Document ID: FAA-2019-0491-0086
Agency: faa
Document Type: Proposed Rule
Title: Interior Parts and Components Fire Protection for Transport Category Airplanes
Posted Date: 2023-08-17T04:00Z

[Federal Register Volume 88, Number 158 (Thursday, August 17, 2023)]
[Proposed Rules]
[Pages 55941-55953]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-16877]

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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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  Federal Register / Vol. 88, No. 158 / Thursday, August 17, 2023 / 
Proposed Rules  

[[Page 55941]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 25, 27, 29, 91, 121, 125 and 135

[Docket No.: FAA-2019-0491; Notice No. 23-12]
RIN 2120-AK34

Interior Parts and Components Fire Protection for Transport 
Category Airplanes

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

ACTION: Supplemental notice of proposed rulemaking.

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SUMMARY: In Notice 19-09, published on July 3, 2019, the FAA proposed 
to amend certain regulations for fire protection of interior 
compartments on transport category airplanes. Based on certain comments 
received, the FAA is providing additional information on its proposed 
elimination of a smoke emissions testing requirement. The FAA is also 
changing its calculations related to the proposed rule's costs and 
benefits. This notice offers interested persons an opportunity to 
comment on these changes.

DATES: Send comments on or before October 2, 2023.

ADDRESSES: Send comments identified by docket number FAA-2019-0491 
using any of the following methods:
     Federal eRulemaking Portal: Go to www.regulations.gov and 
follow the online instructions for sending your comments 
electronically.
     Mail: Send comments to Docket Operations, M-30; U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments 
from the public to better inform its rulemaking process. DOT posts 
these comments, without edit, including any personal information the 
commenter provides, to www.regulations.gov, as described in the system 
of records notice (DOT/ALL-14 FDMS), which can be reviewed at 
www.dot.gov/privacy.
    Docket: Background documents or comments received may be read at 
www.regulations.gov at any time. Follow the online instructions for 
accessing the docket or go to the Docket Operations in Room W12-140 of 
the West Building Ground Floor at 1200 New Jersey Avenue SE., 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Jeff Gardlin, AIR-20, Office of Senior 
Technical Experts, Aircraft Certification Service, Federal Aviation 
Administration, 2200 South 216th Street, Des Moines, WA 98198; 
telephone (206) 231-3146; email [email protected].

SUPPLEMENTARY INFORMATION: 

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 agency'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. It 
revises the safety standards for the flammability characteristics, and 
thus the design, material, and construction, of transport category 
airplanes.

I. Background

A. Summary of Prior Notice of Proposed Rulemaking (NPRM)

    On July 3, 2019, the FAA published in the Federal Register an NPRM 
titled ``Interior Parts and Components Fire Protection for Transport 
Category Airplanes'' (84 FR 31747). In the NPRM, the FAA proposed to 
amend certain airworthiness regulations for fire protection of interior 
compartments on transport category airplanes. The proposal would 
convert those flammability regulations from detailed, prescriptive 
requirements into simpler, performance-based standards. The proposal 
would divide these standards into two categories: those designed to 
protect the airplane and its occupants from the hazards of in-flight 
fires, and those designed to protect the airplane and its occupants 
from the hazards caused by post-crash fires. In addition, the proposal 
would remove test methods, including heat release and smoke emissions 
tests, from the regulations, replacing them with performance-based 
requirements.

B. Response to Public Comments on Proposed Replacement of Smoke 
Emissions Test Requirement With Performance-Based Standards

    The FAA received several comments on its proposal to remove the 
smoke emissions test as a requirement for compliance with the proposed 
performance-based standard of Sec.  25.853(d)(2). As noted in the NPRM, 
proposed Sec.  25.853(d) would provide a general standard that the 
airplane's parts, components, and assemblies maintain survivable cabin 
conditions for enough time to allow evacuation. For large surfaces in 
the passenger cabin, the specific survivability requirement would be 
dependent on the passenger capacity of the proposed airplane, because 
emergency egress is generally much faster on smaller airplanes. For 
airplanes with 19 passengers or less, proposed Sec.  25.853(d)(1) would 
require each large surface in the passenger cabin to be self-
extinguishing when exposed to a small flame for at least 60 seconds. 
For airplanes with a passenger capacity of 20 passengers or more, 
proposed Sec.  25.853(d)(2) would require, with limited exception, that 
each large surface in the passenger cabin resist involvement in a post-
crash fuel fire

[[Page 55942]]

that has entered the fuselage. For the purposes of this requirement, 
`resist involvement' would mean that, when exposed to a post-crash fuel 
fire, the thermal decomposition of the affected materials would not 
produce cabin conditions that would prevent or delay egress, in a time 
less than egress would otherwise occur.
    The traditional means of measuring this capability, and thus the 
FAA's regulatory requirement in appendix F, has been to conduct two 
tests: an examination of the material's heat release, due to the nexus 
of heat release with flashover,\1\ as well as of its smoke emissions, 
since heavy smoke could similarly prevent timely egress. As discussed 
in the NPRM, the FAA has concluded that, for traditional (previously 
approved) materials and material systems, for which compliance data 
already exists, heat release test results alone would be sufficient to 
determine that the material resists involvement in a post-crash fire.
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    \1\ See, e.g., The Case for Relating Flashover to Heat Release 
Rate Measurements on Cabin Materials, Fire Safety Branch, FAA 
Technical Center (Apr. 2, 1986), available at https://www.fire.tc.faa.gov/pdf/fsr-0338.pdf and in the docket.
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    As with all the requirements in Sec.  25.853, applicants must 
currently show compliance via a specific (smoke emissions) test set 
forth in part V of appendix F of part 25, title 14, Code of Federal 
Regulations (14 CFR).
    SABIC, GBH International, Airbus, and several individuals disagreed 
with the FAA's statement in the NPRM that the smoke emissions test 
requirement had not been shown to have contributed to fire safety in an 
actual accident.\2\ These commenters said that because the smoke 
emissions test has long been a requirement, there is no way to know 
whether it has contributed to fire safety. These commenters noted that 
some materials will pass the heat release tests but fail the smoke 
emissions test, and therefore cannot be used under current regulations. 
These commenters asserted that the proposed rule would permit these 
materials' use, with an unknown effect on safety.
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    \2\ Interior Parts and Components Fire Protection for Transport 
Category Airplanes; NPRM. 84 FR 31752 (July 3, 2019).
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    Airbus, Boeing, and the International Coordinating Council of 
Aerospace Industries Associations objected to the NPRM's assertion 
that, since the smoke emissions test was in use by industry before it 
became a regulatory requirement, it would likely continue to be used, 
to some extent, after it was no longer required.\3\ These commenters 
stated that airplane manufacturers would have no incentive to continue 
to conduct the smoke emissions test, if the FAA determined that it did 
not add to safety. SABIC, GHB International, and the Airline Pilots 
Association opined that smoke was a survivability factor in the post-
crash environment, and therefore that the FAA should retain a 
requirement that applicants conduct a smoke emissions test.
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    \3\ Ibid, 84 FR 31753.
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    Regarding the contribution of the smoke emissions test to fire 
safety, the FAA's statement in the NPRM referred to the lack of 
correlation, in full-scale fire tests, between that particular test and 
survivability.\4\ Although the FAA considers the presence of smoke to 
be a significant survivability factor in a post-crash fire, as 
discussed in the NPRM it is the smoke emission test results that have 
not been shown to have clear correlation to survivability. Also, a 
prescriptive smoke emissions test requirement in addition to a heat 
release test requirement will screen out materials that either test, by 
itself, would not. The key question, for this issue in this proposed 
rulemaking, is the extent to which screening out those additional 
materials contributes to occupant survivability in an actual post-crash 
fire; or whether the effect of a regulatory requirement to conduct both 
types of tests is solely to limit the options available to applicants. 
Since some of the comments questioning whether applicants would 
voluntarily conduct a smoke emissions test came from those 
manufacturers, the FAA agrees that its estimate of continued voluntary 
usage of the smoke emissions test by industry was likely incorrect.
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    \4\ Ibid, 84 FR 31752.
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    The NPRM described the heat release rate (HRR) test as a compliance 
method that would be available to meet proposed Sec.  25.853(d)(2).\5\ 
That section would require that materials resist involvement in a post-
crash fire to the extent that survivability would not be affected. The 
NPRM also stated, however, that ``if data from the HRR testing does not 
ensure the post-crash fuel fire performance of a given material, an 
applicant could show compliance via another means.'' \6\ With this 
supplemental notice of proposed rulemaking (SNPRM), the FAA provides 
additional information on methods of showing compliance.
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    \5\ Ibid, 84 FR 31753.
    \6\ Ibid, 84 FR 31753.
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    For existing material systems,\7\ and traditional aircraft parts 
(i.e., those that have already passed the smoke emissions test 
previously in appendix F, part V), successful HRR test results alone 
would be sufficient to show that the material resists involvement in a 
post-crash fire, per Sec.  25.853(d)(2).
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    \7\ A ``material system'' is the underlying chemistry and 
associated processes to produce specific materials.
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    Applicants proposing a design that incorporates a new material or 
material system that has not been previously approved by the FAA, and 
thus for which no compliance data exists, would need to provide more 
data in order to show survivability. Results showing passage of only 
the HRR test would not be sufficient, and applicants would need to 
provide an assessment of the material's smoke emissions 
characteristics. However, since the current regulatory requirement is 
to use both smoke emissions and heat release test results to determine 
whether a material sufficiently resists involvement in a post-crash 
fire, and since the intent of this proposal is not to change the level 
of safety in this regard, for such wholly new materials the FAA would 
accept a compliance demonstration that includes an assessment of both 
heat release and smoke emissions test results.
    Applicants could also combine successful HRR test results with a 
showing that the new material's smoke emissions characteristics are 
consistent with the characteristics of parts for which there is already 
approved data. As explained below, an applicant could show that the new 
material does not have distinctly different characteristics than 
materials that have already been found to meet the current smoke 
emissions test in part V of appendix F.
    To assist applicants' use of smoke emission data as part of their 
showing of survivability, the FAA has updated, and placed in the docket 
for comment with this SNPRM, draft Advisory Circular (AC) 25.853-1A. 
That draft AC references the FAA's development of a modification to the 
apparatus defined in chapter A4 DOT/FAA/TC-17/55, ``Aircraft Materials 
Fire Test Handbook,'' Revision 3, dated June 2019. Chapter A4 includes 
a test known as the ``HR2''. This modification to the test apparatus 
uses a method of continuously assessing smoke with lasers, and accounts 
for the total smoke emission over the course of the test.\8\
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    \8\ Passage of the HR2 test will not be required to demonstrate 
a new materials' smoke emissions characteristics. As described in 
the draft AC, applicants would also be able to use the currently 
required test from the appendix F, part V; the test method in 
chapter 6 of DOT/FAA/AR-00/12; or another FAA-accepted test.
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    In the method provided by the draft AC, an applicant could use a 
proposed material's smoke emissions

[[Page 55943]]

characteristics as part of the required showing of survivability if the 
proposed material generated less than 25 percent more smoke than a 
material that the FAA previously approved based upon the applicant's 
showing of compliance with the smoke test in part V of appendix F.\9\
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    \9\ A difference of 25 percent or more smoke than an approved 
material would prompt the need to further investigate, and 
demonstrate, the survivability performance of the new material.
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    Since applicants do not yet have data from the HR2 regarding smoke 
emissions, they would be able to gather that information outside of 
formal (project-specific) certification testing, as long as the 
applicant has a defined process that is accepted by the FAA. Given that 
applicants have little experience with the new HR2, they will likely be 
conducting non-certification tests to gain that experience. The FAA 
estimates that the costs of gathering this data, and submitting it in 
future projects, would be minimal. In addition, the FAA would welcome 
the opportunity to evaluate candidate materials for which the smoke 
emissions performance is in question. Any such evaluation would result 
in de-identified publicly available data, of potential benefit to all 
applicants.
    The FAA is also making changes to the way costs and benefits are 
assessed based on the forecast for new type certificates, and 
deliveries under those certificates. The FAA also made minor punctation 
corrections to the proposed revisions to the conforming operational 
rules.

C. Need for Supplemental Notice of Proposed Rulemaking (SNPRM)

    This SNPRM is needed since the FAA is proposing to change some of 
its cost and benefit calculations, and explaining certain methods of 
compliance that would use an assessment of smoke emissions to show 
compliance. This SNPRM offers the public opportunity to comment on the 
assumptions and criteria the FAA is using in advance of a final rule.

II. Discussion of Supplemental Proposals

    As previously discussed, there are no changes to the regulatory 
proposals. Since the proposed requirements are performance-based, the 
effect is entirely on the method of compliance to meet one of the 
proposals in light of comments received.

III. 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, as amended by Executive Order 
14094 (``Modernizing Regulatory Review''), 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 $177 million using the most 
current (2022) Implicit Price Deflator for the Gross Domestic Product. 
[The FAA has provided a detailed Regulatory Impact Analysis (RIA) in 
the docket for this rulemaking.] This portion of the preamble 
summarizes the FAA's analysis of the economic impacts of this rule.
    In conducting these analyses, the FAA has determined that this 
rule: will result in benefits that justify costs; is not an 
economically ``significant regulatory action'' as defined in section 
3(f) of Executive Order 12866, as amended; will not have a significant 
economic impact on a substantial number of small entities; will not 
create unnecessary obstacles to the foreign commerce of the United 
States; and will not impose an unfunded mandate on State, local, or 
Tribal governments, or on the private sector. These analyses are 
summarized below.
1. Summary of Costs and Benefits
    The SNPRM is in response to the following changes to the RIA. The 
analysis for the NPRM RIA included the impacts of the rule on U.S. 
manufacturers selling airplanes in the U.S. but did not include impacts 
to foreign operators and foreign manufacturers. This SNPRM analysis 
adds the impacts of the rule on U.S. manufacturers selling airplanes to 
foreign operators, and foreign manufacturers selling airplanes to U.S. 
operators. The NPRM also assumed that all new type certificates would 
be issued at the start of the analysis. The SNPRM is being updated to 
better reflect a more realistic schedule for the introduction of new 
type certificates into the fleet. In this analysis, the introduction of 
new type certificates are spaced over the time horizon of the analysis 
rather than all occurring at the start of the time horizon.
    By extending fire protection requirements to any extensively used 
material located in inaccessible areas, the proposal is likely to be 
beneficial in reducing the likelihood of a fatal accident. Over a 20-
year period of analysis, the FAA estimates the total present value cost 
savings of this SNPRM to be $121.4 million at a seven percent discount 
rate, with annualized cost savings of $11.7 million. The cost savings 
would result from the elimination and streamlining of some tests, which 
would be made possible by the extension of fire protection requirements 
to inaccessible areas. Over the same 20-year period, the FAA estimates 
the total present value costs of this SNPRM to be $107.6 million at a 
seven percent discount rate, with annualized costs of $10.4 million due 
to the extension of fire protection requirements to extensively used 
material in inaccessible areas. A full explanation of how these costs 
and cost savings were estimated may be found in the regulatory impact 
assessment accompanying this SNPRM. The present value net cost savings 
(cost savings minus cost) is $13.8 million, with annualized net cost 
savings of $1.3 million. The following tables summarize the costs and 
cost savings of this proposed rule for U.S. manufacturers, foreign 
manufacturers delivering to U.S. operators and then the total for both 
U.S. manufacturers and foreign manufacturers (delivering to U.S. 
operators).

[[Page 55944]]

                              U.S. Manufacturers \10\--Total Costs and Cost Savings
                                                    [2020 $]
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                                                    19-Year total present value             Annualized
                                                 ---------------------------------------------------------------
                                                        7%              3%              7%              3%
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Cost Savings....................................     $91,083,070    $142,741,271      $8,812,562      $9,965,322
Costs...........................................      56,081,338      74,600,557       5,426,039       5,208,154
                                                 ---------------------------------------------------------------
    Total Net Cost Savings......................      35,001,732      68,140,714       3,386,523       4,757,168
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                            Foreign Manufacturers \11\--Total Costs and Cost Savings
                                                    [2020 $]
----------------------------------------------------------------------------------------------------------------
                                                    19-Year total present value             Annualized
                                                 ---------------------------------------------------------------
                                                        7%              3%              7%              3%
----------------------------------------------------------------------------------------------------------------
Cost Savings....................................     $30,317,272     $47,104,659      $2,933,287      $3,288,559
Costs...........................................      51,520,339      62,218,084       4,984,748       4,343,686
                                                 ---------------------------------------------------------------
    Total Net Cost Savings......................     -21,203,067     -15,113,425      -2,051,461      -1,055,127
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                                          Total Costs and Cost Savings
                                                    [2020 $]
----------------------------------------------------------------------------------------------------------------
                                                   Total U.S. (1) and foreign manufacturers (2) net cost savings
                                                 ---------------------------------------------------------------
                                                    20-Year total present value             Annualized
                                                 ---------------------------------------------------------------
                                                        7%              3%              7%              3%
----------------------------------------------------------------------------------------------------------------
Cost Savings....................................    $121,400,342    $189,845,930     $11,745,849     $13,253,881
Costs...........................................     107,601,677     136,818,641      10,410,787       9,551,840
                                                 ---------------------------------------------------------------
    Total Net Cost Savings......................      13,798,665      53,027,288       1,335,062       3,702,041
----------------------------------------------------------------------------------------------------------------
(1) Includes deliveries by U.S. manufacturers to U.S. operators and to foreign operators (2) Includes deliveries
  by foreign manufacturers to U.S. operators.

2. Who is potentially affected by this proposed rule?
    Manufacturers of part 25 transport category airplanes would be 
potentially affected by the proposed rule.
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    \10\ Includes U.S. manufacturers delivering to U.S. and foreign 
operators.
    \11\ Includes costs for foreign manufacturers deliveries to U.S. 
operators.
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3. Assumptions
     Totals converted to 2020 constant dollars.\12\
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    \12\ Costs were converted to 2020 dollars from 2015 dollars to 
be compliant with OMB guidance. Conversion used Bureau of Economic 
Analysis--Line 1 Gross Domestic Product from Table 1.1.9. Implicit 
Price Deflators for Gross Domestic Product, last revised on March 
25, 2021.
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     Time horizon for analysis 20 years.\13\
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    \13\ A 20-year time horizon was chosen to be inclusive of the 
19-year production cycle for large and the 15-year production cycle 
for small transport category airplanes.
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     Fifty percent of the $42.8 million annual costs for smoke 
emissions testing is incurred by domestic airplane manufacturers.\14\
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    \14\ Fifty percent is an estimate of the share of the worldwide 
transport airplane market held by U.S. manufacturers.
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     Seventeen percent \15\ of the $42.8 million annual costs 
for smoke emissions testing is incurred by non-U.S. manufacturers 
delivering airplanes to U.S. operators.
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    \15\ Seventeen percent is an estimate of the share of deliveries 
of the worldwide transport airplane market from foreign 
manufacturers to U.S. operators, obtained from the fleet analyzer 
database.
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     Cost savings from eliminating smoke emissions tests would 
increase linearly to the level of the current cost savings over 25 
years.\16\
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    \16\ Based on manufacturer recommendation.
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     One U.S. manufacturer of large and one U.S. manufacturer 
of other transport category aircraft.
     One foreign manufacturer of large and two foreign 
manufacturers of other transport category aircraft.
U.S. Manufacturers Delivering to U.S. Operators
Large Transport Category Airplanes \17\
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    \17\ Based on FAA analysis of Boeing data, OAG Aviation 
Solutions Fleet Database, FAA Type Certificate Data Sheet database.
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 Four type certificates over 20 years
 27 airplanes delivered annually per TC
 19-year production run
Other Transport Category Airplanes \18\
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    \18\ Other transport category airplanes are manufactured under 
part 25 and are other than large transport category airplanes.
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 Three type certificates over 15 years
 21 airplanes delivered annually per TC
 15-year production run
U.S. Manufacturers Delivering to Foreign Operators \19\
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    \19\ See appendix A for derivation of deliveries.
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Large Transport Category Airplanes
 Four type certificates over 20 years
 35 aircraft delivered annually per TC
 19-year production run

[[Page 55945]]

Other Transport Category Airplanes
 Three type certificates over 15 years
 14 airplanes delivered annually per TC
 15-year production run
Foreign Manufacturers Delivering to U.S. Operators
Large Transport Category Airplanes
 Two type certificates over 20 years
 16 airplanes delivered annually per TC
 19-year production run
Other Transport Category Airplanes
 Five type certificates over 15 years
 10-15 airplanes delivered annually per TC
 15-year production run
4. Benefits of the Rule
    The proposed new safety requirements to extend the fire protection 
requirements to any extensively used material \20\ located in 
inaccessible areas would result in a safety benefit by reducing the 
likelihood of a fatal accident from a fire in an inaccessible area. 
This benefit was not quantified. Even though there has not been a 
catastrophic in-flight fire of a passenger-carrying airplane since the 
Swissair accident in 1998, the continued occurrence of in-flight fire 
incidents and the growing number of devices using lithium-ion batteries 
increase the risk of a catastrophic accident, a risk that this proposal 
would reduce.
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    \20\ Extensively used materials, for the purpose of this 
rulemaking, means any parts or system of parts that could permit a 
fire to propagate and grow to a hazardous level, for example, air 
ducting, electrical wiring/sleeving, thermal/acoustic insulation, 
and composite fuselage structure.
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5. Costs of This Proposed Rule
    Over a 20-year period of analysis, the FAA estimates the total 
present value costs of this proposed rule to be $107.6 million at a 
seven percent discount rate, with annualized costs of $10.4 million, 
which would result from extending the standards developed for thermal/
acoustic insulation to all extensively used materials in inaccessible 
areas. A full explanation of how these costs were estimated may be 
found in the regulatory impact analysis accompanying this SNPRM.
    Over the same 20-year period, the FAA estimates the total 
quantified cost savings of this proposed rule to be $121.4 million at a 
seven percent discount rate, with annualized cost savings of $11.7 
million. The cost savings would result from the elimination and 
streamlining of some tests, which would be made possible by the 
extension of fire protection requirements to inaccessible areas. The 
total net cost savings of the proposed rule at a seven percent discount 
rate would be $13.8 million, with annualized net cost savings of $1.3 
million.
6. Minimal to No Cost Provisions Including Conforming Changes
    Numerous provisions within this proposal would result in minimal to 
no cost to possibly small cost savings. These include provisions that 
continue to accept previous test methods or current systems in addition 
to proposing new ones, those that maintain current requirements or 
current practice, and small edits to maintain consistency with the 
current rule. Also included are conforming changes to parts 27, 29, 
121, 125, 135, and appendix L to part 121. These sections make 
reference to, or require testing in accordance with, certain sections 
of appendix F to part 25. Because sections of appendix F would be 
removed, some changes refer to the new location of the requirements. 
For airplanes type certificated in accordance with the proposed 
requirements, this change would enable them to be in compliance with 
the operating rules, while allowing aircraft manufactured under 
existing type certificates and the current fleet to comply with the old 
requirements.
    Therefore, this proposed rule would impose no retrofit requirements 
on the current fleet or a production cut-in to aircraft manufactured 
under existing type certificates. Consequently, these provisions would 
impose minimal to no cost. Please see the RIA available in the docket 
for more details.

B. Regulatory Flexibility Determination

    The Regulatory Flexibility Act (RFA) of 1980, Public Law 96-354, 94 
Stat. 1164 (5 U.S.C. 601-612), as amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (Pub. L. 104-121, 110 Stat. 
857, Mar. 29, 1996) and the Small Business Jobs Act of 2010 (Pub. L. 
111-240, 124 Stat. 2504 Sept. 27, 2010), requires Federal agencies to 
consider the effects of the regulatory action on small business and 
other small entities and to minimize any significant economic impact. 
The term ``small entities'' comprises small businesses and not-for-
profit organizations that are independently owned and operated and are 
not dominant in their fields, and governmental jurisdictions with 
populations of less than 50,000.
    The FAA is publishing this Initial Regulatory Flexibility Analysis 
(IRFA) to aid the public in commenting on the potential impacts to 
small entities from this proposal. The FAA invites interested parties 
to submit data and information regarding the potential economic impact 
that would result from the proposal. The FAA will consider comments 
when making a determination or when completing a Final Regulatory 
Flexibility Analysis.
    Under section 603 (b) and (c) of the RFA, an IRFA must contain the 
following:
    (1) A description of the reasons why the action by the agency is 
being considered;
    (2) A succinct statement of the objective of, and legal basis for, 
the proposed rule;
    (3) A description of and, where feasible, an estimate of the number 
of small entities to which the proposed rule will apply;
    (4) A description of the projected reporting, recordkeeping, and 
other compliance requirements of the proposed rule, including an 
estimate of the classes of small entities which will be subject to the 
requirement and the type of professional skills necessary for 
preparation of the report or record;
    (5) An identification, to the extent practicable, of all relevant 
Federal rules that may duplicate, overlap, or conflict with the 
proposed rule; and
    (6) A description of any significant alternatives to the proposed 
rule which accomplish the stated objectives of applicable statutes and 
which minimize any significant economic impact of the proposed rule on 
small entities.
1. Reasons the Action Is Being Considered
    The FAA is issuing this proposal to simplify flammability 
regulations and provide a higher level of safety for transport category 
airplanes. The current regulations are complicated, sometimes 
conflicting, sometimes redundant, occasionally incomplete, and may be 
obsolete for dealing with present-day proposed airplanes. Simplifying 
these regulations can lead to cost savings.
    A key safety benefit of this proposal is the extension of fire 
protection requirements to any extensively used material located in 
inaccessible areas. FAA research found airplanes are at risk due to 
flammable materials in inaccessible areas. FAA testing has indicated 
that typical in-service ducts can quickly spread fire from a small fire 
source in an inaccessible area, while ducts that would meet the new 
requirement can resist that small size fire and not propagate flames. 
Also, due to the rapidly increasing number of

[[Page 55946]]

events due to lithium battery fires, the chances of a lithium battery 
fire in the cabin getting to an inaccessible area are increasing.
2. Objectives and Legal Basis of the Proposed Rule
    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 agency's authority.
    This rulemaking is issued 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, material, construction, quality of work, and 
performance of aircraft that the Administrator finds necessary for 
safety in air commerce. This proposed regulation is within the scope of 
that authority. It would revise the safety standards for the 
flammability characteristics, and thus the design, material, and 
construction, of transport category airplanes.
3. All Federal Rules That May Duplicate, Overlap, or Conflict
    There are no relevant Federal rules that may duplicate, overlap, or 
conflict with the proposed rule.
4. Description and Estimate of the Number of Small Entities
    The FAA used the definition of small entities in the RFA for this 
analysis. The RFA defines small entities as small businesses, small 
governmental jurisdictions, or small organizations. In 5 U.S.C. 601(3), 
the RFA defines ``small business'' to have the same meaning as ``small 
business concern'' under section 3 of the Small Business Act. The Small 
Business Act authorizes the Small Business Administration (SBA) to 
define ``small business'' by issuing regulations.
    SBA (2023) has established size standards for various types of 
economic activities, or industries, under the North American Industry 
Classification System (NAICS).\21\ These size standards generally 
define small businesses based on the number of employees or annual 
receipts.
---------------------------------------------------------------------------

    \21\ Small Business Administration (SBA). 2023. Table of Size 
Standards. Effective Mar 17, 2023. Accessible at www.sba.gov/document/support--table-size-standards.
---------------------------------------------------------------------------

    This proposal would affect U.S. manufacturers of part 25 transport 
category airplanes requesting a new or amended type certificate. 
According to the small business administration, the size standard for 
aircraft manufacturers (NAICS code 336411) to be considered a small 
business is 1,500 employees or less. None of the manufacturers who 
manufacture transport category airplanes have fewer than 1,500 
employees; therefore, none of them are small businesses.
    The proposal might also indirectly affect businesses that modify 
transport category airplanes. At this time, the FAA has not identified 
any affected small entities without larger U.S. or foreign ownership or 
business relationships. The FAA requests comments on this finding.
5. Projected Reporting, Recordkeeping, and Other Compliance 
Requirements
    Requirements are governed by 14 CFR part 21 and are not changing 
with this proposal. Applicants are required to show compliance under 
Sec.  21.20, and this will continue to apply. Therefore, the proposal 
would not impose additional reporting, recordkeeping, or other 
compliance requirements on small entities.
6. Significant Alternatives Considered
    The FAA considered two alternatives to the proposed rule. The first 
alternative was to not make any changes to the fire protection 
requirements. This would leave in place complicated, sometimes 
conflicting, sometimes redundant, occasionally incomplete, and 
potentially obsolete regulations.
    Cost savings would not be achieved. This alternative would also not 
extend fire protection requirements to extensively used materials 
located in inaccessible areas. This would leave airplanes at risk due 
to flammability materials in inaccessible areas.
    The FAA also considered making only some of the proposed changes; 
however, this would provide limited benefit and no safety improvement. 
This is because the significant safety improvements facilitate the 
significant simplifications in the proposal. Without the safety 
enhancements, the amount of simplification would be limited. If the FAA 
proposed only the safety enhancements, the resulting cost would be 
difficult to quantitatively balance against the resulting safety 
improvement. The proposal intends to achieve a significant reduction in 
costs and simplify the requirements, while substantively improving 
safety.
    The FAA expects this proposal would 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 proposed rule and 
determined that it does not exclude imports that meet the safety 
objective. As a result, this proposed rule is not considered as 
creating an unnecessary obstacle to foreign commerce.
    The proposed rule would impose the same costs and cost savings on 
domestic and international manufacturers selling airplanes to airlines 
that wish to operate within the United States because U.S.-registered 
transport category airplanes must comply with part 25 in order to be 
operated within the United States.
    Therefore, the same cost relief would accrue to all manufacturers 
selling airplanes to airlines operating within the U.S. However, the 
effect this proposed rule would have on sales of domestically produced 
airplanes relative to airplanes produced by foreign companies to 
airlines operating abroad and not in the U.S. might be either an 
advantage due to cost savings or a disadvantage due to increased costs, 
depending on the standards to which foreign airplanes are manufactured.

D. Unfunded Mandates Assessment

    The Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1531-1538) 
governs the issuance of Federal regulations that require unfunded 
mandates. An unfunded mandate is a regulation that requires a state, 
local, or Tribal government or the private sector to incur direct costs 
without the Federal government having first provided the funds to pay 
those costs. The FAA determined that the proposed rule will not result 
in the expenditure of $177,000,000 or more by State, local, or Tribal 
governments, in the aggregate, or the private sector, in any one year.

[[Page 55947]]

    This proposed 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 would be no new requirement for information collection associated 
with the previously published NPRM or this SNPRM.

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 proposed regulations.

G. Environmental Analysis

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

IV. Executive Order Determinations

A. Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and 
criteria of Executive Order 13132, Federalism. The agency has 
determined that this action would 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, would 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,\22\ and FAA Order 1210.20, 
American Indian and Alaska Native Tribal Consultation Policy and 
Procedures,\23\ 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.
---------------------------------------------------------------------------

    \22\ 65 FR 67249 (Nov. 6, 2000).
    \23\ FAA Order No. 1210.20 (Jan. 28, 2004), available at https://www.faa.gov/documentLibrary/media/1210.pdf.
---------------------------------------------------------------------------

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

    The FAA analyzed this proposed rule under Executive Order 13211, 
Actions Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). The agency has determined that it 
would not be a ``significant energy action'' under the executive order 
and would not be likely to have a significant adverse effect on the 
supply, distribution, or use of energy.

D. International 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 would have 
no effect on international regulatory cooperation.

V. Additional Information

A. Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The agency 
also invites comments relating to the economic, environmental, energy, 
or federalism impacts that might result from adopting the proposals in 
this document. The most helpful comments reference a specific portion 
of the proposal, explain the reason for any recommended change, and 
include supporting data. To ensure the docket does not contain 
duplicate comments, commenters should send only one copy of written 
comments, or if comments are filed electronically, commenters should 
submit only one time.
    The FAA will file in the docket all comments it receives, as well 
as a report summarizing each substantive public contact with FAA 
personnel concerning this proposed rulemaking. Before acting on this 
proposal, the FAA will consider all comments it receives on or before 
the closing date for comments. The FAA will consider comments filed 
after the comment period has closed if it is possible to do so without 
incurring expense or delay. The agency may change this proposal in 
light of the comments it receives.
    Proprietary or Confidential Business Information: Do not file 
proprietary or confidential business information in the docket. Such 
information must be sent or delivered directly to the person identified 
in the FOR FURTHER INFORMATION CONTACT section of this document, and 
marked as proprietary or confidential. If submitting information on a 
disk or CD ROM, mark the outside of the disk or CD ROM, and identify 
electronically within the disk or CD ROM the specific information that 
is proprietary or confidential.
    Under 14 CFR 11.35(b), if the FAA is aware of proprietary 
information filed with a comment, the agency does not place it in the 
docket. It is held in a separate file to which the public does not have 
access, and the FAA places a note in the docket that it has received 
it. If the FAA receives a request to examine or copy this information, 
it treats it as any other request under the Freedom of Information Act 
(5 U.S.C. 552). The FAA processes such a request under Department of 
Transportation procedures found in 49 CFR part 7.

B. Availability of Rulemaking Documents

    An electronic copy of a rulemaking document may be obtained by 
using the internet--
    1. Search the Federal eRulemaking Portal (www.regulations.gov);
    2. Visit the FAA's Regulations and Policies web page at 
www.faa.gov/regulations_policies/; or
    3. Access the Government Printing Office's web page at 
www.GovInfo.gov.
    Copies may also be obtained by sending a request (identified by 
notice or docket number of this rulemaking) to the Federal Aviation 
Administration, Office of Rulemaking, ARM-1, 800 Independence Avenue 
SW, Washington, DC 20591, or by calling (202) 267-9680.
    All documents the FAA considered in developing this proposed rule, 
including economic analyses and technical reports, may be accessed from 
the internet through the Federal eRulemaking Portal referenced in item 
(1) above.

[[Page 55948]]

List of Subjects

14 CFR Part 25

    Aircraft, Aviation safety, Navigation (air), Reporting and 
recordkeeping requirements.

14 CFR Part 27

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 29

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 91

    Afghanistan, Agriculture, Air carriers, Air taxis, Air traffic 
control, Aircraft, Airmen, Airports, Alaska, Aviation safety, Canada, 
Charter flights, Cuba, Drug traffic control, Ethiopia, Freight, Iraq, 
Libya, Mexico, Noise control, North Korea, Political candidates, 
Reporting and recordkeeping requirements, Security measures, Somalia, 
Syria, Transportation, Yugoslavia.

14 CFR Part 121

    Air carriers, Aircraft, Airmen, Alcohol abuse, Aviation safety, 
Charter flights, Drug abuse, Drug testing, Reporting and recordkeeping 
requirements, Safety, Transportation.

14 CFR Part 125

    Aircraft, Airmen, Aviation Safety, Reporting and recordkeeping 
requirements.

14 CFR Part 135

    Air taxis, Aircraft, Airmen, Alcohol abuse, Aviation Safety, Drug 
abuse, Drug testing, Reporting and recordkeeping requirements.

The Proposed Amendments

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend 14 CFR as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

0
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.

0
2. Amend Special Federal Aviation Regulation No. 109 to part 25 by 
revising paragraphs 12 and 14(e) to read as follows:

Special Federal Aviation Regulation No. 109

* * * * *
    12. Materials for Compartment Interiors. An applicant must comply 
with the applicable provisions of Sec.  25.853, except that 
demonstration of compliance with Sec.  25.853(d)(2) is not required if 
the applicant can show by test, or a combination of test and analysis, 
that the maximum time for evacuation of all occupants does not exceed 
45 seconds under the conditions specified in appendix J to part 25.
* * * * *
    14. * * *
    (e) The surfaces of the galley surrounding the cooktop that would 
be exposed to a fire on the cooktop surface or in cookware on the 
cooktop must be constructed of materials that comply with the 
flammability requirements of Sec.  25.853(c)(2)(ii). This requirement 
is in addition to the flammability requirements typically required of 
the materials in these galley surfaces. During the selection of these 
materials, an applicant must account for the flammability 
characteristics of the materials to ensure these characteristics will 
not be adversely affected by the use of cleaning agents and utensils 
used to remove cooking stains.
* * * * *
0
3. Revise Sec.  25.853 to read as follows:

Sec.  25.853  Interior parts and components fire protection.

    (a) Each airplane part, component, and assembly must protect the 
airplane and its occupants from in-flight and post-crash fire threats. 
For the purposes of this section an airplane part, component, or 
assembly is one that is located within, and including, the fuselage.
    (b) Except as provided in paragraph (e) of this section, an 
applicant must conduct tests to show compliance with paragraphs (c) and 
(d) of this section. Except as provided in paragraph (c)(1)(ii) of this 
section, for any tests used to show compliance, the applicant must use 
a minimum of three specimen sets.
    (c) In-flight requirements. During an in-flight fire, the 
flammability characteristics of each part, component, and assembly must 
not present a hazard to the occupants and must not prevent the 
continued safe flight and landing of the airplane.
    (1) Accessible areas.
    (i) Each part, component, and assembly that is accessible to the 
flightcrew during flight must be self-extinguishing when exposed to a 
small flame.
    (ii) Each receptacle used for the disposal of flammable waste 
material must be fully enclosed, constructed of materials that resist 
penetration from a small ignition source, and must contain fires likely 
to occur in it under normal use. At least one test must show the 
capability of the receptacle to contain those fires under all probable 
conditions of wear, misalignment, and ventilation expected in service.
    (iii) Each ceiling and sidewall liner of a Class B cargo 
compartment must resist penetration by a small flame.
    (2) Inaccessible areas.
    (i) Each extensively used airplane part, component, and assembly 
that is not accessible to the flightcrew during flight but that could 
be subjected to an in-flight fire must not propagate the largest fire 
that, by itself, would not be a hazard to the airplane.
    (ii) Each ceiling and sidewall liner of a Class F cargo 
compartment, if installed to meet the requirements of Sec.  
25.855(b)(2), and of a Class C cargo compartment must resist 
penetration by a fire within that compartment and must protect the 
airplane's structure and critical systems from the effects of that 
fire.
    (iii) Each ceiling and sidewall liner of a Class E cargo 
compartment must resist penetration by a fire within that compartment 
and must protect the airplane's structure and critical systems from the 
effects of that fire, unless the design provides a means other than a 
liner that protects the airplane's structure and critical systems from 
the effects of that fire.
    (iv) The floor liner of any class of cargo compartment, and any 
ceiling and sidewall liner of a Class E cargo compartment, must resist 
penetration by a small flame.
    (v) All other parts, components, and assemblies that are not 
accessible by the flightcrew during flight must be self-extinguishing 
when exposed to a small flame or electrical arc.
    (d) Post-crash requirements. During a post-crash fuel fire, the 
flammability characteristics of each part, component, and assembly must 
maintain survivable cabin conditions for enough time to allow 
evacuation.
    (1) For airplanes with a passenger capacity of 19 or less, each 
large surface in the passenger cabin must be self-extinguishing when 
exposed to a small flame for at least 60 seconds.
    (2) For airplanes with a passenger capacity of 20 or more, each 
large surface in the passenger cabin must resist involvement in a post-
crash fuel fire that has entered the fuselage, except:
    (i) A large surface, no part of which is more than 15'' above the 
floor, need not comply with paragraph (d)(2) of this section if it is 
located in such a manner that it would not be directly exposed to the 
effects of a post-crash fuel fire.

[[Page 55949]]

    (ii) A large surface in the interior of a compartment other than a 
cargo or baggage compartment need not comply with paragraph (d)(2) of 
this section if the interior of the compartment is isolated from the 
main passenger cabin by doors or equivalent means that would normally 
be closed during taxi, takeoff, and landing.
    (3) Each cushion used to support the occupant of a seat or berth 
must resist involvement in a post-crash fuel fire that has entered the 
airplane, and must not propagate that fire.
    (4) In addition to resisting involvement in a post-crash fuel fire 
that has entered the airplane, each flammable metal must be readily 
extinguishable.
    (5) The design must ensure the continued function of all escape 
systems when those systems are exposed to the effects of radiant heat 
from a post-crash fuel fire.
    (e) Exceptions. A part, component, and assembly does not require 
testing to meet the requirements specified in paragraph (c) or (d) of 
this section if it meets the criteria of at least one of the following 
classes:
    (1) Class 1. Parts, components, and assemblies that would each fit 
within a cube measuring two inches on each side and are sufficiently 
separated from the same type of part, component, or assembly such that 
collectively they will not propagate a fire.
    (2) Class 2. Parts, components, and assemblies that are not 
extensively used, are made from materials that are self-extinguishing, 
do not individually exceed a volume of 113 cubic inches, have an 
exposed surface area not exceeding 200 square inches, and do not 
propagate a flame vertically.
    (3) Class 3. Parts, components, and assemblies that applicants can 
show, through a method acceptable to the Administrator, are a size, 
construction, or location that their flammability characteristics do 
not threaten the airplane or its occupants.
    (4) Class 4. Parts, components, and assemblies that are essential 
to the safety of the airplane, its occupants, or the functionality of 
the airplane and cannot reasonably be constructed of a less flammable 
material without compromising the integrity or functionality of that 
part, component, or assembly.
    (5) Class 5. Parts, components, and assemblies that have 
successfully met one or more of the alternate requirements, including 
any applicable conditions, set forth in appendix F to part 25.
    (f) Smoking.
    (1) Smoking is not allowed in lavatories. If smoking is allowed in 
any area occupied by the crew or passengers, an adequate number of 
self-contained, removable ashtrays must be provided in designated 
smoking sections for all seated occupants.
    (2) Regardless of whether smoking is allowed in any other part of 
the airplane, lavatories must have self-contained, removable ashtrays 
located conspicuously on or near the entry side of each lavatory door, 
except that one ashtray may serve more than one lavatory door if the 
ashtray can be seen readily from the cabin side of each lavatory 
served.
0
4. Amend Sec.  25.855 by revising paragraphs (c) and (d) to read as 
follows:

Sec.  25.855  Cargo or baggage compartments.

* * * * *
    (c) Cargo compartment liners must comply with the applicable 
provisions of Sec.  25.853.
    (d) All other materials used in the construction of the cargo or 
baggage compartment, other than material located entirely within a 
Class C cargo or baggage compartment, must be self-extinguishing when 
exposed to a small flame.
* * * * *
0
5. Revise Sec.  25.856 to read as follows:

Sec.  25.856  Thermal/Acoustic insulation materials.

    (a) All thermal/acoustic insulation material installed in 
inaccessible areas of the fuselage must comply with Sec.  
25.853(c)(2)(i) unless it qualifies for one of the exceptions in Sec.  
25.853(e).
    (b) For airplanes with a passenger capacity of 20 or more, all 
thermal/acoustic insulation materials installed in the lower half of 
the airplane fuselage must resist penetration of a post-crash fuel fire 
and provide a minimum of 5 minutes survivability in the occupied 
portions of the airplane, unless the applicant provides an equivalent 
means of post-crash fire penetration protection. This requirement does 
not apply to thermal/acoustic insulation installations that the 
Administrator finds would not contribute to fire penetration 
resistance. For the purposes of this paragraph, thermal/acoustic 
insulation materials include the means of fastening the materials to 
the fuselage.
0
6. Amend Sec.  25.1713 by revising paragraph (c) and adding paragraph 
(d) to read as follows:

Sec.  25.171  3 Fire protection: EWIS.

* * * * *
    (c) All insulation on electrical wire and electrical cable, and all 
materials used to provide additional protection for that wire and 
cable:
    (1) If installed in any area outside of the fuselage, must not 
propagate the largest fire that, by itself, would not be a hazard to 
the airplane, and
    (2) If installed in any area within the fuselage, must meet the 
requirements of Sec.  25.853(c), unless it meets the requirements of 
paragraph (c)(1) of this section.
    (d) To show compliance with paragraph (c) of this section, an 
applicant must conduct tests, unless the applicant can show that the 
insulation and materials are of a size, location, and quantity that 
their flammability characteristics do not threaten the airplane or its 
occupants. For any tests used to show compliance, the applicant must 
use a minimum of three specimen sets.
0
7. Revise appendix F to part 25 to read as follows:

Appendix F to Part 25--Flammability Test Hierarchy

    Applicants may substitute compliance with the standards in the 
first row of the table below by meeting the standards in the first 
column, as indicated at the appropriate intersection, subject to the 
noted conditions:

[[Page 55950]]

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        Standard
                              --------------------------------------------------------------------------------------------------------------------------
                                                                                                                    In-flight cargo
                                    In-flight         Post-crash <20;      In-flight cargo         In-flight          liner fire
         Substitution           accessible; small      small ignition     liner; small flame  inaccessible; fire      penetration      Seat cushion fire
                                 flame resistance     resistance Sec.        penetration       propagation Sec.     resistance Sec.     resistance Sec.
                                  Sec.   25.853        25.853 (d)(1)       resistance Sec.     25.853 (c)(2)(i)   25.853 (c)(2)(ii)/     25.853 (d)(3)
                                    (c)(1)(i)                             25.853 (c)(1)(iii)                             (iii)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Post-crash <20; small          Yes................  No.................  No.................  No................  No................  No.
 ignition resistance Sec.
 25.853(d)(1).
In-flight inaccessible; fire   Yes................  Yes................  No.................  No................  No................  No.
 propagation Sec.
 25.853(c)(2)(i).
Post-crash >=20; large         Yes................  Yes................  No.................  Note 1............  No................  Note 2.
 surface fire resistance Sec.
   25.853(d)(2).
Seat cushion fire resistance   Yes................  Yes................  No.................  No................  No................  No.
 Sec.   25.853(d)(3).
Post-crash >=20; fire          Yes................  Yes................  Yes................  No................  Yes...............  No.
 penetration resistance Sec.
  25.853(b)(2).
In-flight cargo liner fire     Yes................  Yes................  Yes................  Note 3............  No................  No.
 penetration resistance Sec.
  25.853(c)(2)(ii)/(iii).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
\1\ When the facesheet on the back (inaccessible) side of the large surface is of the same material system as the facesheet on the front side.
\2\ When the cushion does not directly support the occupant and can be tested in its actual thickness.
\3\ When the back side of the liner is made from glass fiber reinforced epoxy and phenolic resin.

PART 27--AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT

0
8. The authority citation for part 27 continues to read as follows:

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

0
9. Amend Sec.  27.1365 by revising paragraph (c) to read as follows:

Sec.  27.1365  Electric cables.

* * * * *
    (c) Insulation on electrical wire and cable installed in the 
rotorcraft must be self-extinguishing when tested in accordance with 
appendix F, part I(a)(3), of part 25 of this chapter at amendment 25-
138.

PART 29--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT

0
10. The authority citation for part 29 continues to read as follows:

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

0
11. Amend Sec.  29.853 by revising paragraphs (a) and (b) to read as 
follows:

Sec.  29.853  Compartment interiors.

* * * * *
    (a) The materials (including finishes or decorative surfaces 
applied to the materials) must meet the following test criteria as 
applicable:
    (1) Interior ceiling panels, interior wall panels, partitions, 
galley structure, large cabinet walls, structural flooring, and 
materials used in the construction of stowage compartments (other than 
underseat stowage compartments and compartments for stowing small items 
such as magazines and maps) must be self-extinguishing when tested 
vertically in accordance with the applicable portions of appendix F to 
part 25 of this chapter at amendment 25-138, or other approved 
equivalent methods.
    (2) Floor covering, textiles (including draperies and upholstery), 
seat cushions, padding, decorative and non-decorative coated fabrics, 
leather, trays and galley furnishings, electrical conduit, thermal and 
acoustical insulation and insulation covering, air ducting joint and 
edge covering, cargo compartment liners, insulation blankets, cargo 
covers, and transparencies, molded and thermoformed parts, air ducting 
joints, and trim strips (decorative and chafing) that are constructed 
of materials not covered in paragraph (a)(3) of this section, must be 
self-extinguishing when tested vertically in accordance with the 
applicable portion of appendix F to part 25 of this chapter at 
amendment 25-138, or other approved equivalent methods.
    (3) Acrylic windows and signs, parts constructed in whole or in 
part of elasto-metric materials, edge lighted instrument assemblies 
consisting of two or more instruments in a common housing, seat belts, 
shoulder harnesses, and cargo and baggage tiedown equipment, including 
containers, bins, pallets, etc., used in passenger or crew 
compartments, may not have an average burn rate greater than 2.5 inches 
per minute when tested horizontally in accordance with the applicable 
portions of appendix F to part 25 of this chapter at amendment 25-138, 
or other equivalent methods that the Administrator approves.
    (4) Except for electrical wire and cable insulation, and for small 
parts (such as knobs, handles, rollers, fasteners, clips, grommets, rub 
strips, pulleys, and small electrical parts) that the Administrator 
finds would not contribute significantly to the propagation of a fire, 
materials in items not specified in paragraph (a)(1), (2), or (3) of 
this section may not have a burn rate greater than 4 inches per minute 
when tested horizontally in accordance with the applicable portions of 
appendix F to part 25 of this chapter at amendment 25-138, or other 
equivalent methods that the Administrator approves.
    (b) In addition to meeting the requirements of paragraph (a)(2) of 
this section, seat cushions, except those on flight crewmember seats, 
must meet the test requirements of part II of appendix F to part 25 of 
this chapter at amendment 25-138, or equivalent.
* * * * *
0
12. Amend Sec.  29.1359 by revising paragraph (c) to read as follows:

Sec.  29.1359  Electrical system fire and smoke protection.

* * * * *
    (c) Insulation on electrical wire and cable installed in the 
rotorcraft must be self-extinguishing when tested in accordance with 
appendix F, part I(a)(3), of part 25 of this chapter at amendment 25-
138.

PART 91--GENERAL OPERATING AND FLIGHT RULES

0
13. The authority citation for part 91 continues to read as follows:

    Authority:  49 U.S.C. 106(f), 106(g), 40101, 40103, 40105, 
40113, 40120, 44101, 44111,

[[Page 55951]]

44701, 44704, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 
46306, 46315, 46316, 46504, 46506-46507, 47122, 47508, 47528-47531, 
47534, Pub. L. 114-190, 130 Stat. 615 (49 U.S.C. 44703 note); 
articles 12 and 29 of the Convention on International Civil Aviation 
(61 Stat. 1180), (126 Stat. 11).

0
14. Amend Sec.  91.613 by revising paragraphs (b)(1) introductory text 
and (b)(2) to read as follows:

Sec.  91.613  Materials for compartment interiors.

* * * * *
    (b) * * *
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation is installed in the fuselage as 
replacements after September 2, 2005, the insulation must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended, if it is:
* * * * *
    (2) For airplanes manufactured after September 2, 2005, thermal/
acoustic insulation materials installed in the fuselage must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended.

PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL 
OPERATIONS

0
15. The authority citation for part 121 continues to read as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40103, 40113, 40119, 41706, 
42301 preceding note added by Pub. L. 112-95, sec. 412, 126 Stat. 
89, 44101, 44701-44702, 44705, 44709-44711, 44713, 44716-44717, 
44722, 44729, 44732; 46105; Pub. L. 111-216, 124 Stat. 2348 (49 
U.S.C. 44701 note); Pub. L. 112-95, 126 Stat 62 (49 U.S.C. 44732 
note); Pub. L. 115-254; 132 Stat. 3186 (49. U.S.C. 44701 note).

0
16. Amend Sec.  121.312 by revising paragraphs (b) introductory text, 
(e)(1) introductory text, and paragraphs (e)(2) and (3) to read as 
follows:

Sec.  121.312  Materials for compartment interiors.

* * * * *
    (b) Seat cushions. Seat cushions, except those on flight crewmember 
seats, in each compartment occupied by crew or passengers, must comply 
with the requirements pertaining to seat cushions in Sec.  25.853(c) 
effective on November 26, 1984, or in Sec.  25.853(d) effective on 
[EFFECTIVE DATE OF FINAL RULE] or as subsequently amended, on each 
airplane as follows:
* * * * *
    (e) * * *
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation is installed in the fuselage as 
replacements after September 2, 2005, the insulation must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended, if it is:
* * * * *
    (2) For airplanes manufactured after September 2, 2005, thermal/
acoustic insulation materials installed in the fuselage must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended.
    (3) For airplanes with a passenger capacity of 20 or greater, 
manufactured after September 2, 2009, thermal/acoustic insulation 
materials installed in the lower half of the fuselage must meet the 
flame penetration resistance requirements of Sec.  25.856 of this 
chapter, effective September 2, 2003 or as subsequently amended. If the 
airplane's type design was approved based on a finding of equivalent 
level of safety to Sec.  25.856 in accordance with Sec.  21.21(b)(1) of 
this chapter, the certificate holder is in compliance with this section 
of this part as long as the aircraft conforms to the approved type 
design.
0
17. Amend Sec.  121.314 by revising paragraph (a)(2) to read as 
follows:

Sec.  121.314  Cargo and baggage compartments.

* * * * *
    (a) * * *
    (2) Materials that meet the test requirements of part 25, appendix 
F, part III of this chapter effective on June 16, 1986, or the test 
requirements of Sec.  25.853(c)(2)(ii) of this chapter effective on 
[EFFECTIVE DATE OF FINAL RULE] or as subsequently amended; or
* * * * *
0
18. Revise appendix L to part 121 to read as follows:

Appendix L to Part 121--Type Certification Regulations Made Previously 
Effective

    (a) Appendix L lists regulations in this part that require 
compliance with standards contained in superseded type certification 
regulations that continue to apply to certain transport category 
airplanes. The table below sets out citations to the current CFR 
section, applicable aircraft, superseded type certification 
regulation and applicable time periods, and the CFR edition and 
Federal Register documents where the regulation having prior effect 
is found. Copies of all superseded regulations may be obtained at 
the Federal Aviation Administration Law Library, Room 924, 800 
Independence Avenue SW, Washington, DC.

------------------------------------------------------------------------
                                    Applicable       Provisions: CFR/FR
       Part 121 section              aircraft            references
------------------------------------------------------------------------
Sec.   121.312(a)(1)(i).......  Transport          Heat release rate
                                 category; or       testing. 14 CFR
                                 nontransport       25.853(d)(2)
                                 category type      effective [effective
                                 certificated       date of final rule]:
                                 before January     14 CFR parts 1 to
                                 1, 1965;           59, Revised as of
                                 passenger          January 1, [Federal
                                 capacity of 20     Register revision
                                 or more;           year], and amended
                                 manufactured       by Amdt. [amendment
                                 prior to August    level and Federal
                                 20, 1990.          Register citation
                                                    and publication date
                                                    of final rule].
                                                   Formerly 14 CFR
                                                    25.853(d) effective
                                                    March 6, 1995: 14
                                                    CFR parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1995, and
                                                    amended by Amdt. 25-
                                                    83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a-1)
                                                    effective August 20,
                                                    1986: 14 CFR parts 1
                                                    to 59, Revised as of
                                                    January 1, 1986.

[[Page 55952]]

 
Sec.   121.312(a)(1)(ii)......  Transport          Heat release rate
                                 category; or       testing. 14 CFR
                                 nontransport       25.853(d)(2)
                                 category type      effective [effective
                                 certificated       date of final rule]:
                                 before January     14 CFR parts 1 to
                                 1, 1965;           59, Revised as of
                                 passenger          January 1, [Federal
                                 capacity of 20     Register revision
                                 or more;           year], and amended
                                 manufactured       by Amdt. [amendment
                                 after August 19,   level and Federal
                                 1990.              Register citation
                                                    and publication date
                                                    of the final rule].
                                                   Formerly 14 CFR
                                                    25.853(d) effective
                                                    March 6, 1995: 14
                                                    CFR parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1995, and
                                                    amended by Amdt. 25-
                                                    83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a-1)
                                                    effective September
                                                    26, 1988: 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1988, and
                                                    amended by Amdt. 25-
                                                    66, 53 FR 32584,
                                                    August 25, 1988.
                                                   Smoke testing. 14 CFR
                                                    25.853(d) effective
                                                    March 6, 1995: 14
                                                    CFR parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1995, and
                                                    amended by Amdt. 25-
                                                    83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a-1)
                                                    effective September
                                                    26, 1988: 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1988, and
                                                    amended by Amdt. 25-
                                                    66, 53 FR 32584,
                                                    August 25, 1988.
Sec.   121.312(a)(2)(i).......  Transport          Provisions of 14 CFR
                                 category; or       25.853 in effect on
                                 nontransport       April 30, 1972: 14
                                 category type      CFR parts 1 to 59,
                                 certificate        Revised as of
                                 before January     January 1, 1972.
                                 1, 1965;
                                 application for
                                 type certificate
                                 filed prior to
                                 May 1, 1972;
                                 substantially
                                 complete
                                 replacement of
                                 cabin interior
                                 on or after May
                                 1, 1972.
Sec.   121.312(a)(3)(i).......  Transport          Heat release rate
                                 category type      testing. 14 CFR
                                 certificated       25.853(d) in effect
                                 after January 1,   March 6, 1995: 14
                                 1958;              CFR parts 1 to 59,
                                 nontransport       Revised as of
                                 category type      January 1, 1995; and
                                 certificated       amended by Amdt. 25-
                                 after January 1,   83, 60 FR 6623,
                                 1958, but before   February 2, 1995.
                                 January 1, 1965;  Formerly 14 CFR
                                 passenger          25.853(a-1) in
                                 capacity of 20     effect August 20,
                                 or more;           1986: 14 CFR parts 1
                                 substantially      to 59, Revised as of
                                 complete           January 1, 1986.
                                 replacement of
                                 the cabin
                                 interior on or
                                 after March 6,
                                 1995.
Sec.   121.312(a)(3)(ii)......  Transport          Heat release rate
                                 category type      testing. 14 CFR
                                 certificated       25.853(d)(2)
                                 after January 1,   effective [effective
                                 1958;              date of the final
                                 nontransport       rule]: 14 CFR parts
                                 category type      1 to 59, Revised as
                                 certificated       of January 1,
                                 after January 1,   [Federal Register
                                 1958, but before   revision year], and
                                 January 1, 1965;   amended by Amdt.
                                 passenger          [amendment level and
                                 capacity of 20     Federal Register
                                 or more;           citation and
                                 substantially      publication date of
                                 complete           the final rule].
                                 replacement of    Formerly 14 CFR
                                 the cabin          25.853(d) effective
                                 interior on or     March 6, 1995: 14
                                 after August 20,   CFR parts 1 to 59,
                                 1990.              Revised as of
                                                    January 1, 1995, and
                                                    amended by Amdt. 25-
                                                    83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a-1)
                                                    effective September
                                                    26, 1988: 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1988, and
                                                    amended by Amdt. 25-
                                                    66, 53 FR 32584,
                                                    August 25, 1988.
                                                   Smoke testing. 14 CFR
                                                    25.853(d) effective
                                                    March 6, 1995; 14
                                                    CFR parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1995; and
                                                    amended by Amdt. 25-
                                                    83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a-1)
                                                    effective September
                                                    26, 1988: 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1988, and
                                                    amended by Amdt. 25-
                                                    66, 53 FR 32584,
                                                    August 25, 1988.
Sec.   121.312(b)(1) and (2)..  Transport          Seat cushions. 14 CFR
                                 category           25.853(d)(3)
                                 airplane type      effective [effective
                                 certificated       date of the final
                                 after January 1,   rule]: 14 CFR parts
                                 1958;              1 to 59, Revised as
                                 nontransport       of January 1,
                                 category           [Federal Register
                                 airplane type      revision year], and
                                 certificated       amended by Amdt.
                                 after December     [amendment level and
                                 31, 1964.          Federal Register
                                                    citation and
                                                    publication date of
                                                    the final rule].
                                                   Formerly 14 CFR
                                                    25.853(c) effective
                                                    November 26, 1984:
                                                    14 CFR parts 1 to
                                                    59, Revised as of
                                                    January 1, 1984, and
                                                    amended by Amdt. 25-
                                                    59, 49 FR 43188,
                                                    October 26, 1984.
Sec.   121.312(c).............  Airplane type      Compartment interior
                                 certificated in    requirements. 14 CFR
                                 accordance with    25.853(a) in effect
                                 SFAR No. 41;       March 6, 1995: 14
                                 maximum            CFR parts 1 to 59,
                                 certificated       Revised as of
                                 takeoff weight     January 1, 1995, and
                                 in excess of       amended by Amdt. 25-
                                 12,500 pounds.     83, 60 FR 6623,
                                                    February 2, 1995.
                                                   Formerly 14 CFR
                                                    25.853(a), (b-1), (b-
                                                    2), and (b-3) in
                                                    effect on September
                                                    26, 1978: 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, 1978.
Sec.   121.314(a).............  Transport          Class C or D cargo or
                                 category           baggage compartment
                                 airplanes type     definition. 14 CFR
                                 certificated       25.853(c)(2)(ii)
                                 after January 1,   effective [the
                                 1958.              effective date of
                                                    the final rule]
                                                    (part III of
                                                    appendix F no longer
                                                    exists): 14 CFR
                                                    parts 1 to 59,
                                                    Revised as of
                                                    January 1, [Federal
                                                    Register revision
                                                    year], and amended
                                                    by Amdt. [amendment
                                                    level and Federal
                                                    Register citation
                                                    and publication date
                                                    of the final rule].
                                                   Formerly 14 CFR
                                                    25.857 effective
                                                    June 16, 1986, 14
                                                    CFR parts 1 to 59,
                                                    Revised January 1,
                                                    1997, and amended by
                                                    Amdt. 25-60, 51 FR
                                                    18243, May 16, 1986.
------------------------------------------------------------------------

[[Page 55953]]

    (b) For the purposes of compliance with the sections of 14 CFR 
part 25 referenced in the table in paragraph (a) of this appendix, 
findings of equivalent level of safety in accordance with Sec.  
21.21(b)(1) of this chapter are considered to satisfy the referenced 
requirement.

PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING 
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 
6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH 
AIRCRAFT

0
19. The authority citation for part 125 continues to read as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44705, 
44710-44711, 44713, 44716-44717, 44722.

0
20. Amend Sec.  125.113 by revising paragraphs (c)(1) introductory text 
and paragraph (c)(2) to read as follows:

Sec.  125.113  Cabin interiors.

* * * * *
    (c) * * *
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation is installed in the fuselage as 
replacements after September 2, 2005, the insulation must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended, if it is:
* * * * *
    (2) For airplanes manufactured after September 2, 2005, thermal/
acoustic insulation materials installed in the fuselage must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended.

PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS 
AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT

0
21. The authority citation for part 135 continues to read as follows:

    Authority:  49 U.S.C. 106(f), 106(g), 40113, 41706, 44701-44702, 
44705, 44709, 44711-44713, 44715-44717, 44722, 44730, 45101-45105; 
Pub. L. 112-95, 126 Stat. 58 (49 U.S.C. 44730).

0
22. Amend Sec.  135.169 by revising paragraph (d)(1)(ii) to read as 
follows:

Sec.  135.169  Additional airworthiness requirements.

* * * * *
    (d) * * *
    (1) * * *
    (ii) Materials that meet the test requirements of part 25, appendix 
F, part III of this chapter effective on June 16, 1986, or the test 
requirements of Sec.  25.853(c)(2)(ii) of this chapter effective on 
[EFFECTIVE DATE OF FINAL RULE] or as subsequently amended; or
* * * * *
0
23. Amend Sec.  135.170 by revising paragraphs (b)(2), (c)(1) 
introductory text, and paragraph (c)(2) to read as follows:

Sec.  135.170  Materials for compartment interiors.

* * * * *
    (b) * * *
    (2) For airplanes type certificated after January 1, 1958, seat 
cushions, except those on flight crewmember seats, in any compartment 
occupied by crew or passengers must comply with the requirements 
pertaining to fire protection of seat cushions in Sec.  25.853(c) 
effective November 26, 1984, or in Sec.  25.853(d) effective on 
[EFFECTIVE DATE OF FINAL RULE] or as subsequently amended.
    (c) * * *
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation is installed in the fuselage as 
replacements after September 2, 2005, the insulation must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended, if it is:
* * * * *
    (2) For airplanes manufactured after September 2, 2005, thermal/
acoustic insulation materials installed in the fuselage must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003 or as subsequently amended.

    Issued under authority provided by 49 U.S.C. 106(f), 44701(a), 
and 44703 in Washington, DC.
Lirio Liu,
Executive Director, Aircraft Certification Service.
[FR Doc. 2023-16877 Filed 8-16-23; 8:45 am]
BILLING CODE 4910-13-P