[Federal Register Volume 78, Number 211 (Thursday, October 31, 2013)]
[Proposed Rules]
[Pages 65231-65233]
[FR Doc No: 2013-25663]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0819; Notice No. 25-13-06-SC]

Special Conditions: Bombardier Inc., Models BD-500-1A10 and BD-
500-1A11 series airplanes; Fuselage In-Flight Fire Safety and
Flammability Resistance

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Bombardier
Inc. Model BD-500-1A10 and BD-500-1A11 series airplanes. These
airplanes will have a novel or unusual design feature associated with
the materials used to fabricate the fuselage, which may affect fire
propagation during an in-flight fire. The applicable airworthiness
regulations do not contain adequate or appropriate safety standards for
this design feature. These proposed special conditions contain the
additional safety standards that the Administrator considers necessary
to establish a level of safety equivalent to that established by the
existing airworthiness standards.

DATES: Send your comments on or before December 16, 2013.

ADDRESSES: Send comments identified by docket number [FAA-2013-0819]
using any of the following methods:
     Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending
your comments electronically.
     Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC, between 8 a.m. and 5 p.m.,
Monday through Friday, except federal holidays.
     Fax: Fax comments to Docket Operations at<PHONE_NUMBER>.
    Privacy: The FAA will post all comments it receives, without
change, to http://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov/.
    Docket: Background documents or comments received may be read at
http://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to the Docket Operations in Room W12-140
of the West Building Ground Floor at 1200 New Jersey Avenue SE.,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except federal holidays.

FOR FURTHER INFORMATION CONTACT: Alan Sinclair, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98057-
3356; telephone<PHONE_NUMBER>; facsimile<PHONE_NUMBER>.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
    We will consider all comments we receive on or before the closing
date for comments. We may change these special conditions based on the
comments we receive.

Background

    On December 10, 2009, Bombardier Inc. applied for a type
certificate for their new Model BD-500-1A10 and BD-500-1A11 series
airplanes. The Model BD-500-1A10 and BD-500-1A11 series airplanes are
swept-wing monoplanes with pressurized cabins, and they share an
identical supplier base and significant common design elements. The
fuselages are aluminum alloy material, blended double-bubble design,
sized for nominal 5 abreast seating. Each airplane's powerplant
includes two under-wing Pratt and Whitney PW1524G ultra-high bypass,
geared turbofan engines. Flight controls are fly-by-wire flight with
two passive/uncoupled side sticks. Avionics include five landscape
primary cockpit displays. The dimension of the airplanes encompasses a
wingspan of 115 feet; a height of 37.75 feet; and a length of 114.75
feet for the Model BD-500-1A10 and 127 feet for the Model BD-500-1A11.
Passenger capacity is designated as 110 for the Model BD-500-1A10 and
125 for the Model BD-500-1A11. Maximum takeoff weight is 131,000 pounds
for the Model BD-500-1A10 and 144,000 pounds for the Model BD-500-1A11.
Maximum takeoff thrust is 21,000 pounds for the Model BD-500-1A10 and
23,300 pounds for the Model BD-500-1A11. The range is 3,394 miles
(5,463 kilometers) for both model airplanes. The maximum operating
altitude is 41,000 feet for both model airplanes.
    The Bombardier BD-500-1A10 and BD-500-1A11 series airplanes will be
fabricated using aluminum-lithium materials. The performance of
airplanes consisting of a conventional aluminum fuselage in an
inaccessible in-flight fire scenario is understood based on service
history and extensive intermediate and large-scale fire testing. The
fuselage itself does not contribute to in-flight fire propagation. This
may not be the case for an all-aluminum-lithium fuselage. Experience
has shown that eliminating the fire propagation of the interior
materials and insulation materials tends to increase survivability
since other aspects of in-flight fire safety (e.g., toxic gas emission
and smoke obscuration) are typically by-products of the propagating
fire. The Bombardier BD-

500-1A10 and BD-500-1A11 series airplanes must provide protection
against an in-flight fire propagating along the surface of the
fuselage.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, Bombardier Inc. must show that the Model BD-500-1A10 and
BD-500-1A11 series airplanes meet the applicable provisions of part 25
as amended by Amendments 25-1 through 25-129 thereto.
    If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Model BD-500-1A10 and BD-500-1A11
series airplanes because of a novel or unusual design feature, special
conditions are prescribed under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the special conditions would also
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special
conditions, the Model BD-500-1A10 and BD-500-1A11 series airplanes must
comply with the fuel vent and exhaust emission requirements of 14 CFR
part 34 and the noise certification requirements of 14 CFR part 36 and
the FAA must issue a finding of regulatory adequacy under Sec.  611 of
Public Law 92-574, the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec.  11.38, and they become part of the type-
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Model BD-500-1A10 and BD-500-1A11 series airplanes will
incorporate the following novel or unusual design features: The
fuselage will be fabricated using aluminum-lithium materials instead of
conventional aluminum. This new type of material must provide
protection against an in-flight fire propagating along the surface of
the fuselage.

Discussion

    The Bombardier BD-500-1A10 and BD-500-1A11 series airplanes will be
fabricated using aluminum-lithium materials. The performance of
airplanes consisting of a conventional aluminum fuselage in an
inaccessible in-flight fire scenario is understood based on service
history and extensive intermediate and large-scale fire testing.
Experience has shown that eliminating the fire propagation of the
interior materials and insulation materials tends to increase
survivability since other aspects of in-flight fire safety (e.g., toxic
gas emission and smoke obscuration) are typically by-products of the
propagating fire. The fuselage itself does not contribute to in-flight
fire propagation. This may not be the case for an all-aluminum-lithium
fuselage.
    In the past, fatal in-flight fires have originated in inaccessible
areas of the airplane where thermal/acoustic insulation located
adjacent to the aluminum airplane skin has been the path for flame
propagation and fire growth. Concern over the fire performance of
thermal/acoustic insulation was initially raised by five incidents in
the 1990's, which revealed unexpected flame spread along the insulation
film that covered the thermal/acoustic insulation. In all cases, the
ignition source was relatively modest and, in most cases, was
electrical in origin (e.g., electrical short circuit, arcing caused by
chafed wiring, ruptured ballast case).
    In 1996, the FAA Technical Center began a program to develop new
fire test criteria for insulation films directly relating to in-flight
fire resistance. The current test standard at that time was evaluated
as well as another small-scale test method that has been used by
airplane manufacturers to evaluate flame propagation on thermal/
acoustic insulation materials.
    An inter-laboratory comparison of these methods revealed a number
of deficiencies. A new test method subjecting a material to a pilot
flame while the material is heated by a radiant panel was developed.
The new radiant panel test method and criteria were specifically
established to improve the evaluation of the in-flight fire ignition/
flame propagation of thermal/acoustic insulation materials based on
real-world fire scenarios. While these tests were developed for
thermal/acoustic insulation materials, this same type of test
methodology can be used to assess the flammability characteristics of
the proposed aluminum-lithium material for the fuselage.
    The FAA reviewed the test method proposed by Bombardier Inc. and
determined that a larger flame and test article would be necessary to
make a determination of the potential flammability of the aluminum-
lithium material. It would also be more representative of a real-life
fire scenario.
    The FAA recently conducted additional testing in our Components
Fire Test facility and determined that another way to assess the
survivability within the cabin of the Model BD-500-1A10 and BD-500-1A11
series is to use the cargo liner flammability test (part III of
appendix F to part 25, Test Method to Determine Flame Penetration
Resistance of Cargo Compartment Liners). However, the problem with
using this particular test is that when the aluminum panels melt,
molten globs of aluminum fall directly into the burner, which adversely
affects the flame. So the FAA decided that a similar test for the
measurement of insulation burnthrough resistance could be used (part
VII of appendix F to part 25, Test Method to Determine the Burnthrough
Resistance of Thermal/Acoustic Insulation Materials). Although this
test method uses the same burner as the cargo liner test, it uses a
slightly larger flame. In addition, the burner is not vertical, so
there was no problem with molten material falling into it, requiring
disassembly of the burner. The only slight change was the size of the
sample and the sample holder. These were modified slightly to
accommodate the samples that we received.
    The recent FAA tests that were conducted in our Components Fire
Test facility used a 6 gallon/hour oil burner, the same apparatus used
to determine burnthrough resistance of thermal/acoustic insulation
(part VII of appendix F to part 25). The test used 16 by 24 inch Al-Li
panels that were installed into a sheet steel subframe, which measured
18 by 32 inches (outside dimensions). The subframe had an opening cut
into it, which measured 14.5 by 22.5 inches; this allowed the test
panels to be mounted onto the subframe using .250-20 UNC threaded
bolts.
    The FAA proposes that Bombardier use the test method contained in
part VII of appendix F to part 25, Test Method to Determine the
Burnthrough Resistance of Thermal/Acoustic Insulation Materials, with
the slight changes to the sample size and sample holder as an alternate
test method to show compliance with applicable requirements. Bombardier
Inc. is responsible for finding a suitable testing facility in which to
conduct the testing.

Applicability

    As discussed above, these special conditions are applicable to the
Model BD-500-1A10 and BD-500-1A11 airplanes. Should Bombardier Inc.
apply at a later date for a change to the type certificate to include
another model incorporating the same novel or unusual design feature,
the special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features
on two models of airplanes. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping
requirements.

    The authority citation for these special conditions is as follows:

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

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Bombardier Inc. Model BD-500-1A10 and BD-500-1A11 series airplanes.
    1. Fuselage In-Flight Fire Safety and Flammability Resistance.
Bombardier must demonstrate that the fuselage would not materially
contribute to the propagation of an in-flight fire or introduce any
additional in-flight fire risk.
    2. To demonstrate compliance, the test set-up and methodology must
be commensurate with 14 CFR part 25, appendix F, part VII, except the
size of the test samples, modifications to the sample holder, and the
test methodology would be varied as described below.
    3. In demonstrating that the aluminum-lithium material used to
fabricate the fuselage has equal or better flammability resistance
characteristics than the aluminum alloy sheet typically used as skin
material on similar airplanes, the accepted test methods for compliance
include:
    a. Each test sample must consist of a flat test specimen. A set of
three samples of the material must be tested. The size of each sample
must be 16 inches by 24 inches by 0.063 inches.
    b. The test samples must be installed into a steel sheet subframe
with outside dimensions of 18 inches by 32 inches. The subframe must
have an opening cut into it of 14.5 inches by 22.5 inches. The tests
samples must be mounted onto the subframe using .250-20 UNC threaded
bolts.
    c. Test specimens must be conditioned at 70 [deg]F  5
[deg]F and 55 percent  5 percent humidity for at least 24
hours before testing.
    4. Demonstration of compliance will be achieved if the material is
not ignited during any of the tests.

    Issued in Renton, Washington, on September 12, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2013-25663 Filed 10-30-13; 8:45 am]
BILLING CODE 4910-13-P