[Federal Register Volume 68, Number 147 (Thursday, July 31, 2003)]
[Rules and Regulations]
[Pages 45046-45084]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18612]



[[Page 45045]]

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Part III





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 25, 91, et al.



Improved Flammability Standards for Thermal/Acoustic Insulation 
Materials Used in Transport Category Airplanes; Final Rule

  Federal Register / Vol. 68, No. 147 / Thursday, July 31, 2003 / Rules 
and Regulations  

[[Page 45046]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

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

[Docket No. FAA-2000-7909; Amdt. Nos. 25-110, 91-275, 121-289, 125-43, 
135-85]
RIN 2120-AG91


Improved Flammability Standards for Thermal/Acoustic Insulation 
Materials Used in Transport Category Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting upgraded flammability standards for 
thermal and acoustic insulation materials used in transport category 
airplanes. These standards include new flammability tests and criteria 
that address flame propagation and entry of an external fire into the 
airplane. This action is necessary because the current standards do not 
realistically address situations in which thermal or acoustic 
insulation materials may contribute to the propagation of a fire. This 
action is intended to enhance safety by reducing the incidence and 
severity of cabin fires, particularly those in inaccessible areas where 
thermal and acoustic insulation materials are installed, and providing 
additional time for evacuation by delaying the entry of post-crash 
fires into the cabin.

DATES: This final rule is effective on September 2, 2003.

FOR FURTHER INFORMATION CONTACT: Jeff Gardlin, FAA Airframe and Cabin 
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-
4056; telephone (425) 227-2136, facsimile (425) 227-1149, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION:

Availability of Rulemaking Documents

    You can get an electronic copy of this final rule using the 
Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (http://dms.dot.gov/search);
    (2) Visiting the Office of Rulemaking's Web page at http://www.faa.gov/avr/arm/index.cfm; or
    (3) Accessing the Federal Register's Web page at http://www.access.gpo.gov/su_docs/aces/aces140.html.
    You can also get a copy by submitting 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. Make 
sure to identify the amendment number or docket number of this 
rulemaking.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996 requires FAA to comply with small entity requests for information 
or advice about compliance with statutes and regulations within its 
jurisdiction. Therefore, any small entity that has a question regarding 
this document may contact their local FAA official, or the person 
listed under FOR FURTHER INFORMATION CONTACT. You can find out more 
about SBREFA on the Internet at our site, http://www.faa.gov/avr/arm/sbrefa.htm. For more information on SBREFA, e-mail us at [email protected].

Background

    On September 20, 2000, the FAA published a Notice of Proposed 
Rulemaking (NPRM) in which we proposed to adopt upgraded flammability 
standards for thermal and acoustic insulation materials used in 
transport category airplanes. See 65 FR 56992. The NPRM included the 
following:
    [sbull] A test to measure the propensity of the insulation to 
spread a fire; and
    [sbull] A test to measure the fire penetration resistance of the 
insulation.
    Readers should refer to the NPRM for information about the 
background of this rulemaking, including descriptions of the following:
    [sbull] The types of insulation materials used in airplanes;
    [sbull] Other FAA regulations relating to insulation materials;
    [sbull] Past incidents involving insulation materials; and
    [sbull] Fire safety research activities and findings.
    The background material in the NPRM also contains the basis and 
rationale for these requirements and, except where we have specifically 
expanded on the background elsewhere in this preamble, supports this 
final rule as if it were contained here. That is, any future 
discussions regarding the intent of the requirements may refer to the 
background in the NPRM as though it was in the final rule itself. It is 
therefore not necessary to repeat the background in this document.
    The comment period on the NPRM extended 120 days and closed on 
January 18, 2001. We received comments on the NPRM from twenty-six 
commenters, including aircraft manufacturers, insulation manufacturers, 
aviation industry associations, a labor union, and individuals. None of 
the commenters disagree with the objectives of the proposal. Ten of the 
commenters expressed explicit support for the objectives of the NPRM or 
for the NPRM in general. We discuss specific, substantive comments in 
the ``Discussion of the Final Rule'' section later in this preamble.

Legal Basis for the Final Rule

    The FAA's authorizing legislation gives the agency general 
authority to take actions necessary to carry out the law, including 
prescribing regulations (49 U.S.C. 40113). The FAA is responsible for 
promoting safety in civil aviation and, in carrying out that 
responsibility, has the authority to prescribe minimum standards for 
the design, material, and construction of aircraft, among other things 
(49 U.S.C. 44701).
    The regulations we are adopting today are intended to enhance the 
safety of civil aviation by reducing the possibility that insulation 
materials used in airplanes will contribute to either the spread of 
fire within airplanes or the penetration of external fire into 
airplanes. This final rule requires new airplane type designs to 
include insulation that passes improved flammability tests. It also 
requires manufacturers of new airplanes that enter service after a 
phase-in period to equip them with insulation that passes improved 
flammability tests. Finally, it requires air carriers, operating under 
part 121, to use insulation meeting the new flame propagation 
requirements when they replace insulation.
    The flammability tests we are adopting today will not eliminate all 
damage to, or losses of, airplanes by fire, nor prevent all injuries or 
deaths from airplanes fires. The improved tests will, however, ensure 
that insulation used in airplanes will resist the propagation of fire 
and thereby reduce the severity of fires or the speed with which fires 
spread. They will also ensure that insulation will delay the 
penetration of the airplanes by fire from outside. These effects will 
give flight crews additional time to safely land or taxi, as well as 
giving both passengers and crew more time to safely evacuate airplanes.
    This final rule is focused on the goal of enhancing the safety of 
civil aviation. The regulations adopted today have their origin in 
incidents described in the NPRM where insulation that met our previous 
flammability standards may have contributed to airplane fires. Since we 
published the NPRM, there have been two more incidents where in-flight

[[Page 45047]]

fires occurred that involved thermal or acoustic insulation. The 
flammability tests and criteria adopted today represent the outcome of 
research conducted by our technical center in cooperation with 
acknowledged experts in the field. We believe these tests and criteria 
are the minimum necessary for future designs to provide an adequate 
level of civil aviation safety.
    This final rule enhances safety while at the same time considering 
the impact on the aviation industry. For example, we are adopting 
regulations that become effective for existing type designs after a 
phase-in period. This phase-in period gives manufacturers time to plan 
for changes in designs, manufacturing processes, and sources of supply. 
The flammability test criteria we are adopting are reasonable, as shown 
by research and development and the availability of materials that meet 
the new standards. The flammability test requirements we are adopting 
are flexible. Both the flame propagation test and the burnthrough test 
requirements allow for the development and use of approved equivalent 
tests.
    We acknowledge that this final rule has cost implications for 
airplane manufacturers. There are costs associated with testing, 
obtaining, and installing upgraded insulation. Our analysis of the 
costs and benefits of this final rule shows that the benefits (in the 
form of reduced property damage, injury, and loss of life) outweigh the 
costs. For more information on costs and benefits, see the ``Economic 
Evaluation'' section of this preamble and the Regulatory Evaluation for 
this final rule, which we have placed in the docket for this 
rulemaking. Based on our analysis of the issues involved, taking into 
account our responsibility for civil aviation safety, and the 
administrative record for this rulemaking, including the comments we 
received on the NPRM, this final rule is a proper and reasonable means 
of carrying out our responsibility to enhance civil aviation safety.

Discussion of the Final Rule

    This part of the preamble describes in general terms some of the 
major features of the final rule. A reader who is interested in a quick 
overview of the final rule may find this part useful. If you are 
looking for a detailed description of the final rule, you should look 
at the section-by-section analysis, which appears later in this 
preamble, or the regulatory text itself, which appears at the end of 
this document.
    This final rule requires thermal/acoustic insulation material 
installed in the fuselage of transport category airplanes to pass a 
flame propagation test. The test involves exposing samples of thermal/
acoustic insulation to a radiant heat source and a propane burner flame 
for 15 seconds. The tested insulation must not propagate flame more 
than 2 inches away from the burner. The flame time after removal of the 
burner must not exceed 3 seconds on any specimen. See final part VI of 
Appendix F to Part 25 for more details.
    For airplanes with a passenger capacity of 20 or greater, this 
final rule also requires insulation materials installed in the lower 
half of the airplane to pass a test of resistance to flame penetration. 
The test involves exposing samples of thermal/acoustic insulation 
blankets mounted in a test frame to a burner for four minutes. The 
insulation blankets must prevent flame penetration for at least four 
minutes and must limit the amount of heat that passes through the 
blanket during the test. See final part VII of Appendix F to Part 25 
for more details.
    This final rule requires all transport category airplanes 
manufactured more than two years after the effective date of this final 
rule to comply with the new flame propagation test. This applies to 
airplanes operating under parts 91, 121, 125, and 135. This means that 
manufacturers have two years after the effective date of the final rule 
to begin installing more flame resistant insulation materials in new 
airplanes. This final rule requires all transport category airplanes 
with a passenger capacity of 20 or greater manufactured more than four 
years after the effective date of this final rule to comply with the 
new test of resistance to flame penetration. This applies to airplanes 
operating under part 121.
    Airplanes must also comply with the new flame propagation test when 
thermal/acoustic insulation materials installed in the fuselage are 
replaced more than two years after the effective date of this final 
rule. This requirement applies only to the materials that are replaced.
    Both service history and laboratory testing demonstrate that the 
current flammability requirements applicable to thermal/acoustic 
insulation materials may not be providing the intended protection 
against the spread of fires. Additionally, we consider that increased 
protection against external fire penetrating the fuselage can be 
provided by proper selection of the same material. We consider that the 
new test methods described earlier will not only provide for increased 
in-flight fire safety, by reducing the flammability of thermal/acoustic 
insulation blankets, but will also provide increased time for 
evacuation during externally fed, post-crash fires by increasing 
fuselage burnthrough resistance.

Section-by-Section Analysis

Proposed Sec. Sec.  25.853(a) and 25.855(d)

    Existing Sec.  25.853(a) requires that materials in airplane 
compartment interiors meet the flammability test prescribed in part I 
of Appendix F to Part 25. Existing Sec.  25.855(d) requires materials 
used in construction of cargo or baggage compartments meet the same 
test. In the NPRM, we proposed to add specific exceptions to these 
provisions for ``thermal/acoustic insulation materials.'' The intent of 
this proposal was to make it clear that thermal acoustic insulation was 
not required to meet the requirements of Appendix F, part I, in 
addition to the requirements of Appendix F, parts VI and VII. However, 
as discussed below, this action might have confused the issue of 
whether or not ``small parts'' required testing. We have therefore 
decided not to adopt these proposed changes. As proposed in the NPRM, 
we are deleting language from part I of Appendix F to Part 25 that 
addresses thermal/acoustic insulation materials. This action has the 
same effect as the two proposed additions would have had.

Section 25.856 Thermal/Acoustic Insulation Materials

    Final Sec.  25.856(a) requires thermal/acoustic insulation material 
installed in the fuselage to meet the flame propagation test 
requirements of part VI of Appendix F to Part 25, or other approved 
equivalent test requirements. This requirement does not apply to 
``small parts,'' as defined in part I of Appendix F to Part 25.
    The current flammability requirements focus almost exclusively on 
materials located in occupied compartments (Sec.  25.853) and cargo 
compartments (Sec.  25.855). The potential for an in-flight fire is not 
limited to those specific compartments. Thermal/acoustic insulation is 
installed throughout the fuselage in other areas, such as electrical/
electronic compartments or surrounding air ducts, where the potential 
exists for materials to spread fire as well. The final rule accounts 
for insulation installed in areas that might not otherwise be 
considered within a specific compartment. Final Sec.  25.856(a) is 
applicable to all transport category airplanes, regardless of size or 
passenger capacity, since the consequences of an in-flight fire are not 
related to these factors. We are developing advisory material to 
describe test sample configurations to address

[[Page 45048]]

design details such as tapes and hook-and-loop fasteners.
    One commenter recommended that we exclude ``small parts,'' as 
defined in part I of Appendix F to Part 25, from the requirement that 
insulation materials pass the upgraded flame propagation test. The 
commenter pointed out that there is a ``small parts'' exception to the 
flammability test in part I of Appendix F to Part 25.
    The FAA agrees that ``small parts'' would not be practical to test 
in the flame propagation test apparatus specified in part VI of 
Appendix F to Part 25. In response, we have added to final Sec.  
25.856(a) an exception for ``small parts'' from the requirement to pass 
the upgraded flame propagation test. Under paragraph I(a)(v) of 
Appendix F to Part 25, the FAA considers ``small parts'' to be things 
that would not contribute significantly to a fire, including knobs, 
handles, rollers, fasteners, clips, grommets, rub strips, pulleys, and 
small electrical parts. In addition, ``small parts'' should not be 
installed in proximity to each other. As a result of this change, 
``small parts'' will continue to be governed by existing Sec. Sec.  
25.853 and 25.855 and part I of Appendix F to Part 25.
    One commenter suggested that, based on the language of proposed 
Sec.  25.856, thermal/acoustic insulation not installed in the fuselage 
might also have to pass the upgraded flame propagation test.
    The FAA agrees that the proposed language could allow this 
unintended interpretation. For this reason, we changed final Sec.  
25.856(a) to specify that thermal/acoustic insulation installed in the 
fuselage must meet the flame propagation test requirements.
    A commenter stated that certain interior panels perform both 
thermal and acoustic attenuation functions to some extent and might 
therefore be categorized as thermal/acoustic insulation in the absence 
of a more precise definition.
    The FAA does not intend to require interior panels to comply with 
final Sec.  25.856. These panels are subject to existing heat release 
and smoke emissions requirements in parts IV and V of Appendix F to 
Part 25, which are more relevant to the role of interior panels in fire 
safety. This final rule is aimed at ensuring that thermal/acoustic 
insulation materials, which are usually installed in inaccessible 
areas, do not propagate fire. Their inaccessibility is what creates the 
hazard, especially with regard to in-flight fires. Interior panels are 
accessible and are clearly not exposed to the same threat. Thus, we do 
not apply the final rule to them.
    A commenter stated that certain interior panels often receive 
acoustic damping treatments which, by virtue of their function, could 
be interpreted as requiring compliance under the proposal. The 
commenter recommended that these treatments be required to comply.
    The FAA agrees in part. To the extent that acoustic damping 
treatments applied to the inaccessible sides of interior panels could 
permit fire propagation, they are required to pass the flame 
propagation test. On the other hand, it is clear that the many possible 
combinations of treatments and panels could result in large amounts of 
testing. We intend to investigate whether compliance for such 
treatments can be substantiated by tests on a generic panel, or whether 
testing of the actual panel is necessary. Up to now, we have not 
evaluated acoustical damping treatments in the context of the NPRM. 
Based on comments, it appears that they are typically aluminum based, 
so the adhesive used to bond the treatment to the panel is probably the 
component of concern. We will evaluate any treatments provided for 
review to develop guidance. As proposed in the NPRM, however, this 
final rule requires that thermal/acoustic insulation installed in the 
fuselage pass the flame propagation test. This includes material 
installed on the pressure shell, ducts, floor panels, and within 
equipment bays.
    Final Sec.  25.856(b) requires, for airplanes with a passenger 
capacity of 20 or greater, thermal/acoustic insulation materials 
(including the means of fastening the materials to the fuselage) 
installed in the lower half of the airplane fuselage to meet the flame 
penetration resistance test requirements of part VII of appendix F of 
Part 25, or other approved equivalent test requirements.
    Final Sec.  25.856(b) applies only to airplanes with a passenger 
capacity of 20 or greater. This effectively excludes the smaller 
transport category airplanes, as well as airplanes operating in an all-
cargo mode. The primary reason for this is that airplanes with small 
passenger capacities are not expected to realize a significant benefit 
from enhanced burnthrough protection owing to their very rapid 
evacuation capability. That is, they have a favorable exit-to-passenger 
ratio. Since enhanced burnthrough protection will impose additional 
cost, there must be a commensurate benefit to justify the requirement. 
We do not consider that such benefits are substantial for airplanes 
with low passenger capacities. We chose the 20-passenger threshold to 
be consistent with other occupant safety regulations, such as those for 
interior materials and cabin aisle width. The enhanced burnthrough 
protection provided by this final rule will increase the evacuation 
capability of airplanes with 20 or more passengers, regardless of the 
exit arrangement.
    Final Sec.  25.856(b) applies to insulation materials installed in 
the lower half of the fuselage because that area is most susceptible to 
burnthrough from an external fuel fire. Flames from an external fuel 
fire typically impinge on the fuselage from below. Therefore, the lower 
half of the fuselage derives the most benefit from enhanced burnthrough 
protection. We chose this approach based on full-scale fire test data, 
as documented in the reports referenced in the NPRM, and the potential 
for an airplane to be off its landing gear. When the landing gear 
collapse, an airplane can roll significantly, and the area most 
susceptible to burnthrough can be correspondingly higher on the 
fuselage than when the airplane is on its gear. By providing 
burnthrough protection for the lower half of the fuselage (as opposed 
to just the underside), the final rule takes this situation into 
account.
    This final rule establishes a standard for the ability of thermal/
acoustic insulation to resist penetration by an external flame, rather 
than a standard for fuselage burnthrough per se. This distinction is 
important, since fuselage burnthrough is a complex process, dependent 
on many variables. For example, the ability of the fuselage to resist 
penetration from an external fuel fire is directly related to the 
thickness and material of the skin. Skin thickness varies considerably, 
and essentially means that each airplane type has different burnthrough 
resistance. In addition, factors internal to the airplane can also 
affect penetration of an external fire into the occupied areas. For 
example, differences in the air return grills can influence the time 
required for an external fire to penetrate the occupied area. 
Therefore, establishing a minimum standard for fuselage burnthrough 
resistance and identifying possible means of compliance would be a 
highly complex undertaking.
    This final rule adopts a simple standard that increases the time it 
takes for a fire to penetrate the airplane beyond what currently 
exists, regardless of the specific capability that currently exists. 
Since this increase in time can be achieved by addressing thermal/
acoustic insulation material, and this rule revises the standard for 
insulation to address flame propagation anyway, it is in the public 
interest to incorporate

[[Page 45049]]

criteria that enhance the overall level of safety and that can be 
achieved with reasonable cost. Therefore, this rule addresses two 
aspects of fire safety related to insulation material.
    We intend this final rule to enhance the overall level of safety of 
the airplane when insulation that meets the upgraded flammability tests 
is installed. Because of the need to provide a suitable thermal and 
acoustical environment inside the airplane, we consider it extremely 
unlikely that insulation would be removed as a means to avoid having to 
comply with this rule. In fact, we considered requiring the removal of 
insulation material as an option to address flame propagation issues, 
but rejected it since it would effectively diminish the burnthrough 
capability that currently exists. Should removal of insulation become a 
common practice, we will revisit the need for a specific fuselage 
burnthrough standard.
    A commenter asserted that the NPRM was ambiguous with regard to 
whether materials installed in the lower half of the fuselage would 
have to pass the fire penetration test. The commenter assumed that only 
those materials installed near the exterior skin of the fuselage would 
have to comply. Other commenters were concerned that the proposed 
requirement would apply to any thermal/acoustic insulation installed in 
the lower half, whether or not it would play a role in burnthrough.
    The FAA's intent is that final Sec.  25.856(b) applies to all 
thermal/acoustic insulation installed in the lower half of the fuselage 
that contributes to delaying burnthrough. For example, insulation on 
ducts in the lower half of the fuselage does not have to comply. To 
clarify this point, we added to final Sec.  25.586(b) a statement that 
it does not apply to thermal/acoustic insulation installations that the 
FAA finds would not contribute to fire penetration resistance.
    One commenter recommended that the flame penetration test not be 
limited to airplanes with 20 or more passenger seats. The commenter 
cited an accident involving an airplane with fewer than 20 seats, where 
improved insulation might have provided a benefit.
    The FAA does not agree with the commenter's assessment of the 
potential role of insulation materials in the cited accident. The 
accident involved a non-transport category airplane that does not meet 
the other safety requirements of part 25. Thus, considering the 
addition of insulation materials apart from the other requirements of 
part 25 is not an accurate way to assess potential benefits. As noted 
in the NPRM, we have assessed the potential benefits of requiring 
insulation materials to pass the flame penetration test and have 
concluded that smaller airplanes, with their greater evacuation 
capability, would not realize a benefit commensurate with the costs of 
compliance. Readers should note, however, that this final rule does not 
preclude manufacturers from installing upgraded insulation materials on 
smaller airplanes, if they so choose.
    Several commenters recommended that the requirement for flame 
penetration resistance be applied to insulation materials installed in 
the entire fuselage, not just the lower half. One commenter stated that 
upgraded insulation materials installed in the entire fuselage would 
help protect airplanes from events such as lightning strikes, which 
usually come from above or to the side of the airplane. These 
commenters noted that the NPRM stated that providing such protection 
would not result in great cost. Conversely, several other commenters 
asked that the term ``lower half'' be better defined, or that the 
requirement be changed to something related to the airplane design, 
such as the window line, or the main deck cabin floor.
    The FAA has carefully considered whether insulation materials 
installed in the entire fuselage should have to pass the flame 
penetration test. As discussed in the preamble to the NPRM, the main 
issue is that the benefits of such a requirement would be negligible. 
While a scenario can be envisaged where materials in the upper fuselage 
would provide a benefit, the conditions would be extremely rare, and 
were not evident in the benefit study used to develop the proposal. For 
materials in the upper fuselage to be beneficial, the airplane would 
have to be rolled an extreme amount (by specifying the lower half, the 
requirement already accounts for significant roll), and still be 
intact. While this scenario may not be far-fetched, there must also be 
post-crash fire for there to be any benefit from the materials. An 
accident that causes a combination of severe roll attitude, no fuselage 
rupture, but with a post-crash fire, is extremely rare if even feasible 
and is not considered a reasonable basis on which to base a 
requirement. In addition, while the NPRM characterized the increased 
costs as ``not great,'' it should be noted that they are also not 
trivial. Any added weight would effectively be doubled, and the costs 
of materials would also rise. Since these costs would not be balanced 
by benefit, it would not be appropriate to mandate that the entire 
fuselage be fitted with thermal/acoustic insulation that meets the 
flame penetration requirement. Regarding threats from other in-flight 
occurrences, such as lightning, the flame propagation test required by 
final Sec.  25.856(a), which is applicable to all thermal/acoustic 
insulation installed in the airplane, will provide added protection.
    Final Sec.  235.586(b) applies to thermal/acoustic insulation 
installed in the ``lower half of the airplane fuselage.'' This phrase 
means the area below a horizontal line that bisects the cross section 
of the fuselage, as measured with the airplane in a normal attitude on 
the ground. We have looked at the accident history, as well as research 
testing, and concluded that benefits will be realized with the lower 
half of the fuselage protected. Using another measure, such as the 
window line, or the main cabin floor, would not provide the intended 
benefit, unless those locations were in the upper half of the fuselage. 
We realize that thermal/acoustic insulation installations are not 
typically tied to the upper or lower half of the airplane, so this 
requirement will probably result in either changes to insulation 
installation approaches, or use of the complying material over somewhat 
more than half of the fuselage. Since new installations of insulation 
materials will likely be required for compliance anyway, this is not 
considered to be a significant point.
    The FAA has determined that future design possibilities, such as 
blended wing-body configurations, would have to be addressed 
specifically, if the concept of the lower half is not appropriate.
    As discussed above, final Sec.  25.856(b) applies to thermal/
acoustic insulation installed near the outer skin of the lower half of 
the airplane fuselage. The intent of the rule, however, is to provide a 
barrier that will delay entry of a post-crash fire into the occupied 
areas of the airplane. Therefore, if an airplane were to incorporate 
insulation not on the fuselage shell, but along the underside of the 
floor, this insulation would be subject to the flame penetration test 
of final Sec.  25.856(b). In the case where insulation is installed in 
both places, an applicant may choose which insulation would be subject 
to the flame penetration test. This will be discussed and illustrated 
in more depth in a forthcoming Advisory Circular.
    Both final 25.856(a) and 25.856(b) include a provision that allows 
a manufacturer to substitute approved equivalent methods for the tests 
specified in final parts VI and VII of Appendix F to Part 25. These 
provisions allow for the incorporation of improvements to the test 
methods as

[[Page 45050]]

they are identified, without requiring specific findings of equivalent 
level of safety under 14 CFR 21.21. Experience has shown that such 
improvements frequently originate with the International Aircraft Fire 
Test Working Group (IAMFTWG) and are readily adopted by the industry. 
The IAMFTWG consists of experts in the materials and fire testing 
specialties who help refine and support the development of test methods 
used in aviation, and includes representatives from the airlines, 
airframe manufacturers, material suppliers, and regulatory authorities, 
among others. A representative from the FAA Technical Center chairs 
this group. The IAMFTWG is a technical peer group that contributes to 
FAA research, but its activities are not regulatory in nature. Readers 
should note that final parts VI and VII of Appendix F to Part 25 
constitute the basic requirements, and that such equivalent methods 
that might be developed would have to be adopted in total. It is not 
acceptable to selectively adopt portions of a modified test method that 
has been found to be equivalent and not all of the modified method. We 
will make the determination of an acceptable equivalent method.
    In proposed Sec.  25.856, we stated that these equivalent test 
methods would be ``FAA-approved.'' One commenter suggested that, for 
the sake of consistency with existing regulations, including Sec.  
25.853, this simply read ``approved.'' The FAA agrees that the 
suggested language is consistent with Sec.  25.853. We believe that 
specifying ``FAA-approved'' adds no value. Therefore, we have accepted 
the suggestion and changed the wording of final Sec.  25.856(a) and (b) 
to allow for ``approved equivalent test requirements.'' We consider 
this a non-substantive, editorial change.
    Two commenters, representing the major airframe manufacturers in 
the United States and Europe, urged that the FAA withdraw proposed part 
VII of appendix F to Part 25 and propose instead a general requirement 
for fuselage fire penetration resistance. Other commenters stated that 
the FAA must address areas that currently have no insulation, or areas 
where insulation might be removed. Some commenters stated that 
insulation should be required as part of this rule.
    The FAA disagrees with the comments. As noted in the NPRM, we 
elected to propose a standard related to thermal/acoustic insulation, 
since this approach is known to yield improved fire penetration 
resistance. A requirement related to protection of the fuselage in 
general involves many variables and would be much more complicated to 
define. We recognize that removal of insulation would avoid complying 
with the requirement. This possibility was discussed in the preamble, 
and we noted our intent to monitor this possible course of action. We 
agree that an ideal standard would simply require that the cabin be 
protected from a post-crash fire of specified intensity for an 
additional four minutes, and permit the manufacturer to develop his own 
design approach. At present, we do not have a proposal or test standard 
to address the overall resistance of the fuselage to fire penetration.
    In addition, a proposal of that nature would go beyond the scope of 
the NPRM, since the NPRM only addressed a material standard for 
thermal/acoustic insulation. Nonetheless, it appears that industry is 
considering alternatives that might address the issue more generally, 
and we do not want to dismiss this possibility. A more general 
requirement would also address concerns with areas that do not 
currently have insulation, or where insulation is removed. 
Nevertheless, we consider that there is a need to adopt a standard that 
will provide added post-crash fire protection now, and will proceed 
with adoption of the final rule. Based on the comments, however, we 
consider it appropriate to review the industry's proposal to approach 
burnthrough protection as an airplane performance requirement and, if 
such a standard can be developed, consider it as an alternative means 
of compliance. Therefore, we are considering assigning the Aviation 
Rulemaking Advisory Committee (ARAC) the task of developing a 
recommendation to the FAA for a fuselage burnthrough standard. In the 
meantime, this regulation will be in effect, but will not actually 
require compliance for newly manufactured airplanes until four years 
after the effective date of the rule. If ARAC is successful in 
developing an alternative approach, we will consider whether a change 
to the regulations is appropriate or whether approval as an equivalent 
level of safety under Sec.  21.21(b)(1) is sufficient. Regardless, 
under the provisions of Sec.  21.21(b)(1), any applicant that wishes to 
do so can propose an alternative standard and design features meeting 
the objectives of the requirement at any time.
    As noted in the NPRM, we have no plans to require installation of 
thermal/acoustic insulation in areas that currently do not have this 
insulation installed. Our intent is to take advantage of materials that 
are typically installed to affect a safety improvement, and requiring 
thermal/acoustic insulation to be installed in such areas would not be 
consistent with this intent. In fact, this approach would be more 
consistent with a general requirement for burnthrough protection, as 
discussed above. Therefore, this issue will necessarily be addressed in 
the proposed ARAC activity discussed above.

Part VI of Appendix F to Part 25--Flame Propagation Test

    Final part VI of Appendix to Part 25 consists of a method of 
evaluating the flammability and flame propagation characteristics of 
thermal/acoustic insulation materials when exposed to both a radiant 
heat source and a flame. The test method we are adopting today includes 
specific instructions for constructing the test apparatus, calibrating 
instruments, and conducting the test. It also includes the standards 
the insulation must meet. The test involves exposing samples of 
thermal/acoustic insulation to a radiant heat source and a propane 
burner flame for 15 seconds. The tested insulation must not propagate 
flame more than 2 inches away from the burner. The flame time after 
removal of the burner must not exceed 3 seconds on any specimen.
    This test method is based on American Society of Testing and 
Materials (ASTM) test method E 648, which uses a modest ignition source 
combined with exposure to radiant heat to determine fire propagation 
performance. This test method represents a realistic fire threat and 
imposes realistic success criteria, considering the state of the art of 
insulation materials. The test method we are adopting today is 
substantially the same as the one included in the NPRM, with the 
exception of the burn-length and after-flame standards. We discuss the 
changes to the standards below in the responses to comments. We have 
also made minor editorial changes to the language of the test method 
for clarity. These editorial changes are not substantive.
    One commenter questioned the rationale for applying the flame 
propagation test to all forms of thermal/acoustic insulation, rather 
than just a thin film-encapsulated batting type of thermal/acoustic 
insulation.
    The FAA's intent is to address thermal/acoustic insulation in 
general because of its location and quantity in inaccessible areas of 
the fuselage. The flame propagation test represents a realistic in-
flight fire threat, and a method of assessing the tendency for 
materials to spread fire. We recognize that there may be different 
material/

[[Page 45051]]

installation schemes for which the flame propagation test is not well 
suited. However, up to now, all currently used and prospective 
materials that we have tested have been accommodated by the flame 
propagation test, with no obvious incompatibilities. If an applicant 
identifies an instance where this is not the case, the applicant is 
free to propose an alternative method of compliance that shows 
equivalent level of safety. However, based on the experience gathered 
to date, this would not seem necessary.
    Several commenters addressed specific details of the test 
apparatus, or the test method itself, that are intended to simplify and 
improve the reliability of the tests. These range from correcting 
conversion of measurement units to test sample size to the type of 
radiant panel used.
    The FAA has reviewed the commenters suggested improvements and 
adopted several of the suggested changes as appropriate; those that are 
not adopted verbatim are addressed in principle. Since publication of 
the NPRM, the FAA Technical Center has been working to improve the test 
methods for determining the flammability and flame propagation 
characteristics of thermal/acoustic insulation materials. We have 
revised the test methods in Appendix VI to include these improvements. 
A copy of the Technical Center's report, which includes a summary of 
the improvements, is included in the public docket for this rulemaking.
    We received several comments on proposed paragraph VI(h)(1), which 
would have allowed no flaming beyond two inches to the left of the 
centerline of the point of pilot flame application to the specimen 
tested. One commenter noted that the designation ``to the left'' was 
not clear, and should specify a frame of reference. Other commenters 
noted that the two-inch limit was not specified as an average, or a 
not-to-exceed value for a sample. One commenter proposed that it must 
be an average to be viable. This commenter noted that virtually any 
material will eventually exhibit a burn length greater than two inches 
if enough samples are tested.
    The FAA does not agree that the flame propagation length should be 
adjusted. The intent of the proposal (and this final rule) is to 
require materials that will not propagate a fire. The requirement that 
the flame not propagate more than two inches along the sample is 
intended to account for the damage that occurs as a result of the pilot 
burner, but not to allow any additional flame propagation. We have 
conducted hundreds of tests since issuance of the NPRM, and 
determination of propagation distance has not been a problem. The 
requirement of this rule is not the same as the traditional Bunsen 
burner requirements for ``burn length.'' For a burn-length 
determination, no distinction is made between burning caused by the 
burner itself and self-sustained combustion of the material. The Bunsen 
burner is oriented in the same (vertical) direction as the burn length 
determination, and making a distinction would be difficult at best.
    For this rule, the issue is propagation of a flame beyond the 
damage caused by the pilot burner. The pilot burner is oriented at a 
right angle to the direction of measured flame propagation, making the 
distinction much clearer. A two-inch limit will adequately account for 
the damage caused by the burner, and materials that exceed this limit 
exhibit some tendency to propagate flame. Determination of the extent 
of propagation requires that a person actually watch the test, however. 
An after-the-fact determination is not reliable, and would probably 
result in failure determinations of materials that were, in fact, 
acceptable. Based on all of the data gathered to date, we are satisfied 
that the criteria are readily achievable, and that samples that exceed 
two inches indicate the need for corrective action. Therefore, we are 
adopting the burn-length standard as proposed.
    We received several comments on proposed paragraph VI(h)(2), which 
would have allowed one of three specimens tested to have an after 
flame, which could not have exceeded three seconds in duration. One 
commenter believed that no sample should be permitted to flame after 
removal of the pilot burner. Several other commenters stated that the 
presence of such an ``after flame'' is highly dependent on the ability 
of the person conducting the test to remove the pilot flame at 
precisely 15 seconds, and that slight variation can influence whether 
there is a short after flame. Several commenters recommended an average 
after flame for three samples. Some suggested a maximum total after 
flame time for all samples, with a maximum for any one sample. One 
commenter stated that an average must be allowed, since a single sample 
can effectively prohibit a material from use, regardless of how many 
other samples are tested with satisfactory results.
    The FAA agrees that we should adjust the pass/fail standard. We 
also believe we can adjust the standard without affecting the intent of 
the requirement, which is to prevent insulation materials from 
spreading a fire. Based on the comments and a review of the test data 
acquired to date, we agree that materials that meet the intent of the 
requirement can sometimes fail the test, as proposed. (The proposed 
test standard would have required two of the three test samples to have 
no after flame whatsoever). As noted by commenters, this could be due 
to operator variations in detailed test procedures, material 
variability, or a combination of the two. While we have made every 
effort to remove operator variables from the test method, the 
stringency of the requirement tends to magnify whatever slight 
variations exist. Similarly, slight material variations are inevitable, 
even with the best materials. In light of the above, we have determined 
that we should adjust the pass/fail standard for after-flame time to 
account for slight variations. Therefore, we have revised final 
paragraph VI(h)(2) of appendix F to Part 25 to permit after flame on 
any sample, but require that none of the three samples have an after 
flame time of greater than three seconds. This change allows small 
variability in all of the samples, but retains the intent of the 
requirement that the material not continue to burn after the pilot 
flame is removed.
    Several commenters addressed the fact that insulation materials 
frequently consist of more than a film-covered batting material. These 
commenters point out that tapes and hook-and-loop fastening systems are 
often used on insulation to perform various functions. Some commenters 
state that these additional features must be included in the 
requirement, while others only question how they would be tested if 
they were to be included.
    Final part VI of Appendix F to Part 25 applies to the thermal/
acoustic insulation assembly, which includes tapes or hook-and-loop 
fasteners that are affixed to the film. In addition, research testing 
has shown that these details can have a pronounced effect on the flame 
propagation characteristics of the insulation. We are developing 
advisory material that will explain an acceptable test sample 
configuration to address those details. We recognize that the use of 
tapes, for example, is quite variable, and it may not be possible to 
address each production configuration with a single test sample 
configuration. We hope to be able to establish a critical case that may 
be used to qualify other configurations, and plan to outline this 
approach in the advisory material.
    One commenter noted that, for air ducts in particular, the test 
criteria do not provide sufficient detail as to how they should be 
tested. The commenter contends that we did not give adequate

[[Page 45052]]

consideration to ducting when the proposal was developed, since 
insulation on air ducts is frequently different than that attached to 
the fuselage.
    The FAA agrees that insulation on air ducts has not been addressed 
to the same extent as other insulation. However, the concerns with fire 
propagation are the same, and insulation on air ducts should meet the 
same standard, as noted in the NPRM. We are developing advisory 
material that will include discussion of insulation on air ducts, and 
the proper method of configuring test samples. This might require 
modification to some of the installation practices that are currently 
employed. For example, complete surface bonding of film to the batting 
material requires a large amount of adhesive, and adhesives have been 
shown to be problematic for flame propagation. However, other methods 
are available that will comply.
    The commenter also noted that acoustic treatments are sometimes 
applied to the interior of ducts, and that this treatment should not be 
required to comply since it is not exposed.
    The FAA agrees that this requirement would not apply to acoustic 
treatment completely enclosed by ducts. However, we are studying all 
materials in inaccessible areas, and intend to develop standards for 
such materials that are consistent with the threat level established to 
develop the flame propagation test. In that case, it is likely that the 
duct construction itself would be included.
    Under the current requirements, parts too large to be considered 
``small parts'' require testing, and the basic requirements for the 
test sample construction will be no different under this final rule. 
The major difference is the size of the test sample. Parts that are 
smaller than the test sample size could be addressed on a case-by-case 
basis. We have reduced the sample size from that in proposed paragraph 
VI(c)(2), based on data acquired since publication. See final paragraph 
VI(C)(3). We encourage use of materials and constructions that meet the 
radiant panel test for all such parts, no matter how small.

Part VII of Appendix F to Part 25--Flame Penetration Test

    Final part VII of Appendix to Part 25 consists of a method for 
evaluating the burnthrough resistance characteristics of aircraft 
thermal/acoustic insulation materials when exposed to a high-intensity 
open flame. The test method we are adopting today includes specific 
instructions for constructing the test apparatus, calibrating 
instruments, and conducting the test. It also includes the standards 
the insulation must meet. The test involves use of a kerosene burner 
apparatus that realistically simulates the thermal characteristics of a 
post-crash fire. The test stand and specimen are configured to simulate 
a small section of fuselage frame and stringers with insulation 
material mounted over them. Fuselage skin is not represented in this 
test since the delay in burnthrough afforded by the skin is not 
directly related to the performance of the insulation. The test is 
intended to measure the performance of the insulation installation 
itself. The test involves exposing samples of thermal/acoustic 
insulation blankets mounted in a test frame to a burner for four 
minutes. The insulation blankets must prevent flame penetration for at 
least four minutes and must limit the amount of heat that passes 
through the blanket during the test.
    For new designs, the new burnthrough test method is applicable to 
the insulation as installed on the airplane. Thus, consistent with 
similar flammability testing of other installed materials, the means 
intended to be used for fastening the insulation to the fuselage must 
be accounted for when performing tests. For consistency, the test 
method imposes a standard methodology for fastening. In addition, we 
are developing advisory material concerning the installation of 
insulation that would enable the installer to avoid a specific test on 
the fasteners, etc. Although failures of fasteners or seams during this 
test may not exacerbate flame propagation characteristics, such 
failures could adversely affect the burnthrough protection capability. 
Since research has shown practical fastening means are available for 
ensuring that the insulation material remains in place, we have 
determined that fastening means must be considered for newly 
manufactured airplanes.
    The test method we are adopting today is substantially the same as 
the one included in the NPRM. We discuss changes to the test method 
below in the responses to comments. We have also made minor editorial 
changes to the language of the test method for clarity. These editorial 
changes are not substantive.
    Some commenters asserted the test method has not been demonstrated 
to be repeatable.
    The FAA has sponsored three round-robin test series to date and has 
made refinements to the test method and apparatus as a result. One 
significant problem with the test equipment that has been rectified is 
the use of various shapes and sizes of airflow vanes (stators) inside 
the burner draft tube. For reasons unknown, this inconsistency in 
fabrication developed and significantly contributed to the scatter of 
data obtained during inter-laboratory comparisons. Since all 
laboratories now have the identical stators installed, the inter-
laboratory test correlation should be much better. All test results are 
currently displayed on the IAMFTWG Web site at http://www.fire.tc.faa.gov. The repeatability of results has improved with 
each successive round robin, and we are satisfied that the test is 
sufficiently repeatable for use in the final rule.
    One commenter specifically addressed the effects of altitude as not 
being accounted for in the test method, and proposes that this variable 
among test facilities must be addressed.
    Regarding the potential effects due to altitude of the test 
facility, the FAA agrees that this is possible. In fact, the test 
results seen in the round robin tests discussed above strongly suggest 
that the effects of altitude are responsible for much of the variation. 
It should be noted that the fuel and airflow prescribed in this test 
method are meant to reflect an actual pool fire condition in which the 
fuel/air ratio is typically not stoichiometric. The conditions are 
representative of a large pool fire with respect to the two main 
criteria of temperature and heat flux. Therefore, the differences in 
combustion using the specified airflow and fuel flow values at 
different altitudes would also not be expected to result in a 
stoichiometric process. We agree that an altitude correction factor 
could be implemented in order to obtain more repeatable test results 
from labs located at various altitudes. An applicant would be free to 
propose an alternative method, with supporting data. If requested, we 
will work with an applicant to establish the proper correction.
    Several commenters addressed specific details of the test method 
and test apparatus. One commenter stated that the calibration 
parameters are too narrowly specified to permit reliable calibration. 
The commenter proposed tolerances on the fuel flow and air intake. One 
commenter advised that the combined heat flux/thermocouple calibration 
rig is not practical and separate rigs should be used. Another 
commenter requested clarification of the term ``assembly processes'' 
for sample fabrication.
    The FAA has considered detailed comments on the test apparatus 
itself, and these have been adopted for the most part. The new 
apparatus details are specified in final part VII of Appendix

[[Page 45053]]

F to Part 25, and do not change the scope or intent of the test. As 
noted above, a significant clarification is the use of a standard 
stator vane assembly for the burner draft tube.
    With respect to the calibration requirements, the test method 
prescribes the use of a highly dynamic fire source, the characteristics 
of which are highly transient. Testing has shown that the set-up 
(configuration) of the test burner plays a major role in the 
performance of many materials. The parameters with which to control the 
burner flame, (namely fuel flow rate, air intake velocity, as well as 
the positioning of the components necessary for firing the fuel/air mix 
(stators and igniter set)) must be very tightly controlled in order to 
minimize error between testing facilities. A tolerance of +/-1 gallon 
per hour fuel flow rate is well beyond the limit that is necessary to 
eliminate fluctuation between testing facilities. Similarly, a 
tolerance of +/-100 ft/min air velocity is excessive, and will only 
result in increased fluctuation of test results between testing 
facilities.
    The accuracy of the heat flux measurement of the burner flame is 
highly dependent on the condition of the heat flux transducer, its 
position, and its accuracy. However, we agree that a minimum heat flux 
value (rather than a range, as proposed) is sufficient to establish 
whether a material performs acceptably, and have revised the test 
method accordingly.
    The term ``assembly processes'' is intended to address the way in 
which the thermal/acoustic insulation components are built up. For 
example, for a traditional batting encapsulated in a moisture barrier, 
there may be seams that are heat sealed, or stitched, or utilize a hook 
and loop type closure. These must be included in the test sample. 
However, features added to the surface of the thermal/acoustic 
insulation would not need to be included in the test sample if they do 
not affect the fire penetration resistance. For example, use of tapes 
on the moisture barrier will not require assessment in the fire 
penetration test. Note that these same features will require assessment 
in the flame propagation test of part VI of Appendix F to Part 25.
    Some commenters proposed that the burnthrough time be increased to 
five or six minutes to provide a margin for the desired four minutes, 
or to account for more fire resistant materials. Other commenters 
questioned the heat flux value specified, and proposed that it be 
reduced.
    The FAA does not agree that the burnthrough time should be extended 
to five or six minutes. In the benefit study conducted on behalf of the 
FAA by Cherry & Associates,\1\ a four-minute extension in evacuation 
time is shown to provide a measurable improvement in survivability. 
Beyond four minutes, there is little benefit. Although a product may 
provide more than four minutes of burnthrough protection, this does not 
justify a requirement if no additional benefit is provided.
---------------------------------------------------------------------------

    \1\ FAA Office of Aviation Research, U.S. Dept. of 
Transportation, Fuselage Burnthrough Protection for Increased 
Postcrash Occupant Survivability: Safety Benefit Analysis Based on 
Past Accidents, DOT/FAA/AR-99/57, Sept. 1999. Available at http://www.tc.faa.gov/its/worldpac/techrpt/ar99-57.pdf.
---------------------------------------------------------------------------

    Regarding comments that the time should be extended to provide a 
margin of safety that will ensure four minutes of protection, we agree 
that a certification requirement cannot assure that every material lot 
and batch will perform identically. However, this would be true 
regardless of the time specified in the regulation. We consider that 
the rule should not account for variation in material lot or batch. The 
certification requirement is intended to address the basic material and 
installation scheme in accordance with the type design. The 
manufacturer will need to develop quality control procedures to ensure 
consistent performance of the material.
    The heat flux measurement provision is included in the pass/fail 
criteria to account for materials that behave similarly to a flame 
arrestor, and do not inhibit heat transfer. The heat flux measurement 
provides an indication of the hazard inside the airplane, but 
supplements, rather than replaces, the basic requirement to resist 
flame penetration. Flame penetration time is the fundamental concern. 
This can be described as the time at which the test burner flames 
directly cause a breach to form in the insulation material, thereby 
allowing the flames to pass through from the front to the back face. 
For some materials, the failure event is catastrophic and the 
occurrence can be measured quite accurately. However, it can be 
difficult to measure the event for other longer-lasting materials, as 
the failure does not occur instantaneously, but rather gradually over 
time. These materials typically allow a very small breach to occur 
initially, and the breach gradually increases in size as the test 
progresses. As a guideline, a material can be considered to fail when 
the size of the breach reaches 0.25 inch in diameter.
    There have been instances where tested insulation materials 
(insulation and film) have ignited on the back face and caused surface 
propagation to occur. This surface propagation is not considered a 
burnthrough and would be acceptable, provided the heat flux level 
measured behind the sample does not exceed 2.0 Btu/ft\2\ sec at any 
time during the test. However, since the same materials will also be 
required to meet the flame propagation standard of part VI of Appendix 
F to Part 25, it is likely that a material exhibiting this type of back 
face ignition would be screened out by that test.
    There have been other instances whereby flames can reach the back 
side of the insulation materials by passing through passageways created 
between blankets or between the sample and the test frame. This 
typically occurs between clamping locations, and is generally not a 
function of the material's flame penetration resistance, but rather a 
result of improper mounting. This occurrence should not be considered a 
failure, provided the material is not breached when inspected after the 
test. We will address issues related to material overlap and 
installation in a forthcoming Advisory Circular.
    Several commenters addressed the issue of attachment of thermal/
acoustic insulation to the fuselage. Some commenters noted what they 
consider to be a conflict between proposed Sec.  25.856 and proposed 
part VII of Appendix F to Part 25, since the regulation requires that 
the means of attachment comply, but the appendix specifies an 
attachment scheme for test. Several commenters state that advisory 
material is needed to establish acceptable means of attachment, and 
stress its importance in providing burnthrough protection.
    The FAA does not agree that the wording of proposed Sec.  25.856 
and part VII of Appendix F to Part 25 are in conflict. As noted in the 
NPRM, the test fixture is intended to test the material system in a 
manner that will ensure its retention since, for the sake of 
simplicity, the fixture does not replicate any specific airplane. In 
other words, the installation must meet the requirement, but, for 
simplicity, the test method does not include installation details. We 
have participated in a research program with the Civil Aviation 
Authority (CAA) in the United Kingdom to assess acceptable installation 
methods. Acceptable methods can only be established using 
representative airframe structure, since the interaction between the 
attachment and the airframe will influence the performance of an 
otherwise acceptable material. In addition to the collaborative effort 
with the CAA, we have conducted additional full-scale fire tests to 
assess

[[Page 45054]]

the sensitivity of burnthrough performance to minor installation 
variations. As a result of this research, we are developing an advisory 
circular that describes acceptable methods of installation. The 
advisory circular addresses attachment schemes, overlap between the 
insulation and airframe structure and overlap of more than one 
insulation blanket. We recognize that other methods of installation may 
be equally acceptable, or necessary, particularly with insulation 
systems that are different from those described in the AC. However, an 
applicant would need to demonstrate that alternative approaches provide 
an equivalent level of safety. Such demonstrations would require 
testing of a scale appropriate to the feature being investigated.
    One commenter disagrees with discussing detailed installation 
methods in an advisory circular. The commenter states that installation 
methods should be part of the rule, and not separated into an AC.
    The FAA does not agree. The installation methods are, in fact, part 
of the regulation. However, in order to address the installation 
methods in the certification test method, the test fixture would have 
to be modified for each installation, which is impractical and could 
lead to a lack of standardization. In addition, it is doubtful that the 
scale of the oil burner test could adequately assess certain 
installation issues that would be significant in a post crash fire. For 
these reasons, we have elected to simplify the test method, and provide 
guidance on acceptable installation methods. An applicant is free to 
propose testing that would substantiate the actual installation, but we 
do not intend to require this when the advisory material covers the 
installation methodology.
    One commenter states that the test method does not adequately 
address ``non-conforming'' materials, such as rigid foams, and could 
result in the placement of a fire barrier that is closer to the 
calorimeter than is the case for traditional blanket materials. The 
commenter contends that the relationship of the barrier to the 
calorimeter can affect the test results.
    The FAA agrees that the relative position of the fire barrier and 
the calorimeter can influence the test results. However, we do not 
agree that moving the barrier closer to the calorimeter will always 
have negative effects. The relationship of the burner to the 
calorimeter is constant, so the relative performance of the barrier 
material, whatever it is, is based on the effect of the burner at the 
calorimeter location. To vary this relationship would compromise the 
standardization of the test method. We recognize that the test method 
is only representative of, and not identical to, the actual fire 
threat. Therefore, an applicant would be free to demonstrate that a 
particular design approach provides the same level of safety if the 
applicant believes that the test setup does not adequately evaluate the 
design.

Operating Requirements in Parts 91, 121, 125, and 135

Newly Manufactured Airplanes

    This final rule requires transport category airplanes operating 
under parts 91, 121, 125, and 135 to comply with the new standards 
relative to flame propagation in final Sec.  25.856(a). This portion of 
the final rule applies to airplanes manufactured more than two years 
after the effective date of this final rule. These requirements are 
found in final Sec. Sec.  91.613(b)(2), 121.312(e)(2), 125.113(c)(2), 
and 135.170(c)(2). We are adopting these requirements exactly as 
proposed in the NPRM except for adding the words ``in the fuselage'' to 
make clear that only thermal/acoustic insulation materials installed in 
the fuselage are subject to the requirements.
    Since there are materials currently available that will meet the 
new standards, these requirements impose minimal additional costs. 
These requirements are applicable to airplanes manufactured more than 
two years after the effective date of the final rule. Two years is 
considered sufficient time to allow for material production capacity to 
be developed and for disposition of existing inventory.
    Readers should note that these requirements differ from previous 
rulemaking related to flammability of materials in that the 
applicability to newly manufactured airplanes is not limited to 
operations under part 121. The reasons for this are that the rule adds 
minimal cost and the potential for an in-flight fire is not limited to 
air carrier operations.
    In accordance with Sec.  21.17, these new standards are applicable 
to new type certificates for which application is made after the 
effective date of the final rule. In addition to changing the design 
standards for future type certificate applications, we consider that 
the benefits from improved flammability standards can be realized for 
existing designs as well. The technology exists today so that these 
benefits can be obtained in a cost-effective manner by applying the 
standards under some circumstances to newly manufactured airplanes and 
to existing airplanes when insulating materials are replaced. Our means 
for obtaining benefits earlier than would be provided by changing 
design standards is to revise the operating rules. Requirements for 
newly manufactured airplanes become a basic airworthiness requirement 
for those airplanes and apply throughout their service life. 
Requirements for the existing fleet relate to materials that are 
replaced in service. This latter aspect of the rule does not affect 
newly manufactured airplanes, since they are already required to comply 
by virtue of their date of manufacture.

Replacement of Existing Insulation

    This final rule requires that thermal/acoustic insulation 
materials, when installed as replacements more than two years after the 
effective date of this final rule, meet the new flame propagation test 
requirements of final Sec.  25.856(a). This requirement applies to 
existing transport category airplanes operating under parts 91, 121, 
125, and 135 and to the same types of airplanes manufactured within two 
years of the effective date of this final rule. See final Sec. Sec.  
91.613(b)(1), 121.312(e)(1), 125.113(c)(1), and 135.170(c)(1). We are 
adopting these requirements exactly as proposed in the NPRM except for 
adding the words ``in the fuselage'' to make clear that only thermal/
acoustic insulation materials installed in the fuselage are subject to 
the requirements.
    This action provides for the gradual attrition of materials 
installed under earlier standards. Since there are existing materials 
that meet the new standards, and since those materials cost and weigh 
only marginally more than other materials, this should result in 
negligible additional cost to operators.
    As with newly manufactured airplanes, it is appropriate to address 
not only those airplanes operated in part 121 air carrier service, but 
other operations as well, since the flame propagation portion of this 
final rule enhances safety over the current regulatory requirements, 
and can be done inexpensively.
    Although it is difficult to quantify the benefits of piecemeal 
replacement of materials, the cost of replacement is low and adds 
minimal burden. This final rule allows time for attrition of current 
inventories and acquisition of new materials. Replacement insulation 
does not have to comply until two years after the effective date of 
this final rule. We expect this requirement to have little impact since 
only a relatively small amount of insulation materials are replaced 
every year.

[[Page 45055]]

Larger Airplanes Operating Under Part 121

    This final rule requires newly manufactured airplanes with a 
passenger capacity of 20 or greater operating under part 121 to comply 
with the burnthrough protection standards in final Sec.  25.856(b). See 
final Sec.  121.312(e)(3). This requirement applies to airplanes 
manufactured more than four years after the effective date of the final 
rule. Although there are materials currently available that will meet 
the standards, these materials are not widely used. Therefore, we 
expect the burnthrough portion of the rule to require both material 
and, in many cases, design changes. As discussed in the context of the 
part 25 changes, these design changes relate primarily to the means of 
fastening the insulation to the fuselage structure. For those airplanes 
that require design changes, we recognize that adequate time is 
necessary to perform the necessary engineering and to obtain approval 
for the changes. We consider four years to be a reasonable time to 
implement any design changes and configuration control measures 
required to account for the new standard and to allow for material 
availability.
    Generally, airplanes operated under parts 91, 125, and 135 carry 
fewer passengers than airplanes operating under part 121 and can, as a 
result, be evacuated more quickly. Therefore, we consider that the 
additional evacuation time provided by enhanced fuselage burnthrough 
protection would not provide the same increase in safety for these 
airplanes. In light of the costs associated with requiring compliance 
with the burnthrough standard, imposing the requirement would have a 
negligible benefit. This conclusion is similar to the conclusion, 
discussed in the context of the proposed part 25 burnthrough standard, 
not to impose the new standard for airplanes with fewer than 20 
passengers. However, since transport category airplanes can be operated 
under different regulatory requirements throughout their service life, 
it is likely that most, if not all, affected newly manufactured 
transport category airplanes will comply, to account for potential 
future part 121 operations.

Replacement

    This final rule does not require installation of materials 
complying with the burnthrough test standards in all transport category 
airplanes because it would not provide a substantial benefit. If the 
fuselage is subjected to an external fire, it is unlikely that 
insulation complying with this standard that has been installed in a 
portion of the fuselage would significantly delay burnthrough if the 
rest of the fuselage contains insulation that does not comply with the 
new standard. As discussed previously, in order to be effective against 
burnthrough, new insulation materials would also have to be installed 
in a manner that would allow them to remain in place when exposed to an 
external fire. Requiring that the means of fastening, and the 
associated engineering necessary to incorporate design changes, be 
accounted for on a material replacement basis would be very expensive, 
with negligible benefit.

Date of Manufacture

    For the purposes of this final rule, we consider the date of 
manufacture to be the date on which inspection records show that an 
airplane is in a condition for safe flight. This is not necessarily the 
date on which the airplane is in conformity with the approved type 
design, or the date on which a certificate of airworthiness is issued, 
since some items not relevant to safe flight, such as passenger seats, 
may not be installed at that time. It could be earlier, but would be no 
later, than the date on which the first flight of the airplane occurs. 
This definition has been used in previous rulemaking, including the 
preamble to our February 2, 1995, final rule entitled Improved 
Flammability Standards for Materials Used in the Interiors of Transport 
Category Airplane Cabins (60 FR 6616, 6617).

Compliance Time

    Commenters were divided as to whether more or less time should be 
allowed for compliance by newly manufactured airplanes with the flame 
propagation requirement of final Sec.  25.856(a). No commenter provided 
any data to support this position, although one commenter noted that it 
might be required to make part number changes in order to facilitate a 
material changeover, which will take time. Another commenter noted that 
a longer compliance period for retrofit of non-compliant insulation on 
air ducts on a particular airplane type was permitted in accordance 
with an airworthiness directive, and this seems inconsistent with the 
proposal.
    With respect to comments that the compliance period for newly 
manufactured airplanes should be adjusted either up or down, in the 
absence of any data to support either position, the FAA cannot justify 
a change. While we agree that part number changes might be necessary, 
it is not the only method to assure configuration control. Any other 
method in which configuration control is assured would be acceptable. 
Therefore, a change to the compliance time is not justified on this 
basis.
    Finally, the comment that the proposed compliance time does not 
coincide with a similar airworthiness directive is not relevant to this 
rule. The airworthiness directive requires retrofit of airplanes that 
are already in service. This is a much more labor intensive and 
complicated process than incorporating a different material in 
production. Therefore no change is made to the compliance time for 
flame propagation.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1995 (44 U.S.C 
3507(d)), we have determined that there are no requirements for 
information collection associated with this final rule.

International Compatibility

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

Economic Evaluation, Regulatory Flexibility Determination, Trade Impact 
Assessment, and Unfunded Mandates Assessment

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs each Federal agency 
proposing or adopting a regulation to first make a reasoned 
determination that the benefits of the intended regulation justify its 
costs. Second, the Regulatory Flexibility Act of 1980 requires agencies 
to analyze the economic impact of regulatory changes on small entities. 
Third, the Trade Agreements Act prohibits agencies from setting 
standards that create unnecessary obstacles to the foreign commerce of 
the United States. In developing U.S. standards, this act requires 
agencies to consider international standards, and use them where 
appropriate as the basis of U.S. standards. Fourth, the Unfunded 
Mandates Reform Act of 1995 requires agencies to prepare a written 
assessment of the costs and benefits and other effects of proposed and 
final rules. An assessment must be prepared only for rules that impose 
a Federal mandate on State, local, or tribal governments, or on

[[Page 45056]]

the private sector, likely to result in a total expenditure of $100 
million or more in any one year (adjusted for inflation).
    In conducting these analyses, the FAA has determined that this rule 
has benefits that justify its costs. This rulemaking does not impose 
costs sufficient to be considered ``significant'' under the economic 
standards for significance under Executive Order 12866. Due to public 
interest, however, it is considered significant under the Executive 
Order and DOT policy. This rule will not have a significant impact on a 
substantial number of small entities. This rule has no affect on trade-
sensitive activity. This rule does not impose an unfunded mandate on 
state, local, or tribal governments, or on the private sector. The FAA 
has placed these analyses in the docket and summarized them below.

Benefits and Costs

Benefits

    This rule will generate safety benefits by averting accidents that 
involve propagation of flame on the film bags that encase thermal 
acoustic insulation batting, and by mitigating accidents that involve 
fire burning through from outside an airplane into its cabin. Over a 
20-year analysis period the rule is expected to avert one catastrophic 
accident and a recoverable accident. The estimated present value of the 
combined flame propagation and burnthrough benefits is about $222.6 
million in constant 2001 dollars.

Flame Propagation Benefits

    When an in-flight fire that propagates on insulation in an 
inaccessible area is detected soon enough, diversion of the flight is 
likely, thus averting death, injury, and damage to the airplane. 
However, if such a fire is not detected until it grows beyond the 
capacity of the aircrew to control, a catastrophic accident with 100 
percent fatalities and the complete loss of the airplane can result. 
The estimate of the expected benefits of complying with the flame 
propagation requirements is based on averting such a catastrophic 
accident. The components of this estimate include (1) averting the 
deaths; (2) averting the loss of the airplane; and (3) averting the 
costs of investigating the accident.
    An example of a potential future averted accident (basis accident) 
is the catastrophic accident that occurred on September 2, 1998, when 
Swissair Flight 111 crashed off the coast of Nova Scotia, Canada, with 
the loss of 229 lives. Although the Transportation Safety Board of 
Canada has not released its final investigative report, on August 28, 
2001, that agency issued Aviation Safety Recommendations, stating that 
``* * *The most significant material flammability deficiency discovered 
has been the inappropriate flammability characteristics of the MPET-
covered thermal acoustic insulation blankets* * *''
    In September 2001, the Fire Safety Section of the FAA's William J. 
Hughes Technical Center provided its professional engineering opinion 
that ``* * *this rule change will likely prevent one catastrophic in-
flight accident over a twenty-year period after implementation.''
    The Section supports its judgment as follows:

    ``During the study period from 1967 through 1998 three fatal in-
flight fires occurred on 121 carriers in North America and an 
additional six throughout the rest of the world in which the fire 
was in an inaccessible area and the thermal/acoustic film may have 
played an important role. A review of recent incident, accident, and 
service difficulty reports indicates that there are between three 
and five in-flight fires causing serious damage on part 121 aircraft 
in the U.S. per year. Most of those occurrences included the spread 
of fire on the thermal/acoustic film. Preliminary information 
obtained on one accident (Air Tran Airways, DC-9-32 on November 29, 
2000, at Atlanta, Georgia) indicates that had the fire started a 
little later in the flight the aircraft would not have been able to 
make it back to the airport.
    Given the above, it is estimated that one catastrophic in-flight 
fire accident will occur every ten years in the U.S. Thermal 
acoustic insulation film makes up a large percentage of the surface 
area in the inaccessible areas of airplanes. If this rule change 
were fully implemented, it would eliminate 50% of the annual 3 to 5 
in-flight fires, thus halving the likelihood of a catastrophic 
accident to one in every 20 years.'' (emphasis added)

    The expected present-value benefits from averting a catastrophic 
accident are estimated to include: averting fatalities ($110 million); 
averting the loss of an airplane hull ($16 million); and averting the 
costs of an accident investigation ($1 million). These benefits total 
to $127 million.

Burnthrough Benefits

    The estimated burnthrough benefits of this rule are based in the 
September 1999 report ``Fuselage Burnthrough Protection for Increased 
Postcrash Occupant Survivability: Safety Benefit Analysis Based on Past 
Accidents,'' DOT/FAA/AR-99/57 (http://www.tc.faa.gov/its/act141/reportpage.html), hereafter referred to as the Cherry Study. This study 
concludes that four minutes of additional resistance to burnthrough 
will result in averting 10.1 fatalities and 13.5 injuries per year over 
the worldwide fleet of passenger-carrying airplanes. The FAA adjusted 
these fatalities and injuries so as to apply only to part 25 airplanes 
in part 121 service over the forecast period. The present value total 
benefit of $95 million includes $50 million from averted fatalities, 
$34 million from averted injuries, and $11 million from averted 
accident investigations

Benefit Summary

    Thus, over the 20-year period of analysis examined in this 
evaluation, the estimated total present value of flame propagation and 
burnthrough benefits is $222.6 million.

                                                                   Summary of Benefits
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                    Monetary benefits
                                              Monetary benefits    Monetary benefits  derived by averting loss of       derived by       Total monetary
                                                  derived by                    aircraft or injuries                averting accident       benefits
                                               averting deaths                                                        investigations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flame Propagation...........................             $110.3  loss of aircraft--$15.6..........................               $1.4             $127.3
Burnthrough.................................               50.5  Injuries--33.9...................................               10.8             * 95.3
                                             --------------------
    Total...................................              160.8  49.5.............................................               12.2           * 222.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Rounded


[[Page 45057]]

Estimates of Costs

    This evaluation examines four components of cost: (1) The 
acquisition of test apparatus used to establish the new testing 
standards; (2) the installation and the maintenance of insulating 
material to meet the flame propagation requirement; (3) the 
installation of insulating material to meet the burnthrough 
requirement; and (4) engineering costs, including those of 
configuration management, which includes changing (also called 
``rolling'') parts numbers.
    Final rule evaluation estimates differ from those of the NPRM 
evaluation with respect to cost components (1), (2) and (4), as follow:
    [sbull] The cost of test apparatus was excluded;
    [sbull] Costs of material to be installed and replaced for the 
flame propagation requirement were added;
    [sbull] The cost of a fuel-weight penalty for burnthrough 
compliance was added;
    [sbull] The engineering cost of possible changes in design and 
installation of insulation blankets was eliminated;
    [sbull] Costs of the engineering work of configuration management 
were greatly increased.
    Each of the four components of the cost estimate is considered in 
turn below.
    The cost of test apparatus was excluded because this cost of 
compliant insulation is expected to include the cost of test apparatus. 
To include the cost of test apparatus will result in counting the cost 
of test apparatus twice.
    This final rule evaluation found that flame propagation material 
requirements is expected to add cost and weight that was not considered 
in the NPRM evaluation. While neither installation during manufacture 
nor replacement during maintenance is expected to add to labor costs, 
each will add to cost of material and to weight. The incremental cost 
of the insulation is $2.05 per square yard. The additional weight will 
result in additional fuel cost.
    Unlike the NPRM this final rule evaluation assigns a minimal cost 
to the design and installation expense. This change in approach results 
from FAA technical opinions that became available after the completion 
of the NPRM evaluation. FAA technical opinions state that the common 
method of installation shown will meet burnthrough requirements if a 
layer of ceramic paper is laminated inside the outboard layer (the 
layer next to the aluminum skin of the airplane) of the metalized 
polyvinylfloride film. As the method of installation will not change, 
there will be no additional engineering expense for design and 
installation.
    While one commenter stated that the FAA's NPRM estimate of 
engineering costs was greatly overstated, this final rule evaluation 
finds that the NPRM estimate of the costs of the engineering work of 
configuration management costs was low. Considering other comments and 
clarifications about the formalization, technical and regulatory 
requirements, and organizational complexity involved in managing 
aviation parts nomenclature, the FAA revised its NPRM cost estimate 
upward.
    The agency accepts the industry estimate that as much as eight 
hours can be required to fully effect changes in nomenclature for each 
aviation part involved in compliance. These eight hours make up the 
time needed for work that begins with the initiation of a change in (or 
with the introduction of new) nomenclature, and that ends with the 
completion of the authorized and documented release of that 
nomenclature to all appropriate holders.

Summary of Cost

    Flame propagation present-value compliance costs are estimated to 
be approximately $76.2 million. The burnthrough present-value 
compliance costs are expected to be approximately $32.2 million. Thus 
the total cost for this rule is $108.4 million (total does not add due 
to rounding). The specific cost elements for flame propagation and 
burnthough are present in the Summary of Costs table.

                                                Summary of Costs
----------------------------------------------------------------------------------------------------------------
                                                    Maintenance
                                        New           driven        Added fuel      Engineering
                                   installation     replacement     weight cost        costs        Total costs
                                   material cost       cost
----------------------------------------------------------------------------------------------------------------
Flame Propagation...............           $13.8            $2.8            $1.5           $58.1           $76.2
Burnthrough.....................            20.6  ..............             2.0             9.6            32.2
                                 -----------------
    Total.......................  ..............  ..............  ..............  ..............           108.4
----------------------------------------------------------------------------------------------------------------

Comparison of Benefits and Costs

    When discounted at 7 per cent annually, the present value of the 
overall benefits of this final rule is about $222.6 million in constant 
2001 dollars. Estimated overall costs are about $108.4 million in 2001 
dollars. Thus, taken as a whole, the rule is cost effective. The 
discounted present values of the benefits of the flame propagation 
requirements are about $127.3 million, and comparable costs are about 
$76.2 million. The discounted present values of benefits of the 
burnthrough requirements are about $95.3 million, and comparable costs 
are about $32.2 million. Thus, each part of the rule, considered 
separately, is cost effective.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a 
principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
to fit regulatory and informational requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to 
regulation.'' To achieve that principle, the Act requires agencies to 
solicit and consider flexible regulatory proposals and to explain the 
rationale for their actions. The Act 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 proposed or 
final rule will have a significant economic impact on a substantial 
number of small entities. If the determination is that it will, the 
agency must prepare a regulatory flexibility analysis as described in 
the Act.
    However, if an agency determines that a proposed or final rule is 
not expected to have a significant economic impact on a substantial 
number of small entities, section 605(b) of the 1980 act provides that 
the head of the agency may so certify and a regulatory flexibility 
analysis is not required. The certification must include a statement 
providing the factual basis for this determination, and the reasoning 
should be clear.

[[Page 45058]]

    The FAA conducted the required review of this final rule, and finds 
the following:
    (1) Engineering and manufacturing costs of this rule apply to 
manufacturers of part 25 airplanes. No such manufacturer is a small 
business;
    (2) In December 2000, the FAA identified 28 airlines that were 
small businesses. This evaluation assumes each will replace about 2.8% 
of the insulation in each of its airplanes with rule compliant 
insulation yearly, on a maintenance-driven basis. Fleet sizes of those 
27 carriers still in business range from 2 to 24. The FAA believes the 
average annual cost of compliance for these carriers will approximate 
$60 per airplane. Based on fleet size, the annual costs incurred by 
average small business carrier is estimated at $420. This amount is 
less than an hour of annual operating cost for the airplanes affected 
by this rule;
    (3) Because the FAA believes that manufacturers will pass along 
their increased compliance costs to the airlines the agency reviewed 
the scope and significance of these costs to operators. The discounted 
present (2001) value of the average airplane newly delivered in 2006 
(the first year both flame propagation and burnthrough requirements 
will be implemented) is about $34.8 million in constant 2001 dollars. 
Assuming the manufacturer spreads engineering costs (for each 
requirement) over a 10-year production run, about $12,000 will be added 
to the cost of the average airplane. Material costs for both 
requirements will add another $11,000. Thus, about $23,000, or just 
under seven one-hundredths of one percent is added to the cost of the 
average airplane that might be acquired by the average small business 
airline. The FAA believes a small business airline that will acquire, 
or will secure the use of a $34.8 million capital asset will not be 
burdened by this small increment.
    Accordingly, pursuant to the Regulatory Flexibility Act, 5 U.S.C. 
605(b), the Federal Aviation Administration certifies that this rule 
will not have a significant economic impact on a substantial number of 
small entities.

International Trade Impact Assessment

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
engaging in any standards or related activities that create unnecessary 
obstacles to the foreign commerce of the United States. Legitimate 
domestic objectives, such as safety, are not considered unnecessary 
obstacles. The statute also requires consideration of international 
standards and where appropriate, that they be the basis for U.S. 
standards.
    In accordance with the above statute, the FAA has assessed the 
potential effect of this final rule and has determined that it will 
impose the same costs on domestic and international manufacturing 
entities, and will impose minimal operating costs on domestic 
operators. The agency believes this final rule will approximate a 
neutral impact on trade.

Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (the Act), 
enacted as Pub. L. 104-4 on March 22, 1995, requires each Federal 
agency, to the extent permitted by law, to prepare a written assessment 
of the effects of any Federal mandate in a proposed or final agency 
rule that may result in the expenditure by State, local, and tribal 
governments, in the aggregate, or by the private sector, of $100 
million or more (adjusted annually for inflation) in any one year. 
Section 204(a) of the Act, 2 U.S.C. 1534(a), requires the Federal 
agency to develop an effective process to permit timely input by 
elected officers (or their designees) of State, local, and tribal 
governments on a proposed ``significant intergovernmental mandate.''
    A ``significant intergovernmental mandate'' under the Act is any 
provision in a Federal agency regulation that would impose an 
enforceable duty upon State, local, and tribal governments, in the 
aggregate, of $100 million (adjusted annually for inflation) in any one 
year. Section 203 of the Act, 2 U.S.C. 1533, which supplements section 
204(a), provides that before establishing any regulatory requirements 
that might significantly or uniquely affect small governments, the 
agency shall have developed a plan that, among other things, provides 
for notice to potentially affected small governments, if any, and for a 
meaningful and timely opportunity to provide input in the development 
of regulatory proposals.
    This rule does not contain any significant Federal 
intergovernmental or private sector mandate. Therefore, the analytical 
requirements of Title II of the Unfunded Mandates Reform Act of 1995 do 
not apply.
    In estimating the costs associated with this final rule, we refined 
the analysis that we prepared for the September 20, 2000 NPRM. See 65 
FR 56998. At that time, we estimated the total discounted costs of the 
NPRM to be $68.2 million. As stated above, we estimate the total 
discounted cost of the final rule to be $108.4 million. The primary 
reason for the increase in the cost estimate is that we believe that 
the NPRM cost estimate of configuration management was too low. Based 
on comments we received on the NPRM about the complexity of managing 
aviation parts nomenclature, we revised the cost estimate upward.
    Several commenters on our estimates of the costs of the proposed 
rule address our use of a particular commercial product in the cost and 
benefit assessment. Some commenters note that the material discussed is 
actually a family of materials, rather than a single product, and it 
could be misleading to imply that only one material is being 
considered. Other commenters object to the use of any trade name, and 
state that this implies that the FAA is endorsing a particular product.
    As discussed in the NPRM, the FAA specifically requested 
information on materials that manufacturers would use to comply with 
the requirement. This was because we could not obtain definitive 
information on the optimal means of compliance, and were forced to rely 
on information available to make an assessment of the costs of 
compliance. In so doing, we used as an example a product where the 
performance and cost information could be readily obtained. This is not 
a product endorsement, or even a suggestion of a preferred means of 
compliance. It is merely an example that could be quantified to 
illustrate what the cost of compliance could be. In order for this 
information to be of any value, the particular product has to be 
mentioned. Otherwise, there would be no way for the public to comment 
on the validity of our estimates.

Executive Order 13132, Federalism

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

Environmental Analysis

    FAA Order 1050.1D defines FAA actions that may be categorically 
excluded from preparation of a National Environmental Policy Act (NEPA) 
environmental impact statement. In accordance with FAA Order 1050.1D, 
appendix 4, paragraph 4(j), this rulemaking action qualifies for a 
categorical exclusion.

[[Page 45059]]

Energy Impact

    The energy impact of this final rule has been assessed in 
accordance with the Energy Policy and Conservation Act (EPCA) and 
Public Law 94-163, as amended (42 U.S.C. 6362) and FAA Order 1053.1. It 
has been determined that the final rule is not a major regulatory 
action under the provisions of the EPCA.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the Administrator, when modifying regulations in Title 
14 of the CFR in a manner affecting intrastate aviation in Alaska, to 
consider the extent to which Alaska is not served by transportation 
modes other than aviation, and to establish such regulatory 
distinctions as he or she considers appropriate. Because this final 
rule applies to the certification of future designs of transport 
category airplanes and their subsequent operation, it could affect 
intrastate aviation in Alaska. Because no comments were received 
regarding this regulation affecting intrastate aviation in Alaska, we 
will apply the rule in the same way that it is being applied 
nationally.

List of Subjects

14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 91

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 121

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements, Safety, Transportation

14 CFR Part 125

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 135

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

The Amendment

0
In consideration of the foregoing, the Federal Aviation Administration 
amends parts 25, 91, 121, 125, and 135 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(g), 40113, 44701-44702, and 44704.


0
2. Add Sec.  25.856 to read as follows:


Sec.  25.856  Thermal/Acoustic insulation materials.

    (a) Thermal/acoustic insulation material installed in the fuselage 
must meet the flame propagation test requirements of part VI of 
Appendix F to this part, or other approved equivalent test 
requirements. This requirement does not apply to ``small parts,'' as 
defined in part I of Appendix F of this part.
    (b) For airplanes with a passenger capacity of 20 or greater, 
thermal/acoustic insulation materials (including the means of fastening 
the materials to the fuselage) installed in the lower half of the 
airplane fuselage must meet the flame penetration resistance test 
requirements of part VII of Appendix F to this part, or other approved 
equivalent test requirements. This requirement does not apply to 
thermal/acoustic insulation installations that the FAA finds would not 
contribute to fire penetration resistance.

0
3. Amend appendix F to part 25 as follows:
0
a. In part I, paragraph (a)(1)(ii), by removing the words ``thermal and 
acoustical insulation and insulation covering'' and ``insulation 
blankets'' from the first sentence.
0
b. In part I, by removing and reserving paragraph (a)(2)(i).
0
c. By adding parts VI and VII to read as follows:

Appendix F to Part 25--[Amended]

* * * * *

Part VI--Test Method To Determine the Flammability and Flame 
Propagation Characteristics of Thermal/Acoustic Insulation 
Materials

    Use this test method to evaluate the flammability and flame 
propagation characteristics of thermal/acoustic insulation when 
exposed to both a radiant heat source and a flame.
    (a) Definitions.
    ``Flame propagation'' means the furthest distance of the 
propagation of visible flame towards the far end of the test 
specimen, measured from the midpoint of the ignition source flame. 
Measure this distance after initially applying the ignition source 
and before all flame on the test specimen is extinguished. The 
measurement is not a determination of burn length made after the 
test.
    ``Radiant heat source'' means an electric or air propane panel.
    ``Thermal/acoustic insulation'' means a material or system of 
materials used to provide thermal and/or acoustic protection. 
Examples include fiberglass or other batting material encapsulated 
by a film covering and foams.
    ``Zero point'' means the point of application of the pilot 
burner to the test specimen.
    (b) Test apparatus.

[[Page 45060]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.003

    (1) Radiant panel test chamber. Conduct tests in a radiant panel 
test chamber (see figure 1 above). Place the test chamber under an 
exhaust hood to facilitate clearing the chamber of smoke after each 
test. The radiant panel test chamber must be an enclosure 55 inches 
(1397 mm) long by 19.5 (495 mm) deep by 28 (710 mm) to 30 inches 
(maximum) (762 mm) above the test specimen. Insulate the sides, 
ends, and top with a fibrous ceramic insulation, such as Kaowool 
MTM board. On the front side, provide a 52 by 12-inch 
(1321 by 305 mm) draft-free, high-temperature, glass window for 
viewing the sample during testing. Place a door below the window to 
provide access to the movable specimen platform holder. The bottom 
of the test chamber must be a sliding steel platform that has 
provision for securing the test specimen holder in a fixed and level 
position. The chamber must have an internal chimney with exterior 
dimensions of 5.1 inches (129 mm) wide, by 16.2 inches (411 mm) deep 
by 13 inches (330 mm) high at the opposite end of the chamber from 
the radiant energy source. The interior dimensions must be 4.5 
inches (114 mm) wide by 15.6 inches (395 mm) deep. The chimney must 
extend to the top of the chamber (see figure 2).

[[Page 45061]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.004

    (2) Radiant heat source. Mount the radiant heat energy source in 
a cast iron frame or equivalent. An electric panel must have six, 3-
inch wide emitter strips. The emitter strips must be perpendicular 
to the length of the panel. The panel must have a radiation surface 
of 12\7/8\ by 18\1/2\ inches (327 by 470 mm). The panel must be 
capable of operating at temperatures up to 1300[deg]F (704[deg]C). 
An air propane panel must be made of a porous refractory material 
and have a radiation surface of 12 by 18 inches (305 by 457 mm). The 
panel must be capable of operating at temperatures up to 1,500[deg]F 
(816[deg]C). See figures 3a and 3b.

[[Page 45062]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.005


[[Page 45063]]


[GRAPHIC] [TIFF OMITTED] TR31JY03.006

    /(i) Electric radiant panel. The radiant panel must be 3-phase 
and operate at 208 volts. A single-phase, 240 volt panel is also 
acceptable. Use a solid-state power controller and microprocessor-
based controller to set the electric panel operating parameters.
    (ii) Gas radiant panel. Use propane (liquid petroleum gas--2.1 
UN 1075) for the radiant panel fuel. The panel fuel system must 
consist of a venturi-type aspirator for mixing gas and air at 
approximately atmospheric pressure. Provide suitable instrumentation 
for monitoring and controlling the flow of fuel and air to the 
panel. Include an air flow gauge, an air flow regulator, and a gas 
pressure gauge.
    (iii) Radiant panel placement. Mount the panel in the chamber at 
30[deg] to the horizontal specimen plane, and 7\1/2\ inches above 
the zero point of the specimen.
    (3) Specimen holding system.
    (i) The sliding platform serves as the housing for test specimen 
placement. Brackets may be attached (via wing nuts) to the top lip 
of the platform in order to accommodate various thicknesses of test 
specimens. Place the test specimens on a sheet of Kaowool 
MTM board or 1260 Standard Board (manufactured by Thermal 
Ceramics and available in Europe), or equivalent, either resting on 
the bottom lip of the sliding platform or on the base of the 
brackets. It may be necessary to use multiple sheets of material 
based on the thickness of the test specimen (to meet the sample 
height requirement). Typically, these non-combustible sheets of 
material are available in \1/4\ inch (6 mm) thicknesses. See figure 
4. A sliding platform that is deeper than the 2-inch (50.8mm) 
platform shown in figure 4 is also acceptable as long as the sample 
height requirement is met.

[[Page 45064]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.007

    (ii) Attach a \1/2\ inch (13 mm) piece of Kaowool MTM 
board or other high temperature material measuring 41\1/2\ by 8\1/4\ 
inches (1054 by 210 mm) to the back of the platform. This board 
serves as a heat retainer and protects the test specimen from 
excessive preheating. The height of this board must not impede the 
sliding platform movement (in and out of the test chamber). If the 
platform has been fabricated such that the back side of the platform 
is high enough to prevent excess preheating of the specimen when the 
sliding platform is out, a retainer board is not necessary.
    (iii) Place the test specimen horizontally on the non-
combustible board(s). Place a steel retaining/securing frame 
fabricated of mild steel, having a thickness of \1/8\ inch (3.2 mm) 
and overall dimensions of 23 by 13\1/8\ inches (584 by 333 mm) with 
a specimen opening of 19 by 10\3/4\ inches (483 by 273 mm) over the 
test specimen. The front, back, and right portions of the top flange 
of the frame must rest on the top of the sliding platform, and the 
bottom flanges must pinch all 4 sides of the test specimen. The 
right bottom flange must be flush with the sliding platform. See 
figure 5.

[[Page 45065]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.008

    (4) Pilot Burner. The pilot burner used to ignite the specimen 
must be a BernzomaticTM commercial propane venturi torch 
with an axially symmetric burner tip and a propane supply tube with 
an orifice diameter of 0.006 inches (0.15 mm). The length of the 
burner tube must be 2\7/8\ inches (71 mm). The propane flow must be 
adjusted via gas pressure through an in-line regulator to produce a 
blue inner cone length of \3/4\ inch (19 mm). A \3/4\ inch (19 mm) 
guide (such as a thin strip of metal) may be soldered to the top of 
the burner to aid in setting the flame height. The overall flame 
length must be approximately 5 inches long (127 mm). Provide a way 
to move the burner out of the ignition position so that the flame is 
horizontal and at least 2 inches (50 mm) above the specimen plane. 
See figure 6.

[[Page 45066]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.009

    (5) Thermocouples. Install a 24 American Wire Gauge (AWG) Type K 
(Chromel-Alumel) thermocouple in the test chamber for temperature 
monitoring. Insert it into the chamber through a small hole drilled 
through the back of the chamber. Place the thermocouple so that it 
extends 11 inches (279 mm) out from the back of the chamber wall, 
11\1/2\ inches (292 mm) from the right side of the chamber wall, and 
is 2 inches (51 mm) below the radiant panel. The use of other 
thermocouples is optional.
    (6) Calorimeter. The calorimeter must be a one-inch cylindrical 
water-cooled, total heat flux density, foil type Gardon Gage that 
has a range of 0 to 5 BTU/ft\2\-second (0 to 5.7 Watts/cm\2\).
    (7) Calorimeter calibration specification and procedure.
    (i) Calorimeter specification.
    (A) Foil diameter must be 0.25 +/-0.005 inches (6.35 +/-0.13 
mm).
    (B) Foil thickness must be 0.0005 +/-0.0001 inches (0.013 +/-
;0.0025 mm).
    (C) Foil material must be thermocouple grade Constantan.
    (D) Temperature measurement must be a Copper Constantan 
thermocouple.
    (E) The copper center wire diameter must be 0.0005 inches (0.013 
mm).
    (F) The entire face of the calorimeter must be lightly coated 
with ``Black Velvet'' paint having an emissivity of 96 or greater.
    (ii) Calorimeter calibration.
    (A) The calibration method must be by comparison to a like 
standardized transducer.
    (B) The standardized transducer must meet the specifications 
given in paragraph VI(b)(6) of this appendix.
    (C) Calibrate the standard transducer against a primary standard 
traceable to the National Institute of Standards and Technology 
(NIST).
    (D) The method of transfer must be a heated graphite plate.
    (E) The graphite plate must be electrically heated, have a clear 
surface area on each side of the plate of at least 2 by 2 inches (51 
by 51 mm), and be \1/8\ inch +/-\1/16\ inch thick (3.2 +/-1.6 mm).
    (F) Center the 2 transducers on opposite sides of the plates at 
equal distances from the plate.
    (G) The distance of the calorimeter to the plate must be no less 
than 0.0625 inches (1.6 mm), nor greater than 0.375 inches (9.5 mm).
    (H) The range used in calibration must be at least 0-3.5 BTUs/
ft\2\ second (0-3.9 Watts/cm\2\) and no greater than 0-5.7 BTUs/
ft\2\ second (0-6.4 Watts/cm\2\).
    (I) The recording device used must record the 2 transducers 
simultaneously or at least within \1/10\ of each other.
    (8) Calorimeter fixture. With the sliding platform pulled out of 
the chamber, install the calorimeter holding frame and place a sheet 
of non-combustible material in the bottom of the sliding platform 
adjacent to the holding frame. This will prevent heat losses during 
calibration. The frame must be 13\1/8\ inches (333 mm) deep (front 
to back) by 8 inches (203 mm) wide and must rest on the top of the 
sliding platform. It must be fabricated of \1/8\ inch (3.2 mm) flat 
stock steel and have an opening that accommodates a \1/2\ inch (12.7 
mm) thick piece of refractory board, which is level with the top of 
the sliding platform. The board must have three 1-inch (25.4 mm) 
diameter holes drilled through the board for calorimeter insertion. 
The distance to the radiant panel surface from the centerline of the 
first hole (``zero'' position) must be 7\1/2\ +/-\1/8\ inches (191 
+/-3 mm). The distance between the centerline of the first hole to 
the centerline of the second hole must be 2 inches (51 mm). It must 
also be the same distance from the centerline of the second hole to 
the centerline of the third hole. See figure 7. A calorimeter 
holding frame that differs in construction is acceptable as long as 
the height from the centerline of the first hole to the radiant 
panel and the distance between holes is the same as described in 
this paragraph.

[[Page 45067]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.010

    (9) Instrumentation. Provide a calibrated recording device with 
an appropriate range or a computerized data acquisition system to 
measure and record the outputs of the calorimeter and the 
thermocouple. The data acquisition system must be capable of 
recording the calorimeter output every second during calibration.
    (10) Timing device. Provide a stopwatch or other device, 
accurate to +/-1 second/hour, to measure the time of application of 
the pilot burner flame.
    (c) Test specimens.
    (1) Specimen preparation. Prepare and test a minimum of three 
test specimens. If an oriented film cover material is used, prepare 
and test both the warp and fill directions.
    (2) Construction. Test specimens must include all materials used 
in construction of the insulation (including batting, film, scrim, 
tape etc.). Cut a piece of core material such as foam or fiberglass, 
and cut a piece of film cover material (if used) large enough to 
cover the core material. Heat sealing is the preferred method of 
preparing fiberglass samples, since they can be made without 
compressing the fiberglass (``box sample''). Cover materials that 
are not heat sealable may be stapled, sewn, or taped as long as the 
cover material is over-cut enough to be drawn down the sides without 
compressing the core material. The fastening means should be as 
continuous as possible along the length of the seams. The specimen 
thickness must be of the same thickness as installed in the 
airplane.
    (3) Specimen Dimensions. To facilitate proper placement of 
specimens in the sliding platform housing, cut non-rigid core 
materials, such as fiberglass, 12\1/2\ inches (318mm) wide by 23 
inches (584mm) long. Cut rigid materials, such as foam, 11\1/2\ +/-
\1/4\ inches (292 mm +/-6mm) wide by 23 inches (584mm) long in order 
to fit properly in the sliding platform housing and provide a flat, 
exposed surface equal to the opening in the housing.
    (d) Specimen conditioning. Condition the test specimens at 70 +/
-5[deg]F (21 +/-2[deg]C) and 55% +/-10% relative humidity, for a 
minimum of 24 hours prior to testing.
    (e) Apparatus Calibration.
    (1) With the sliding platform out of the chamber, install the 
calorimeter holding frame. Push the platform back into the chamber 
and insert the calorimeter into the first hole (``zero'' position). 
See figure 7. Close the bottom door located below the sliding 
platform. The distance from the centerline of the calorimeter to the 
radiant panel surface at this point must be 7.\1/2\ inches +/-\1/8\ 
(191 mm +/-3). Prior to igniting the radiant panel, ensure that the 
calorimeter face is clean and that there is water running through 
the calorimeter.
    (2) Ignite the panel. Adjust the fuel/air mixture to achieve 1.5 
BTUs/ft\2\-second +/-5% (1.7 Watts/cm\2\ +/-5%) at the ``zero'' 
position. If using an electric panel, set the power controller to 
achieve the proper heat flux. Allow the unit to reach steady state 
(this may take up to 1 hour). The pilot burner must be off and in 
the down position during this time.
    (3) After steady-state conditions have been reached, move the 
calorimeter 2 inches (51 mm) from the ``zero'' position (first hole) 
to position 1 and record the heat flux. Move the calorimeter to 
position 2 and record the heat flux. Allow enough time at each 
position for the calorimeter to stabilize. Table 1 depicts typical 
calibration values at the three positions.

                       Table 1.--Calibration Table
------------------------------------------------------------------------
          Position               BTU's/ft\2\sec          Watts/cm\2\
------------------------------------------------------------------------
``Zero'' Position...........                   1.5                   1.7
Position 1..................        1.51-1.50-1.49        1.71-1.70-1.69
Position 2..................             1.43-1.44             1.62-1.63
------------------------------------------------------------------------


[[Page 45068]]

    (4) Open the bottom door, remove the calorimeter and holder 
fixture. Use caution as the fixture is very hot.
    (f) Test Procedure.
    (1) Ignite the pilot burner. Ensure that it is at least 2 inches 
(51 mm) above the top of the platform. The burner must not contact 
the specimen until the test begins.
    (2) Place the test specimen in the sliding platform holder. 
Ensure that the test sample surface is level with the top of the 
platform. At ``zero'' point, the specimen surface must be 7\1/2\ 
inches +/-\1/8\ inch (191 mm +/-3) below the radiant panel.
    (3) Place the retaining/securing frame over the test specimen. 
It may be necessary (due to compression) to adjust the sample (up or 
down) in order to maintain the distance from the sample to the 
radiant panel (7\1/2\ inches +/-\1/8\ inch (191 mm+/-3) at ``zero'' 
position). With film/fiberglass assemblies, it is critical to make a 
slit in the film cover to purge any air inside. This allows the 
operator to maintain the proper test specimen position (level with 
the top of the platform) and to allow ventilation of gases during 
testing. A longitudinal slit, approximately 2 inches (51mm) in 
length, must be centered 3 inches +/-\1/2\ inch (76mm+/-13mm) from 
the left flange of the securing frame. A utility knife is acceptable 
for slitting the film cover.
    (4) Immediately push the sliding platform into the chamber and 
close the bottom door.
    (5) Bring the pilot burner flame into contact with the center of 
the specimen at the ``zero'' point and simultaneously start the 
timer. The pilot burner must be at a 27[deg] angle with the sample 
and be approximately \1/2\ inch (12 mm) above the sample. See figure 
7. A stop, as shown in figure 8, allows the operator to position the 
burner correctly each time.
[GRAPHIC] [TIFF OMITTED] TR31JY03.011

    (6) Leave the burner in position for 15 seconds and then remove 
to a position at least 2 inches (51 mm) above the specimen.
    (g) Report.
    (1) Identify and describe the test specimen.
    (2) Report any shrinkage or melting of the test specimen.
    (3) Report the flame propagation distance. If this distance is 
less than 2 inches, report this as a pass (no measurement required).
    (4) Report the after-flame time.
    (h) Requirements.
    (1) There must be no flame propagation beyond 2 inches (51 mm) 
to the left of the centerline of the pilot flame application.
    (2) The flame time after removal of the pilot burner may not 
exceed 3 seconds on any specimen.

Part VII--Test Method To Determine the Burnthrough Resistance of 
Thermal/Acoustic Insulation Materials

    Use the following test method to evaluate the burnthrough 
resistance characteristics of aircraft thermal/acoustic insulation 
materials when exposed to a high intensity open flame.
    (a) Definitions.
    Burnthrough time means the time, in seconds, for the burner 
flame to penetrate the test specimen, and/or the time required for 
the heat flux to reach 2.0 Btu/ft2sec (2.27 W/
cm2) on the inboard side, at a distance of 12 inches 
(30.5 cm) from the front surface of the insulation blanket test 
frame, whichever is sooner. The burnthrough time is measured at the 
inboard side of each of the insulation blanket specimens.
    Insulation blanket specimen means one of two specimens 
positioned in either side of

[[Page 45069]]

the test rig, at an angle of 30[deg] with respect to vertical.
    Specimen set means two insulation blanket specimens. Both 
specimens must represent the same production insulation blanket 
construction and materials, proportioned to correspond to the 
specimen size.
    (b) Apparatus.
    (1) The arrangement of the test apparatus is shown in figures 1 
and 2 and must include the capability of swinging the burner away 
from the test specimen during warm-up.

[[Page 45070]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.012


[[Page 45071]]


    (2) Test burner. The test burner must be a modified gun-type 
such as the Park Model DPL 3400. Flame characteristics are highly 
dependent on actual burner setup. Parameters such as fuel pressure, 
nozzle depth, stator position, and intake airflow must be properly 
adjusted to achieve the correct flame output.
[GRAPHIC] [TIFF OMITTED] TR31JY03.013


[[Page 45072]]


    (i) Nozzle. A nozzle must maintain the fuel pressure to yield a 
nominal 6.0 gal/hr (0.378 L/min) fuel flow. A Monarch-manufactured 
80[deg] PL (hollow cone) nozzle nominally rated at 6.0 gal/hr at 100 
lb/in2 (0.71 MPa) delivers a proper spray pattern.
    (ii) Fuel Rail. The fuel rail must be adjusted to position the 
fuel nozzle at a depth of 0.3125 inch (8 mm) from the end plane of 
the exit stator, which must be mounted in the end of the draft tube.
    (iii) Internal Stator. The internal stator, located in the 
middle of the draft tube, must be positioned at a depth of 3.75 
inches (95 mm) from the tip of the fuel nozzle. The stator must also 
be positioned such that the integral igniters are located at an 
angle midway between the 10 and 11 o'clock position, when viewed 
looking into the draft tube. Minor deviations to the igniter angle 
are acceptable if the temperature and heat flux requirements conform 
to the requirements of paragraph VII(e) of this appendix.
    (iv) Blower Fan. The cylindrical blower fan used to pump air 
through the burner must measure 5.25 inches (133 mm) in diameter by 
3.5 inches (89 mm) in width.
    (v) Burner cone. Install a 12 +0.125-inch (305 +/-3 mm) burner 
extension cone at the end of the draft tube. The cone must have an 
opening 6 +/-0.125-inch (152 +/-3 mm) high and 11 +/-0.125-inch (280 
+/-3 mm) wide (see figure 3).
    (vi) Fuel. Use JP-8, Jet A, or their international equivalent, 
at a flow rate of 6.0 +/-0.2 gal/hr (0.378 +/-0.0126 L/min). If this 
fuel is unavailable, ASTM K2 fuel (Number 2 grade kerosene) or ASTM 
D2 fuel (Number 2 grade fuel oil or Number 2 diesel fuel) are 
acceptable if the nominal fuel flow rate, temperature, and heat flux 
measurements conform to the requirements of paragraph VII(e) of this 
appendix.
    (vii) Fuel pressure regulator. Provide a fuel pressure 
regulator, adjusted to deliver a nominal 6.0 gal/hr (0.378 L/min) 
flow rate. An operating fuel pressure of 100 lb/in\2\ (0.71 MPa) for 
a nominally rated 6.0 gal/hr 80[deg] spray angle nozzle (such as a 
PL type) delivers 6.0 +/-0.2 gal/hr (0.378 +/-0.0126 L/min).

[[Page 45073]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.014


[[Page 45074]]


    (3) Calibration rig and equipment.
    (i) Construct individual calibration rigs to incorporate a 
calorimeter and thermocouple rake for the measurement of heat flux 
and temperature. Position the calibration rigs to allow movement of 
the burner from the test rig position to either the heat flux or 
temperature position with minimal difficulty.
    (ii) Calorimeter. The calorimeter must be a total heat flux, 
foil type Gardon Gage of an appropriate range such as 0-20 Btu/ft 
\2\-sec (0-22.7 W/cm \2\), accurate to +/-3% of the indicated 
reading. The heat flux calibration method must be in accordance with 
paragraph VI(b)(7) of this appendix.
    (iii) Calorimeter mounting. Mount the calorimeter in a 6- by 12- 
+/-0.125 inch (152- by 305- +/-3 mm) by 0.75 +/-0.125 inch (19 mm +/
-3 mm) thick insulating block which is attached to the heat flux 
calibration rig during calibration (figure 4). Monitor the 
insulating block for deterioration and replace it when necessary. 
Adjust the mounting as necessary to ensure that the calorimeter face 
is parallel to the exit plane of the test burner cone.

[[Page 45075]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.015


[[Page 45076]]


[GRAPHIC] [TIFF OMITTED] TR31JY03.016


[[Page 45077]]


    (iv) Thermocouples. Provide seven \1/8\-inch (3.2 mm) ceramic 
packed, metal sheathed, type K (Chromel-alumel), grounded junction 
thermocouples with a nominal 24 American Wire Gauge (AWG) size 
conductor for calibration. Attach the thermocouples to a steel angle 
bracket to form a thermocouple rake for placement in the calibration 
rig during burner calibration (figure 5).
    (v) Air velocity meter. Use a vane-type air velocity meter to 
calibrate the velocity of air entering the burner. An Omega 
Engineering Model HH30A is satisfactory. Use a suitable adapter to 
attach the measuring device to the inlet side of the burner to 
prevent air from entering the burner other than through the 
measuring device, which would produce erroneously low readings. Use 
a flexible duct, measuring 4 inches wide (102 mm) by 20 feet long 
(6.1 meters), to supply fresh air to the burner intake to prevent 
damage to the air velocity meter from ingested soot. An optional 
airbox permanently mounted to the burner intake area can effectively 
house the air velocity meter and provide a mounting port for the 
flexible intake duct.
    (4) Test specimen mounting frame. Make the mounting frame for 
the test specimens of \1/8\-inch (3.2 mm) thick steel as shown in 
figure 1, except for the center vertical former, which should be \1/
4\-inch (6.4 mm) thick to minimize warpage. The specimen mounting 
frame stringers (horizontal) should be bolted to the test frame 
formers (vertical) such that the expansion of the stringers will not 
cause the entire structure to warp. Use the mounting frame for 
mounting the two insulation blanket test specimens as shown in 
figure 2.
    (5) Backface calorimeters. Mount two total heat flux Gardon type 
calorimeters behind the insulation test specimens on the back side 
(cold) area of the test specimen mounting frame as shown in figure 
6. Position the calorimeters along the same plane as the burner cone 
centerline, at a distance of 4 inches (102 mm) from the vertical 
centerline of the test frame.

[[Page 45078]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.017


[[Page 45079]]


    (i) The calorimeters must be a total heat flux, foil type Gardon 
Gage of an appropriate range such as 0-5 Btu/ft2-sec (0-
5.7 W/cm2), accurate to +/-3% of the indicated reading. 
The heat flux calibration method must comply with paragraph VI(b)(7) 
of this appendix.
    (6) Instrumentation. Provide a recording potentiometer or other 
suitable calibrated instrument with an appropriate range to measure 
and record the outputs of the calorimeter and the thermocouples.
    (7) Timing device. Provide a stopwatch or other device, accurate 
to +/-1%, to measure the time of application of the burner flame and 
burnthrough time.
    (8) Test chamber. Perform tests in a suitable chamber to reduce 
or eliminate the possibility of test fluctuation due to air 
movement. The chamber must have a minimum floor area of 10 by 10 
feet (305 by 305 cm).
    (i) Ventilation hood. Provide the test chamber with an exhaust 
system capable of removing the products of combustion expelled 
during tests.
    (c) Test Specimens.
    (1) Specimen preparation. Prepare a minimum of three specimen 
sets of the same construction and configuration for testing.
    (2) Insulation blanket test specimen.
    (i) For batt-type materials such as fiberglass, the constructed, 
finished blanket specimen assemblies must be 32 inches wide by 36 
inches long (81.3 by 91.4 cm), exclusive of heat sealed film edges.
    (ii) For rigid and other non-conforming types of insulation 
materials, the finished test specimens must fit into the test rig in 
such a manner as to replicate the actual in-service installation.
    (3) Construction. Make each of the specimens tested using the 
principal components (i.e., insulation, fire barrier material if 
used, and moisture barrier film) and assembly processes 
(representative seams and closures).
    (i) Fire barrier material. If the insulation blanket is 
constructed with a fire barrier material, place the fire barrier 
material in a manner reflective of the installed arrangement For 
example, if the material will be placed on the outboard side of the 
insulation material, inside the moisture film, place it the same way 
in the test specimen.
    (ii) Insulation material. Blankets that utilize more than one 
variety of insulation (composition, density, etc.) must have 
specimen sets constructed that reflect the insulation combination 
used. If, however, several blanket types use similar insulation 
combinations, it is not necessary to test each combination if it is 
possible to bracket the various combinations.
    (iii) Moisture barrier film. If a production blanket 
construction utilizes more than one type of moisture barrier film, 
perform separate tests on each combination. For example, if a 
polyimide film is used in conjunction with an insulation in order to 
enhance the burnthrough capabilities, also test the same insulation 
when used with a polyvinyl fluoride film.
    (iv) Installation on test frame. Attach the blanket test 
specimens to the test frame using 12 steel spring type clamps as 
shown in figure 7. Use the clamps to hold the blankets in place in 
both of the outer vertical formers, as well as the center vertical 
former (4 clamps per former). The clamp surfaces should measure 1 
inch by 2 inches (25 by 51 mm). Place the top and bottom clamps 6 
inches (15.2 cm) from the top and bottom of the test frame, 
respectively. Place the middle clamps 8 inches (20.3 cm) from the 
top and bottom clamps.

[[Page 45080]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.018


[[Page 45081]]


    (Note: For blanket materials that cannot be installed in 
accordance with figure 7 above, the blankets must be installed in a 
manner approved by the FAA.)
    (v) Conditioning. Condition the specimens at 70[deg] +/-5[deg]F 
(21[deg] +/-2[deg]C) and 55% +/-10% relative humidity for a minimum 
of 24 hours prior to testing.
    (d) Preparation of apparatus.
    (1) Level and center the frame assembly to ensure alignment of 
the calorimeter and/or thermocouple rake with the burner cone.
    (2) Turn on the ventilation hood for the test chamber. Do not 
turn on the burner blower. Measure the airflow of the test chamber 
using a vane anemometer or equivalent measuring device. The vertical 
air velocity just behind the top of the upper insulation blanket 
test specimen must be 100 +/-50 ft/min (0.51 +/-0.25 m/s). The 
horizontal air velocity at this point must be less than 50 ft/min 
(0.25 m/s).
    (3) If a calibrated flow meter is not available, measure the 
fuel flow rate using a graduated cylinder of appropriate size. Turn 
on the burner motor/fuel pump, after insuring that the igniter 
system is turned off. Collect the fuel via a plastic or rubber tube 
into the graduated cylinder for a 2-minute period. Determine the 
flow rate in gallons per hour. The fuel flow rate must be 6.0 +/-0.2 
gallons per hour (0.378 +/-0.0126 L/min).
    (e) Calibration.
    (1) Position the burner in front of the calorimeter so that it 
is centered and the vertical plane of the burner cone exit is 4 +/-
0.125 inches (102 +/-3 mm) from the calorimeter face. Ensure that 
the horizontal centerline of the burner cone is offset 1 inch below 
the horizontal centerline of the calorimeter (figure 8). Without 
disturbing the calorimeter position, rotate the burner in front of 
the thermocouple rake, such that the middle thermocouple (number 4 
of 7) is centered on the burner cone.

[[Page 45082]]

[GRAPHIC] [TIFF OMITTED] TR31JY03.019


[[Page 45083]]


    Ensure that the horizontal centerline of the burner cone is also 
offset 1 inch below the horizontal centerline of the thermocouple 
tips. Re-check measurements by rotating the burner to each position 
to ensure proper alignment between the cone and the calorimeter and 
thermocouple rake. (Note: The test burner mounting system must 
incorporate ``detents'' that ensure proper centering of the burner 
cone with respect to both the calorimeter and the thermocouple 
rakes, so that rapid positioning of the burner can be achieved 
during the calibration procedure.)
    (2) Position the air velocity meter in the adapter or airbox, 
making certain that no gaps exist where air could leak around the 
air velocity measuring device. Turn on the blower/motor while 
ensuring that the fuel solenoid and igniters are off. Adjust the air 
intake velocity to a level of 2150 ft/min, (10.92 m/s) then turn off 
the blower/motor. (Note: The Omega HH30 air velocity meter measures 
2.625 inches in diameter. To calculate the intake airflow, multiply 
the cross-sectional area (0.03758 ft2) by the air 
velocity (2150 ft/min) to obtain 80.80 ft3/min. An air 
velocity meter other than the HH30 unit can be used, provided the 
calculated airflow of 80.80 ft3/min (2.29 m3/
min) is equivalent.)
    (3) Rotate the burner from the test position to the warm-up 
position. Prior to lighting the burner, ensure that the calorimeter 
face is clean of soot deposits, and there is water running through 
the calorimeter. Examine and clean the burner cone of any evidence 
of buildup of products of combustion, soot, etc. Soot buildup inside 
the burner cone may affect the flame characteristics and cause 
calibration difficulties. Since the burner cone may distort with 
time, dimensions should be checked periodically.
    (4) While the burner is still rotated to the warm-up position, 
turn on the blower/motor, igniters and fuel flow, and light the 
burner. Allow it to warm up for a period of 2 minutes. Move the 
burner into the calibration position and allow 1 minute for 
calorimeter stabilization, then record the heat flux once every 
second for a period of 30 seconds. Turn off burner, rotate out of 
position, and allow to cool. Calculate the average heat flux over 
this 30-second duration. The average heat flux should be 16.0 +/-0.8 
Btu/ft2 sec (18.2 +/-0.9 W/cm \2\).
    (5) Position the burner in front of the thermocouple rake. After 
checking for proper alignment, rotate the burner to the warm-up 
position, turn on the blower/motor, igniters and fuel flow, and 
light the burner. Allow it to warm up for a period of 2 minutes. 
Move the burner into the calibration position and allow 1 minute for 
thermocouple stabilization, then record the temperature of each of 
the 7 thermocouples once every second for a period of 30 seconds. 
Turn off burner, rotate out of position, and allow to cool. 
Calculate the average temperature of each thermocouple over this 30-
second period and record. The average temperature of each of the 7 
thermocouples should be 1900[deg]F +/- 100[deg]F (1038 +/- 
56[deg]C).
    (6) If either the heat flux or the temperatures are not within 
the specified range, adjust the burner intake air velocity and 
repeat the procedures of paragraphs (4) and (5) above to obtain the 
proper values. Ensure that the inlet air velocity is within the 
range of 2150 ft/min +/-50 ft/min (10.92 +/-0.25 m/s).
    (7) Calibrate prior to each test until consistency has been 
demonstrated. After consistency has been confirmed, several tests 
may be conducted with calibration conducted before and after a 
series of tests.
    (f) Test procedure.
    (1) Secure the two insulation blanket test specimens to the test 
frame. The insulation blankets should be attached to the test rig 
center vertical former using four spring clamps positioned as shown 
in figure 7 (according to the criteria of paragraph (c)(4) or 
(c)(4)(i) of this part of this appendix).
    (2) Ensure that the vertical plane of the burner cone is at a 
distance of 4 +/-0.125 inch (102 +/-3 mm) from the outer surface of 
the horizontal stringers of the test specimen frame, and that the 
burner and test frame are both situated at a 30[deg] angle with 
respect to vertical.
    (3) When ready to begin the test, direct the burner away from 
the test position to the warm-up position so that the flame will not 
impinge on the specimens prematurely. Turn on and light the burner 
and allow it to stabilize for 2 minutes.
    (4) To begin the test, rotate the burner into the test position 
and simultaneously start the timing device.
    (5) Expose the test specimens to the burner flame for 4 minutes 
and then turn off the burner. Immediately rotate the burner out of 
the test position.
    (6) Determine (where applicable) the burnthrough time, or the 
point at which the heat flux exceeds 2.0 Btu/ft2-sec 
(2.27 W/cm2).
    (g) Report.
    (1) Identify and describe the specimen being tested.
    (2) Report the number of insulation blanket specimens tested.
    (3) Report the burnthrough time (if any), and the maximum heat 
flux on the back face of the insulation blanket test specimen, and 
the time at which the maximum occurred.
    (h) Requirements.
    (1) Each of the two insulation blanket test specimens must not 
allow fire or flame penetration in less than 4 minutes.
    (2) Each of the two insulation blanket test specimens must not 
allow more than 2.0 Btu/ft2-sec (2.27 W/cm2) 
on the cold side of the insulation specimens at a point 12 inches 
(30.5 cm) from the face of the test rig.

PART 91--GENERAL OPERATING AND FLIGHT RULES

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

    Authority: 49 U.S.C. 106(g), 40103, 40113, 40120, 44101, 44111, 
44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 46306, 
46315, 46316, 46502, 46504, 46506-46507, 47122, 47508, 47528-47531.


0
5. Amend Sec.  91.613 by redesignating the existing text as paragraph 
(a), and adding paragraph (b) to read as follows:


Sec.  91.613  Materials for compartment interiors.

* * * * *
    (b) Thermal/acoustic insulation materials. For transport category 
airplanes type certificated after January 1, 1958:
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation materials are installed in the fuselage as 
replacements after September 2, 2005, those materials must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003.
    (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.

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

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

    Authority: 49 U.S.C. 106(g), 40113, 40119, 44101, 44701-44702, 
44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-44904, 
44912, 46105.


0
7. Amend Sec.  121.312 by adding paragraph (e) to read as follows:


Sec.  121.312  Materials for compartment interiors.

* * * * *
    (e) Thermal/acoustic insulation materials. For transport category 
airplanes type certificated after January 1, 1958:
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation materials are installed in the fuselage as 
replacements after September 2, 2005, those materials must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003.
    (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.
    (3) For airplanes with a passenger capacity of 20 or greater, 
manufactured after September 3, 2007, 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.

[[Page 45084]]

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

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

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

0
9. Amend Sec.  125.113 by adding paragraph (c) to read as follows:


Sec.  125.113  Cabin interiors.

* * * * *
    (c) Thermal/acoustic insulation materials. For transport category 
airplanes type certificated after January 1, 1958:
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation materials are installed in the fuselage as 
replacements after September 2, 2005, those materials must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003.
    (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.

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

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

    Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44709, 
44711-44713, 44715-44717, 44722.


0
11. Amend Sec.  135.170 by adding paragraph (c) to read as follows:


Sec.  135.170  Materials for compartment interiors.

* * * * *
    (c) Thermal/acoustic insulation materials. For transport category 
airplanes type certificated after January 1, 1958:
    (1) For airplanes manufactured before September 2, 2005, when 
thermal/acoustic insulation materials are installed in the fuselage as 
replacements after September 2, 2005, those materials must meet the 
flame propagation requirements of Sec.  25.856 of this chapter, 
effective September 2, 2003.
    (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.

    Issued in Washington, DC on July 14, 2003.
Marion Blakey,
Administrator.
[FR Doc. 03-18612 Filed 7-30-03; 8:45 am]
BILLING CODE 4910-13-P