Special Conditions: Airbus, A350-900 Series Airplane; Crashworthiness-Emergency Landing Conditions, 1337-1339 [2014-00104]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 79, Number 5 (Wednesday, January 8, 2014)]
[Proposed Rules]
[Pages 1337-1339]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-00104]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0892; Notice No. 25-13-21-SC]


Special Conditions: Airbus, A350-900 Series Airplane; 
Crashworthiness--Emergency Landing Conditions

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. These airplanes will have a novel or unusual 
design feature associated with crashworthiness of carbon fiber 
reinforced plastic used in the construction of the fuselage. 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

[[Page 1338]]

necessary to establish a level of safety equivalent to that established 
by the existing airworthiness standards.

DATES: Send your comments on or before February 24, 2014.

ADDRESSES: Send comments identified by docket number FAA-2013-0892 
using any of the following methods:
     Federal eRegulations Portal: Go to https://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 https://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 https://DocketsInfo.dot.gov/.
    Docket: Background documents or comments received may be read at 
https://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: Todd Martin, FAA, Airframe/Cabin 
Safety, ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98057-3356; 
telephone (425) 227-1178; 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 ask that you send us two copies of written comments.
    We will consider all comments we receive on or before the closing 
date for comments. We may change these proposed 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 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 XWB 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.
    Changes in the structural behavior of the Airbus Model A350-900 
series airplanes compared to currently certificated designs could 
degrade the survivability of Model A350-900 series occupants in crash 
conditions that are within the limits of survivability for other 
designs.
    There is no aircraft-level survivable crash condition specified in 
the airworthiness regulations, and metallic aircraft have not been 
specifically designed against survivable impact conditions. However, 
the structural behavior of previously certificated aircraft in a 
survivable crash event and the associated limits are considered 
generally acceptable. It is therefore reasonable to expect that a 
design using new materials, such as the Model A350-900 series airplanes 
use, should be assessed to ensure that the material meets the currently 
accepted level of safety. The FAA and industry have collected a 
significant amount of experimental data as well as data from crashes of 
transport category airplanes that show a high occupant survival rate at 
vertical descent velocities up to 30 ft/sec. Based on this information, 
the FAA finds it appropriate and necessary for an assessment of the 
Model A350-900 series airplanes to span a range of airplane vertical 
descent speeds up to 30 ft/sec.

Type Certification Basis

    Under Title 14, Code of Federal Regulations (14 CFR) 21.17, Airbus 
must show that the Model A350-900 series meets the applicable 
provisions of 14 CFR part 25, as amended by Amendments 25-1 through 25-
129.
    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 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 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 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, 
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 will incorporate the following 
novel or unusual design feature: fuselage fabricated with a combination 
of carbon fiber reinforced plastic (CFRP) and metallic structure. This 
is a novel and unusual design feature for a large transport airplane. 
Structure fabricated from CFRP may behave differently than metallic 
structure in crash conditions because of differences in material 
ductility, stiffness, failure modes, and energy absorption 
characteristics. Therefore, the impact response characteristics of the 
Model A350-900 series airplane must be evaluated to ensure that its 
survivable crashworthiness characteristics provide at least the same 
level of safety as those of a similarly sized airplane constructed from 
traditionally used metallic materials.
    There are no existing regulations that adequately address this 
potential difference in impact response

[[Page 1339]]

characteristics for what are considered survivable crash conditions. 
The proposed special conditions are necessary to ensure a level of 
safety equivalent to that provided by 14 CFR part 25.

Discussion

    Factors in crash survivability are retention of items of mass, 
maintenance of occupant emergency egress paths, maintenance of 
acceptable acceleration and loads experienced by the occupants, and 
maintenance of a survivable volume. To provide the same level of safety 
as exists with conventional airplane construction, Airbus should show 
that the Model A350-900 series airplanes have sufficient 
crashworthiness capabilities under foreseeable survivable impact 
events. To show this, Airbus should evaluate the impact response 
characteristics of the Model A350-900 series airplane to ensure that 
its crashworthiness characteristics are not significantly different 
from those of a similarly sized airplane built from traditionally used 
metallic materials.
    In their evaluation of the Model A350-900 series airplane response 
to an impact event, Airbus should demonstrate that the structural 
behavior is similar to that expected from a metallic airframe of 
similar size to the Model A350-900, or incorporate mitigating design 
features that provide a similar level of safety.
    Airbus should demonstrate either through analysis using validated 
analytical tools or by direct test evidence that the crash dynamics of 
the A350 fuselage structure provides a level of occupant protection 
consistent with previously certificated large transport category 
airplanes.

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 Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Airbus Model A350-900 series airplanes.
    The Airbus Model A350-900 series airplanes must provide an 
equivalent level of occupant safety and survivability to that provided 
by previously certificated wide-body transports of similar size under 
foreseeable survivable impact events for the following four criteria. 
In order to demonstrate an equivalent level of occupant safety and 
survivability, the applicant must demonstrate that Model A350-900 
series airplanes meet the following criteria for a range of airplane 
vertical descent velocities up to 30 ft/sec.
    1. Retention of items of mass. The occupants, i.e., passengers, 
flight attendants, and flightcrew, must be protected during the impact 
event from release of seats, overhead bins, and other items of mass due 
to the impact loads and resultant structural deformation of the 
supporting airframe and floor structures. The applicant must show that 
loads due to the impact event and resultant structural deformation of 
the supporting airframe and floor structure at the interface of the 
airplane structure to seats, overhead bins, and other items of mass are 
comparable to those of previously certificated wide-body transports of 
similar size for the range of descent velocities stated above. The 
attachments of these items need not be designed for static emergency 
landing loads in excess of those defined in Sec.  25.561 if impact 
response characteristics of the Airbus Model A350-900 series airplanes 
yield load factors at the attach points that are comparable to those 
for a previously certificated wide-body transport category airplane.
    2. Maintenance of acceptable acceleration and loads experienced by 
the occupants. The applicant must show that the impact response 
characteristics of the Airbus Model A350-900 series airplane, 
specifically the vertical acceleration levels experienced at the seat/
floor interface and loads experienced by the occupants during the 
impact events, are consistent with those found in Sec.  25.562(b) or 
with levels expected for a previously certificated wide-body transport 
category airplane for the conditions stated above.
    3. Maintenance of a survivable volume. For the conditions stated 
above, the applicant must show that all areas of the airplane occupied 
for takeoff and landing provide a survivable volume comparable to that 
of previously certificated wide-body transports of similar size during 
and after the impact event. This means that structural deformation will 
not result in infringement of the occupants' normal living space so 
that passenger survivability will not be significantly affected.
    4. Maintenance of occupant emergency egress paths. The evacuation 
of occupants must be comparable to that from a previously certificated 
wide-body transport of similar size. To show this, the applicant must 
show that the suitability of the egress paths, as determined following 
the vertical impact events, is comparable to the suitability of the 
egress paths of a comparable, certificated wide-body transport, as 
determined following the same vertical impact events.

    Issued in Renton, Washington, on October 22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-00104 Filed 1-7-14; 8:45 am]
BILLING CODE 4910-13-P