[Federal Register Volume 84, Number 128 (Wednesday, July 3, 2019)]
[Proposed Rules]
[Pages 31747-31769]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-13646]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

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

[Docket No.: FAA-2019-0491; Notice No. 19-09]
RIN 2120-AK34


Interior Parts and Components Fire Protection for Transport 
Category Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA is proposing to amend certain airworthiness 
regulations for fire protection of interior compartments on transport 
category airplanes. This proposal would convert those flammability 
regulations from detailed, prescriptive requirements into simpler, 
performance-based standards. This 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, this proposal would remove test methods from 
the regulations and allow applicants, in certain cases, to demonstrate 
compliance either without conducting tests or by providing independent 
substantiation of the flammability characteristics of a proposed 
material. This action is necessary to eliminate unnecessary testing, 
increase standardization, and improve safety. This proposal includes 
conforming changes to parts 27, 29, 91, 121, 125, and 135.

DATES: Send comments on or before October 1, 2019.

ADDRESSES: Send comments identified by docket number FAA-2019-0491 
using any of the following methods:
     Federal eRulemaking Portal: Go to http://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 
http://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: For questions concerning this action, 
contact Jeff Gardlin, AIR-600, Policy and Innovation Division, Aircraft 
Certification Service, Federal Aviation Administration, 2200 South 
216th Street, Des Moines, WA 98198; telephone and fax (206) 231-3146; 
email Jeff.Gardlin@faa.gov.

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 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 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.

Table of Contents

I. Overview of the Proposed Rule
II. Background
    A. Statement of the Problem
    B. History
    C. Aviation Rulemaking Advisory Committee
III. Discussion of the Proposal
    A. Flammability Testing Requirements
    1. Bunsen Burner Test (Current Sec.  25.853(a) and Part I of 
Appendix F to Part 25)
    2. Oil Burner Test for Seat Cushions (Current Sec.  25.853(c) 
and Part II of Appendix F to Part 25)
    3. Heat Release Rate Test (Current Sec.  25.853(d) and Part IV 
of Appendix F to Part 25)
    4. Smoke Emissions Test (Current Sec.  25.853(d) and Part V of 
Appendix F to Part 25)
    5. Oil Burner Test for Cargo Compartment Liners (Current Sec.  
25.855(c) and Part III of Appendix F to Part 25)
    6. Radiant Panel Test for Thermal/Acoustic Insulation (Current 
Sec.  25.856(a) and Part VI of Appendix F to Part 25)
    7. Oil Burner Test for Thermal/Acoustic Insulation (Current 
Sec.  25.856(b) and Part VII of Appendix F to Part 25)
    8. Radiant Heat Resistance Test for Escape Slides (Sec.  
25.853(d)(5))
    9. Fire Containment Compliance of Waste Receptacles (Current 
Sec.  25.853(h))
    10. Extensively Used Materials in Inaccessible Areas (Proposed 
Sec.  25.853(c)(2)(i))
    11. Exclusions from Testing (Proposed Sec.  25.853(e))
    12. Pass/Fail Criteria
    B. Reorganization of Appendix F to Part 25
    1. General Structure
    2. Hierarchy of Tests
    C. Conformal and Editorial Changes
    D. Advisory Material
    E. Application of Sec. Sec.  21.17
    F. Application of Sec. Sec.  21.101
IV. Regulatory Notices and Analyses
    A. Regulatory Evaluation
    1. Summary of Costs and Benefits
    2. Who is potentially affected by this proposed rule?
    3. Assumptions:
    4. Benefits of This Rule
    5. Costs of This Proposed Rule
    6. Minimal to No Cost Provisions Including Conforming Changes

[[Page 31748]]

    B. Regulatory Flexibility Determination
    1. A Description of the Reasons Why the Action by the Agency Is 
Being Considered
    2. A Succinct Statement of the Objectives of, and Legal Basis 
for, the Proposed Rule
    3. Description and, Where Feasible, an Estimate of the Number of 
Small Entities to Which the Proposed Rule Would 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 That Will Be Subject to 
the Requirement and the Types 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
    6. A Description of any Significant Alternatives to the Proposed 
Rule
    C. International Trade Impact Assessment
    D. Unfunded Mandates Assessment
    E. Paperwork Reduction Act
    F. International Compatibility
    G. Environmental Analysis
V. Executive Order Determinations
    A. Executive Order 13132, Federalism
    B. Executive Order 13211, Regulations That Significantly Affect 
Energy Supply, Distribution, or Use
    C. Executive Order 13771, Reducing Regulation and Controlling 
Regulatory Costs
VI. Additional Information
    A. Comments Invited
    B. Availability of Rulemaking Documents

I. Overview of the Proposed Rule

    This proposed amendment would eliminate and modify certain 
flammability and fire protection requirements of title 14, Code of 
Federal Regulations (14 CFR) part 25. The proposed changes would 
organize these requirements based on the type of fire--in-flight or 
post-crash--that is likely to affect a given component, part, or 
material, rather than basing such standards on the part's composition 
or function. In addition, the proposal would extend the fire protection 
requirements to any extensively used material \1\ located in 
inaccessible areas.
---------------------------------------------------------------------------

    \1\ 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.
---------------------------------------------------------------------------

    The FAA proposes to convert the testing methods in appendix F to 
part 25 from regulations into guidance material. The proposal would 
also eliminate redundant or non-value-added tests when a more severe 
test is acceptable.
    This proposal would replace mandatory testing methods with 
performance-based standards for flammability and fire protection. This 
change would improve safety and standardization and would be applicable 
to materials currently used to construct parts and components as well 
as to new materials that become available in the future. As discussed 
in section III.E of the NPRM, all of the proposed changes are 
interrelated. These proposals to remove or simplify requirements are 
only possible, from a safety perspective, because of other proposed 
changes that would compensate for removing requirements.
    These revised regulations would affect applicants seeking new type 
certificates for transport category airplanes. These revised 
regulations would not apply to transport category airplanes currently 
in production under existing type certificates, unless the FAA approves 
a manufacturer's request to comply with an amendment level that 
incorporates these proposed changes, or a manufacturer triggers the 
requirement via an application for a significant product-level change 
under Sec.  21.101.
    Over a 19-year period of analysis, the FAA estimates the total 
present value costs of this proposed rule to be $71.1 million at a 
seven percent discount rate, with annualized costs of $6.9 million due 
to the extension of fire protection requirements to extensively used 
material in inaccessible areas. Over the same 19-year period, the FAA 
estimates the total quantified cost savings of this proposed rule to be 
$119.8 million at a seven percent discount rate, with annualized cost 
savings of $11.6 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 19-year period, the proposed rule 
would result in a net cost savings (cost savings minus costs) of $48.7 
million at a seven percent discount rate, with annualized net cost 
savings of $4.8 million. The following table summarizes the costs and 
cost savings of this proposed rule.

                                     Costs and Savings of the Proposed Rule
----------------------------------------------------------------------------------------------------------------
                                           19-year total present value                   Annualized
                                     ---------------------------------------------------------------------------
                                              7%                 3%                 7%                 3%
----------------------------------------------------------------------------------------------------------------
Cost Savings........................       $119,848,146       $178,395,887        $11,595,669        $12,454,509
Costs...............................         71,105,318         80,387,114          6,879,654          5,612,136
                                     ---------------------------------------------------------------------------
    Total Cost Savings..............         48,742,829         98,008,773          4,716,016          6,842,373
----------------------------------------------------------------------------------------------------------------

    Airplane occupant safety benefits were not quantified. However, the 
proposed new safety requirements to extend the fire protection 
requirements to any extensively used material 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. 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. Thus, the FAA believes there are safety benefits to this 
proposed rule in addition to cost savings.

II. Background

A. Statement of the Problem

    Current part 25 regulations organize fire protection requirements 
for components in airplane interior compartments by the function, and 
sometimes composition, of each component. Appendix F to part 25 details 
comprehensive, mandatory testing methods. Each part of appendix F 
provides the test method required for a specific type of part or 
material, with the exception of part I, which applies to nearly all 
parts and materials and contains multiple test methods. While this 
method of organization is useful in standardizing the applicable tests 
and ensuring consistency among test results, regardless of the testing 
facility, it can create difficulties when an applicant wishes to 
deviate from the detailed test provisions, for example to implement 
improvements. Also, a given component

[[Page 31749]]

can be subject to multiple regulatory requirements depending on the 
component's composition, and the requirements may conflict with one 
another. In addition, it can be difficult to determine the applicable 
requirements, especially when applicants propose new components or 
materials that are not listed in Sec.  25.853 and for which testing 
methods have not yet been developed. A final problem is that, with the 
exception of thermal/acoustic insulation and electrical wiring, the 
current fire protection requirements only apply to components and 
materials in occupiable areas or cargo compartments. The current 
requirements do not apply to components, parts, and materials in other 
areas, even if extensively used, and such components can be critical 
for fire safety.

B. History

    The regulations governing the flammability of materials on 
transport category airplanes have evolved significantly since their 
adoption in 1964.\2\ When initially adopted, these regulations mandated 
the most fire-resistant materials practically available at that time, 
without consideration of the types of fires to which each material 
might be exposed. The regulations described flammability requirements 
in terms of the objective--materials had to be at least flash 
resistant,\3\ and certain types of parts had to be flame resistant,\4\ 
a more stringent requirement. Until 1984, FAA flammability regulations 
only required applicants to demonstrate that proposed materials could 
resist small ignition sources such as a lit match or cigarette. The 
flammability requirements only applied to materials in compartments 
that could be occupied by passengers or crew.
---------------------------------------------------------------------------

    \2\ Published in the Federal Register on December 24, 1964 (29 
FR 18289) and available on the internet at http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/861ae0b1f7efc3ee85256453007b0e8a/beee068568b285ea86256cc900543c9f!OpenDocument.
    \3\ Flash resistant is defined as having a burn rate of no more 
than 20 inches per minute when exposed to a Bunsen burner flame. See 
FAA Flight Standards Service Release No. 453, dated November 9, 
1961; and Advisory Circular (AC) 25-17A, Change 1, ``Transport 
Airplane Cabin Interiors Crashworthiness Handbook,'' dated May 24, 
2016.
    \4\ Flame resistant is defined as having a burn rate of no more 
than 4 inches per minute when exposed to a Bunsen burner flame.
---------------------------------------------------------------------------

    Beginning with the 1984 adoption of improved flammability standards 
for seat cushions, the FAA revised the flammability requirements for 
other specific parts and components, including large surface areas, 
cargo compartment liners, and thermal/acoustic insulation. The FAA also 
revised and expanded mandatory test methods to ensure consistency in 
testing methodology and results. The FAA based these revised 
requirements on the type of fire threat (in-flight and post-crash) 
expected for a given component. However, the regulations continued to 
set standards for specific components, based on their function or 
construction.
    Since the adoption of those flammability requirements, research 
into fire safety identified significant differences between the hazards 
posed by a post-crash fire and those posed by an in-flight fire.
    Post-crash fires, or ``fuel fires'' since they are primarily fed by 
spilled aviation fuel, present two primary hazards to the airplane's 
occupants. First, a fuel fire can be a significant source of smoke and 
toxic gases. If these gases enter the cabin, they can cause injury and 
significantly reduce survivability. Second, a fuel fire can ignite 
cabin materials, which can accelerate the fire's growth. Research \5\ 
by the FAA has found that the best way to prevent the first hazard--
smoke and toxic gases--is to prevent the fire from penetrating the 
fuselage. The best way to prevent the second hazard--ignition of cabin 
materials--is to minimize the heat release \6\ of cabin materials, so 
that they do not contribute significant energy to the fire. Post-crash 
fires can also reduce the time available for evacuation. The FAA 
studied the time necessary to complete evacuation and determined that 
roughly 90 percent of actual evacuations are completed within 5 
minutes.\7\ This proposal specifically references that 5-minute time 
when discussing protection under post-crash fire conditions. Proposed 
Sec.  25.853(d) would add general flammability requirements to provide 
occupants time to evacuate during post-crash fires.
---------------------------------------------------------------------------

    \5\ See ``Application of Full-Scale Fire Tests to Characterize 
and Improve the Aircraft Postcrash Fire Environment,'' Constantine 
P. Sarkos, International Colloquium on Advances in Combustion 
Toxicology, April 11-13, 1995, available on the internet at https://www.fire.tc.faa.gov/pdf/fsr-0196.pdf; and FAA Report No. DOT/FAA/AR-
TN11/8, ``Improvements in Aircraft Fire Safety Derived from FAA 
Research over the Last Decade,'' dated May 2011, available on the 
internet at https://www.fire.tc.faa.gov/pdf/TN11-8.pdf. Both of 
these reports are also available in the Docket.
    \6\ Heat release is the amount of heat energy created by a 
material when burned. The maximum heat release occurs when the 
material is burning most intensely. Also, see ``Improved 
Flammability Standards for Materials Used in the Interiors of 
Transport Category Airplane Cabins,'' published in the Federal 
Register on July 21, 1986 (51 FR 26206) and available on the 
internet at http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/E2F0F4B91D02ADFB862568E7005C097C?OpenDocument.
    \7\ See FAA Report No. DOT/FAA/AR-09/18, ``Determination of 
Evacuation and Firefighting Times Based on an Analysis of Aircraft 
Accident Fire Survivability Data,'' dated May 2009, available in the 
Docket and on the internet at https://www.fire.tc.faa.gov/pdf/09-18.pdf.
---------------------------------------------------------------------------

    In contrast, the primary hazard from in-flight fires is to the 
continued safe flight and landing of the airplane. In-flight fires have 
historically only been a direct hazard to continued safe flight and 
landing when they begin in an area inaccessible to a person with a 
hand-held fire extinguisher. These areas tend to be in cargo 
compartments or behind interior panels, such as sidewalls or ceilings. 
The principal risk with such fires is that they grow and spread without 
the ability of the flightcrew to access and combat them, and then 
degrade critical systems and occupant survivability. The components, 
parts, and materials with the most potential to contribute to an in-
flight fire hazard are the most extensive, including insulation, 
wiring, air ducts, and structure. FAA research determined that 
materials that self-extinguish and do not propagate a flame provide an 
acceptable level of safety. In-flight fires in areas that are readily 
accessible to a person with a hand-held fire extinguisher are still a 
concern, but are much less likely to evolve into a threat to the 
airplane. Therefore, these two types of fires (in-flight and post-
crash) require different flammability standards.
    Several elements of fire safety research were involved in the 
development of these flammability requirements. First, the FAA analyzed 
accident and incident data to identify the nature of the fire and its 
potential to affect the airplane and its occupants. Next, the threat 
was replicated (to the extent possible), and detailed measurements were 
made to characterize the key parameters \8\ of the type of fire and its 
potential effect on the airplane and occupants. Finally, a laboratory 
test was developed that correlated with, and was derived from, the type 
of fire, so that repeatable and reproducible results could be obtained 
to assess the adequacy of proposed designs. This latter step was an 
evolutionary process as test protocols (test methods and test 
equipment) were continuously refined. Once the results for a particular 
protocol were reliable and repeatable, the FAA selected that test 
protocol, even though improvements in methods and equipment are 
expected to continue. A key consideration in this proposal is the 
availability of approved test methods in

[[Page 31750]]

advisory material \9\ to support all of the proposed requirements.
---------------------------------------------------------------------------

    \8\ For example, temperature, radiant heat flux, flame kinetic 
energy.
    \9\ This advisory material will take the form of several 
proposed ACs, as discussed in section III.D of this NPRM.
---------------------------------------------------------------------------

C. Aviation Rulemaking Advisory Committee

    In light of the problems with the current part 25 regulations 
previously discussed, the FAA recognized that it needs a new approach 
to the regulatory structure of flammability requirements. Since 
amendments to the regulations since the 1980s had been based on an 
assessment of the type of fire, but not structured that way in the 
regulatory text, the FAA determined that the regulations should align 
with the type of fire that could threaten the airplane. However, 
because of the scope of the change under consideration, the FAA tasked 
the Aviation Rulemaking Advisory Committee (ARAC) \10\ to review the 
FAA's proposed approach and provide recommendations. ARAC assigned the 
task to the Materials Flammability Working Group (MFWG) under the 
Transport Airplane and Engines Issues Group (TAEIG), an ARAC 
subcommittee. The MFWG reviewed the proposed concept and, in a report 
\11\ dated July 2012, recommended its adoption along with several 
associated advisory circulars (ACs). The MFWG also raised several 
questions that required FAA resolution prior to rulemaking, including 
consideration of an approved materials list, availability of advisory 
material, and means to address so-called rogue failures.
---------------------------------------------------------------------------

    \10\ Published in the Federal Register on August 27, 2010 (75 FR 
52807) and available on the internet at https://www.govinfo.gov/content/pkg/FR-2010-08-27/pdf/2010-21333.pdf.
    \11\ See ``Materials Flammability Working Group Report,'' dated 
July 9, 2012, available in the Docket and on the internet at https://www.fire.tc.faa.gov/materials.asp.
---------------------------------------------------------------------------

    When drafting the NPRM, the FAA determined that a more 
comprehensive estimate of costs and benefits was necessary. Therefore, 
the FAA put the rulemaking project on hold and re-tasked ARAC \12\ to 
provide an estimate of costs and benefits. The FAA provided assumptions 
to use in making those estimates. ARAC reassigned the task to the MFWG. 
The MFWG completed the task and submitted a report \13\ in October 
2015. This proposal is based on recommendations and information 
provided in both MFWG reports and addresses the open issues raised by 
the MFWG.
---------------------------------------------------------------------------

    \12\ Published in the Federal Register on January 20, 2015 (80 
FR 2772) and available on the internet at https://www.govinfo.gov/content/pkg/FR-2015-01-20/pdf/2015-00749.pdf.
    \13\ See ``Materials Flammability Working Group Continuation of 
Task Report,'' dated October 7, 2015, available in the Docket.
---------------------------------------------------------------------------

III. Discussion of the Proposal

    The current regulatory structure in the primary regulations that 
this action proposes to amend, Sec. Sec.  25.853, 25.855, 25.856, and 
25.1713, organizes the flammability requirements by the type of testing 
required for a specific part or component. Section 25.853 applies to 
parts and components that are located in compartments that can be 
occupied by crew or passengers, and requires compliance with the 
applicable parts of appendix F to part 25. Section 25.855 states 
similar requirements that are applicable to cargo or baggage 
compartments; Sec.  25.856 provides requirements for thermal/acoustic 
insulation materials; and Sec.  25.1713 addresses electrical wiring 
components. Each of these sections requires compliance with a 
particular test method in appendix F.
    For example, Sec.  25.853(a) requires that all materials used in 
occupiable compartments meet the test criteria (Bunsen burner) in part 
I of appendix F to part 25. Section 25.853(d) requires certain interior 
components, including partitions, ceilings, and wall panels, to also 
meet the heat release rate (HRR) \14\ and smoke emission test 
requirements in parts IV and V of appendix F. This proposal would 
eliminate the requirement to meet the tests in part I of appendix F for 
components required to comply with Sec.  25.853(d), since the Bunsen 
burner tests do not add any level of safety for components that meet 
part IV of appendix F.
---------------------------------------------------------------------------

    \14\ The heat release rate test measures both total heat release 
and peak heat release rate.
---------------------------------------------------------------------------

    This proposed amendment would revise Sec.  25.853 to apply to 
general categories of parts or components rather than to specific 
items. For example, Sec.  25.853(d)(1) would apply to large surface 
area components, rather than to partitions, ceilings, and wall panels. 
It would set performance standards for those components based on the 
type of fire the component is likely to be exposed to and whether or 
not its location is accessible during flight.
    Stating the requirements as performance standards would make them 
applicable to parts and materials that are not listed in the current 
regulations and to new materials in emerging areas of aviation design. 
These include materials used in inaccessible portions of the fuselage, 
escape slides, and the use of flammable metals in the cabin.
    The mandatory testing methods in appendix F to part 25 would be 
removed. Instead, appendix F would allow applicants to omit certain 
tests if the material passes certain more severe tests. Advisory 
material would provide the details of approved test methods. By moving 
compliance testing methods to advisory material, applicants would have 
more flexibility to propose alternative methods, and the FAA would have 
more flexibility to approve improved testing methods.
    This proposal would also standardize the required number of test 
samples, and pass rate, among the various tests. Proposed Sec.  
25.853(b) would require a minimum of three specimen sets for any test 
used to show compliance.
    Because fewer post-crash flammability requirements currently apply 
to airplanes designed to carry 19 or fewer passengers, many of the 
proposed simplifications would only apply to larger airplanes. For the 
same reason, for airplanes designed to carry 19 or fewer passengers, 
fewer in-flight flammability tests would be eliminated by meeting post-
crash flammability test requirements. Thus, applicants for type 
certification of airplanes with 19 or fewer passengers might not 
benefit from the same degree of simplified testing, as would applicants 
seeking approval of larger airplanes.

A. Flammability Testing Requirements

1. Bunsen Burner Test (Current Sec.  25.853(a) and Part I of Appendix F 
to Part 25)
    Sections 25.853 and 25.855 require Bunsen burner testing of all 
materials used in interior compartments, and in certain parts of cargo 
compartments, even if an additional, more severe test is required. 
Bunsen burner tests, detailed in part I of the current appendix F to 
part 25, have multiple variations that are used to determine the 
resistance of materials to flame, flame penetration, or flame 
propagation. Although Bunsen burner tests would be an acceptable means 
of compliance for several requirements, this proposal would eliminate 
the requirement for Bunsen burner testing when a required test method 
simulates a post-crash fire. Bunsen burner testing to address in-flight 
fire threats would be less frequently required, since extensively used 
materials would be required to meet a more stringent standard, and 
materials and parts that are not extensively used may show their in-
flight fire resistance by more than one means.
    Two other requirements intended to protect the airplane from in-
flight fires, proposed Sec.  25.853(c)(1)(i) regarding parts or 
components that are accessible

[[Page 31751]]

to the flightcrew during flight, and proposed Sec.  25.853(c)(2)(iv) 
regarding floor liners in cargo compartments, would require that those 
parts, components, and materials be self-extinguishing when exposed to 
a small flame,\15\ unless another regulation requires the materials to 
meet a higher standard, such as a post-crash test. Applicants would 
typically use the 12-second vertical Bunsen burner test to show that 
the materials are self-extinguishing. This proposal would eliminate the 
requirement for materials to pass horizontal Bunsen burner tests 
because other requirements would ensure acceptable flammability 
characteristics of any other materials for which that test is currently 
applied. This includes parts currently listed in appendix F, part I, 
paragraph (a)(1)(iv) of part 25, such as clear plastic windows and 
signs, which would fall under one of the proposed requirements for a 
more stringent test, unless the applicant is able to show the part or 
material serves a necessary function and has no suitable substitute 
material.
---------------------------------------------------------------------------

    \15\ Represented by a flame from a Bunsen burner.
---------------------------------------------------------------------------

    For post-crash fires on transport category airplanes with 19 or 
fewer passengers, this proposal would, as a practical matter, retain 
the requirement, currently in appendix F, part I, paragraph (b)(4) of 
part 25, that the applicant conduct a 60-second vertical Bunsen burner 
test for large surface interior materials. That test, unlike the 12-
second vertical test, screens out materials, such as certain 
thermoplastics, that have unacceptable flammability performance, even 
though the test method is not specifically designed to represent post-
crash fires. Because of the greater evacuation capability inherent in 
these smaller airplanes, they are not, and would not under this 
proposal, be subject to the more severe post-crash, fire-based 
standards for interior materials and lower lobe \16\ fire penetration 
proposed in Sec. Sec.  25.853(d)(2) and 25.856(b), respectively.
---------------------------------------------------------------------------

    \16\ For the purpose of this NPRM, ``lower lobe'' refers to the 
geometric lower half of the airplane fuselage.
---------------------------------------------------------------------------

    This proposal would also continue to require, in Sec.  
25.853(c)(1)(i), that waste receptacles (compartments) and cargo 
compartment liners resist fire penetration. One means of compliance 
would continue to be the 45-degree orientation Bunsen burner test, 
which is currently described in part I of appendix F to part 25, but 
would be removed from part 25 and made available in guidance material. 
However, if an applicant proposes to construct waste compartments from 
the same materials as will be used for other interior features that are 
required to meet the HRR test,\17\ no Bunsen burner test would be 
required. The fire containment test for the waste compartments would 
still be required. Most cargo compartment liners, as components in an 
inaccessible area, would still be required by proposed Sec.  
25.853(c)(2) to meet the flammability performance standard currently 
encompassed by the oil burner test in part III of appendix F. 
Exceptions would include liners on the floor and certain aspects of 
Class E cargo compartment liners, which would only need to pass the 45-
degree Bunsen burner test, i.e., resist penetration by a small flame 
(proposed Sec.  25.853(c)(iv)).
---------------------------------------------------------------------------

    \17\ Part 25, appendix F, part IV.
---------------------------------------------------------------------------

    Finally, for materials that must be self-extinguishing under 
current regulations, the FAA has reviewed the detailed pass/fail 
criteria for the vertical Bunsen burner test in appendix F, part I, 
paragraph (b)(4) of part 25 and concluded that those criteria could 
also be simplified. The current pass/fail criteria are regulatory and 
involve burn length, after-flame time, extinguishing time of any drips, 
and, in some cases, after-glow time. These criteria would no longer be 
regulatory. Instead, proposed AC 25.853-4X would describe one means of 
compliance that incorporates only the criteria of burn length and that 
the material be self-extinguishing. The self-extinguishing criteria 
would apply to drips as well as the test sample.
2. Oil Burner Test for Seat Cushions (Current Sec.  25.853(c) and Part 
II of Appendix F to Part 25)
    Currently, Sec.  25.853(c) requires that seat cushions, except 
those on flight crewmember seats, meet the test requirements of part II 
of appendix F to part 25, which involves the use of an oil burner. The 
oil burner test for cushions simulates the effect of a post-crash fire 
by exposing the material to a high-intensity open flame to evaluate its 
burn resistance and other characteristics.
    This proposal would extend this level of flammability performance 
to any cushion, including flight crewmember seats and mattresses on 
berths. When the FAA adopted its current flammability rule \18\ for 
seat cushions, the materials available to applicants were limited, and 
it was not clear that flightcrew could achieve the posture and comfort 
necessary to safely operate the airplane using materials that complied 
with the oil burner test. However, since that time, advances in cushion 
materials have essentially eliminated this issue and any reason for 
different treatment of flight crewmember seats. Mattresses or other 
cushions on berths should meet the same standards. The omission of 
cushions on berths in the current Sec.  25.853(c) was largely an 
oversight in the way the FAA worded the rule.\19\
---------------------------------------------------------------------------

    \18\ Published in the Federal Register on October 26, 1984 (49 
FR 43188) and available on the internet at http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/31FBF691A3BCE69C86256825004F9E02?OpenDocument.
    \19\ Section 25.853(c) specifically referred to ``seats,'' 
whereas elsewhere in the regulations, seats and berths are both 
mentioned when requirements apply to both. From a fire safety 
standpoint, there is no distinction.
---------------------------------------------------------------------------

    Proposed Sec.  25.853(d)(3) would create a performance-based 
standard for the flammability of seat cushions. In the event that a 
post-crash fire enters the airplane, the seat cushions would have to 
resist involvement in that fire, and not propagate it. (Resist, for the 
purposes of this proposed rule, means to not become involved in a fire 
to the extent that survivability is adversely affected, commensurate 
with the historical benefit provided by the oil burner test. 
Involvement, for the purposes of this proposed rule, means ignition, 
pyrolysis, or combustion.) Since the oil burner test represents the 
hazard posed by a post-crash fire, it would continue to be, in most 
cases, an acceptable test to show compliance with this proposed rule. 
However, in certain applications, an applicant could show compliance 
with the HRR test. The oil burner test measures both flame spread and 
material consumption rates, and the HRR test only measures the latter. 
Therefore, an applicant's use of the HRR test will generally be limited 
to designs where flame spread does not affect safety, and would, in 
most circumstances, apply to small cushions or cushions such as padding 
on an angled surface. Proposed appendix F to part 25 would allow this 
substitution of one test method for another.
    The proposed revisions to Sec.  25.853 would no longer require 
cushions to meet a Bunsen burner test because the oil burner test, 
which most applicants would use to demonstrate the flammability 
performance of their cushions, is more severe. Although the Bunsen 
burner test would not be required for seat cushions, applicants could 
still choose to generate Bunsen burner test data, where that data may 
be used to support substitution of upholstery (dress covers) under the 
provisions of proposed Sec.  25.853(e)(3).
    This proposal would also remove the mandatory and detailed testing 
methods from appendix F to part 25. Instead, AC 25.853-2X, would 
provide guidance on

[[Page 31752]]

acceptable tests, including the oil burner test and use of the HRR 
test.
3. Heat Release Rate Test (Current Sec.  25.853(d) and Part IV of 
Appendix F to Part 25)
    Currently, the requirements to conduct the HRR test, in Sec.  
25.853(d) and part IV of appendix F to part 25, apply to specific 
interior features: Interior ceiling and wall panels, partitions, galley 
structures, large cabinets, and cabin stowage compartments that are in 
a passenger compartment that may be occupied during takeoff and 
landing.
    This proposal would replace this requirement with performance-based 
standards in Sec.  25.853(d)(2) applicable to any large \20\ surface 
area in the same compartment, based on the type of fire it may be 
exposed to, and without regard to whether a particular surface is 
associated with a specific feature. These revisions, therefore, would 
extend the flammability requirements to all large surface areas within 
the portions of the fuselage currently covered by the HRR tests. This 
proposal would remove the details of HRR tests from appendix F to part 
25. HRR tests would be one means of compliance, and detailed in 
proposed AC 25.853-1A.
---------------------------------------------------------------------------

    \20\ For purposes of this proposed rule, ``large'' excludes 
surfaces that are less than 1 square foot and includes all surfaces 
that are 2 square feet and greater, with square footage in between 
as explained in amendment 25-83 (60 FR 6615, February 2, 1995), 
which is available on the internet at https://www.govinfo.gov/content/pkg/FR-1995-02-02/pdf/95-2114.pdf.
---------------------------------------------------------------------------

    A design development that the FAA did not anticipate following the 
1986 adoption of part IV of appendix F to part 25, which details the 
HRR test, and a change to Sec.  25.853(a) to require the HRR test (at 
amendment 25-61 \21\), was industry's use of large area panels on seat 
assemblies.\22\ Because Sec.  25.853(d) at amendment 25-83 \23\ 
(paragraph (a) at amendment 25-61) does not list seats, the FAA has 
applied special conditions to address fire protection of these large-
area parts. The proposed revisions to Sec.  25.853 would eliminate the 
need for these special conditions, since the revisions would apply to 
any component or part that is a large surface within the fuselage.
---------------------------------------------------------------------------

    \21\ Published in the Federal Register on July 21, 1986 (51 FR 
26206).
    \22\ In this context, seat assemblies include the seat and 
furniture associated with that seat. The furniture need not be an 
airplane sidewall or bulkhead to affect the overall post-crash 
flammability characteristics and therefore should simply be treated 
as a large surface area.
    \23\ Published in the Federal Register on February 2, 1995 (60 
FR 6615) and available on the internet at https://www.govinfo.gov/content/pkg/FR-1995-02-02/pdf/95-2570.pdf.
---------------------------------------------------------------------------

    The FAA also proposes, however, that this broader standard only 
apply to items more than 15 inches above the floor because full-scale 
fire tests \24\ show that (with the exception of materials near the 
fire entry point) the materials very near the floor do not 
significantly contribute to a post-crash fire until conditions have 
become non-survivable. Therefore, in order to simplify compliance 
demonstrations and focus the requirement on the most critical 
components, proposed Sec.  25.853(d)(2)(i) would only apply to large-
surface components and parts that are more than 15 inches from the 
cabin floor. For example, a kick panel that extends upward from the 
floor to 16 inches above the floor would be required to pass the HRR 
test. For airplanes with more than one passenger deck, the 15-inch 
dimension would apply to each deck separately. The FAA based the 15-
inch dimension on test data and the objective of such materials not 
adversely affecting safety. This provision is relieving and should 
reduce costs. The proposal to exclude surfaces 15 inches and below 
would not apply to large area surfaces on seats because seats could be 
located in or near a fire's entry point through the fuselage and, 
therefore, would be more likely to be involved in a post-crash fire. 
FAA full-scale fire tests have shown that there could be an adverse 
impact on safety if parts on seats that are less than 15 inches from 
the floor did not meet the heat release requirements.\25\
---------------------------------------------------------------------------

    \24\ One example is FAA Report No. DOT/FAA/TC-13/52, 
``Development of a Laboratory-Scale Flammability Test for Magnesium 
Alloys Used in Aircraft Seat Construction,'' dated February 2014, 
available in the Docket and on the internet at https://www.fire.tc.faa.gov/pdf/TC-13-52.pdf.
    \25\ FAA Report No. DOT/FAA/TC-16/42, ``A Comparison of 
Performance of OSU-Compliant Versus Non-OSU-Compliant Thermoplastics 
Used in the Lower Area of Aircraft Seats during a Simulated Post-
Crash Fire Scenario,'' dated September 2017, available in the Docket 
and on the internet at https://www.fire.tc.faa.gov/pdf/TC-16-42.pdf.
---------------------------------------------------------------------------

4. Smoke Emissions Test (Current Sec.  25.853(d) and Part V of Appendix 
F to Part 25)
    This proposal would remove the requirement for testing of smoke 
emissions. The smoke emissions test, detailed in the current part V of 
appendix F to part 25 that is required by Sec.  25.853(d), measures the 
smoke emissions characteristics of materials used in cabin components. 
The smoke emissions test is currently required in addition to the HRR 
test. The FAA adopted the smoke emissions test requirement at amendment 
25-66 \26\ after concluding that smoke may hamper emergency egress and 
is, therefore, a survivability factor in the event of a fire. Thus, all 
materials, parts, and components that must meet the HRR test 
requirements are also required to pass the smoke emissions test in 
accordance with current Sec.  25.853(d).
---------------------------------------------------------------------------

    \26\ See ``Improved Flammability Standards for Materials Used in 
the Interiors of Transport Category Airplane Cabins,'' published in 
the Federal Register on August 25, 1988 (53 FR 32564) and available 
on the internet at http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/7B29EAF2EAC36594862568FC005465CD?OpenDocument.
---------------------------------------------------------------------------

    However, FAA research data have also shown that, for the materials 
and configurations typically used in transport category airplanes, the 
heat release of the materials used drives occupant survivability, 
rather than the materials' smoke emission. Heat release dictates how 
quickly the conditions progress to flashover.\27\ Before flashover, 
conditions are largely survivable. Due to the importance of heat 
release, the FAA initially adopted regulations (at amendment 25-61) 
that only contained requirements for the HRR test and did not address 
smoke emission.
---------------------------------------------------------------------------

    \27\ A flashover is the near-simultaneous ignition of all 
combustible material within an enclosed area.
---------------------------------------------------------------------------

    In fact, the data do not correlate smoke emission test results with 
post-crash survivability as they do with heat release. The FAA is 
unaware of any data showing that smoke emission testing has contributed 
to fire safety in an actual accident. Although the rule has been in 
effect for more than 20 years and has prevented applicants from using 
certain materials, the FAA has concluded, pursuant to the following 
discussions, that the smoke emission testing requirement is not adding 
to post-crash fire safety. The smoke emission requirement may be 
contributing to in-flight fire safety, but the extent of that 
contribution is unknown. However, by adding standards for extensively 
used materials in inaccessible areas, the potential contribution to an 
in-flight fire from materials that would no longer be subject to the 
smoke emission requirement will be minimized. For example, the proposal 
would eliminate the test that measures smoke emissions for certain 
large surface area parts, such as sidewalls. If a fire was to propagate 
on ducting behind the sidewall (an inaccessible area), it could spread 
to a sidewall that had not been tested for smoke emission, and the 
quantity of smoke could become a risk to continued safe flight and 
landing. If the ducting met the flammability standard in this proposal, 
the fire would not reach the sidewall, and the quantity of smoke would 
be minimal. Thus, the relief in the smoke emission requirements for 
sidewalls depends on improving the

[[Page 31753]]

standards for ducting. This philosophy of interdependency is true 
throughout the proposal.
    The MFWG discussed smoke emission testing at length during its 
activity leading to this proposal, but the MFWG did not reach a 
consensus on whether the FAA should retain a requirement for smoke 
emission testing. Some members were concerned that the removal of the 
requirement could lead to applicants using materials with excessive 
smoke emission properties, if those materials offered weight or cost 
advantages. Other members believed the FAA could eliminate the smoke 
emission test requirement because smoke emissions had not been 
correlated to post-crash survivability, and FAA data suggested it was 
not needed. Also, most airplane manufacturers have their own design 
standards that include tests for smoke emissions. These internal 
manufacturer requirements were in place before the FAA adopted the 
current regulatory requirement; therefore, the FAA expects they would 
remain in use to some extent if the regulatory requirement were 
removed. Thus, the FAA anticipates that some of the smoke emission 
testing that existed before the current regulatory requirement would 
continue to take place if this proposed amendment removed the 
regulatory requirement. In other words, manufacturers might choose to 
maintain the design standards that were in place before amendment 25-66 
\28\ was adopted. Amendment 25-66 imposed a certification process that 
drives costs, in terms of the quantity of tests, the documentation 
necessary, and the engineering assessments to identify the correct 
tests. These costs would be relieved by this proposed rule and are 
included in the cost savings estimates.
---------------------------------------------------------------------------

    \28\ See ``Improved Flammability Standards for Materials Used in 
the Interiors of Transport Category Airplane Cabins,'' published in 
the Federal Register on August 25, 1988 (53 FR 32564). Available at 
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/7B29EAF2EAC36594862568FC005465CD?OpenDocument.
---------------------------------------------------------------------------

    Based on this information, the FAA proposes to remove the 
requirement for testing of smoke emissions. However, because smoke is 
an important survivability parameter, and materials that have high 
smoke emission without significant HRR are theoretically possible, 
Sec.  25.853 of this proposal would establish a general performance 
standard that components must maintain occupant survivability during a 
post-crash fire. One means of showing compliance would be HRR testing, 
described in chapter A4 of FAA Report No. DOT/FAA/TC-17/55, ``Aircraft 
Materials Fire Test Handbook,'' Revision 3, dated June 2019. 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. The FAA anticipates, however, that HRR tests will be 
adequate to determine the post-crash fire performance of components 
made from materials currently in use such as phenolic, epoxy, and 
thermoplastic.
5. Oil Burner Test for Cargo Compartment Liners (Current Sec.  
25.855(c) and Part III of Appendix F to Part 25)
    Proposed Sec.  25.853(c)(2) would set performance standards 
requiring all Class C, and certain Class E and F, cargo compartment 
ceiling and sidewall liners to resist penetration by a fire within that 
compartment and protect the airplane's structure and critical systems 
from the effects of those fires. The section on cargo or baggage 
compartments would include a reference (Sec.  25.855(c)) requiring 
compliance with the applicable provisions of Sec.  25.853(c). In 
addition, as a minor editorial change, this proposal eliminates the 
term ``panels'' from ``liner panels,'' the term used in the current 
regulation. Most liners are panels. However, many components serving 
the role of the cargo compartment liner are not panels, and the term 
can sometimes be confusing. The proposed rule would simply refer to 
cargo compartment liners, but there would be no change in the scope of 
the requirement.
    Currently, Sec.  25.855(b) requires any Class B through E, and 
certain Class F, cargo compartments to have a liner. Section 25.855(c) 
requires the ceiling and sidewall liner panels of Class C and F cargo 
compartments to meet the requirements currently in part III of appendix 
F to part 25, the oil burner test (proving resistance to flame 
penetration). The requirement for cargo compartment liners to resist 
fire penetration would be retained, as a performance standard, in Sec.  
25.853(c)(2)(ii). Proposed Sec.  25.853(c)(1)(iii) would continue to 
require Class B cargo compartment liners, as well as any other cargo 
compartment liners, to resist penetration from a small ignition source. 
This requirement is currently met using the less severe 45-degree 
Bunsen burner test required by appendix F, part I, paragraph (a)(2)(ii) 
of part 25. A Class F cargo compartment is not required to have a liner 
if it has other means of containing a fire and protecting critical 
systems and structure, but if it does have a liner, it is currently 
required by Sec.  25.855(b)(2) to meet the oil burner test like Class C 
cargo compartments.
    With this proposal, all Class E cargo compartment liners necessary 
to protect critical systems and structure would be required to meet 
standards identical to those required of Classes C and F, under 
proposed Sec.  25.853(c)(2)(iii). The FAA's rationale for requiring the 
same performance of those cargo compartment liners is that any cargo 
compartment liner necessary to protect the airplane structure or its 
systems should also protect against in-flight cargo fires.
    The oil burner test would continue to be an acceptable means of 
showing that the liner resists penetration as that test represents the 
hazard posed by in-flight cargo fires, but this proposal would remove 
the requirement to pass the test in part III of appendix F to part 25, 
which would become an optional means of compliance under proposed AC 
25.853-1A.
    Other methods of meeting the proposed performance standards for 
Class E cargo compartments could be the use of fire containment covers 
or containers, or dedicated shrouds to protect flight-critical systems. 
In such cases, proposed Sec.  25.853(c)(2)(iv) would still require the 
liner to resist penetration from a small ignition source, which could 
be shown by passing the 45-degree Bunsen burner test, which also would 
be described in proposed AC 25.853-1A.
    In addition, application of Sec.  25.855(c) has often resulted in 
multiple tests for a given liner configuration or slight variants of 
the configuration. This regulation would be replaced by the performance 
standards discussed previously, and proposed AC 25.855-1X would provide 
guidance on simplified methods that should reduce the testing required 
to show compliance.
    Lastly, this proposal would eliminate the requirement in Sec.  
25.855(d) to test the flammability of materials used in the 
construction of items such as cargo covers and tiedown equipment within 
a Class C cargo compartment. Section 25.855(d) currently applies to all 
other materials used in the construction of the cargo or baggage 
compartment and requires testing according to part I of appendix F to 
part 25, the Bunsen burner tests, for any such materials. This proposal 
would add an exception to Sec.  25.855(d) for materials located 
entirely within a Class C cargo or baggage compartment. The rationale 
for this proposed relief is that Class C compartments are already 
required by Sec.  25.857(c) to withstand and contain a fire from cargo 
or baggage of arbitrary

[[Page 31754]]

flammability characteristics, and these compartments must have a fire 
suppression system. Materials used within the Class C compartment would 
be no more flammable than the cargo itself. Since the cargo makes up 
most of the potential fire load, requiring all of these materials or 
components to be tested does not add to safety. However, this proposal 
would not provide similar relief for other classifications of cargo 
compartments because those compartments use different approaches to 
fire protection.
    These proposed changes would apply to cargo compartments, not cargo 
containers, even though the National Transportation Safety Board has 
recommended improved flammability standards for cargo containers. Cargo 
containers \29\ are used in a variety of applications, including within 
Class C cargo compartments. Unlike the cargo compartments that house 
them, cargo containers are usually not part of the airplane type 
design, and so are not directly affected by the requirements of part 
25. The FAA often approves cargo containers in accordance with 
Technical Standard Order (TSO) C90d, ``Cargo Pallets, Nets and 
Containers (Unit Load Devices),'' which contains minimum performance 
standards for the container itself, without regard to the type of 
compartment where the container will be used. The FAA's analysis of 
potential regulatory actions with respect to cargo containers is 
ongoing and independent of this proposal.
---------------------------------------------------------------------------

    \29\ Cargo containers are portable devices that are carried 
within airplane cargo compartments to transport cargo or baggage. 
They are used to facilitate loading and maximize use of space.
---------------------------------------------------------------------------

6. Radiant Panel Test for Thermal/Acoustic Insulation (Current Sec.  
25.856(a) and Part VI of Appendix F to Part 25)
    Thermal/acoustic insulation protects the airplane and occupants 
from temperature and acoustic extremes, and it is often located in 
places not accessible to the flightcrew during flight. This proposal 
would remove the requirement for radiant panel testing of thermal/
acoustic insulation, currently in Sec.  25.856(a) and part VI of 
appendix F to part 25. This proposal would instead require that 
thermal/acoustic insulation comply with proposed Sec.  25.853(c)(2)(i), 
which would set performance standards for all extensively used parts, 
components, and assemblies that are not accessible to the flightcrew 
during flight. The proposed performance is that the parts not propagate 
the largest fire that, by itself, would not be a hazard to the 
airplane. The reason this standard was selected, originally by the 
MFWG, is to prevent the risk that a fire that is any larger would be a 
hazard to the airplane and its occupants, regardless of the materials 
used.
    One means of showing compliance with the proposed performance 
standards for inaccessible materials would be the radiant panel test 
method, which determines the flammability and flame propagation 
characteristics of thermal/acoustic insulation when it is exposed to 
both a radiant heat source and a flame. This method would be detailed 
in proposed AC 25.856-1A.
    In contrast, thermal/acoustic insulation that is accessible to the 
flightcrew during flight would only be required to be self-
extinguishing when exposed to a small flame, as set forth in proposed 
Sec.  25.853(c)(1)(i).
7. Oil Burner Test for Thermal/Acoustic Insulation (Current Sec.  
25.856(b) and Part VII of Appendix F to Part 25)
    For airplanes with a passenger capacity of 20 or more, this 
proposal would revise Sec.  25.856(b) to state two performance 
standards, that thermal/acoustic insulation installed in the lower half 
of the fuselage resist penetration of a post-crash fuel fire and 
provide at least 5 minutes of survivability in the occupied portions of 
the airplane. Section 25.856(b) currently requires that thermal/
acoustic insulation installed in the lower half of the fuselage meet 
the burnthrough resistance (or oil burner) test in part VII of appendix 
F to part 25 unless the FAA determines that the insulation would not 
contribute to fire penetration resistance. If thermal/acoustic 
insulation is not installed, there is currently no requirement that the 
airplane resist post-crash fire penetration.
    The MFWG recommended that the FAA expand the applicability of the 
burnthrough resistance requirement beyond just insulation, to require a 
means of providing post-crash fire penetration protection. For some 
airplane designs, that approach could require some other type of fire 
barrier, in areas where insulation is not installed, that would have to 
meet the same performance standards as thermal/acoustic insulation.
    The FAA is not proposing to adopt the MFWG recommendation to expand 
the applicability of the burnthrough resistance requirement. It is 
difficult to quantify the benefits of requiring a fire penetration 
barrier, since the majority of in-production airplanes are largely 
insulated in the lower lobe. Adding a fire barrier to areas not 
traditionally insulated, such as the wing box or certain cargo areas, 
would provide some, albeit limited, fire safety benefit. In addition, 
with the increased use of composite skin structure, some airplane 
models have fire penetration resistance without using insulation. 
However, if the FAA were to separately require fire penetration 
resistance for the entire lower lobe, applicants would incur 
substantial development costs, including increased testing, and more 
significantly, increased airplane weight. The FAA cannot, at present, 
justify these costs against the potential benefits they would provide. 
Instead, proposed Sec.  25.856(b) would allow for another means of 
providing fire penetration resistance, and proposed AC 25.856-2B would 
address the use of fuselage structure in an equivalent means of 
providing fire penetration resistance. These provisions should reduce 
the administrative actions necessary if an applicant chooses to provide 
a fire penetration barrier by means other than insulation.
8. Radiant Heat Resistance Test for Escape Slides (Sec.  25.853(d)(5))
    Proposed Sec.  25.853(d)(5) would incorporate a requirement from 
TSO-C69C, ``Emergency Evacuation Slides, Ramps, Ramp/Slides, and Slide/
Rafts,'' for applicants to conduct tests to ensure the continued 
functioning of escape systems when those systems are exposed to the 
effects of radiant heat from a post-crash fuel fire. Since all escape 
slides currently comply with the radiant heat resistance requirement of 
TSO-C69C, this proposal would add no compliance burden. Compliance with 
TSO-C69C would also provide the necessary data for compliance with the 
new part 25 requirement. Proposed AC 25.853-6X would contain details of 
the radiant heat test method and pass/fail criteria and would include 
refinements developed since the TSO-C69C was last updated.
9. Fire Containment Compliance of Waste Receptacles (Current Sec.  
25.853(h))
    The fire containment requirements for waste receptacles would 
remain the same with this proposal. However, because of the 
reorganization of Sec.  25.853, this proposal would move the waste 
receptacle requirements from Sec.  25.853(h) to proposed Sec.  
25.853(c)(1)(ii). In addition, proposed Sec.  25.853(c)(1)(ii) would 
require at least one test specimen to show compliance. This change is 
necessary because proposed Sec.  25.853(b) adds a general test 
requirement that three specimen sets be used to show compliance with 
proposed Sec. Sec.  25.853(c) and (d). Requiring one test specimen for 
waste receptacles is

[[Page 31755]]

consistent with the current Sec.  25.853(h), which requires 
demonstration by test.
    Waste receptacles face the threat of an in-flight fire occurring 
within the receptacle. The current Sec.  25.853(h) addresses this 
threat, but the requirement does not specify a test method from 
appendix F to part 25 as do the other paragraphs of the current Sec.  
25.853. AC 25-17A, Change 1, ``Transport Airplane Cabin Interiors 
Crashworthiness Handbook,'' dated May 24, 2016, currently summarizes an 
acceptable method of compliance for waste receptacles. This method 
would be updated in chapter B1 of FAA Report No. DOT/FAA/TC-17/55, in 
order to reflect current knowledge about in-flight fire sources and 
typical waste materials.
10. Extensively Used Materials in Inaccessible Areas (Proposed Sec.  
25.853(c)(2)(i))
    The FAA is proposing new fire safety standards that would apply to 
all materials that are extensively used within and including the 
fuselage but are not accessible in flight. Proposed Sec.  25.853(c) 
would set a performance standard of prohibiting the flammability 
characteristics of parts, components, and materials involved in an in-
flight fire from creating a hazard to the occupants or to the continued 
safe flight of the airplane. For the purposes of this proposed rule, 
the ``flammability characteristics'' of a part, component, or assembly 
(or the materials from which they are made) are all of the ways those 
items respond to a particular fire threat. Such flammability 
characteristics include the material's ease of ignition, its tendency 
to propagate a flame, and its HRR, as well as other parameters 
correlated with heat release, including the emission of smoke and toxic 
gases.
    Proposed Sec.  25.853(c)(2)(i) would set the performance standard 
that extensively used parts, components, and assemblies must not 
propagate the largest fire that, by itself, would not be a hazard to 
the airplane.
    When the FAA adopted the flammability requirements for thermal/
acoustic insulation in 2003 (amendment 25-111),\30\ the FAA's 
regulatory evaluation estimated that the requirements would mitigate 
\31\ roughly half the potentially catastrophic in-flight fires that 
might occur over a 20-year period. In order to more completely address 
the risk due to in-flight fire, the FAA determined that all extensively 
used materials in inaccessible areas should have the same level of fire 
resistance as thermal/acoustic insulation, currently addressed in Sec.  
25.856(a). Therefore, proposed Sec.  25.853(c)(2)(i) would set the same 
performance standard for extensively used parts in inaccessible areas 
that is in the current Sec.  25.856(a).
---------------------------------------------------------------------------

    \30\ See ``Improved Flammability Standards for Thermal/Acoustic 
Insulation Materials Used in Transport Category Airplanes,'' 
published in the Federal Register on July 31, 2003 (68 FR 45045) and 
available on the internet at https://www.govinfo.gov/content/pkg/FR-2003-07-31/pdf/03-18612.pdf.
    \31\ I.e., prevent the fire from becoming catastrophic.
---------------------------------------------------------------------------

    To further explain the reason for this proposal, the parts and 
materials of primary concern in inaccessible areas are electrical 
wiring, ducting, and composite structure. Each of these is 
``extensively used,'' in the meaning set forth in this proposal, and 
could permit a fire to propagate inside the airplane. Since the areas 
in question are not accessible by the flightcrew, there is no effective 
way to fight the fire, so the flammability (flame propagation) 
resistance of the materials is paramount in in-flight fire safety. This 
proposal would also revise Sec.  25.856(a), which states the 
requirements for thermal/acoustic insulation, to require the same 
performance standards as Sec.  25.853(c)(2)(i). This would have the 
effect of limiting the applicability of the in-flight flame propagation 
requirement to thermal/acoustic insulation that is located in an area 
that is inaccessible in flight. Proposed AC 25.853-5X would provide 
additional detail on the types of components that are affected by this 
requirement, as well as methods of compliance.
    Section 25.1713, ``Fire protection: EWIS,'' applies to electrical 
wire and cable wherever it is used. Materials used in any electrical 
wire and cable insulation, including protective shrouds, are considered 
extensively used. This proposal would restate the current fire 
protection requirements relative to whether the wire is installed 
within or outside the fuselage. For electrical wiring interconnected 
systems (EWIS) components installed within the fuselage, under proposed 
Sec.  25.1713(c)(2) the insulation would have to meet the performance 
standards in proposed Sec.  25.853(c), which includes different 
standards for installations in areas that are accessible and 
inaccessible in-flight, and in a post-crash environment. For EWIS 
installed outside the fuselage, because such areas are inaccessible, 
proposed Sec.  25.1713(c)(1) would require that such components not 
propagate the largest fire that, by itself, would not be a hazard to 
the airplane. This proposal would also add a new paragraph (d) to Sec.  
25.853 to require testing, except for wiring installations that would 
not pose a risk to fire safety. Proposed AC 25.853-5X would provide 
accepted test methods for showing compliance with the new performance 
standards.
    Other extensively used materials include nonmetallic or flammable 
metals used in some fuselage construction today. Since the use of these 
materials in this manner constitutes a novel or unusual design feature, 
the FAA has addressed the issue of in-flight fire safety for designs 
using these materials through special conditions. Those special 
conditions are intended to ensure that the use of nonmetallic or 
flammable metal structure does not reduce the level of in-flight fire 
safety from the level that would have been provided with a traditional 
metallic fuselage. Proposed Sec.  25.853(a) would include the fuselage 
in the fire protection requirements regardless of the type of material 
used in its construction and would eliminate the need for such special 
conditions. Proposed Sec.  25.853(d)(4) would require that flammable 
metals used in cabin construction be able to resist a post-crash fire, 
and that they be readily extinguishable. ``Readily extinguishable,'' in 
this instance, means that a fire extinguishing system in common use in 
aviation (including a hand-held fire extinguisher or airport emergency 
response) can promptly extinguish the materials, rather than spreading 
the fire or otherwise making the fire worse.
    Under Sec.  25.853(c)(2) of this proposal, the back sides of many 
existing interior features (e.g., galleys, sidewalls, ceilings) would 
meet the definition of extensively used and would, therefore, be 
required to show by test their fire propagation resistance. However, 
the FAA has assessed the performance of these materials, both in 
service and in testing. Since the materials' fire propagation 
resistance has been satisfactory, and because they are subject to other 
flammability requirements, the FAA does not see a need to require 
additional tests for the portion of these parts that face inaccessible 
areas. Therefore, proposed appendix F to part 25 and proposed AC 
25.853-1A would summarize conditions under which methods of compliance 
other than testing would be acceptable in order to meet the in-flight 
fire requirements for inaccessible areas.
    Proposed Sec.  25.853(c)(2)(v) would require that all other parts, 
components, and materials located in inaccessible areas be self-
extinguishing when exposed to a small flame or electrical arc. However, 
since these would by definition be components that are not extensively 
used, an applicant could document a process whereby the

[[Page 31756]]

flammability of parts used in inaccessible areas is controlled to meet 
the required level of safety of the proposed rule. Specifically, an 
applicant could show that its design/production system includes 
provisions such that parts used in inaccessible areas have only known 
flammability characteristics, or any parts that do have unknown 
flammability characteristics are insignificant in the event of a fire. 
Proposed AC 25.853-1A would discuss this in more detail.
11. Exclusions From Testing (Proposed Sec.  25.853(e))
    Proposed Sec.  25.853(e) would allow applicants to substantiate 
certain components without the testing required by Sec.  25.853(b). 
Section 25.853(e) would establish five classes of parts that would not 
require certification testing in order to show compliance. Each 
individual class would be based on a combination of factors that affect 
fire safety and complexity of certification. The classes maintain the 
level of safety provided in the current regulations.
    The applicant would have to prove that the part or component meets 
the criteria of one of the five classes listed in proposed Sec.  
25.853(e), in order to obtain the FAA's approval to exempt those parts 
from testing. Proposed AC 25.853-1A would provide examples that would 
qualify for this relief and guidance for justifying it.
    The classes are as follows:
     Class 1 parts are small (each able to fit, in its 
entirety, within a cube measuring two inches on each side) and 
separated from one another so that they will not propagate a fire.
     Class 2 parts are larger than Class 1 parts and are self-
extinguishing. These parts would be limited in size to a volume of 113 
cubic inches and an exposed area of 200 square inches.
     Class 3 parts are those that the applicant 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. By threaten, the FAA means 
pose a risk to continued safe flight and landing or a hazard to the 
occupants.
     Class 4 parts are those that are essential to the safety 
of the airplane, its occupants, or the functionality \32\ of the 
airplane and cannot reasonably be made from a material that meets the 
flammability requirements without compromising the part's integrity or 
functionality. Although this paragraph provides an exception, the FAA 
expects the proposed design would come as closely as possible to full 
compliance, including the use of best available materials and showing 
that there is no adverse effect on safety.
---------------------------------------------------------------------------

    \32\ Such necessary functionality does not include entertainment 
systems but would include lavatories and potable water tanks.
---------------------------------------------------------------------------

     Class 5 parts are those that have already passed a more 
stringent test as outlined in appendix F to part 25.
    All of these provisions would apply to testing requirements for 
both the in-flight and post-crash fires.
    The FAA is proposing these exceptions because the current general 
exclusion of small parts from testing requirements in part I of 
appendix F to part 25 has been problematic. There is currently no 
definition of small parts in the flammability regulations, only 
examples. Since testing is not required, the flammability 
characteristics of those small parts can be unknown. In addition, there 
is no consideration of accessibility, extensive use, or potential type 
of fire exposure. Adopting different classes of parts would simplify 
the requirements and bring standardization to those situations where 
parts are not tested. Proposed AC 25.853-1A would provide examples that 
would qualify for this relief and guidance on justifying it.
12. Pass/Fail Criteria
    This proposal would remove the detailed pass/fail criteria from 
appendix F to part 25. Section 25.853(b) of this proposal would define 
the number of specimen sets required for tests that the applicant uses 
to show compliance. The applicable proposed AC would provide approved 
number of passing samples for certain testing methods.
    The detailed pass/fail criteria, currently in appendix F to part 
25, are specific to the test method. Depending on what the test is 
measuring, the pass/fail criteria relate to the key parameters of 
interest (e.g., burn length, extinguishing time, HRR) necessary to meet 
the level of safety that the requirement. The pass/fail criteria are 
based on a required number of test samples and the number of samples 
that meet the specified criteria. All of the current test methods 
require at least three sets of test samples, which may include more 
than one specimen depending on the test method.
    Some current test methods require the average value of the test 
results to be at or below a certain level; others require that no 
sample can fail. For example, the seat cushion test in current appendix 
F to part 25 requires that two thirds of the test samples meet certain 
criteria as well as the average of all test samples. One of the key 
ongoing difficulties with these criteria is how to recover from failure 
of a single sample, where that sample may be an outlier. For those 
methods that require an average, simply testing more samples improves 
the statistical significance of the average, and has generally been 
acceptable (although the FAA must approve in advance the number of 
additional samples to be tested). For test methods that do not permit 
any sample to exceed specified values, a failure of one sample is 
problematic, since one failure would violate the criteria no matter how 
many additional samples are tested. Such failures are often attributed 
to so-called ``rogue'' samples: Samples that have some irregular 
characteristic that makes their performance unrepresentative of the 
material (part or component) in general. While rogue samples 
undoubtedly occur, it is often difficult to pinpoint their cause.
    This proposal would address this issue in Sec.  25.853(b) by 
standardizing the number of samples and required pass rate: 80 percent 
for every new or improved test method, based on a minimum of three test 
sample sets. The effect would be that if only three samples are tested, 
all must pass. If one of the three samples fails, then at least two 
additional samples would be needed to obtain an 80 percent passing 
rate. This standard would be effectively relieving for tests on 
thermal/acoustic insulation and Class C cargo compartment liners 
because those methods in part III of appendix F to part 25 currently 
permit no failures. In contrast, this method could be more stringent 
for Bunsen burner and HRR tests because it could require more samples. 
The method is similar to the method currently required for testing seat 
cushions. However, since this proposal would eliminate many Bunsen 
burner tests and the test for smoke emissions (all in appendix F), even 
if an applicant needed additional samples to show compliance, the total 
number of required tests should be very close to the number required 
today. Also, samples that are invalidated due to an assignable cause 
could still be discarded and replaced with new samples.
    Most of the test methods currently in use would continue to be 
acceptable for certification. An applicant could choose to use these 
existing methods to show compliance with the relevant portions of this 
proposal. However, the FAA considers the revised versions of these test 
methods, as documented in FAA Report No. DOT/FAA/TC-17/55, to be more 
reliable than the previous versions. The only test methods currently 
required that would not be carried forward under this proposal are

[[Page 31757]]

the horizontal Bunsen burner test and the test for smoke emissions. If 
an applicant uses a current test method to comply with a performance 
standard in this proposal, then the applicant should use existing pass/
fail criteria (including all measured parameters). In that case, an 
applicant would be trading the lower reliability of the older test 
method against the need to prepare additional test samples. For new 
tests, such as those for extensively used materials in inaccessible 
areas, at this time there are no proven optional methods to those 
presented in the proposed guidance, which includes the 80-percent 
criteria.
    The table below identifies each test method; the current location 
of the detailed test method in regulatory requirements and non-
regulatory procedures; and the location where each test method could be 
found, in non-regulatory procedures, if this proposal is adopted.

------------------------------------------------------------------------
                                    Currently
                                   approved (or     Non[dash]regulatory
          Test method               required)            procedures
                                    procedures
------------------------------------------------------------------------
Bunsen burner.................  Part I of          AMFTH,** Chapters A1
                                 appendix F to      and A2.
                                 part 25, AMFTH,*
                                 Chapters 1-4.
Oil burner--seats.............  Part II of         AMFTH,** Chapters A5.
                                 appendix F to
                                 part 25, AMFTH,*
                                 Chapter 7.
Oil burner--cargo liner.......  Part III of        AMFTH,** Chapters B2.
                                 appendix F to
                                 part 25, AMFTH,*
                                 Chapter 8.
Oil burner--insulation........  Part VII of        AMFTH,** Chapter A5.
                                 appendix F to
                                 part 25.
Oil burner--Mg alloy..........  N/A..............  AMFTH,** Chapter A6.
Heat release rate.............  Part IV of         AMFTH,** Chapter A4.
                                 appendix F to
                                 part 25, AMFTH,*
                                 Chapter 5.
Radiant heat--escape slide....  TSO C69C.........  AMFTH,** Chapter A2.
Radiant panel.................  Part VI of         AMFTH,** Chapter B2.
                                 appendix F to
                                 part 25.
Vertical flame propagation--    N/A..............  AMFTH,** Chapter B5.
 Wiring.
Vertical flame propagation--    N/A..............  AMFTH,** Chapter B4.
 Ducting.
Vertical flame propagation--    N/A..............  AMFTH,** Chapter B3.
 Composite structure.
Fire containment..............  AMFTH,* Chapter    AMFTH,** Chapter B1.
                                 10.
------------------------------------------------------------------------
* FAA Report No. DOT/FAA/AR-00/12, ``Aircraft Materials Fire Test
  Handbook,'' dated April 2000.
** FAA Report No. DOT/FAA/TC-17/55, ``Aircraft Materials Fire Test
  Handbook,'' Revision 3, dated June 2019.

    While the previous test methods, as shown in the table above, would 
continue to be acceptable, the FAA will not continue to refine these 
methods to improve their repeatability and reproducibility. The FAA's 
future focus on refining and improving test methods will be on the new 
and improved test methods documented in FAA Report No. DOT/FAA/TC-17/
55, since these are now the preferred methods and would become the 
preferred methods of compliance with the performance standards of this 
proposal.

B. Reorganization of Appendix F to Part 25

1. General Structure
    The FAA is proposing to substantively change appendix F to part 25 
by removing its many specifications for flammability tests and adding a 
list of flammability test methods that applicants can use in lieu of 
other test methods. The FAA would remove and update the detailed 
testing criteria from the current appendix F, although it would 
continue to be available in advisory material. This proposal would 
provide flexibility for applicants in showing compliance with the 
proposed revisions to the fire protection standards in Sec.  25.853.
    Currently, appendix F to part 25 is divided into seven parts, each 
providing details of different test methods, with variations for 
specific airplane parts, and acceptable outcomes for each test 
variation. Because of the importance of maintaining standardization, 
these test methods are very detailed and, therefore, lengthy. Since 
appendix F to part 25 is a regulation, applicants must get the FAA's 
approval to depart from any of the test details. As the test methods 
have become more complicated and sophisticated over time, following 
every detail has become more important in obtaining reliable results. 
Conversely, as technology advances, providing more opportunities to 
refine and improve the test methods, requests for deviation from 
appendix F to part 25 have become more frequent. To deal with these 
requests, the FAA issued a policy statement to permit use of FAA Report 
No. DOT/FAA/AR-00/12 as an acceptable method of compliance for many of 
the test methods in appendix F to part 25. The FAA also developed a 
method for updating the handbook, so that improvements could be 
implemented quickly and used by industry without extensive 
administrative burden.
    Given this experience, the FAA has determined that the detailed 
test methods should no longer be regulatory.
    In conjunction with this proposal, the detailed test methods would 
be contained in ACs (see section III.D, ``Advisory Materials'' of this 
NPRM), which are easier to update than a regulation and allow for more 
flexibility as refinements and improvements to the test methods become 
available. As with any advisory material, the method would not be 
mandatory, but applicants would have to justify and obtain approval of 
other compliance methods.
    To improve the effectiveness of the handbook approach to 
compliance, a new document would serve as a compendium of the relevant 
test methods. The associated ACs would reference this compendium, and 
the FAA would update it as advances and improvements in test methods 
and equipment are developed. However, the original version and 
subsequent versions of the compendium would remain an acceptable method 
of compliance with these proposed regulations, unless the FAA discovers 
a deficiency in a given version, or changes the regulatory requirements 
after notice and comment.
2. Hierarchy of Tests
    This proposal would add provisions to appendix F to part 25 that 
would allow applicants to demonstrate compliance with a requirement in 
one of the proposed paragraphs of Sec.  25.853 via a test method at 
least as rigorous as one acceptable for showing compliance with the 
original requirement. Appendix F to part 25 would contain a table of 
these performance standards indicating whether showing compliance with 
one standard would be sufficient to satisfy showing compliance with 
another. This table would help applicants determine the relative

[[Page 31758]]

severity of the testing methods that the FAA would find acceptable for 
showing compliance and, therefore, would allow applicants to eliminate 
redundant or non-value-added testing. Since the critical performance 
parameters (e.g., flame propagation and fire penetration) differ 
according to the type of fire (in-flight or post-crash fuel fire), the 
proposed revisions to appendix F to part 25 would clarify which types 
of compliance tests the FAA would find acceptable as substitutions for 
a given type of fire threat.
    This would allow a successful result on other, more stringent, 
testing to prove that a given material will not pose a hazard in that 
type of fire. For example, appendix F to part 25 would allow applicants 
to use a successful HRR test to show compliance with the requirement to 
pass a Bunsen burner test, or to use a post-crash fire test method, 
coupled with experience for certain classes of materials, to show 
compliance with an otherwise required in-flight fire test method. The 
FAA has determined that, for certain classes of materials, complying 
with one requirement provides sufficient data to show compliance with 
another, subject to certain conditions. Each instance where compliance 
with the post-crash requirements is sufficient to meet the in-flight 
requirement would be discussed in more detail in proposed AC 25.853-1A.
    An example of the allowable use of a post-crash requirement to meet 
an in-flight requirement would be for the back sides of the large 
interior surfaces (sidewalls, ceilings, floors, galleys, etc.) not 
exposed to the cabin. As discussed previously, these surfaces would be 
subject to proposed Sec.  25.853(c)(2), which would require that, for 
in-flight fires, extensively used materials in inaccessible areas not 
propagate the largest fire that, by itself, would not be a hazard to 
the airplane. The vertical flame propagation test is currently the 
expected means of compliance to this standard. However, with the 
exception of floor panels, the types of materials used for these 
applications have not been a safety concern for in-flight fires, and 
these materials would still have to meet the stringent requirements 
related to heat release for the post-crash environment. With the 
proposed hierarchy table in appendix F to part 25, if these materials 
pass the HRR tests, they would not also have to pass the vertical flame 
propagation test.
    The same allowance is true for the back side of cargo compartment 
liners, even though they are subject to a different probable type of 
fire threat (post-crash fuel fires) and required by appendix F to be 
tested using the oil burner test. Although the oil burner and vertical 
flame propagation tests are not universal substitutes for each other, 
the materials on the back of cargo compartment liners have exhibited 
satisfactory behavior in the presence of in-flight fires, as 
demonstrated by FAA testing, and should not require further testing by 
the vertical flame propagation test. Should new materials be developed 
whose performance in an in-flight fire has not been established, then 
the proposed rule would provide the means to address and allow them, 
and both test methods may be necessary to demonstrate that compliance. 
This would be indicated in the note to the table in proposed appendix F 
to part 25.
    As a final note, the FAA recognizes that its current regulations 
provide flexibility for an applicant via the repeated provision 
allowing ``other approved test methods.'' However, this provision does 
not adequately address the need for consistency in test methods because 
it is optional, and each applicant could seek approval of a unique 
alternative method. This can result in the same material passing one 
applicant's test and failing another, even though both test methods 
could be approved by the FAA. The FAA expects that this proposal would 
provide the same level of flexibility, but increased consistency over 
time as consensus on testing methods develops.

C. Conformal and Editorial Changes

    Special Federal Aviation Regulation (SFAR) 109 to part 25 also 
requires compliance with certain paragraphs of Sec.  25.853 that would 
be changed by this proposal. Consequently, the FAA would modify SFAR 
109 so that those requirements continue after Sec.  25.853 is amended.
    Certain sections of 14 CFR parts 27 and 29, for normal and 
transport category rotorcraft, currently require testing in accordance 
with appendix F to part 25. Although this proposal would remove those 
testing requirements from appendix F for transport category airplanes, 
the FAA does not propose to remove or change those requirements for 
normal and transport category rotorcraft. Therefore, this proposal 
would add an amendment level to the appendix F references in Sec. Sec.  
27.1365, 29.853, and 29.1359 to continue those requirements after 
appendix F is amended.
    The proposed rule would also remove certain testing requirements 
regarding average burn length from paragraphs (a)(1) and (a)(2) of 
Sec.  29.853 because those requirements are redundant with current 
appendix F to part 25.
    Operational rules in certain sections of 14 CFR parts 91, 121, 125, 
and 135 also currently require testing in accordance with Sec. Sec.  
25.853 and 25.856 and appendix F to part 25. The FAA proposes to add 
the phrase ``or as subsequently amended'' to Sec. Sec.  91.613, 
121.312, 121.314, 125.113, 135.169, and 135.170, so that airplanes 
approved in accordance with the amendment resulting from this proposal 
would be able to comply with the operational rules. The ``or'' in that 
phrase serves the purpose of making compliance with this proposal or a 
later amendment optional.
    In addition, appendix L to part 121 contains information regarding 
referenced sections of part 25 that have subsequently changed through 
amendments. Appendix L would also be updated to conform to this 
proposal.
    These changes to parts 25, 27, 29, 91, 121, 125, and 135 would have 
no substantive impact on safety or the cost of compliance.
    This proposal also contains some editorial changes to existing 
regulatory language, where that language does not reflect how the rule 
is applied, or its intent. Specifically, current Sec.  25.853(e) 
excepts certain compartments from compliance with Sec.  25.853(d) if 
they are isolated by a door that would be closed during an emergency 
landing condition. In practice, this exception has been applied when 
such compartments are isolated by a door that is closed for taxi, 
takeoff, and landing, in general. The proposal is changed accordingly 
and will have no impact on the requirement. The proposal moves this 
exception in Sec.  25.853(e) for parts inside of compartments isolated 
from the main passenger cabin to a new Sec.  25.853(d)(2)(ii).
    Current Sec.  25.853(h) requires that disposal receptacles be made 
from materials that are ``fire resistant.'' The term ``fire resistant'' 
is defined in 14 CFR part 1 as having properties equivalent to aluminum 
alloy appropriate for the purpose. In practice, the means of compliance 
has been by meeting the test method specified in current part I of 
appendix F for Class B cargo compartment liners, which is to resist 
penetration by a small flame. The proposal would state the requirement 
in that way to avoid any ambiguity regarding the level of protection 
required. This will also have no impact since it aligns the rule 
language with how the requirement has historically been actually met.
    This proposal contains only minor editorial changes to the 
requirements related to smoking in Sec.  25.853(f) and (g). The 
requirements would remain the

[[Page 31759]]

same, but the paragraphs would be renumbered and restated for clarity.

D. Advisory Material

    The FAA is developing six new ACs and revising three ACs that will 
be published for public comment concurrently with this NPRM. These 
proposed ACs can be found in the same public docket as this NPRM. The 
draft ACs would provide guidance for acceptable means, but not the only 
means, of showing compliance with proposed Sec. Sec.  25.853, 25.855, 
and 25.856. The FAA will accept public comments on the following 
proposed ACs on the ``Aviation Safety Draft Documents Open for 
Comment'' web page at http://www.faa.gov/aircraft/draft_docs/:
    1. AC 25.853-1A, ``Flammability Requirements for Transport Category 
Airplanes.''
    2. AC 25.853-2X, ``Flammability Requirements for Aircraft Seat 
Cushions.''
    3. AC 25.853-3X, ``Flammability Testing Requirements for Commonly 
Constructed Parts, Construction Details, and Materials Used on 
Transport Category Airplanes.''
    4. AC 25.853-4X, ``Vertical Bunsen Burner Tests.''
    5. AC 25.853-5X, ``Flammability Requirements for Materials in 
Inaccessible Areas of Transport Category Airplanes.''
    6. AC 25.853-6X, ``Flammability Requirements for Escape System 
Materials for Transport Category Airplanes.''
    7. AC 25.855-1X, ``Flammability Requirements of Cargo Liners for 
Transport Category Airplanes.''
    8. AC 25.856-1A, ``Thermal/Acoustic Insulation Flame Propagation 
Test Method Details.''
    9. AC 25.856-2B, ``Fuselage Burnthrough Protection.''
    The FAA is also revising Report No. DOT/FAA/AR-00/12 to update the 
test methods contained within this report, as described previously. 
This interim report will be published concurrently with this NPRM as 
FAA Report No. DOT/FAA/TC-17/55, and it can be found in the same public 
docket as this NPRM.

E. Application of Sec. Sec.  21.17

    This proposal would revise the flammability standards for transport 
category airplanes, but would not impose any requirements to retrofit 
existing airplanes or conduct a production-cut in on new airplanes. 
Since this proposal would simplify or remove some of the flammability 
requirements, some applicants may wish to use the standards of this 
proposal instead of an earlier amendment level. Applicants may elect to 
apply the later amendment under Sec.  21.17 or seek exceptions in 
accordance with Sec.  21.101.
    Section 21.17(e) permits an applicant for a type certificate to 
elect compliance with an amendment effective after the date of 
application, as long as all ``directly related'' amendments, as 
determined by the FAA, are complied with as well.
    The FAA has considered which regulatory amendments must be regarded 
as ``directly related'' and, therefore, applied together under Sec.  
21.17. An analysis of what is ``directly related'' requires examination 
of which provisions have been made more flexible and which have been 
made more stringent because these factors are often causally related. 
In some areas, the additional flexibility is the result of a 
requirement that has become more stringent. The primary areas of 
increased flexibility are the proposed removal of the testing 
requirements in appendix F, and the proposed removal of the smoke 
emission requirement. The removal of the appendix F testing 
requirements is only possible, from a safety perspective, because of 
the additional performance standards for inaccessible areas. The main 
area where requirements would become more stringent is extensively used 
components in inaccessible regions of the airplane. These areas are 
mainly threatened by in-flight fires, although improved flammability 
resistance of materials can also benefit post-crash safety. Therefore, 
the FAA considers the entire proposal to be interrelated, such that all 
the proposed changes could be characterized as ``directly related'' to 
each other. However, the FAA expects that a practical application of 
the ``directly related'' provision could simplify compliance under 
Sec.  21.17 and maximize safety, as discussed below.
    Among those components that would be subjected to new test methods 
under this proposal, composite fuselage structure is already subject to 
meeting special conditions, and this proposal would codify the 
requirements in those conditions. Also, aviation-grade electrical 
wiring is for the most part already compliant with the proposed 
flammability requirements. Ducting is one area, however, where many of 
the currently used parts would not meet the proposed requirement for 
extensively used materials in inaccessible areas, and where a 
significant safety benefit would accrue from the higher standard. The 
type of fire that primarily threatens ducting is in-flight. However, 
accidents have shown that ducting can spread and intensify post-crash 
fires. Thus, the safety improvement that would result from applying the 
proposed standards to ducts would enhance fire safety with regard to 
both types of fire, and the FAA considers this safety enhancement 
integral to the proposed changes that would reduce or eliminate other 
testing.
    Therefore, an applicant that elects compliance with the amendment 
level that results from this proposal, in order to take advantage of 
the provisions that reduce or eliminate tests, would also have to 
ensure that ducting complies with the new standards proposed in Sec.  
25.853(c)(2).
    The exception to the requirement to apply directly related changes 
when an applicant elects compliance with the later amendment would be 
the substitution of tests in proposed appendix F to part 25. Such 
substitution is already allowed under the current flammability rules, 
which repeatedly allow applicants to show compliance by ``other 
equivalent method.'' Applicants could apply proposed appendix F to part 
25 to models approved under earlier certification bases without 
affecting safety and without applying other portions of the proposal. 
An applicant's selection of the amendment that most materially 
contributes to safety could eliminate the need to run multiple tests on 
many parts with the recognition that some tests are sufficiently 
stringent that they would satisfy the concerns addressed by other 
tests. Substituting some tests would neither eliminate the need to 
conduct smoke emissions tests, nor alter the applicability of current 
requirements. Proposed appendix F to part 25 would simply permit 
substitution of one test method for another, where the substitute 
method has been determined to be more stringent.
     Example 1: An applicant for a supplemental type 
certificate desires to use only the new appendix F that would result 
from this proposal. In this case, the applicant would be limited to 
applying the hierarchy of appendix F, and no other relief.
     Example 2: An applicant for a change to a type certificate 
(either through amended or supplemental type certification) desires to 
elect compliance with the entire amendment that results from this 
proposal. The applicant must comply with Sec.  25.853(c)(2)(i) as it 
pertains to air ducting, even if the air ducting is unchanged or not 
affected by the proposed design change. Any other provision of the 
proposed rule could then be included at the applicant's choosing.

[[Page 31760]]

F. Application of Sec. Sec.  21.101

    Section 21.101(a) requires design change applicants to meet the 
standards in effect on the date of application that are applicable to 
the change and areas affected by the change, unless exceptions are 
requested and are granted under the provisions of Sec.  21.101(b). 
Section 21.101(b) allows the applicant to show compliance with an 
earlier amendment level for changes found to be not significant, or 
found to not materially contribute to safety, or found to be 
impractical. The FAA does not regard any of the standards proposed here 
as impractical. The degree to which application of these standards 
would ``materially contribute to safety'' will depend on the current 
design.
    As discussed previously, acceptable wiring would be documented in 
proposed AC 25.853-5X and include wiring already widely used by 
applicants; the safety of composite fuselage structure will have been 
covered by special conditions; and ducting may comply with these 
proposed standards, even though certification testing has not been 
performed. In those cases, an applicant may be able to argue that 
including the later amendment would not materially contribute to 
safety, but that use of other provisions (e.g., those that would 
eliminate tests) of the proposal would provide significant benefits to 
the applicant. In that case, the FAA agrees that compliance with the 
later amendment could be acceptable to eliminate tests, provided 
improved design features used to justify the exception are a condition 
of the certification basis in the ``Additional Design Requirements and 
Conditions'' section of the type certificate data sheet.
    The following examples illustrate how this could work in practice:
     Example 1: An applicant for a significant product-level 
change seeks exception, under Sec.  21.101(b), from the amendment that 
results from this proposal on the basis that full compliance would not 
materially contribute to safety. As discussed above, an exception would 
have to be based on substantial compliance with this proposal, such 
that few components are not in compliance, and they would not be 
significant from a fire safety standpoint.
     Example 2: An applicant applies for a fuselage length 
change. The change is considered a significant product-level change per 
the guidance in AC 21.101-1B. AC 21.101-1B also states that the 
simultaneous introduction of a new cabin interior is considered related 
since occupant safety considerations are impacted by a cabin length 
change. The FAA considers this proposed amendment to be directly 
related to occupant safety. As such, for a fuselage change, this 
proposed amendment would be an applicable requirement for the airplane 
(e.g., changed and unchanged areas of the airplane would need to meet 
the requirement). The applicant may request an exception under Sec.  
21.101 by showing compliance with this proposal to a substantial 
extent, such that the few parts not in compliance would not be 
significant from a fire safety standpoint.

IV. Regulatory Notices and Analyses

A. Regulatory Evaluation

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 and Executive Order 13563 direct 
that each Federal agency shall propose or adopt a regulation only upon 
a reasoned determination that the benefits of the intended regulation 
justify its 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 as amended) prohibits agencies from setting standards 
that create unnecessary obstacles to the foreign commerce of the United 
States. In developing U.S. standards, the Trade Agreements Act requires 
agencies to consider international standards and, where appropriate, 
that they be the basis of U.S. standards. 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 likely to result 
in the expenditure by State, local, or tribal governments, in the 
aggregate, or by the private sector, of $100 million or more annually 
(adjusted for inflation with base year of 1995). This portion of the 
preamble summarizes the FAA's analysis of the economic impacts of this 
proposed rule. We suggest readers seeking greater detail read the full 
regulatory evaluation, a copy of which we have placed in the docket for 
this rulemaking.
    In conducting these analyses, FAA has determined that this proposed 
rule: (1) Has benefits that justify its costs; (2) is not an 
economically ``significant regulatory action'' as defined in section 
3(f) of Executive Order 12866; (3) is not ``significant'' as defined in 
DOT's Regulatory Policies and Procedures; (4) would not have a 
significant economic impact on a substantial number of small entities; 
(5) would not create unnecessary obstacles to the foreign commerce of 
the United States; and (6) would not impose an unfunded mandate on 
State, local, or tribal governments, or on the private sector by 
exceeding the threshold identified above. These analyses are summarized 
below.
1. Summary of Costs and Benefits
    By extending fire protection requirements to any extensively used 
material located in inaccessible areas the proposal is likely to be 
beneficial by reducing the likelihood of a fatal accident. Over a 19-
year period of analysis, the FAA estimates the total present value cost 
savings of this proposed rule to be $119.8 million at a seven percent 
discount rate, with annualized cost savings of $11.6 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 19-year period, the 
FAA estimates the total present value costs of this proposed rule to be 
$71.1 million at a seven percent discount rate, with annualized costs 
of $6.9 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 NPRM. The present value 
net cost savings (cost savings minus cost) is $48.7 million, with 
annualized net cost savings of $4.7 million. The following table 
summarizes the costs and cost savings of this proposed rule.

                                   Summary of Costs and Cost Savings (2016 $)
----------------------------------------------------------------------------------------------------------------
                                           19-year total present value                   Annualized
                                     ---------------------------------------------------------------------------
                                              7%                 3%                 7%                 3%
----------------------------------------------------------------------------------------------------------------
Cost Savings........................       $119,848,146       $178,395,887        $11,595,669        $12,454,509

[[Page 31761]]

 
Costs...............................         71,105,318         80,387,114          6,879,654          5,612,136
                                     ---------------------------------------------------------------------------
    Total Net Cost Savings..........         48,742,828         98,008,773          4,716,015          6,842,373
----------------------------------------------------------------------------------------------------------------

2. Who is potentially affected by this proposed rule?
    Manufacturers of part 25 transport category airplanes would be 
potentially affected by the proposed rule.
3. Assumptions
     Totals converted to 2016 constant dollars.\33\
---------------------------------------------------------------------------

    \33\ Calculations were presented in 2015 dollars because most 
cost estimates were received in 2015 but totals were then converted 
to 2016 dollars to be compliant with OMB guidance implementing 
Executive Order 13771.
---------------------------------------------------------------------------

     Time horizon for analysis 19 years.\34\
---------------------------------------------------------------------------

    \34\ A 19-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.
---------------------------------------------------------------------------

     Fifty percent of the current $42.8 million annual costs 
for smoke emissions testing is incurred by domestic airplane 
manufacturers.\35\
---------------------------------------------------------------------------

    \35\ Fifty percent is an estimate of the share of the worldwide 
transport airplane market held by U.S. manufacturers.
---------------------------------------------------------------------------

     Cost savings from eliminating smoke emissions tests would 
increase linearly to the level of the current cost savings over 25 
years.\36\
---------------------------------------------------------------------------

    \36\ Based on manufacturers recommendation in MFWG Report.
---------------------------------------------------------------------------

     Large transport category aircraft.\37\
---------------------------------------------------------------------------

    \37\ Based on FAA analysis of Boeing data, OAG Aviation 
Solutions Fleet Database, FAA Type Certificate Data Sheet database.
---------------------------------------------------------------------------

    [cir] One manufacturer.
    [cir] Four type certificates.
    [cir] Twenty-seven airplanes produced annually.
    [cir] Nineteen-year production period.
     Small transport category aircraft.\38\
    [cir] One manufacturer.
    [cir] Three type certificates.
    [cir] Twenty-one airplanes produced annually.
    [cir] Fifteen-year production cycle.
4. Benefits of This Rule
    The proposed new safety requirements to extend the fire protection 
requirements to any extensively used material \38\ 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 fortunately 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.
---------------------------------------------------------------------------

    \38\ 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.
---------------------------------------------------------------------------

5. Costs of This Proposed Rule
    Over a 19-year period of analysis, the FAA estimates the total 
present value costs of this proposed rule to be $71.1 million at a 
seven percent discount rate, with annualized costs of $6.9 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 assessment accompanying this NPRM.
    Over the same 19-year period, the FAA estimates the total 
quantified cost savings of this proposed rule to be $119.8 million at a 
seven percent discount rate, with annualized cost savings of $11.6 
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 $48.7 million, with annualized net cost savings of $4.7 
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. The proposed changes to 
these parts also include language to operating requirements. This new 
language would give operators the choice of meeting the proposed 
requirements, or complying with the old 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.

B. Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) 
establishes ``as a principle of regulatory issuance that agencies shall 
endeavor, consistent with the objectives of the rule and of applicable 
statutes, to fit regulatory and informational requirements to the scale 
of the businesses, organizations, and governmental jurisdictions 
subject to regulation. To achieve this principle, agencies are required 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions to assure that such proposals are given 
serious consideration.'' The RFA covers a wide range of small entities, 
including small businesses, not-for-profit organizations, and small 
governmental jurisdictions.
    Agencies must perform a review to determine whether a rule would 
have a significant economic impact on a substantial number of small 
entities. Under Section 603 of the RFA, the FAA has prepared an initial 
regulatory flexibility analysis addressing the following:

[[Page 31762]]

     A description of the reasons why the action by the agency 
is being considered.
     A succinct statement of the objectives of, and legal basis 
for, the proposed rule.
     A description and, where feasible, an estimate of the 
number of small entities to which the proposed rule will apply.
     A description of the projected reporting, recordkeeping, 
and other compliance requirements of the proposed rule, including an 
estimate of the classes of small entities that would be subject to the 
requirement and the types of professional skills necessary for 
preparation of the report or record.
     An identification, to the extent practicable, of all 
relevant federal rules that may duplicate, overlap, or conflict with 
the proposed rule.
     A description of any significant alternatives to the 
proposed rule that accomplish the stated objectives of applicable 
statutes, and that minimize any significant economic impact of the 
proposed rule on small entities.
1. A Description of the Reasons Why the Action by the Agency Is Being 
Considered
    The FAA is publishing this proposed rule 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 airplanes. Simplifying these 
regulations can lead to cost savings.
    A key safety benefit of this proposed rule 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 events due to lithium 
battery fires, the chances of a lithium battery fire in the cabin 
getting to an inaccessible area are increasing.
2. A Succinct Statement of the Objectives of, and Legal Basis for, 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 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.
3. Description and, Where Feasible, an Estimate of the Number of Small 
Entities To Which the Proposed Rule Would Apply
    This proposed rule would affect U.S. manufacturers of part 25 
transport category airplanes requesting a new 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 proposed rule 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.
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 That Will be Subject to the Requirement 
and the Types of Professional Skills Necessary for Preparation of the 
Report or Record
    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 proposed 
rule would not impose additional reporting, recordkeeping, or other 
compliance requirements on small entities.
5. An Identification, to the Extent Practicable, of All Relevant 
Federal Rules That May Duplicate, Overlap, or Conflict With the 
Proposed Rule
    There are no federal rules that may duplicate, overlap, or conflict 
with this proposal.
6. A Description of any Significant Alternatives to the Proposed Rule
    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, conflicting, 
redundant, occasionally incomplete, and 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 proposed rule would not result in a 
significant economic impact on a substantial number of small entities. 
The FAA requests comments on this finding.

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

[[Page 31763]]

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

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement 
assessing the effects of any Federal mandate in a proposed or final 
agency rule that may result in an expenditure of $100 million or more 
(in 1995 dollars) in any one year by State, local, and tribal 
governments, in the aggregate, or by the private sector; such a mandate 
is deemed to be a ``significant regulatory action.'' The FAA currently 
uses an inflation-adjusted value of $155.0 million in lieu of $100 
million.
    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 this proposed rule.

F. International Compatibility

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

V. 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 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.

C. Executive Order 13609, 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.

D. Executive Order 13771, Reducing Regulation and Controlling 
Regulatory Costs

    Executive Order 13771 titled ``Reducing Regulation and Controlling 
Regulatory Costs,'' directs that, unless prohibited by law, whenever an 
executive department or agency publicly proposes for notice and comment 
or otherwise promulgates a new regulation, it shall identify at least 
two existing regulations to be repealed. In addition, any new 
incremental costs associated with new regulations shall, to the extent 
permitted by law, be offset by the elimination of existing costs. Only 
those rules deemed significant under section 3(f) of Executive Order 
12866, ``Regulatory Planning and Review,'' are subject to these 
requirements.
    As determined in section IV.A, above, this is not a significant 
rule under Executive Order 12866. Accordingly, this rule is not subject 
to the requirements of Executive Order 13771.

VI. 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: Commenters should 
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

[[Page 31764]]

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 rulemaking documents may be obtained from the 
internet by--
    1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);
    2. Visiting the FAA's Regulations and Policies web page at http://www.faa.gov/regulations_policies; or
    3. Accessing the Government Printing Office's web page at http://www.gpo.gov/fdsys/.
    Copies may also be obtained by sending a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue SW, Washington, DC 20591, or by calling (202) 267-9680. 
Commenters must identify the docket or notice number of this 
rulemaking.
    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.

List of Subjects

14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping requirements

14 CFR Part 27

    Aircraft, Aviation safety

14 CFR Part 29

    Aircraft, Aviation safety

14 CFR Part 91

    Air carrier, Air taxis, Air traffic control, Aircraft, Airmen, 
Airports, Alaska, Aviation safety, Canada, Charter flights, Cuba, Drug 
traffic control, Ethiopia, Freight, Incorporation by reference, Iraq, 
Mexico, Noise control, North Korea, Political candidates, Reporting and 
recordkeeping requirements, Somalia, Syria, Transportation

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 Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend chapter 1 of title 14, Code of Federal 
Regulations 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) General. 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) Testing. 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

[[Page 31765]]

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.
    (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.  25.1713  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:

[[Page 31766]]

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:

--------------------------------------------------------------------------------------------------------------------------------------------------------
          Substitution                                                                   Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                    In-flight cargo
                                       In-flight        Post-crash <20;     In-flight cargo        In-flight          liner fire
                                   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 ignition    Yes...............  No................  No................  No................  No................  No.
 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 surface    Yes...............  Yes...............  No................  Note \1\..........  No................  Note \2\.
 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).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.

* * * * *

[[Page 31767]]

    (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: 106(f), 106(g), 1155, 40101, 40103, 40105, 40113, 
40120, 44101, 44111, 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:  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).

0
16. Amend Sec.  121.312 by revising paragraphs (b) introductory text, 
(e)(1) introductory text, and (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.

------------------------------------------------------------------------
                                                     Provisions: CFR/FR
      Part 121 section         Applicable aircraft       references
------------------------------------------------------------------------
Sec.   121.312(a)(1)(i).....  Transport category;   Heat release rate
                               or nontransport       testing. 14 CFR
                               category type         25.853(d)(2)
                               certificated before   effective
                               January 1, 1965;      [effective date of
                               passenger capacity    final rule]: 14 CFR
                               of 20 or more;        parts 1 to 59,
                               manufactured prior    Revised as of
                               to August 20, 1990.   January 1, [Federal
                                                     Register revision
                                                     year], and amended
                                                     by Amdt. [amendment
                                                     level and Federal
                                                     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 31768]]

 
Sec.   121.312(a)(1)(ii)....  Transport category;   Heat release rate
                               or nontransport       testing. 14 CFR
                               category type         25.853(d)(2)
                               certificated before   effective
                               January 1, 1965;      [effective date of
                               passenger capacity    final rule]: 14 CFR
                               of 20 or more;        parts 1 to 59,
                               manufactured after    Revised as of
                               August 19, 1990.      January 1, [insert
                                                     Federal Register
                                                     revision year], and
                                                     amended by Amdt.
                                                     [amendment level
                                                     and Federal
                                                     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 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 category;   Provisions of 14 CFR
                               or nontransport       25.853 in effect on
                               category type         April 30, 1972: 14
                               certificate before    CFR parts 1 to 59,
                               January 1, 1965;      Revised as of
                               application for       January 1, 1972.
                               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 category    Heat release rate
                               type certificated     testing. 14 CFR
                               after January 1,      25.853(d) in effect
                               1958; nontransport    March 6, 1995: 14
                               category type         CFR parts 1 to 59,
                               certificated after    Revised as of
                               January 1, 1958,      January 1, 1995;
                               but before January    and amended by
                               1, 1965; passenger    Amdt. 25-83, 60 FR
                               capacity of 20 or     6623, February 2,
                               more; substantially   1995.
                               complete
                               replacement of the
                               cabin interior on
                               or after March 6,
                               1995.
                                                    Formerly 14 CFR
                                                     25.853(a-1) in
                                                     effect August 20,
                                                     1986: 14 CFR parts
                                                     1 to 59, Revised as
                                                     of January 1, 1986.
Sec.   121.312(a)(3)(ii)....  Transport category    Heat release rate
                               type certificated     testing. 14 CFR
                               after January 1,      25.853(d)(2)
                               1958; nontransport    effective
                               category type         [effective date of
                               certificated after    final rule]: 14 CFR
                               January 1, 1958,      parts 1 to 59,
                               but before January    Revised as of
                               1, 1965; passenger    January 1, [Federal
                               capacity of 20 or     Register revision
                               more; substantially   year], and amended
                               complete              by Amdt. [amendment
                               replacement of the    level and Federal
                               cabin interior on     Register citation
                               or after August 20,   and publication
                               1990.                 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 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 category    Seat cushions. 14
                               airplane type         CFR 25.853(d)(3)
                               certificated after    effective
                               January 1, 1958;      [effective date of
                               nontransport          final rule]: 14 CFR
                               category airplane     parts 1 to 59,
                               type certificated     Revised as of
                               after December 31,    January 1, [Federal
                               1964.                 Register revision
                                                     year], and amended
                                                     by Amdt. [amendment
                                                     level and Federal
                                                     Register citation
                                                     and publication
                                                     date of 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
                               accordance with       CFR 25.853(a) in
                               SFAR No. 41;          effect March 6,
                               maximum               1995: 14 CFR parts
                               certificated          1 to 59, Revised as
                               takeoff weight in     of January 1, 1995,
                               excess of 12,500      and amended by
                               pounds.               Amdt. 25-83, 60 FR
                                                     6623, February 2,
                                                     1995.

[[Page 31769]]

 
                                                    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 category    Class C or D cargo
                               airplanes type        or baggage
                               certificated after    compartment
                               January 1, 1958.      definition. 14 CFR
                                                     25.853(c)(2)(ii)
                                                     effective
                                                     [effective date of
                                                     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 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.
------------------------------------------------------------------------

    (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:  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 (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:  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 (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 the authority provided by 49 U.S.C. 106(f), 
44701(a), and 44703 in Washington, DC, on June 12, 2019.
Chris Carter,
Acting Executive Director, Aircraft Certification Service.
[FR Doc. 2019-13646 Filed 7-1-19; 8:45 am]
 BILLING CODE 4910-13-P


