[Federal Register Volume 65, Number 183 (Wednesday, September 20, 2000)]
[Proposed Rules]
[Pages 56992-57022]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-23550]



[[Page 56991]]

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Part II





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 25, et al.



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

  Federal Register / Vol. 65, No. 183 / Wednesday, September 20, 2000 / 
Proposed Rules  

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

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

[Docket No. FAA-2000-7909; Notice No. 00-09]
RIN 2120-AG91


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes upgraded flammability standards for 
thermal/acoustic insulation materials typically installed behind 
interior panels in transport category airplanes, by adopting new 
flammability test methods and criteria that specifically address flame 
propagation and entry of an external fire into the airplane 
(burnthrough) under realistic fire scenarios. This proposed rule change 
is considered necessary because the current standards do not 
realistically address situations in which thermal/acoustic insulation 
materials may contribute to the propagation of a fire. The proposed 
standards are intended to reduce the incidence and severity of cabin 
fires, particularly those ignited in inaccessible areas where thermal/
acoustic insulation materials are typically installed. In addition, 
these proposed standards are also intended to provide an increased 
level of safety with respect to post-crash fires by delaying the entry 
of such a fire into the cabin, thereby providing additional time for 
evacuation and enhancing survivability. These new standards, in 
addition to being proposed for new type designs, are also proposed for 
newly manufactured airplanes entering part 121 service. Additionally, 
the proposed flame propagation standards are also proposed for newly 
manufactured airplanes entering parts 91, 125, and 135 service.

DATES: Comments must be received on or before January 18, 2001.

ADDRESSES: Comments on this document should be mailed or delivered, in 
duplicate, to: U.S. Department of Transportation Dockets, Docket No. 
FAA-2000-7909, 400 Seventh Street SW., Room Plaza 401, Washington, DC 
20590. Comments also may be sent electronically to the following 
Internet address: [email protected]. Comments may be filed and 
examined in Room Plaza 401 between 10 a.m. and 5 p.m. weekdays, except 
Federal holidays, In addition, the FAA is maintaining an information 
docket of comments in the Transport Airplane Directorate (ANM-100), 
Federal Aviation Administration, Northwest Mountain Region, 1601 Lind 
Avenue SW., Renton, WA 98055-4056. Comments in the information docket 
may be examined between 7:30 a.m. and 4 p.m. weekdays, except Federal 
holidays.

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

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed action by submitting such written data, views, or arguments as 
they may desire. Comments relating to the environmental, energy, 
federalism, or economic impact that might result from adopting the 
proposals in this document are also invited. Substantive comments 
should be accompanied by cost estimates. Comments must identify the 
regulatory docket or notice number and be submitted in duplicate to the 
DOT Rules Docket address specified above.
    All comments received, as well as a report summarizing each 
substantive public contact with FAA personnel concerning this proposed 
rulemaking, will be filed in the docket. The docket is available for 
public inspection before and after the comment closing date.
    All comments received on or before the closing date will be 
considered by the Administrator before taking action on this proposed 
rulemaking. Comments filed late will be considered as far as possible 
without incurring expense or delay. The proposals in this document may 
be changed in light of the comments received.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this document must include a pre-addressed, 
stamped postcard with those comments on which the following statement 
is made: ``Comments to Docket No. FAA-2000-7909.'' The postcard will be 
date stamped and mailed to the commenter.

Availability of NPRMs

    An electronic copy of this document may be downloaded using a modem 
and suitable communications software from the FAA regulations section 
of the Fedworld electronic bulletin board service (telephone: 703-321-
3339), or the Government Printing Office's (GPO) electronic bulletin 
board service (telephone: 202-512-1661).
    Internet users may reach the FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the GPO's web page at http://www.access.gpo.gov/nara for access to recently published rulemaking 
documents.
    Any person may obtain a copy of this document 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. Communications must identify the notice number 
or docket number of this NPRM.
    Persons interested in being placed on the mailing list for future 
rulemaking documents should request from the above office a copy of 
Advisory Circular No. 11-2A, Notice of Proposed Rulemaking Distribution 
System, which describes the application procedure.

Background

    Insulation is installed, typically behind airplane interior panels, 
in order to protect the occupants, cargo, and equipment of an airplane 
from thermal and acoustic extremes associated with environmental 
conditions and engine noise sources. This insulation is typically 
located in the passenger or cargo compartments of an airplane, although 
it may be located in any other compartment where insulation may be 
desired.
    Insulation is usually constructed in the form of what is commonly 
referred to as a ``blanket.'' These insulation blankets are typically 
composed of: (1) A batting, of a material generically referred to as 
fiberglass (or glass fiber, or glass wool, with Owens Corning's 
Fiberglas being one example); and (2) a film covering to 
contain the batting and to resist moisture penetration, usually 
metalized or non-metalized polyethylene terephthalate (PET), with 
DuPont's Mylar being one example, or metalized polyvinyl 
fluoride (PVF), with DuPont's Tedlar being one example. 
Another type of film, used on certain specific airplanes, is polyimide. 
It should be noted that, irrespective of the type of film, there are 
variations associated with its assembly for manufacture that result in 
differences in performance from a fire safety standpoint. These 
variations include the density of the film, the type and fineness of 
the scrim bonded to the film, and the adhesive used to bond the scrim

[[Page 56993]]

to the film. The scrim is usually constructed of either nylon or 
polyester and is bonded to the backside of the film to add shape and 
strength to the surface area. The scrim resembles a screen, and the 
mesh can vary in fineness. The type of adhesive used to bond the scrim 
to the film also varies. Adhesive is frequently the repository of any 
fire retardant in the assembled sheet.

Current Regulations Pertinent to Thermal/Acoustic Insulation 
Materials

    The current regulations pertaining to thermal/acoustic insulation 
address neither the thermal nor acoustic performance aspects, but 
rather the materials' tendency to propagate flame. The intent of the 
requirement is to ensure that insulation materials do not represent a 
significant fuel source in the event of a fire, or provide a medium for 
a fire to spread inside the airplane. The existing FAA regulations have 
focused on ensuring that insulation blankets comply with the basic 
``Bunsen burner'' flammability requirements described below.
    In addition to performing their originally intended functions, 
thermal/acoustic blankets have also been shown to delay what is termed 
fuselage burnthrough. (Fuselage burnthrough refers to the penetration 
of a post-crash external fire through the fuselage skin and insulation 
into an interior compartment.) This delay of burnthrough serves to 
increase the time available for occupants to evacuate an airplane. 
However, this valuable attribute, which is believed to be a 
characteristic inherent to some degree in all existing insulation 
blankets, has not been addressed or required in the regulations.
    The FAA has adopted a number of regulations that address 
flammability concerns on airplanes. The current flammability 
requirements pertinent to discussions in this notice are as follows:
    Section 25.853(a), ``Compartment interiors,'' requires that 
materials in compartments occupied by crew or passengers must meet the 
applicable test criteria of part I of appendix F to 14 CFR part 25.
    Section 25.855(d), ``Cargo or baggage compartments,'' requires that 
for cargo and baggage compartments not occupied by crew or passengers, 
materials used in the construction of said compartments must meet the 
applicable test criteria of part I of appendix F to part 25.
    The applicable test criteria referenced in the requirements listed 
above are defined in paragraph (a)(1)(ii) of part I of appendix F to 
part 25, and prescribe that insulation materials must be self-
extinguishing after having been subjected to the flame of a Bunsen 
burner for 12 seconds, in accordance with the procedures defined in 
paragraph (b)(4) of part I of appendix F. The average burn length may 
not exceed 8 inches, and the average flame time after removal of the 
flame source may not exceed 15 seconds. Drippings from the test 
specimen may not continue to flame for more than an average of 5 
seconds after falling. These criteria were adopted in 1972 and are 
those in use today. The purpose of these test criteria is to ensure 
that materials be self-extinguishing when exposed to likely ignition 
sources under actual conditions. Based on the service record at the 
time these criteria were adopted, these criteria appeared to provide 
the level of protection intended.
    Section 91.613, ``Materials for compartment interiors,'' requires 
that airplanes certificated in accordance with SFAR No. 41, with a 
maximum certificated takeoff weight in excess of 12,500 pounds, comply 
within 1 year of issuance of the airworthiness certificate with the 
requirements of Secs. 25.853(a), (b), (b-1), (b-2), and (b-3), in 
effect on September 26, 1978.
    Section 121.312(c), ``All interior materials, airplanes type 
certificated in accordance with SFAR No. 41 of 14 CFR part 21,'' 
requires that affected airplanes with a maximum certificated takeoff 
weight in excess of 12,500 pounds must have interior materials that 
comply with Sec. 25.853(a), in effect on March 6, 1995 (formerly 
Sec. 25.853(a), (b), (b-1), (b-2), and (b-3) in effect on September 26, 
1978). Section 121.312(d), ``All interior materials; other airplanes,'' 
requires that materials must comply with the applicable requirements 
under which the airplane was type certificated.
    Section 125.113(a)(1) & (2), ``Cabin interiors,'' requires that 
upon the first major overhaul of an airplane cabin or refurbishing of 
the cabin interior, all materials in each compartment used by the crew 
or passengers that do not meet the following requirements must be 
replaced with materials that meet these requirements: Sec. 25.853 in 
effect on April 30, 1972, for airplanes for which the type certificate 
application was filed prior to May 1, 1972; and the materials 
requirement under which the airplane was type certificated for 
airplanes for which the type certificate application was filed on or 
after May 1, 1972.
    Section 135.170, ``Materials for compartment interiors,'' 
specifically applies to airplanes that conform to an amended or 
supplemental type certificate issued in accordance with SFAR No. 41 for 
a maximum certificated takeoff weight in excess of 12,500 pounds. 
Paragraph (a) of this section requires that, one year after issuance of 
the initial airworthiness certificate issued in accordance with SFAR 
No. 41, the airplane must meet the compartment interior requirements 
set forth in Sec. 25.853(a) in effect on March 6, 1995 [formerly 
Sec. 25.853(a), (b), (b-1), (b-2), and (b-3) in effect on September 26, 
1978]. This section also requires certain additional airworthiness 
requirements concerning the use of particular materials for various 
cabin interior components on airplanes other than commuter category 
airplanes and airplanes certificated under SFAR No. 41.

Incidents Involving Insulation Materials

    The FAA is aware of at least six events in which the flammability 
characteristics of thermal/acoustic insulation material may have been a 
contributing factor. In November of 1993, a fire occurred in a 
McDonnell Douglas MD-87 airplane while it was taxiing in from a landing 
at Copenhagen, Denmark. The fire was found to have been initiated by an 
electrical fault behind a sidewall, but investigators later determined 
that the insulation materials contributed to the propagation of the 
fire. In November of 1995, a cabin fire occurred in a McDonnell Douglas 
MD-82 airplane prior to takeoff at Turin, Italy. The cause of the fire 
was attributed to a ruptured lighting ballast. In that case, other 
interior materials played a more significant role in propagating the 
fire, but there was evidence that the fire also propagated on the film 
of the insulation.
    In June of 1996, the FAA received a letter from the Civil Aviation 
Authority of China (CAAC), which described three incidents of interior 
fires that occurred in China in 1994 and 1995. Those incidents involved 
McDonnell Douglas and Boeing airplanes and were caused by electrical 
problems or inappropriate maintenance actions. In each of those cases, 
physical damage to the airplane was minimal, but there was clear 
evidence that the fires had propagated on the insulation.
    The FAA had been doing research to develop a new standard and had 
issued several reports on evaluations of test methods. The FAA 
initiated investigations and research, described later in this notice, 
to determine the appropriateness of applying existing Bunsen burner 
flammability criteria to thermal/acoustic insulation, as typically 
installed in concealed and inaccessible areas, and to develop more 
suitable criteria if considered necessary.

[[Page 56994]]

    On September 2, 1998, an MD-11 airplane experienced a catastrophic 
accident as the result of an inflight fire. Although the cause of the 
accident has not been determined, the FAA considers that it is likely 
that the fire spread on the thermal/acoustic insulation, and has 
published proposed airworthiness directives to address the affected 
material (64 FR 43966, August 12, 1999). Those airworthiness directives 
are applicable to certain model DC-9-80 (MD-80), MD-90, DC-10-30/30F, 
and MD-11/11F airplanes and require removal of the worst performing 
material (metalized Mylar).

Fire Safety Research--General

    The FAA has adopted an aggressive program to improve airplane fire 
safety. As a result, stringent new test methods were adopted that 
significantly upgraded the flammability standards for airplane 
materials associated with seat cushions, large interior panels, cargo 
compartment liners, and fire detection and suppression equipment for 
the majority of cargo compartments in the fleet. In order to maximize 
the safety benefit, the most significant areas were addressed first, 
with subsequent rulemaking addressing additional areas according to 
their relative priority in fire safety.
    Those improvements addressed what the FAA considered to be the most 
significant areas of airplane interiors, from a flammability 
standpoint, and provided improved design requirements for new 
airplanes, as well as upgraded requirements for the existing fleet. All 
of these improvements were supported by research conducted, for the 
most part, at the FAA William J. Hughes Technical Center.

Fire Safety Research--Thermal/Acoustic Insulation Materials

    As an initial response to the incidents described above, the FAA 
conducted a review of both the part 25, appendix F, required test 
method, and a test method used by certain segments of the industry to 
assess the flammability of thermal/acoustic insulation. That test 
method involves the use of alcohol-soaked cotton swabs that are ignited 
and then placed on a 16-  x  24-inch sample of insulation material. 
Tests utilizing this method were conducted at the FAA Technical Center 
in 1997, and at other test facilities around the world. (Ref. FAA 
Report DOT/FAA/AR-97/58, ``Evaluation of Fire Test Methods for Aircraft 
Thermal Acoustical Insulation,'' dated September 1997, a copy of which 
is available in the docket for this rulemaking.) This multi-facility 
test program showed that the ``cotton-swab'' test did provide better 
discrimination among materials than did the existing Bunsen burner 
certification test method.
    During 1997 and 1998, the Aerospace Industries Association (AIA) 
conducted additional testing at the FAA Technical Center, using a full-
scale fuselage frame section. The purpose of these tests was to 
determine whether the cotton-swab test method was an adequate 
certification test method. The results of these tests showed that there 
were materials that could pass the cotton-swab test but would still 
propagate a flame in a large-scale environment. In addition, because 
the ignition source used was limited to a large cotton swab, the test 
did not simulate other sources of ignition, specifically any other 
burning material or electrical arcing. Based on these results, the FAA 
concluded that there was no effective test method that represented 
material behavior under full-scale test conditions. It was determined 
that a new test method was required.
    Thermal/acoustic insulation impacts fire safety in two ways. First, 
due to its concealed location behind interior panels, if not 
sufficiently fire resistant it can provide a path for undetected fire 
propagation. As noted earlier, the current certification test requires 
that these materials be self-extinguishing after exposure to a Bunsen 
burner flame. Second, the insulation blankets can provide protection 
against fuselage burnthrough.
    The FAA has been studying fuselage burnthrough since the late 
1980's and has determined that by improving thermal/acoustic 
insulation, the time before an external fire penetrates the fuselage 
can be extended. In conjunction with the Civil Aviation Authority (CAA) 
of the United Kingdom (UK), and the Direction Generale de l'Aviation 
Civile (DGAC) of France, research was undertaken to assess the current 
capability of airplane fuselages to resist burnthrough from an external 
fuel fire. That research demonstrated the importance of thermal/
acoustic insulation in the burnthrough process and is documented in the 
following reports: ``Fuselage Burnthrough from Large Exterior Fuel 
Fires,'' Federal Aviation Administration final report DOT/FAA/CT-90/10, 
July 1994; ``Full-Scale Test Evaluation of Aircraft Fuel Fire 
Burnthrough Resistance Improvements,'' Federal Aviation Administration 
report DOT/FAA/AR-98/52, January 1999; and ``Burnthrough Resistance of 
Fuselages: Further Investigation,'' CAA Paper 95003, Civil Aviation 
Authority, London 1995. (A copy of each report is in the docket for 
this rulemaking.) Findings as a result of that research indicate that 
without making any other change to the airplane, improved thermal/
acoustic insulation can delay the entry of a post-crash fuel fire by 
several minutes, thus prolonging the time available for escape. 
Conversely, the absence of thermal/acoustic insulation can allow 
earlier entry of a fire into the airplane. Although there are other 
factors that affect fuselage burnthrough (e.g., fuselage skin and floor 
panel characteristics, ventilation systems, etc.), research 
demonstrated that the simplest and most effective approach to improving 
burnthrough resistance was to improve the fire resistance of the 
insulation.
    In the course of carrying out this research, a medium-scale test 
method that could be correlated with full-scale testing was developed 
in the UK. This test method was valuable in reducing the number of 
full-scale tests required to establish baseline data, but the size and 
complexity of the apparatus made it impractical for regulatory 
purposes. Consequently, smaller-scale testing, using a modified 
apparatus of the type currently used for certification testing of seat 
cushions and cargo compartment liners, was developed in France. This 
work was coordinated with the International Aircraft Materials Fire 
Test Working Group (IAMFTWG). 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 
participative technical peer group that contributes to FAA research, 
but its activities are not regulatory in nature.
    In July of 1997, the FAA determined that the separate investigative 
work on burnthrough and on flame propagation should be combined, with 
the aim of producing a single test method. The reason for this decision 
was to maximize the benefit from any requirements that resulted from 
the test method. However, during the test development period, it became 
clear that a single test was not practical. This is because the two 
phenomena are distinctly different, and performance in one area does 
not predict performance in the other. Therefore, the FAA has developed 
two tests, which are discussed below. (These tests are documented in 
draft FAA Report DOT/FAA/AR-99/44, ``Development of Improved 
Flammability Criteria for Aircraft Thermal/Acoustic Insulation,''

[[Page 56995]]

a copy of which will be placed in the docket when finalized. 
Additionally, Internet users may access the FAA Technical Center's web 
page at http://www.fire.tc.faa.gov for additional research relating to 
the test methods.)

Flame Propagation

    In order to address the issue of fire propagation, the FAA 
conducted a series of small, medium, and full-scale tests with various 
insulation materials. These tests identified various characteristics of 
these materials that were significant as to whether or not the 
materials would spread a fire from an otherwise small ignition source. 
In particular, the FAA found that a piloted controlled ignition under 
conditions of radiant heat tends to predict the materials' performance 
in a full-scale fire. The influence of these characteristics is further 
dependent on the fire threat, and much of the FAA's work was aimed at 
identifying a realistic threat.
    In conducting small-scale tests, the FAA found that many of the 
materials currently used tend to shrink or, in some cases, melt away 
from a flame faster than the flame can propagate on the material. That 
is, the mechanical properties of the material tend to dominate its 
combustion properties. However, the FAA also found that the same 
materials could behave differently if they were pre-heated, such as 
might occur in a confined space. In that case, some materials that 
self-extinguish when tested as a small test specimen at room 
temperature exhibit flame propagation tendencies that suggest the 
potential to grow into a large fire. The size of the ignition source 
and degree to which heat can be trapped determine whether the material 
will exhibit this behavior. If the ignition source is large enough, and 
the space confined, even highly fire-resistant materials will propagate 
a fire. However, confined spaces and potential ignition sources of 
varying sizes exist throughout the airplane.
    The FAA has adapted 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 was developed to qualify flooring, but lends 
itself very effectively to insulation materials. (A copy of the ASTM 
test method is in the public docket for this rulemaking.) The FAA has 
developed a calibration method that will impose representative heat 
flux, as derived from full-scale tests, on the insulation materials. 
This test is considered to represent a realistic fire threat, and at 
the same time imposes reasonable success criteria, considering the 
state-of-the-art of insulation materials. The tests conducted by the 
FAA to qualify this standard indicate that some of the materials 
currently used will pass the new standard. This method is described in 
detail in proposed part VI to appendix F of part 25.

Burnthrough

    This test method involves use of a kerosene burner apparatus, 
modified slightly from its configuration as used in other certification 
testing, 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 frames 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 itself. This test 
method is described in detail in proposed part VII to appendix F of 
part 25.

Discussion of the Proposal

    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, the FAA considers that 
increased protection against external fire penetrating the fuselage can 
be provided by proper selection of the same material. The FAA considers 
that the new test methods described earlier would not only provide for 
increased in-flight fire safety, by reducing the flammability of 
thermal/acoustic insulation blankets, but would also provide increased 
time for evacuation during externally fed, post-crash fires by 
increasing fuselage burnthrough resistance. The FAA therefore proposes 
to amend the current regulations as follows:

Proposed Part 25 Requirements

    The FAA proposes to adopt the new test methods described earlier as 
new part VI and part VII requirements to appendix F. One aspect of the 
proposed requirements is a test to measure the propensity of the 
insulation to spread a fire. This test method is specified in proposed 
part VI to appendix F. The second aspect of the proposal is a test to 
measure the fire penetration resistance of the insulation, and is 
specified in proposed part VII to appendix F. The proposed requirements 
are new flammability test standards that would be applied to thermal/
acoustic insulation in lieu of the current standard.
    In addition, in view of the fact that current flammability 
requirements focus almost exclusively on materials located in occupied 
compartments (Sec. 25.853) and cargo compartments (Sec. 25.855), this 
proposal includes the adoption of a new Sec. 25.856, which would 
address thermal/acoustic insulation materials wherever installed. This 
aspect of the proposal recognizes the role that thermal/acoustic 
insulation in other areas may have in either flame propagation and/or 
fuselage burnthrough protection, and would subject the thermal/acoustic 
materials in those compartments to the proposed flammability standards.
    In accordance with Sec. 21.17, these new standards would apply to 
new type certificates for which application is made after the effective 
date of the final rule.

Flame Propagation

    The FAA proposes a new standard to address flame propagation of 
thermal/acoustic insulation, regardless of where it is installed in the 
airplane. The current flammability requirements focus almost 
exclusively on materials located in occupied compartments (Sec. 25.853) 
and cargo compartments (Sec. 25.855). However, the FAA considers that 
the potential for an inflight fire is not limited to those specific 
compartments. Thermal/acoustic insulation is installed throughout the 
airplane in other areas, such as electrical/electronic (E/E) 
compartments or surrounding air ducts, where there is the potential for 
materials to spread a fire as well. By applying the standards only to 
certain compartments, the intended safety benefit would not be realized 
for materials installed in other areas of the airplane. The proposal 
would therefore account for insulation installed in areas such as 
equipment bays and wrapped around ducts that might not otherwise be 
considered within a specific compartment. The flame propagation 
provisions of this proposal would apply to all transport category 
airplanes, regardless of size or passenger capacity, since the 
consequences of an inflight fire are not related to those factors.

Burnthrough

    Lower Half: The FAA has considered whether to make the burnthrough 
requirement applicable to only certain areas of the fuselage; that is, 
those areas considered to be most susceptible to penetration by an 
external fire. The lower portion of the fuselage is the most 
susceptible to burnthrough from an external fuel fire because flames 
from

[[Page 56996]]

such a fire would typically impinge on the fuselage from below. 
Therefore, the lower portion would derive the most benefit from 
enhanced burnthrough protection. Although the additional costs 
associated with providing this same protection to the remainder of the 
airplane are not great, the benefits would be negligible. Therefore, 
the proposed requirement for burnthrough protection would apply only to 
insulation materials installed in the lower half of the fuselage. It 
should be noted that the ``lower half'' is above the cabin floor for 
most airplanes. This point was chosen based on full-scale fire test 
data, as documented in the previously referenced reports, and the 
potential for the airplane to be off its landing gear. That is, in 
conditions of landing gear collapse, the 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, this situation is also accounted for.
    Applicability: The FAA considers that the requirement for 
burnthrough protection should be made applicable 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 it is expected that enhanced burnthrough protection will 
impose additional cost, there must be a commensurate benefit to justify 
such a proposal. The FAA does not consider that such benefits are 
substantial for airplanes with low passenger capacities. The specific 
discriminant of 20 passengers was chosen to be consistent with other 
occupant safety regulations, such as those for interior materials and 
cabin aisle width. The FAA considers that the evacuation capability of 
airplanes with 20 or more passengers, regardless of the exit 
arrangement, could be improved by enhanced burnthrough protection. The 
FAA invites comments on this aspect of the proposal.
    Installation Details: For new designs, the proposed new burnthrough 
test method would apply 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 would have to be accounted for when performing tests. 
For consistency, the test method would impose a standard methodology 
for fastening. In addition to this proposal, the FAA is 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, it is proposed that fastening 
means be considered for newly manufactured airplanes.
    Fuselage Burnthrough Alternative: This proposed rule would 
establish a standard for thermal/acoustic insulation that addresses 
that material's ability to resist penetration of an external flame, 
rather than a rule 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 notice proposes a simple standard that has been shown to 
increase 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 since this 
proposal would revise the standard for insulation to address flame 
propagation anyway, it is in the public interest to incorporate 
criteria that enhance the overall level of safety and that can be 
achieved with reasonable cost. Therefore, the standards proposed in 
this notice address two aspects of fire safety related to insulation 
material.
    Although this proposal does not require that insulation be 
installed, it would enhance the overall level of safety of the airplane 
when insulation is installed. Because of the need to provide a suitable 
thermal and acoustical environment inside the airplane, the FAA 
considers it extremely unlikely that insulation would be removed as a 
means to avoid compliance with this rule. In fact, the removal of 
insulation material was considered as an option to address the flame 
propagation issues, but was rejected since it would effectively 
diminish the burnthrough capability that currently exists. Should 
removal of insulation become a common practice, the FAA will revisit 
the need for a specific fuselage burnthrough standard.

Equivalency (Applies to Both Burnthrough and Flame Propagation)

    The proposed changes to appendix F include a provision for FAA-
approved equivalent methods. This provision, which is included in other 
parts of appendix F, is intended to allow for the incorporation of 
improvements to the test methods as 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 IAMFTWG and are readily adopted by the industry. It should be 
noted that the proposed standards of appendix F constitute the basic 
requirement, and that such equivalent methods that might be developed 
would have to be adopted in total. It would not be acceptable to 
selectively adopt portions of a modified test method that has been 
found to be equivalent and not all of the modified method. The 
determination of an acceptable equivalent method would be made by the 
FAA.

Proposed Operating Requirements

    In addition to changing the design standards for future type 
certificate applications, the FAA considers 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. The FAA's 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 
proposed for the existing fleet relate to materials that are replaced 
in service. This latter aspect of the proposal would

[[Page 56997]]

not affect newly manufactured airplanes, since they would already be 
required to comply by virtue of their date of manufacture.

Flame Propagation

    New Production: The FAA proposes that newly manufactured airplanes 
entering the fleet in parts 91, 121, 125, and 135 service be required 
to comply with the new standards relative to flame propagation. Since 
there are materials currently available that will meet the proposed 
standards, this requirement would impose minimal additional costs. This 
requirement would apply 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 disposition of existing inventory.
    It should be noted that this proposal differs from previous 
rulemaking related to flammability of materials in that the 
applicability to newly manufactured airplanes is not limited to 
operations under part 121. However, in this case the proposal would 
effectively add no cost, and the potential for an inflight fire is not 
limited to air carrier operations. The FAA invites comments on this 
aspect of the proposal.
    Replacement: Amendments to parts 91, 121, 125, and 135 are proposed 
to require that insulation materials, when installed as replacements, 
meet the new flame propagation test requirements of Sec. 25.856. This 
proposal would provide for the gradual attrition of earlier materials. 
Since there are existing materials that meet the proposed standards, 
and since those materials cost and weigh no more than other materials, 
this should result in no 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 
proposal would enhance safety over the current regulatory requirements, 
and can be done at no cost. The language in proposed changes to part 
121 differs from that in other parts to make it clear that the 
replacement aspect of this proposal does not in any way provide relief 
from the basic requirements for newly manufactured airplanes. As 
discussed below, part 121 differs from other parts in that airplanes 
manufactured after a specified date (four years after the effective 
date of the final rule) would have to comply with the burnthrough 
protection standard, as well as the flame propagation standard, and 
these requirements would also apply to replacement materials 
subsequently installed in those airplanes. To avoid possible confusion, 
the requirement for replacement materials to comply only with the flame 
propagation standard would apply to airplanes manufactured before the 
specified date.
    Although it is difficult to quantify the benefits of piecemeal 
replacement of materials, in this case the benefit is without cost and 
adds no burden. In order to allow for attrition of current inventories 
and acquisition of the new materials, the FAA is proposing a 2-year 
compliance time, after which insulation materials that are replaced 
would have to be replaced with materials meeting the new flame 
propagation standards. This requirement is expected to apply to a 
relatively small amount of materials that are replaced every year. As 
with newly manufactured airplanes, two years is considered sufficient 
time to allow for material production capacity to be developed and 
disposition of existing inventory.

Burnthrough Protection

    New Production: The FAA also proposes that newly manufactured 
airplanes entering the fleet in part 121 operations be required to 
comply with the new standards relative to burnthrough protection. This 
requirement would apply to airplanes manufactured more than 4 years 
after the effective date of the final rule. Although there are 
materials currently available that will meet the proposed standards, 
these materials are not widely used. Therefore, the burnthrough portion 
of the proposal is expected to require both material and, in many 
cases, design changes to implement. As discussed in the context of the 
proposed 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, the FAA recognizes that adequate 
time is necessary to perform the necessary engineering and to obtain 
approval for the changes. Four years is considered 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, the FAA considers 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 not be cost effective. 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 would comply, in order to 
account for potential future part 121 operations. The FAA invites 
comments on this aspect of the proposal.
    Replacement: This proposal does not include a requirement to use 
materials complying with the burnthrough test standards because the FAA 
considers that such a requirement would not be cost effective. 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 not be cost 
effective.

Date of Manufacture

    For the purposes of this proposal, the date of manufacture is 
considered 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 Amendment 121-247, Improved Flammability Standards for 
Materials Used in the Interiors of Transport Category Airplanes, (60 FR 
6616), Sec. 121.312 and Sec. 121.343, Flight recorders.

[[Page 56998]]

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1995 (44 U.S.C 
3507(d)), the FAA has determined that there are no requirements for 
information collection associated with this proposed 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. The FAA has 
determined that there are no ICAO Standards and Recommended Practices 
that correspond to these proposed regulations.

Regulatory Evaluation Summary

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs that each Federal agency 
shall propose or adopt a regulation only upon a reasoned determination 
that the benefits of the intended regulation justify its costs. Second, 
the Regulatory Flexibility Act of 1980 requires agencies to analyze the 
economic effect of regulatory changes on small entities. Third, the 
Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires each 
Federal agency 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, or tribal governments, in the 
aggregate, or by private sector, of $100 million or more annually 
(adjusted for inflation). These analyses have been completed, are 
summarized below, and fully discussed in the full regulatory 
evaluation. The FAA invites the public to provide comments and 
supporting data on the assumptions made in this evaluation. All 
comments received will be considered in the final regulatory 
evaluation.

Costs of Proposed Rule

    Testing results at the FAA's Technical Center show that insulation 
materials are commercially available that will meet the FAA's proposed 
requirements for both flame propagation and burnthrough. The estimates 
presented below are preliminary and may overstate the actual material 
costs to affected operators, because other, less expensive materials 
may be developed as the proposed tests become known. The FAA solicits 
information from manufacturers, air carriers, and insulation blanket 
manufacturers to refine these estimates.

Insulation Material Unit Costs and Weights

    Insulation material costs are a function of the size of the 
airplane and its thermal and acoustical needs, which, in turn, depend 
on the configuration of the airplane, its performance characteristics, 
and its utilization. Based on dimensional, material weight, and cost 
information received from airplane manufacturers, air carriers, and 
insulation blanket manufacturers, and the results of testing by the 
FAA's Technical Center, the FAA has determined that some materials that 
would meet the proposed test requirements cost and weigh no more than 
materials currently being installed in newly-produced airplanes. 
Because the proposed rule would apply to newly-produced airplanes 
(i.e., no airplanes would be removed from service for retrofit), only 
the incremental costs of these improved blankets and engineering costs 
to effect any design changes are attributable to the rule.
    The FAA estimates that insulation blankets currently installed in 
transport category airplanes are composed of an average of 3 inches of 
fiberglass batting covered with a film. Under the proposed requirements 
for affected part 121 airplanes with 20 or more passenger seats, the 
FAA assumes that the blankets in the lower half of the fuselage would 
be composed of an average of 2 inches of fiberglass batting and 1 inch 
of Curlon batting (a material that would meet the proposed 
requirements for burnthrough protection), and the blankets in the upper 
half would be composed of an average of 3 inches of fiberglass. 
Blankets would be enclosed in metalized PVF, a film shown to meet the 
proposed flame propagation requirements. Airplanes with fewer than 20 
passenger seats would continue to have an average of 3 inches of 
fiberglass batting covered with metalized PVF film.
    Other materials may also be used, but these may be more expensive 
or add substantial weight to the blankets. The FAA solicits information 
concerning the materials that would be used to comply with the proposed 
requirements.
    The FAA has determined that there would be no incremental cost (for 
either materials or weight) of installing insulation in airplanes with 
fewer than 20 passenger seats, because some materials that are 
currently used would meet the proposed requirements for flame 
propagation. For airplanes with 20 or more passengers, the additional 
cost would be that of replacing 1 inch of fiberglass with 1 inch of 
Curlon. Because Curlon and fiberglass are 
comparable in weight, there would be no weight penalty associated with 
Curlon's use.

Part 121  Airplanes Produced Between 2000 and 2019

    In order to determine the number and types of transport category 
airplanes added to the U.S. air carrier (part 121) fleet during the 
years 2000-2019, the FAA reviewed its own forecast as well as those of 
Boeing and Airbus. The FAA estimated the number of airplanes that would 
be affected by the proposed rule and manufactured between 2000 and 
2019.\1\
---------------------------------------------------------------------------

    \1\ These estimates include airplanes produced under new type 
certificates.
---------------------------------------------------------------------------

    Of the estimated 10,943 newly produced N-registered transport 
category airplanes expected to join the part 121 fleet during that 20-
year period, 8,781 would be required to have fuselage burnthrough 
protection. An estimated 2,162 newly-produced transport category 
airplanes with fewer than 20 seats would be exempt from this proposed 
requirement.
    The FAA has determined that some insulation materials that are 
currently used would meet the proposed requirements for flame 
propagation; therefore, the FAA attributes no incremental costs from 
this requirement. The total discounted cost for these 8,781 airplanes 
that would be required to have burnthrough protection over 20 years is 
$52.6 million, or $22.6 million discounted to present value at seven 
percent. The annualized cost over 20 years is $2.1 million.
    The proposed requirement for transport category airplanes operating 
under parts 91, 125, and 135 would be only for improved insulation 
meeting the proposed flame propagation standards, and the FAA has 
determined that there would be no incremental costs from this 
requirement.

Engineering Costs

    Manufacturers would incur costs of changing installation drawings 
and production part numbers for the new insulation blankets of newly 
produced currently certificated airplanes.\2\ Estimates of the time to 
accomplish these changes are a function of the size of the airplane and 
whether or not the blanket configuration would have to be changed. The 
process of accomplishing these tasks would involve a series of steps, 
including changing the drawings (part numbers and, when necessary, 
blanket configurations) and reviews and

[[Page 56999]]

approvals by various groups (e.g., engineering, weight and balance, 
stress groups).
---------------------------------------------------------------------------

    \2\ There would be no costs attributable to the proposed rule 
for airplanes of new type designs, because these engineering costs 
are for changes to drawings.
---------------------------------------------------------------------------

    The FAA estimates that there would be 15 models of currently 
certificated airplanes in operation under part 121 at the time the 
proposed rule would be effective. (The FAA assumes there would be six 
models of two-engine narrowbody airplanes, six models of two-engine 
widebody airplanes, two of which would be cargo models, and three 
models of four-engine widebody airplanes.) The FAA estimates the 
burdened hourly rate for an engineer is $130. If only blanket materials 
change, the FAA estimates costs would total $13.8 million. If both 
blanket materials and their configurations change, the estimated costs 
would be $48.9 million. These costs would occur in the first 2 years 
after the effective date of the rule. Discounted costs, assuming half 
the cost would be incurred in 2000 and half in 2001, would range from 
$12.5 million to $44.2 million. The FAA solicits information concerning 
the engineering costs to part 121 airplane manufacturers, including 
information concerning the need for blanket configuration changes.
    Because airplane models operated under part 125 are typically the 
same airplane models that are operated under part 121, there would be 
no additional engineering costs to those models. Manufacturers of other 
transport category airplanes, that is, those operating under parts 91 
or 135, would also incur engineering costs. The FAA estimates these 
costs to be $750,000, or $678,000 discounted to present value.

Testing Equipment

    Manufacturers of insulation blankets or blanket components would 
incur costs to test blankets or blanket components. Two tests are 
proposed: a flame propagation test and a burnthrough test.
    The flame propagation test (also called the critical radiant flux 
test) is based on a test method developed for floor-covering systems, 
Standard Test Method ASTM E 648 for Critical Radiant Flux of Floor-
Covering Systems using a Radiant Head Energy Source. The FAA's 
Technical Center has modified the test method for purposes of measuring 
flame propagation on insulation materials. A rig that is used for ASTM 
E 648 testing costs about $50,000. The FAA expects that airplane 
manufacturers, insulation blanket fabricators, and chemical company 
manufacturers would purchase or construct 12 of these modified rigs. 
The costs, therefore, would be $720,000. The FAA assumes that these 
costs would be incurred in the first year of the rule. Based on the 
assumption that the proposed rule would become effective in the year 
2000, the costs of flame propagation testing equipment would be 
$673,000 discounted to present value.
    The proposed burnthrough test was developed through the joint 
sponsorship of the FAA, the Civil Aviation Authority of the United 
Kingdom (UK), and the Direction Generale de l'Aviation Civile (DGAC) of 
France, with the FAA's Technical Center providing the test 
standardization. The equipment would include a gun-type test burner 
that uses kerosene for a fuel source and various components that 
measure heat flux, temperature, air velocity, and time. The test rig 
would be provided with an exhaust system to remove combustion products. 
The FAA estimates that the test apparatus would cost about $10,000. 
Again, the FAA expects that airplane manufacturers, insulation blanket 
fabricators, and chemical companies would purchase 12 rigs. The costs, 
therefore, would be $120,000 for 12 rigs, or $112,000 discounted to 
present value.
    Manufacturers currently have facilities and personnel that conduct 
blanket certification testing; therefore, the FAA has attributed no 
other costs to testing materials.

Total Costs of the Proposed Rule

    If only blanket material changes are made, the total costs over the 
years 2000-2019 are $68.0 million, or $36.5 million discounted to 
present value. Improved insulation costs account for about 77 percent 
of total nondiscounted costs, while engineering costs account for 21 
percent and testing equipment accounts for 1 percent.
    If manufacturers need to make configuration changes as well as 
material changes to their drawings, the FAA estimates that total costs 
would be $103.1 million over the years 2000-2019, or $68.2 million 
discounted to present value. In this scenario, engineering costs 
account for 51 percent of total nondiscounted costs, improved 
insulation costs account for 48 percent, and testing equipment accounts 
for 1 percent.
    In both scenarios, the greatest costs would be incurred during the 
first 2 years after the effective date, when airplane and insulation 
blanket manufacturers and testing labs would incur costs. On a per 
airplane basis, the costs would average between $6,200 and $9,400, 
depending on whether or not configuration changes were needed.

Benefits of the Proposed Rule

    On September 2, 1998, Swissair Flight 111 crashed off the coast of 
Nova Scotia, Canada, with a loss of 229 lives.
    Although the Transportation Safety Board of Canada has not released 
its report of the probable causes of the Swissair accident, preliminary 
evidence points to burning thermal/acoustical insulation above the 
cockpit ceiling as contributing to the crash. The airplane, a McDonnell 
Douglas MD-11, used insulation blankets composed of fiberglass covered 
with metalized Mylar. The FAA considers that replacement of 
metalized Mylar may be necessary and is proceeding to address 
the affected material by airworthiness directive.
    There have been other reports of fires in which the flammability of 
the thermal/acoustical insulation was a contributing factor. These 
accidents and incidents indicate that the flammability of the thermal/
acoustic insulation can be a significant factor in contributing to the 
spread of a fire, either inflight or after a crash. The proposed rule 
would reduce those threats by requiring newly produced airplanes to use 
improved insulation that passes the proposed requirements for flame 
propagation and fuselage burnthrough.
    The FAA, in conjunction with the CAA-UK and the DGAC of France, 
conducted research to assess the current capability of airplane 
fuselages to resist burnthrough from an external fuel fire. That 
research demonstrated the importance of thermal/acoustic insulation in 
the burnthrough process. Without making any other change to the 
airplane, these studies showed that improved thermal/acoustic 
insulation can delay the entry of a post-crash fuel fire by several 
minutes, thus prolonging the time available for escape. Although there 
are other factors that affect fuselage burnthrough, it was demonstrated 
that the simplest and most effective approach to improving burnthrough 
resistance was to improve the fire resistance of the insulation.
    A study by R.G.W. Cherry & Associates Limited examined the 
International Cabin Safety Research Technical Group's Survivable 
Accidents Database to identify and extract data for airplane accidents 
where fuselage burnthrough was an issue in the survivability of the 
occupants. A burnthrough accident was defined as: ``An aircraft 
accident where the fuselage skin was penetrated by an external fire 
while live occupants were on board.'' A survivable accident is one 
``where there were one or more survivors or there was potential for 
survival.'' Only survivable

[[Page 57000]]

or potentially survivable accidents in which there were fire injuries 
were selected for analysis.
    Seventeen accidents involving 2,201 occupants and occurring between 
1966 and 1993 were identified by Cherry & Associates. In analyzing 
accidents, Cherry & Associates took into account improvements that 
might have been made to numbers of fatalities and injuries if the 
airplanes had been configured to later requirements. These later 
requirements were:
     Floor proximity lighting/marking
     Seat cushion flammability
     Reduced heat release of cabin interior materials
     Improved access to type III exits
    Cherry & Associates derived benefits based on the airplane 
standards at the time of the accident and on airplanes assumed to be 
configured to later requirements. Because the proposed rule would apply 
to newly produced airplanes, the results based on later requirements 
are those used in the FAA's benefits analysis.
    Of the 140 worldwide fire related fatal accidents in the 
International Cabin Safety Research Technical Group's Survivable 
Accidents Database at the time of Cherry & Associate's study, only 54 
percent had sufficient data to assess whether burnthrough occurred. 
Assuming the accidents that did not have sufficient data have a similar 
benefit potential to those that do, the actual benefits would be 1.85 
times (1/0.54) the analyzed benefits.
    The FAA's Technical Center has determined that the burnthrough 
protection requirements of this proposed rule would provide an 
additional 4 minutes for occupants to exit an airplane. Cherry & 
Associates' analysis shows that an additional 4 minutes would result in 
10.1 lives saved per year worldwide. Because the proposed rule would 
apply only to newly produced airplanes of U.S. registry, the FAA has 
adjusted this estimate downward.
    The Cherry report states that the authors do not believe that ``* * 
* the number of fatalities and injuries will change markedly for the 
near future.'' The FAA disagrees. Based on FAA and industry forecasts, 
the number of transport category passenger airplanes in the world fleet 
is expected to grow by 109 percent over the years 2000--2019, while the 
number of airplanes in the U.S. fleet is expected to grow by 97 
percent. The number of passengers enplaned by U.S. carriers is expected 
to grow by 107 percent. Therefore, the FAA has estimated that Cherry's 
estimate of 10.1 lives saved per year would increase by about 2.157 
percent per year or by 50 percent by 2019.
    The FAA estimates that 37.2 fatalities that would have occurred on 
airplanes of U.S. registry would be avoided over 20 years by the 
proposed rule's requirement for burnthrough protection. Assuming 
society is willing to pay $2.7 million to avoid a fatality, burnthrough 
protection for the newly produced airplanes in the U.S. fleet would 
result in a nondiscounted total benefit of $100.5 million over the 20-
year period, or $37.7 million discounted to present value.
    There would also be benefits from the proposed flame propagation 
requirement. As several of the incidents and accidents reviewed for 
this analysis and described in the complete regulatory evaluation show, 
the potential for ignition from electrical arcing or other sources can 
be high. The proposed flame propagation requirements would ensure that, 
if ignition occurred, the resultant flame would not spread on the 
thermal/acoustic insulation.
    The FAA is unable to quantify these benefits. However, preventing 
the loss of one airplane and its passengers over the 20-year period is 
not unlikely. Assuming such a loss would occur at the midpoint of the 
analysis, or in 2009, with 169 passengers, the nondiscounted loss would 
be $455.5 million, or $231.5 million discounted to present value 
(again, assuming society's willingness to pay $2.7 million to avoid a 
fatality). This loss does not include the value of the airplane. Even 
without loss of life, as several of the incidents show, a hull loss 
could exceed tens of millions of dollars. The FAA therefore has 
determined that this proposed rule would be cost beneficial.

Initial Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (FRA) 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 
businesses, organizations, and governmental jurisdictions subject to 
regulation.'' To achieve that principle, the RFA requires agencies to 
solicit and consider flexible regulatory proposals and to explain the 
rationale for their actions. The RFA covers a wide-range of small 
entities, including small businesses, not-for-profit organizations, and 
small governmental jurisdictions.
    Agencies must perform a review to determine whether a 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 (RFA) as 
described in the RFA. 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 an RFA is not 
required. The certification must include a statement providing the 
factual basis for this determination, and the reasoning should be 
clear.
    The FAA conducted the required review of this proposed rule. The 
engineering costs would be incurred by manufacturers of transport 
category airplanes, none of whom is a small entity. Testing equipment 
costs would be incurred by airplane manufacturers, insulation blanket 
fabricators, and chemical companies. The FAA has determined that none 
of these entities that are expected to conduct testing is small. 
Finally, the cost of a newly produced passenger airplane outfitted with 
burnthrough protection would be greater because of the proposed rule. 
The FAA cannot determine who would purchase these airplanes, but the 
incremental cost of burnthrough protection would not exceed $11,000 (in 
a four-engine widebody), an amount that would represent an 
insignificant percentage of the total cost of a new airplane.
    Accordingly, pursuant to the Regulatory Flexibility Act, 5 U.S.C. 
605(b), the Federal Aviation Administration certifies that this 
proposed rule would not have a significant economic impact on a 
substantial number of small entities.

International Trade Impact Assessment

    The provisions of this proposed rule would have little or no impact 
on trade for U.S. firms doing business in foreign countries and foreign 
firms doing business in the United States.

Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (the Act), 
enacted as Public Law 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 1 year. 
Section 204(a) of the Act, 2 U.S.C. 1534(a), requires the Federal

[[Page 57001]]

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 1 
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 proposed rule does not contain any significant Federal 
intergovernmental or private sector mandate. Therefore, the 
requirements of Title II of the Unfunded Mandates Reform Act of 1995 do 
not apply.

Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and 
criteria of Executive Order 13132, Federalism. The FAA has determined 
that this action would 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, the FAA has determined that 
this notice of proposed rulemaking would 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 assessment or environmental impact statement. In 
accordance with FAA Order 1050.1D, appendix 4, paragraph 4(j), this 
rulemaking action qualifies for a categorical exclusion.

Energy Impact

    The energy impact of the proposed 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). It has been determined 
that it 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 proposed 
rule would apply to the certification of future designs of transport 
category airplanes and their subsequent operation, it could, if 
adopted, affect intrastate aviation in Alaska. The FAA therefore 
specifically requests comments on whether there is justification for 
applying the proposed rule differently to intrastate operations in 
Alaska.

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 Proposed Amendments

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend parts 25, 91, 121, 125, and 135 of 
Title 14 of the Code of Federal Regulations as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

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

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

    2. Amend Sec. 25.853 by revising paragraph (a) to read as follows:


Sec. 25.853  Compartment interiors.

* * * * *
    (a) Except for thermal/acoustic insulation materials, materials 
(including finishes or decorative surfaces applied to the materials) 
must meet the applicable test criteria prescribed in part I of appendix 
F of this part, or other approved equivalent methods, regardless of the 
passenger capacity of the airplane.
* * * * *
    3. Amend Sec. 25.855 by revising paragraph (d) to read as follows:


Sec. 25.855  Cargo or baggage compartments.

* * * * *
    (d) Except for thermal/acoustic insulation materials, all other 
materials used in the construction of the cargo or baggage compartment 
must meet the applicable test criteria prescribed in part I of appendix 
F of this part or other approved equivalent methods.
* * * * *
    4. Add Sec. 25.856 to read as follows:


Sec. 25.856  Insulation materials.

    Thermal/acoustic insulation material must meet the flame 
propagation test requirements of part VI of appendix F of this part, or 
other FAA-approved equivalent test requirements. In addition, for 
airplanes with a passenger capacity of 20 or greater, 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 of this part, or other FAA-approved equivalent test 
requirements.
    5. Amend appendix F to part 25 as follows:
    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.
    b. In part I, by removing and reserving paragraph (a)(2)(i).
    c. By adding parts VI and VII to read as follows:

[[Page 57002]]

Appendix F to Part 25

* * * * *

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

    This test method is used 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--(1) Thermal acoustic insulation. Thermal/
acoustic insulation is defined as a material or system of materials 
used to provide thermal and/or acoustic protection. Examples include 
a film-covering material encapsulating a core material such as 
fiberglass or other batting material and foams.
    (2) Radiant heat source. The radiant heat source is an air-gas 
fueled radiant heat energy panel or equivalent.
    (b) Test apparatus (as schematically shown in figure 1).
    [GRAPHIC] [TIFF OMITTED] TP20SE00.000
    

[[Page 57003]]


    (1) Radiant panel test chamber. Tests shall be conducted in a 
radiant panel test chamber (see figure 1). The test chamber shall be 
located under an exhaust hood to facilitate clearing the chamber of 
smoke after each test. The radiant panel test chamber shall consist 
of an enclosure 55 inches (1400 mm) long by 19.5 (500 mm) deep by 28 
(710 mm) to 30 inches (maximum) (762 mm) above the test specimen. 
The sides, ends, and top shall be insulated with a fibrous ceramic 
insulation such as Kaowool M \TM\ board. The front side shall be 
provided with an approximately 52-by 10-inch (1321 by 254mm) draft 
free, high temperature, glass observation window, to facilitate 
viewing the sample during testing. Below the window is a door, which 
provides access to the movable specimen platform holder. The bottom 
of the test chamber shall consist of a sliding steel platform, which 
has provisions for securing the test specimen holder in a fixed and 
level position. The chamber shall have an internal chimney with 
exterior dimensions of 5.1 inches (129mm) wide, by 16.2 inches (411 
mm) deep by 13 inches (330mm) high at the opposite end of the 
chamber from the radiant energy source. The interior dimensions are 
4.5 inches (114mm) wide by 15.6 inches (395mm) deep. The chimney 
extends to the top of the chamber (see figure 2).
[GRAPHIC] [TIFF OMITTED] TP20SE00.001


[[Page 57004]]


    (2) Radiant heat source. The radiant heat energy source shall be 
a panel of porous refractory material mounted in a cast iron frame 
or equivalent. The panel shall have a radiation surface of 12 by 18 
inches (305 by 457mm). The panel shall be capable of operating at 
temperatures up to 1500 deg.F (816 deg.C). See figure 3. An 
equivalent panel must satisfy the calibration conditions and produce 
test results equivalent to the air-gas panel, for any material 
tested.
[GRAPHIC] [TIFF OMITTED] TP20SE00.002

[GRAPHIC] [TIFF OMITTED] TP20SE00.003


[[Page 57005]]


    (i) Radiant panel heating system. The radiant panel fuel shall 
be propane (liquid petroleum gas--2.1 UN 1075). The panel fuel 
system shall consist of a venturi-type aspirator for mixing gas and 
air at approximately atmospheric pressure. Suitable instrumentation 
will be necessary for monitoring and controlling the flow of fuel 
and air to the panel. Instrumentation shall include an air flow 
gauge, an air flow regulator, and a gas pressure gauge.
    (ii) Radiant panel placement. The panel shall be mounted in the 
chamber at 30Sec. to the horizontal specimen plane.
    (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. A sheet of 
refractory material may be placed and supported by the lip in the 
open bottom (base) of the sliding platform for samples that do not 
require height compensation. The refractory material may be placed 
on the bottom of the brackets to hold the test specimen (for height 
requirement) if necessary. See figure 4.
[GRAPHIC] [TIFF OMITTED] TP20SE00.004


[[Page 57006]]


    (ii) A \1/2\ inch (13mm) piece of Kaowool M \TM\ board or other 
high temperature material measuring 41\1/2\ by 8\1/4\ inches (1054 
by 210mm) shall be attached to the back side of the platform. This 
board will serve as a heat retainer and will protect the test 
specimen from excessive preheating. The height of this board must 
not be too high such that it impedes the sliding platform movement 
(in and out) of the test chamber.
    (iii) The test specimen shall be placed horizontally on the 
refractory base (or brackets). A stainless steel retaining frame 
(AISI Type 300 UNA-NO8330), or equivalent, having a thickness of 
0.078 inches (1.98mm) and overall dimensions of 44 \3/4\ by 12\3/4\ 
inches (1137 by 320mm) with a specimen opening of 40 by 7\7/8\ 
inches (1016 by 140mm) shall be placed on top of the test specimen. 
The retaining frame shall have two \1/2\ inch (12.7mm) holes drilled 
at each end for positioning the frame to the two stud bolts at each 
end of the sliding platform. See figure 5.
[GRAPHIC] [TIFF OMITTED] TP20SE00.005


[[Page 57007]]


    (iv) A securing frame (acting as a clamping mechanism) 
constructed of mildsteel may be placed over the test specimen. The 
securing frame overall dimensions are 42\1/2\ by 10\1/2\ inches 
(1080 by 267mm) with a specimen opening of 39\1/2\ by 7\1/2\ inches 
(1003 by 190mm). Hence, the exposed area of test specimen exposed to 
the radiant panel is 39\1/4\ by 7\1/4\ inches (996 by 184mm). See 
figure 6. It is not necessary to physically fasten the securing 
frame over the test specimen due to the weight of the frame itself.
[GRAPHIC] [TIFF OMITTED] TP20SE00.006


[[Page 57008]]


    (4) Pilot burner. The pilot burner used to ignite the specimen 
is a Bernzomatic \TM\ commercial propane venturi torch with an 
axially symmetric burner tip having a propane supply tube with an 
orifice diameter of 0.006 inches (0.15mm). The length of the burner 
tube is 2\7/8\ inches (71mm). The propane flow is adjusted via gas 
pressure through an in-line regulator to produce a blue inner cone 
length of \3/4\ inch (19mm). A \3/4\ inch (19mm) guide (such as a 
thin strip of metal) may be spot welded to the top of the burner to 
aid in setting the flame height. There shall be a means provided to 
move the burner out of the ignition position so that the flame is 
horizontal and at least 2 inches (50mm) above the specimen plane. 
See figure 7.
[GRAPHIC] [TIFF OMITTED] TP20SE00.007

    (5) Thermocouples. A 24 American Wire Gauge (AWG) Type K 
(Chromel-Alumel) thermocouple shall be installed in the test chamber 
for temperature monitoring. It shall be inserted into the chamber 
through a small hole drilled through the back of the chamber. The 
thermocouple shall be placed such that it extends 11 inches (279mm) 
out from the back of the chamber wall, 11\1/2\ inches (292mm) from 
the right side of the chamber wall, and is 2 inches (51mm) below the 
radiant panel. The use of other thermocouples is optional.
    (6) Calorimeter. The calorimeter shall 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 5.6 Watts/
cm2).
    (7) Calorimeter calibration specification and procedure.
    (i) Calorimeter Specification.
    (A) Foil diameter shall be 0.25 0.005 inches (6.35 
0.13mm).
    (B) Foil thickness shall be 0.0005 0.0001 inches 
(0.013 0.0025mm).
    (C) Foil material shall be thermocouple grade Constantan.
    (D) Temperature measurement shall be a Copper Constantan 
thermocouple.
    (E) The copper center wire diameter shall be 0.0005 inches 
(0.013mm).
    (F) The entire face of the calorimeter shall be lightly coated 
with ``Black Velvet'' paint having an emissivity of 96 or greater.
    (ii) Calorimeter calibration.
    (A) The calibration method shall be by comparison to a like 
standardized transducer.
    (B) The standardized transducer shall meet the specification 
given in paragraph (b)(6) of this part of this appendix.
    (C) It shall be calibrated against a primary standard by the 
National Institute of Standards and Technology (NIST).
    (D) The method of transfer shall be a heated graphite plate.
    (E) The graphite plate shall be electrically heated, have a 
clear surface area on each side of the plate of at least 2 by 2 
inches (51 by 51mm), and be \1/8\ inch \1/16\ inch thick 
(3.2 1.6mm).
    (F) The 2 transducers shall be centered on opposite sides of the 
plates at equal distances from the plate.
    (G) The distance of the calorimeter to the plate shall be no 
less than 0.0625 inches (1.6mm), nor greater than 0.375 inches 
(9.5mm).
    (H) The range used in calibration shall be at least 0-3.5 BTUs/
ft 2 second (0-3.9Watts/cm2) and no greater 
than 0-5.6 BTUs/ft 2 second (0-5 Watts/cm2.
    (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. The frame is 
13\1/8\ inches (333mm) deep (front to back) by 8 inches (203mm) wide 
and rests on the top of the sliding platform. It is fabricated of 
\1/8\ inch (3.2mm) flat stock steel and has an opening that 
accommodates a \1/2\ inch (12.7mm) thick piece of Kaowool 
MTM board, which is level with the top of the sliding 
platform. The board has three 1 inch (25.4mm) diameter holes drilled 
through the board for calorimeter insertion. The distance from the 
outside frame (right side) to the centerline of the first hole 
(``zero'' position) is 1\7/8\ inches (47mm). The distance between 
the centerline of the first hole to the centerline of the second 
hole is 2 inches (51mm). It is also the same distance from the 
centerline of the second hole to the centerline of the third hole. 
See figure 8.

[[Page 57009]]

[GRAPHIC] [TIFF OMITTED] TP20SE00.008


[[Page 57010]]


    (9) Instrumentation. A calibrated recording device with an 
appropriate range or a computerized data acquisition system shall be 
provided 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. A stopwatch or other device, accurate to 
1 second/hour, shall be provided to measure the time of 
application of the pilot burner flame.
    (c) Test specimens.
    (1) Specimen preparation. A minimum of three test specimens 
shall be prepared and tested.
    (2) Construction. Test specimens shall 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, 43 inches long (1092mm) by 11 inches (279mm) wide. Cut a 
piece of film cover material (if used) large enough to cover the 
core material. There are a number of ways to prepare the sample. 
These include stapling the film cover around the ends (as the ends 
are not exposed to the radiant heat source), wrapping the core 
material and taping it at the bottom, and heat sealing the sample. 
The specimen thickness must be of the same thickness as installed in 
the airplane.
    (d) Specimen conditioning. The specimens shall be conditioned at 
70 5  deg.F (21 2  deg.C) and 55% 
10% relative humidity, for a minimum of 24 hours prior 
to testing.
    (e) 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 8. Close the bottom door located 
below the sliding platform. The centerline of the calorimeter is 
1\7/8\ inches (46mm) from the end of the holding frame. The distance 
from the centerline of the calorimeter to the radiant panel surface 
at this point is 7.5 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% (1.8 Watts/cm2 
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 is off during this time.
    (3) After steady-state conditions have been reached, move the 
calorimeter 2 inches (51mm) from the ``zero'' position (first hole) 
to the second position and record the heat flux. Move the 
calorimeter to the third position and record the heat flux. Allow 
enough time at each position for the calorimeter to stabilize.
    (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 (51mm) 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 is 7\1/2\ inches 
\1/8\ inch (191mm 3) below the radiant 
panel.
    (3) With film/fiberglass assemblies, it may be necessary to 
puncture small holes 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). The holes should be made in 
the sides/ and or the corners of the test specimen using a needle-
like tool.
    (4) Place the retaining frame over the test specimen. The 
securing frame may be used if the samples have been stapled and tend 
to shrink away from the radiant heat source. 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 (191mm3) at ``zero'' 
position).
    (5) Immediately push the sliding platform into the chamber and 
close the bottom door.
    (6) 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 shall be at a 27 deg. angle with the sample 
and be \1/2\ inch (12mm) above the sample. See figure 8. A stop, as 
shown in figure 9, allows the operator to position the burner in the 
correct position each time.
[GRAPHIC] [TIFF OMITTED] TP20SE00.009


[[Page 57011]]


    (7) Leave the burner in position for 15 seconds and then remove 
to a position at least 2 inches (51mm) above the specimen.
    (g) Report. (1) Identify and describe the specimen being tested.
    (2) Report any shrinkage or melting of the test specimen.
    (3) Report the flame time.
    (4) Report the after flame time.
    (h) Requirements. (1) No flaming beyond 2 inches (51mm) to the 
left of the centerline of the point of pilot flame application is 
allowed.
    (2) Of the 3 specimens tested, only 1 specimen may have an after 
flame. That after flame may not exceed 3 seconds.

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

    The following test method is used to evaluate the burnthrough 
resistance characteristics of aircraft thermal-acoustic insulation 
materials when exposed to a high intensity open flame.
    (a) Definitions--(1) Burnthrough time. The burnthrough time is 
measured at the inboard side of each of the insulation blanket 
specimens. The burnthrough time is defined as the time required, 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/ft\2\sec on the 
inboard side, at a distance of 12 inches from the front surface of 
the insulation blanket test frame, whichever is sooner.
    (2) Specimen set. A specimen set consists of two insulation 
blanket specimens. Both specimens must represent the same production 
insulation blanket construction and materials, proportioned to 
correspond to the specimen size.
    (3) Insulation blanket specimen. The insulation blanket specimen 
is one of two specimens positioned in either side of the test rig, 
at an angle of 30 deg. with respect to vertical.
    (b) Apparatus--(1) The arrangement of the test apparatus is 
shown in figures 1 and 2 and shall include swinging the burner away 
from the test specimen during warm-up.
[GRAPHIC] [TIFF OMITTED] TP20SE00.010


[[Page 57012]]


    (2) Test burner. The test burner shall be a modified gun-type 
such as the Park Model DPL 3400. Flame characteristics may be 
enhanced with the optional use of a static disc turbulator or a 
temperature compensation fuel nozzle.
[GRAPHIC] [TIFF OMITTED] TP20SE00.011


[[Page 57013]]


    (i) Nozzle. A nozzle is required to 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/in\2\ (0.71 MPa) has been found to deliver a proper 
spray pattern. Minor deviations to the fuel nozzle spray angle, fuel 
pressure, or other similar parameters are acceptable if the nominal 
fuel flow rate and temperature and heat flux measurements conform to 
the requirements of paragraph (e) of this part of this appendix.
    (ii) Burner cone. A 12 0.125-inch (305 6 
mm) burner extension cone shall be installed at the end of the draft 
tube. The cone shall have an opening 6 0.125-inch (152 
6 mm) high and 11 0.125-inch (280 
6 mm) wide (figure 3).
BILLING CODE 4910-13-U

[[Page 57014]]

[GRAPHIC] [TIFF OMITTED] TP20SE00.012

BILLING CODE 4910-13-C

[[Page 57015]]

    (iii) Fuel. JP-8, Jet A, or their international equivalent has 
been found to satisfactorily deliver a 6.0 0.2 gal/hr 
flow rate. 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 (e) of this part of this appendix.
    (iv) Fuel pressure regulator. A fuel pressure regulator, 
adjusted to deliver 6.0 gal/hr (0.378 L/min) nominal, shall be 
provided. An operating fuel pressure of 100 lb/in\2\ for a 6.0 gal/
hr 80 deg. spray angle nozzle (such as a PL type) has been found to 
be satisfactory to deliver 6.0 0.2 gal/hr (0.378 L/min).
    (3) Calibration rig and equipment. (i) A calibration rig shall 
be constructed to incorporate a calorimeter and thermocouple rake 
for the measurement of both heat flux and temperature. A combined 
temperature and heat flux calibration rig enables a quick transition 
between these devices, so that the influence of air intake velocity 
on heat flux and temperature can be analyzed without necessitating 
removal of the calibration rig. Individual calibration rigs are also 
acceptable.
    (ii) Calorimeter. The calorimeter shall 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 shall be in 
accordance with appendix F, part VI, paragraph (b)(7).
    (iii) Calorimeter mounting. The calorimeter shall be mounted 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 a calibration rig for 
attachment to the test rig during calibration (figure 4). The 
insulating block shall be monitored for deterioration and replaced 
when necessary. The mounting shall be adjusted as necessary to 
ensure that the calorimeter face is parallel to the exit plane of 
the test burner cone.

[[Page 57016]]

[GRAPHIC] [TIFF OMITTED] TP20SE00.013


[[Page 57017]]


    (iv) Thermocouples. Seven \1/8\-inch ceramic packed, metal 
sheathed, type K (Chromel-alumel), grounded junction thermocouples 
with a nominal 24 American Wire Gauge (AWG) size conductor shall be 
provided for calibration. The thermocouples shall be attached to a 
steel angle bracket to form a thermocouple rake for placement in the 
calibration rig during burner calibration (figure 5).
[GRAPHIC] [TIFF OMITTED] TP20SE00.014


[[Page 57018]]


    (v) Air velocity meter. A vane-type air velocity meter must be 
used to calibrate the velocity of air entering the burner. An Omega 
Engineering Model HH30A has been shown to be satisfactory. A 
suitable adapter used to attach the measuring device to the inlet 
side of the burner is required to prevent air from entering the 
burner other than through the device, which would produce 
erroneously low readings.
    (4) Test specimen mounting frame. The mounting frame for the 
test specimens shall be fabricated of \1/8\-inch thick steel as 
shown in figure 1, except for the center vertical former, which 
should be \1/4\-inch 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. The mounting frame 
shall be used for mounting the two insulation blanket test specimens 
as shown in figure 2.
    (5) Backface calorimeters. Two total heat flux Gardon type 
calorimeters shall be mounted above the insulation test specimens on 
the back side (cold) area of the test specimen mounting frame as 
shown in figure 6. The calorimeters must be positioned along the 
same plane as the burner cone centerline, at a distance of 4 inches 
from the centerline of the test frame. The heat flux calibration 
shall be in accordance with appendix F, part VI, paragraph (b)(7).
[GRAPHIC] [TIFF OMITTED] TP20SE00.015


[[Page 57019]]


    (6) Instrumentation. A recording potentiometer or other suitable 
calibrated instrument with an appropriate range shall be provided to 
measure and record the outputs of the calorimeter and the 
thermocouples.
    (7) Timing device. A stopwatch or other device, accurate to +/-
1%, shall be provided to measure the time of application of the 
burner flame and burnthrough time.
    (8) Test chamber. Tests should be performed 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.
    (i) Ventilation hood. The test chamber must be provided with an 
exhausting system capable of removing the products of combustion 
expelled during tests.
    (c) Test specimens--(1) Specimen preparation. A minimum of three 
specimen sets of the same construction and configuration shall be 
prepared for testing.
    (2) The insulation blanket test specimen. (i) For batt-type 
materials such as fiberglass, the constructed, finished blanket 
specimen assemblies shall be 32 inches wide by 36 inches long, 
exclusive of heat sealed film edges.
    (ii) For rigid and other non-conforming types of insulation 
materials, the finished test specimens shall fit into the test rig 
in such a manner as to replicate the actual in-service installation.
    (3) Construction. Each of the specimens tested shall be 
fabricated 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, the fire barrier material 
shall be placed in a manner reflective of the installed arrangement 
(e.g., if the material will be placed on the outboard side of the 
insulation material, inside the moisture film, it must be placed 
accordingly in the test specimen).
    (ii) Insulation material. Blankets that utilize more than one 
variety of insulation (composition, density, etc.) shall 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, 
separate tests must be performed on each combination. For example, 
if a polyimide film is used in conjunction with an insulation in 
order to enhance the burnthrough capabilities, the same insulation 
with a polyvinyl fluoride must also be tested.
    (iv) Installation on test frame. The blanket test specimens must 
be attached to the test frame using 12 steel spring type clamps as 
shown in figure 7. The clamps must be used to hold the blankets in 
place in both of the outer vertical formers, as well as the center 
vertical former (4 clamps per former). Place the top and bottom 
clamps 6 inches from the top and bottom of the test frame, 
respectively. Place the middle clamps 8 inches from the top and 
bottom clamps.
[GRAPHIC] [TIFF OMITTED] TP20SE00.016



[[Page 57020]]


    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. The specimens shall be conditioned 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 shall be 100 50 ft/min. The horizontal air 
velocity at this point shall be less than 50 ft/min.
    (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 shall be 6.0 
0.2 gallons per hour.
    (e) Calibration. (1) Secure the calibration rig to the test 
specimen frame. Position the burner so that it is centered in front 
of the calibration rig, and the vertical plane of the burner cone 
exit is at a distance of 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 burner position, slide the thermocouple rake portion 
of the calibration rig in front of the burner, such that the middle 
thermocouple (number 4 of 7) is centered on the burner cone. Ensure 
that the horizontal centerline of the burner cone is also offset 1 
inch below the horizontal centerline of the thermocouple tips.\3\ If 
individual calibration rigs are used, swing the burner to each 
position to ensure proper alignment between the cone and the 
calorimeter and thermocouple rake.
---------------------------------------------------------------------------

    \3\ The calibration rig must incorporate ``detents'' that ensure 
proper centering of both the calorimeter and the thermocouple rake 
with respect to the burner cone, so that rapid positioning of these 
devices can be achieved during the calibration procedure.
[GRAPHIC] [TIFF OMITTED] TP20SE00.017


[[Page 57021]]


    (2) Position the air velocity meter in the adapter, 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, then turn off blower/motor.
    (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 out of the test 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 test 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.
    (5) Position the thermocouple rake in front of the burner. 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 test 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.
    (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.
    (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 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. 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.
    (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/temperature on the back face of the insulation blanket test 
specimen, and the time at which the maximum occurred.
    (h) Requirements. (1) Neither of the two insulation blanket test 
specimens shall allow fire/flame penetration in less than 240 
seconds
    (2) Neither of the two insulation blanket test specimens shall 
allow more than 2.0 Btu/ft2-sec on the cold side of the 
insulation specimens at a point 12 inches from the face of the test 
rig.

PART 91--GENERAL OPERATING AND FLIGHT RULES

    6-8. 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.

    9. 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 [2 years after the effective 
date of the final rule], when thermal/acoustic insulation materials are 
installed as replacements after [2 years after the effective date of 
the final rule], those materials must meet the flame propagation 
requirements of Sec. 25.856 of this chapter, effective [insert final 
rule effective date].
    (2) For airplanes manufactured after [2 years after the effective 
date of the final rule], thermal/acoustic insulation materials must 
meet the flame propagation requirements of Sec. 25.856 of this chapter, 
effective [insert final rule effective date].

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

    10. 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.

    11. 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 [2 years after the effective 
date of the final rule], when thermal/acoustic insulation materials are 
installed as replacements after [2 years after the effective date of 
the final rule], those materials must meet the flame propagation 
requirements of Sec. 25.856 of this chapter, effective [insert final 
rule effective date].
    (2) For airplanes manufactured after [2 years after the effective 
date of the final rule], thermal/acoustic insulation materials must 
meet the flame propagation requirements of Sec. 25.856 of this chapter, 
effective [insert final rule effective date].
    (3) For airplanes manufactured after [4 years after the effective 
date of the final rule], thermal/acoustic insulation materials must 
meet the flame penetration resistance requirements of Sec. 25.856 of 
this chapter, effective [insert final rule effective date].

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

    12. 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.

    13. 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 [2 years after the effective 
date of the final rule], when thermal/acoustic

[[Page 57022]]

insulation materials are installed as replacements after [2 years after 
the effective date of the final rule], those materials must meet the 
flame propagation requirements of Sec. 25.856 of this chapter, 
effective [insert final rule effective date].
    (2) For airplanes manufactured after [2 years after the effective 
date of the final rule], thermal/acoustic insulation materials must 
meet the flame propagation requirements of Sec. 25.856 of this chapter, 
effective [insert final rule effective date].

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

    14. 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.

    15. 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 [2 years after the effective 
date of the final rule], when thermal/acoustic insulation materials are 
installed as replacements after [2 years after the effective date of 
the final rule], those materials must meet the flame propagation 
requirements of Sec. 25.856 of this chapter, effective [insert final 
rule effective date].
    (2) For airplanes manufactured after [2 years after the effective 
date of the final rule], thermal/acoustic insulation materials must 
meet the flame propagation requirements of Sec. 25.856 of this chapter, 
effective [insert final rule effective date].

    Issued in Washington, DC, on September 8, 2000.
Elizabeth Erickson,
Director, Aircraft Certification Service.
[FR Doc. 00-23550 Filed 9-19-00; 8:45 am]
BILLING CODE 4910-13-U