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[Federal Register Volume 79, Number 33 (Wednesday, February 19, 2014)]
[Rules and Regulations]
[Pages 9380-9382]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-03586]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0819; Special Conditions No. 25-519-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: Final special conditions.

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SUMMARY: These special conditions are issued for the Bombardier Inc. 
Models BD-500-1A10 and BD-500-1A11 series airplanes. These airplanes 
will have novel or unusual design features when compared to the state 
of technology envisioned in the airworthiness standards for transport 
category airplanes. These features are 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 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: Effective Date: March 21, 2014.

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 425-227-2195; facsimile 425-227-1232.

SUPPLEMENTARY INFORMATION:

Background

    On December 10, 2009, Bombardier Inc. applied for a type 
certificate for their new Models BD-500-1A10 and BD-500-1A1 series 
airplanes (hereafter collectively referred to as ``C-series''). The C-
series airplanes are swept-wing monoplanes with an aluminum alloy 
fuselage sized for 5-abreast seating. 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.
    The Bombardier C-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 C-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 C-series airplanes meet 
the applicable provisions of part 25, as amended by Amendment 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 C-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 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 C-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

[[Page 9381]]

the type-certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Bombardier C-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 C-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 C-series airplanes 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.

Discussion of Comments

    Notice of proposed special conditions No. 25-13-06-SC for the 
Bombardier C-series airplanes was published in the Federal Register on 
October 31, 2013 (78 FR 65231). No comments were received, and the 
special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Models BD-500-1A10 and BD-500-1A11 series airplanes. Should Bombardier 
Inc. apply at a later date for a change to the type certificate to 
include another model on the same type certificate 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 model series 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 Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Bombardier Inc. Models BD-500-1A10 and 
BD-500-1A11 (C-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.

[[Page 9382]]

    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 January 22, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-03586 Filed 2-18-14; 8:45 am]
BILLING CODE 4910-13-P
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