[Federal Register: July 31, 2003 (Volume 68, Number 147)]
[Rules and Regulations]
[Page 45045-45084]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31jy03-18]
[[Page 45045]]
-----------------------------------------------------------------------
Part III
Department of Transportation
-----------------------------------------------------------------------
Federal Aviation Administration
-----------------------------------------------------------------------
14 CFR Parts 25, 91, et al.
Improved Flammability Standards for Thermal/Acoustic Insulation
Materials Used in Transport Category Airplanes; Final Rule
[[Page 45046]]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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:
jeff.gardlin@faa.gov.
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 9-AWA-
SBREFA@faa.gov.
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