[Federal Register Volume 78, Number 221 (Friday, November 15, 2013)]
[Proposed Rules]
[Pages 68775-68777]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-27413]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0898; Notice No. 25-13-33-SC]


Special Conditions: Airbus, Model A350-900 Series Airplane; 
Composite Fuselage In-Flight Fire/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 Airbus Model 
A350-900 series airplanes. This airplane will have a novel or unusual 
design features associated with the in-flight fire and flammability 
resistance of the composite fuselage. Experience has shown that 
eliminating fire propagation on the surface of interior and insulating 
materials enhances survivability since the threats from an in-flight 
fire (e.g., toxic gas emission and smoke obscuration) are typically by-
products of a propagating fire. The Airbus Model A350-900 series 
airplanes must provide protection against an in-flight fire propagating 
along the surface of the fuselage. Special conditions are needed to 
address this design feature. 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 30, 2013.

ADDRESSES: Send comments identified by docket number FAA-2013-0898 
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 9 a.m. and 5 p.m., 
Monday through Friday, except federal holidays.
     Fax: Fax comments to Docket Operations at 202-493-2251.
    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: Jeff Gardlin, FAA, Airframe/Cabin 
Safety, ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98057-3356; 
telephone (425) 227-2136; facsimile (425) 227-1320.

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 proposed 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 August 25, 2008, Airbus applied for a type certificate for their 
new Model A350-900 series airplane. Later, Airbus requested and the FAA 
approved an

[[Page 68776]]

extension to the application for FAA type certification to June 28, 
2009, The Model A350-900 series has a conventional layout with twin 
wing-mounted Rolls Royce Trent engines. It features a twin aisle 9-
abreast economy class layout, and accommodates side-by-side placement 
of LD-3 containers in the cargo compartment. The basic Model A350-900 
series configuration will accommodate 315 passengers in a standard two-
class arrangement. The design cruise speed is Mach 0.85 with a Maximum 
Take-Off Weight of 602,000 lbs. Airbus proposes the Model A350-900 
series to be certified for extended operations (ETOPS) beyond 180 
minutes at entry into service for up to a 420-minute maximum diversion 
time.
    Experience has shown that eliminating fire propagation on the 
surface of interior and insulating materials enhances survivability 
since the threats from an in-flight fire (e.g., toxic gas emission and 
smoke obscuration) are typically by-products of a propagating fire. The 
Airbus Model A350-900 series airplane must provide protection against 
an in-flight fire propagating along the surface of the fuselage.
    In the past, fatal in-flight fires have originated in inaccessible 
areas of the aircraft where the thermal/acoustic insulation located 
adjacent to the aluminium aircraft 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 covering material. 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). From 1972 until 2003 these materials were required to 
comply with a basic ``Bunsen burner'' requirement per Title 14 Code of 
Federal Regulations (14 CFR) 25.853(a), 25.855(d), and part 25, 
Appendix F, part I, paragraph (a)(1)(ii). These requirements prescribed 
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 part 25, Appendix F, part I, paragraph 
(b)(4). The average burn was not to exceed eight inches and the average 
flame time after removal of the flame source was not to exceed 15 
seconds. Drippings from the test specimen were not to continue to flame 
for more than an average of five seconds after falling.
    Further concern with the flammability of thermal/acoustic 
insulation was raised by the Transportation Safety Board (TSB) of 
Canada during their investigation of the fatal Swiss Air MD-11 in-
flight fire accident that occurred in September 1998 and involved 229 
fatalities. TSB investigators reported that the fatal fire appeared to 
have been confined to the area above the cockpit and forward cabin 
ceiling and involved the insulation blankets. On August 21, 2001, the 
TSB recommended that flammability standards for interior materials 
should be based on realistic ignition scenarios and prevent the use of 
materials that sustain or propagate a fire.
    In 1996, the FAA Technical Center began a program to develop new 
fire test criteria for insulation films directly relating to the 
resistance of in-flight fire propagation. The current test standard 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. Other small-scale tests 
developed by the FAA Technical Center did demonstrate that some 
insulation films would ignite and propagate flame in a confined space. 
As a result, a series of large-scale fire tests were conducted in a 
mock-up of the attic area above the passenger cabin ceiling. In a 
confined space, ignition and flame propagation may occur because of 
more extensive radiating heat and the trapping of melted film/scrim. 
Temperature (heat release) data was recorded and the degree of flame 
propagation was observed from the large-scale tests. A radiant panel 
test standard for flooring materials was a test method that provided 
good correlation to the large-scale model. The test method involved 
subjecting a material to a pilot flame while the material is heated by 
a radiant panel.
    The previously described development program resulted in a new test 
method (radiant panel test) and test criteria specifically established 
for improving the in-flight fire ignition/flame propagation of thermal/
acoustic insulation materials. A new part 25 airworthiness standard, 
Sec.  25.856, became effective in September 2003, Amendment 25-111, 
requiring that all thermal/acoustic insulation materials installed in 
the fuselage must comply to this flammability and flame propagation 
requirement. 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.''

Type Certification Basis

    Under Title 14, Code of Federal Regulations (14 CFR) 21.17, Airbus 
must show that the Model A350-900 series airplane meets the applicable 
provisions of 14 CFR part 25, as amended by Amendments 25-1 through 25-
128.
    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 A350-900 series because of a 
novel or unusual design feature, special conditions are prescribed 
under 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 proposed special conditions would 
also apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and 
proposed special conditions, the Model A350-900 series 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 section 611 of Public Law 
92-574, the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, 
under Sec.  11.38, and they become part of the type-certification basis 
under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Airbus Model A350-900 series airplane will incorporate the 
following novel or unusual design features: fuselage fabricated with 
composite materials.

Discussion

    The Airbus Model A350-900 series airplane will make extensive use 
of composite materials in the fabrication of the majority of the wing, 
fuselage skin, stringers, spars, and most other structural elements of 
all major sub-assemblies of the airplane. Despite the major change from 
aluminum to composite material for the fuselage, the Model A350-900 
series must have in-flight survivability such that the composite 
fuselage does not propagate a fire. A methodology for assessing the in-
flight fire survivability of an all-composite fuselage is therefore 
needed.
    The FAA believes that one way to assess the survivability within 
the cabin of the Model A350-900 series airplane is to conduct large-
scale tests. This large-scale test would utilize a mock-up

[[Page 68777]]

of an Airbus Model A350-900 series airplane fuselage skin/structure 
section of sufficient size to assess any tendency for fire propagation. 
The fire threat used to represent the realistic ignition source in the 
airplane would consist of a 4'' x 4'' x 9'' polyurethane foam block and 
10 ml of Heptane. This ignition source provides approximately three 
minutes of flame time and would be positioned at various points and 
orientations within the mocked up installation to impinge on those 
areas of the fuselage considered to be most crucial.
    This fire threat was established based on an assessment of a range 
of potential ignition sources, coupled with possible contamination of 
materials. The FAA considers this a severe fire threat, encompassing a 
variety of scenarios. However, should ignition or fire sources of a 
greater severity be identified, the special condition or its method of 
compliance would need to be modified in order to take the more severe 
threat into account.

Applicability

    As discussed above, these proposed special conditions apply to 
Airbus Model A350-900 series airplanes. Should Airbus apply later for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, the proposed special 
conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on the Airbus Model A350-900 series 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 Condition

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special condition as part of the type certification basis for 
Airbus Model A350-900 series airplanes.

Composite Fuselage In-Flight Fire/Flammability Resistance

    In addition to the requirements of Sec.  25.853(a) governing 
material flammability, the following special condition applies:
    The Airbus Model A350 composite fuselage structure must be shown to 
be resistant to flame propagation under the fire threat used to develop 
Sec.  25.856(a). If products of combustion are observed beyond the test 
heat source, they must be evaluated and found acceptable.

    Issued in Renton, Washington, on November 12, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-27413 Filed 11-14-13; 8:45 am]
BILLING CODE 4910-13-P