceiling panel—the failure of which would not compromise the structural integrity of the airplane.

In the context of this rule, the term “floor” means a structural floor, such as a passenger or cargo floor that carries airplane structural loads. The floor of an overhead crew rest area, which is elevated above the main floor, would not be a structural floor unless it carries airplane structural loads. However, if partition failure is allowed to occur in such a compartment, then to protect the safety of the persons in the compartment and below it, only partitions other than the crew rest floor should be designed to fail, rather than the floor itself. As previously stated, § 25.365(g) requires the applicant to take all reasonable design precautions to protect occupants.

The term “bulkhead,” as used in this rulemaking, means a structural pressure bulkhead or other wall that carries airframe structural loads. The FAA considers a non-structural, non-pressure bulkhead to be a partition because it does not carry airplane structural loads. The applicability of this rule is limited to partitions because the integrity of bulkheads and floors must be maintained to ensure continued safe flight and landing.

Small compartments. This final rule revises § 25.365(g) to allow failure of partitions for the decompression condition specified in § 25.365(e)(2). Section 25.365(e)(2), which was not changed as a result of this rulemaking, states that small compartments may be combined with an adjacent pressurized compartment and both considered as a single compartment for openings that cannot reasonably be expected to be confined to the small compartment. This regulation was added at amendment 25–71 to § 25.365 (55 FR 13474, Apr. 10, 1990). The FAA defines “small compartment” as a compartment with an exposed fuselage surface area of two times the formula hole size, or less. Applicants may propose alternative definitions.

As indicated in the final rule preamble for amendment 25–71, if an applicant is using the small-compartment exception, then two conditions must be evaluated: (1) The small compartment is combined with an adjacent pressurized compartment and both considered as a single compartment for the maximum size opening specified by the formula; and (2) An opening of the maximum size expected to remain confined in the small compartment would be considered in the small compartment. In keeping with the definition of “small compartment,” the FAA defines “the maximum size expected to remain confined” in any compartment evaluated under § 25.365(e)(2) to be one-half of the exposed fuselage area of that compartment.

Seated occupant: The FAA considers the term “seated occupants,” as used in the preamble of the NPRM and this final rule, to be synonymous with the regulatory (§ 25.365(g)) term of “occupants while in their seats.”

J. Safety Factors of § 25.365(d)

Airbus commented that the FAA should introduce a discussion of removing the 1.33 safety factor specified in § 25.365(d) in the context of a general update to § 25.365. This comment is unrelated to the change to § 25.365(g), and is outside the scope of this rulemaking.

K. Miscellaneous

This final rule omits the proposed words “The applicant shows that” from § 25.365(g)(2)(ii) because such language is unnecessary given the 14 CFR 21.20(a) requirement for applicants for a type certificate to show compliance with all applicable regulations.

V. Regulatory Notices and Analyses

A. Regulatory Evaluation

Federal agencies consider impacts of regulatory actions under a variety of executive orders and other requirements. First, Executive Order 12866 and Executive Order 13563 direct that each Federal agency shall propose or adopt a regulation only upon a reasoned determination that the benefits of the intended regulation justify the costs. Second, the Regulatory Flexibility Act of 1980 (Pub. L. 96–354) requires agencies to analyze the economic impact of regulatory changes on small entities. Third, the Trade Agreements Act (Pub. L. 96–39) prohibits agencies from setting standards that create unnecessary obstacles to the foreign commerce of the United States. Fourth, the Unfunded Mandates Reform Act of 1995 (Pub. L. 104–4) requires agencies to prepare a written assessment of the costs, benefits, and other effects of proposed or final rules that include a Federal mandate that may result in the expenditure by State, local, and tribal governments, in the aggregate, or by the private sector, of $100 million or more (adjusted annually for inflation) in any one year. The current threshold after adjustment for inflation is $176 million using the most current (2022) Implicit Price Deflator for the Gross Domestic Product. This portion of the preamble summarizes the FAA's analysis of the economic impacts of this rule.

This final rule codifies current practice and will not result in additional costs or significant benefits to airplane manufacturers. As noted previously, in some cases, the FAA accepted the possibility of local partition failure based on a finding of equivalent level of safety. This final rule will relieve the administrative burden for type certification applicants who might otherwise be required to submit requests for an equivalent level of safety under § 21.21(b)(1). However, cost savings for the FAA will be minimal because the FAA received only two such type certification applications in the past 5 years and does not expect numerous similar applications in the future. Cost savings for industry will be minimal because the cost of administration of the FAA's finding of equivalent safety on each applicable certification project is not high, even though it is applied several times per year. The FAA, therefore, has determined that this final rule is not a “significant regulatory action” as defined in section 3(f) of Executive Order 12866.

B. Regulatory Flexibility Act

The Regulatory Flexibility Act of 1980 (Pub. L. 96–354) (RFA) establishes “as a principle of regulatory issuance that agencies shall endeavor, consistent with the objectives of the rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the businesses, organizations, and governmental jurisdictions subject to regulation.” To achieve this principle, agencies are required to solicit and consider flexible regulatory proposals and to explain the rationale for their actions to assure that such proposals are given serious consideration. The RFA covers a wide range of small entities, including small businesses, not-for-profit organizations, and small governmental jurisdictions.

Agencies must perform a review to determine whether a rule will have a significant economic impact on a substantial number of small entities. If the agency determines that it will, the agency must prepare a regulatory flexibility analysis as described in the RFA.

However, if an agency determines that a rule is not expected to have a significant economic impact on a substantial number of small entities, section 605(b) of the RFA provides that the head of the agency may so certify and a regulatory flexibility analysis is not required.

This final rule will only have impact on applicants for type certification of transport category airplanes. All such United States transport category airplane manufacturers exceed the Small Business Administration small-entity criteria of 1,500 employees.

If an agency determines that a rulemaking will not result in a significant economic impact on a substantial number of small entities, the head of the agency may so certify under section 605(b) of the RFA. Therefore, based on the foregoing analysis, as provided in section 605(b), the head of the FAA certifies that this rulemaking will not result in a significant economic impact on a substantial number of small entities.

C. International Trade Impact Assessment

The Trade Agreements Act of 1979 (Pub. L. 96–39), as amended by the Uruguay Round Agreements Act (Pub. L. 103–465), prohibits Federal agencies from establishing standards or engaging in related activities that create unnecessary obstacles to the foreign commerce of the United States. Pursuant to these Acts, the establishment of standards is not considered an unnecessary obstacle to the foreign commerce of the United States, so long as the standard has a legitimate domestic objective, such as the protection of safety, and does not operate in a manner that excludes imports that meet this objective. The statute also requires consideration of international standards and, where appropriate, that they be the basis for U.S. standards. The FAA has assessed the potential effect of this final rule and determined that it will impose no costs on domestic and international entities and thus has a neutral trade impact.

D. Unfunded Mandates Assessment

Fourth, the Unfunded Mandates Reform Act of 1995 (Pub. L. 104–4) requires agencies to prepare a written assessment of the costs, benefits, and other effects of proposed or final rules that include a Federal mandate that may result in the expenditure by State, local, and tribal governments, in the aggregate, or by the private sector, of $100 million or more (adjusted annually for inflation) in any one year. The current threshold after adjustment for inflation is $177 million using the most current (2022) Implicit Price Deflator for the Gross Domestic Product. This final rule does not contain such a mandate; therefore, the requirements of Title II of the Act do not apply.

E. Paperwork Reduction Act

The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires that the FAA consider the impact of paperwork and other information collection burdens imposed on the public. The FAA has determined that there is no new requirement for information collection associated with this final rule.

F. International Compatibility

In keeping with U.S. obligations under the Convention on International Civil Aviation, it is FAA policy to conform to International Civil Aviation Organization (ICAO) Standards and Recommended Practices to the maximum extent practicable. The FAA has determined that there are no ICAO Standards and Recommended Practices that correspond to these regulations.

G. Environmental Analysis

FAA Order 1050.1F identifies FAA actions that are categorically excluded from preparation of an environmental assessment or environmental impact statement under the National Environmental Policy Act (NEPA) in the absence of extraordinary circumstances. The FAA has determined this rulemaking action qualifies for the categorical exclusion identified in paragraph 5–6.6f for regulations and involves no extraordinary circumstances.

VI. Executive Order Determinations

A. Executive Order 13132, Federalism

The FAA has analyzed this final rule under the principles and criteria of Executive Order (E.O.) 13132, Federalism. The FAA has determined that this action will not have a substantial direct effect on the States, or the relationship between the Federal Government and the States, or on the distribution of power and responsibilities among the various levels of government, and, therefore, will not have federalism implications.

B. Executive Order 13175, Consultation and Coordination With Indian Tribal Governments

Consistent with Executive Order 13175, Consultation and Coordination with Indian Tribal Governments,70 and FAA Order 1210.20, American Indian and Alaska Native Tribal Consultation Policy and Procedures,71 the FAA ensures that Federally Recognized Tribes (Tribes) are given the opportunity to provide meaningful and timely input regarding proposed Federal actions that have the potential to affect uniquely or significantly their respective Tribes. At this point, the FAA has not identified any unique or significant effects, environmental or otherwise, on tribes resulting from this proposed rule.

C. Executive Order 13211, Regulations That Significantly Affect Energy Supply, Distribution, or Use

The FAA analyzed this final rule under E.O. 13211, Actions Concerning Regulations that Significantly Affect Energy Supply, Distribution, or Use (May 18, 2001). The FAA has determined that it is not a “significant energy action” under the executive order and is not likely to have a significant adverse effect on the supply, distribution, or use of energy.

D. Executive Order 13609, Promoting International Regulatory Cooperation

Executive Order 13609, Promoting International Regulatory Cooperation, promotes international regulatory cooperation to meet shared challenges involving health, safety, labor, security, environmental, and other issues and to reduce, eliminate, or prevent unnecessary differences in regulatory requirements. The FAA has analyzed this action under the policies and agency responsibilities of Executive Order 13609, and has determined that this action will have no effect on international regulatory cooperation.

VII. Additional Information

A. Electronic Access and Filing

A copy of the NPRM, all comments received, this final rule, and all background material may be viewed online at www.regulations.gov using the docket number listed above. A copy of this final rule will be placed in the docket. Electronic retrieval help and guidelines are available on the website. It is available 24 hours each day, 365 days each year. An electronic copy of this document may also be downloaded from the Office of the Federal Register's website at www.federalregister.gov and the Government Publishing Office's website at www.govinfo.gov. A copy may also be found at the FAA's Regulations and Policies website at www.faa.gov/​regulations_​policies.

Copies may also be obtained by sending a request to the Federal Aviation Administration, Office of Rulemaking, ARM–1, 800 Independence Avenue SW, Washington, DC 20591, or by calling (202) 267–9677. Commenters must identify the docket or notice number of this rulemaking.

All documents the FAA considered in developing this final rule, including economic analyses and technical reports, may be accessed in the electronic docket for this rulemaking.

B. Small Business Regulatory Enforcement Fairness Act

The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 1996 requires the FAA to comply with small entity requests for information or advice about compliance with statutes and regulations within its jurisdiction. A small entity with questions regarding this document may contact its local FAA official, or the person listed under the FOR FURTHER INFORMATION CONTACT heading at the beginning of the preamble. To find out more about SBREFA on the internet, visit https://www.faa.gov/​regulations_​policies/​rulemaking/​sbre_​act/​.

List of Subjects in 14 CFR Part 25

• Aircraft
• Aviation safety
• Navigation (air)
• Reporting and recordkeeping requirements

The Amendment

In consideration of the foregoing, the Federal Aviation Administration amends chapter I of title 14, Code of Federal Regulations as follows:

PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

1. The authority citation for part 25 continues to read as follows:

Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702 and 44704.

2. Amend § 25.365 by revising paragraph (g) to read as follows:

§ 25.365

Pressurized compartment loads.

* * * * *

(g)(1) Except as provided in paragraph (g)(2) of this section, bulkheads, floors, and partitions in pressurized compartments for occupants must be designed to withstand the conditions specified in paragraph (e) of this section. In addition, reasonable design precautions must be taken to minimize the probability of parts becoming detached and injuring occupants while in their seats.

(2) Partitions adjacent to the opening specified in paragraph (e)(2) of this section need not be designed to withstand that condition provided—

(i) Failure of the partition would not interfere with continued safe flight and landing; and

(ii) Designing the partition to withstand the condition specified in paragraph (e)(2) of this section would be impractical.

Issued under authority provided by 49 U.S.C. 106(f) and 44701(a) in Washington, DC, on or about June 6, 2023

Billy Nolen,

Acting Administrator.

Footnotes

1.  An ELOS finding is made when the design does not comply with the applicable airworthiness provisions, but compensating factors, such as the incorporation of mitigating features ( e.g., lanyards to restrain loose parts, or frangible structure to cause structural failure in a direction away from the seated occupant), provide an equivalent level of safety in accordance with 14 CFR 21.21(b)(1). The FAA documents an ELOS finding in an ELOS memorandum that communicates to the public the rationale for the FAA's determination of the design's equivalency to the level of safety intended by the regulations.