Special Conditions: Airbus Model A380-800 Airplane, Crashworthiness, 46102-46104 [05-15649]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 152 (Tuesday, August 9, 2005)]
[Proposed Rules]
[Pages 46102-46104]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-15649]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM319; Notice No. 25-05-14-SC]


Special Conditions: Airbus Model A380-800 Airplane, 
Crashworthiness

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for the Airbus A380-
800 airplane. This airplane will have novel or unusual design features 
when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. Many of these 
novel or unusual design features are associated with the complex 
systems and the configuration of the airplane, including its full-
length double deck. For these design features, the applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards regarding crash survivability. 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. 
Additional special conditions will be issued for other novel or unusual 
design features of the Airbus Model A380-800 airplane.

DATES: Comments must be received on or before September 23, 2005.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, 
Attention: Rules Docket (ANM-113), Docket No. NM319, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056; or delivered in duplicate to the 
Transport Airplane Directorate at the above address. All comments must 
be marked: Docket No. NM319. Comments may be inspected in the Rules 
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Holly Thorson, FAA, International 
Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone 
(425) 227-1357; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting 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 ask that you send us two copies of written 
comments.
    We will file in the docket all comments we receive as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these proposed special conditions. The docket is available 
for public inspection before and after the comment closing date. If you 
wish to review the docket in person, go to the address in the ADDRESSES 
section of this notice between 7:30 a.m. and 4 p.m., Monday through 
Friday, except Federal holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late, if it is 
possible to do so without incurring expense or delay. We may change the 
proposed special conditions in light of the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

[[Page 46103]]

Background

    Airbus applied for FAA certification/validation of the 
provisionally-designated Model A3XX-100 in its letter AI/L 810.0223/98, 
dated August 12, 1998, to the FAA. Application for certification by the 
Joint Aviation Authorities (JAA) of Europe had been made on January 16, 
1998, reference AI/L 810.0019/98. In its letter to the FAA, Airbus 
requested an extension to the 5-year period for type certification in 
accordance with 14 CFR 21.17(c). The request was for an extension to a 
7-year period, using the date of the initial application letter to the 
JAA as the reference date. The reason given by Airbus for the request 
for extension is related to the technical challenges, complexity, and 
the number of new and novel features on the airplane. On November 12, 
1998, the Manager, Aircraft Engineering Division, AIR-100, granted 
Airbus' request for the 7-year period, based on the date of application 
to the JAA.
    In its letter AI/LE-A 828.0040/99 Issue 3, dated July 20, 2001, 
Airbus stated that its target date for type certification of the Model 
A380-800 has been moved from May 2005, to January 2006, to match the 
delivery date of the first production airplane. In accordance with 14 
CFR 21.17(d)(2), Airbus chose a new application date of April 20, 1999, 
and requested that the 7-year certification period which had already 
been approved be continued. The part 25 certification basis for the 
Model A380-800 airplane was adjusted to reflect the new application 
date.
    The Model A380-800 airplane will be an all-new, four-engine jet 
transport airplane with a full double-deck, two-aisle cabin. The 
maximum takeoff weight will be 1.235 million pounds with a typical 
three-class layout of 555 passengers.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Airbus must show that the 
Model A380-800 airplane meets the applicable provisions of 14 CFR part 
25, as amended by Amendments 25-1 through 25-98. If the Administrator 
finds that the applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for the Airbus A380-800 
airplane because of novel or unusual design features, special 
conditions are prescribed under the provisions of 14 CFR 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Airbus Model A380-800 airplane 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. In addition, the 
FAA must issue a finding of regulatory adequacy pursuant to section 611 
of Public Law 93-574, the ``Noise Control Act of 1972.''
    Special conditions, as defined in 14 CFR 11.19, are issued in 
accordance with 14 CFR 11.38 and become part of the type certification 
basis in accordance with 14 CFR 21.17(a)(2), Amendment 21-69, effective 
September 16, 1991.
    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, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design features, the special conditions would also apply to the 
other model under the provisions of 14 CFR 21.101(a)(1), Amendment 21-
69, effective September 16, 1991.

Discussion of Novel or Unusual Design Features

    With its complex configuration including a full-length double deck, 
the Model A380 airplane has a novel and unusual design relative to 
large transport category airplanes which have been previously 
certificated under 14 CFR part 25. The A380 should provide a level of 
crash survivability which is at least equivalent to that demonstrated 
for such conventional large transport airplanes. However, its size and 
configuration could cause the airplane to be subject to effects of 
scale that decrease the ability of the occupants to survive a crash 
landing, compared to the occupants of those conventional airplanes.
    Currently, 14 CFR 25.561 contains design load conditions covering 
emergency landings or minor crash landings for the local structures 
which support passengers, equipment, cargo, and other large items of 
mass in the passenger compartment. However, neither 14 CFR 25.561 nor 
any other part 25 requirements address the structural capability of the 
airframe as a whole in a crash landing. Service experience indicates 
that--even without specific regulatory requirements--the airframes of 
conventional transport category airplanes show reasonable structural 
capability in crash landings. Therefore, in the past we have not 
considered it necessary to specify design load conditions addressing 
the structural capability of the airplane as a whole in a crash 
landing.
    The FAA, however, has no information to indicate whether an 
airplane the size and configuration of the A380 would provide 
reasonable airframe structural capability in a crash landing without a 
specific regulatory requirement. Therefore, the FAA is proposing 
special conditions which specify testing and analysis to ensure that 
the Model A380 provides a level of crash survivability equivalent to 
that of conventional large transport category airplanes. These special 
conditions address only the vertical loading of the fuselage. The 
longitudinal loading is not significantly different from that of a 
conventional transport category airplane and thus is adequately 
addressed by part 25.
    For the special conditions, it is necessary to establish a 
reference point to compare the structural capability of the A380 
airplane with the structural capability of current generation airplanes 
in a crash. This reference point is referred to as the ``Limit of 
Reasonable Survivability.'' It is defined--in terms of the vertical 
descent rate--as the level of structural degradation that would lead, 
either directly or by exceedance of physiological limits of the 
occupants, to a significant reduction in the probability of survival in 
an otherwise survivable incident. (An incident can be unsurvivable due 
to a non-structural cause, such as a fire. An otherwise survivable 
incident, then, is one in which no fire or other cause makes the 
incident unsurvivable.). We intend that this Limit of Reasonable 
Survivability must be determined first for the current generation of 
the applicant's airplanes and then for the A380 to show that the latter 
has equal or better characteristics at the same vertical descent rate.
    The special conditions contain a provision to ensure that the 
supporting airframe structure is strong and rigid enough to provide 
survivable living space and to hold seats, overhead bins, and other 
items of mass in place, even if the local attachment hardware is 
designed to exceed the minimum strength required by Sec.  25.561. To 
provide this protection, the special conditions specify that the 
airframe structure must be able to support the loads imposed by items 
of mass, assuming that their local supporting structure does not fail, 
thus relieving the load on the supporting airframe structure. This 
assumption will ensure that the airframe structure will not collapse, 
even if the strength of the local attachment for items of mass exceeds 
the strength required by Sec.  25.561. Since

[[Page 46104]]

it is the airframe as a whole and its survivable living space that are 
the subject of these special conditions, the FAA does not intend to 
increase the strength requirements of Sec.  25.561 by special 
condition. Therefore, the special conditions state explicitly that the 
attachments of items of mass need not be designed for static emergency 
landing loads in excess of those specified in Sec.  25.561.
    Since larger airframe structures typically have more volume within 
which to absorb energy, they normally provide occupants with reasonable 
protection from crash loads. Therefore, the effects of the A380 design 
on occupant loads are not expected to be significant. In order to 
confirm that this assumption is correct, these special conditions 
require an assessment of the effect of the design on the occupant 
loads. For the purposes of these special conditions, an analytical tool 
known as the Dynamic Response Index (DRI) is used to make the 
assessment. DRI was developed through research and is documented in 
USAA VSCOM TR 89-D-22B, ``Aircraft Crash Survival Design Guide, Volume 
II, Aircraft Design Crash Impact Conditions and Human Tolerance.'' DRI 
approximates the effect of an impact on spinal load. Based on the 
results of the assessment using DRI, any additional, detailed occupant 
load considerations can be established.

Applicability

    As discussed above, these special conditions are applicable to the 
Airbus A380-800 airplane. Should Airbus apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design features, these special conditions 
would apply to that model as well under the provisions of Sec.  
21.101(a)(1), Amendment 21-69, effective September 16, 1991.

Conclusion

    This action affects only certain novel or unusual design features 
of the Airbus A380-800 airplane. It is not a rule of general 
applicability, and it affects only the applicant which applied to the 
FAA for approval of these features on the airplane.

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, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Airbus A380-800 airplane.
    In addition to the requirements of Sec. Sec.  25.561, 25.562, 
25.721, and 25.785, the following special conditions apply:
    It must be demonstrated that the Model A380 provides a level of 
crash survivability equivalent to that of conventional large transport 
airplanes. This may be achieved by demonstrating by test or validated 
analysis that--at impacts up to a vertical descent rate representing 
the Limit of Reasonable Survivability--the structural capability of 
typical fuselage sections is equal to or better than that of a 
conventional large transport airplane.
    (The Limit of Reasonable Survivability is defined as the level of 
structural degradation that would either directly or by exceedance of 
physiological limits of the occupants lead to a significant reduction 
in the probability of survival in an otherwise survivable incident.) 
The results of this demonstration must show the following:
    a. Structural deformation will not result in infringement of the 
occupants' normal living space.
    b. The occupants will be protected from the release of seats, 
overhead bins, and other items of mass due to structural deformation of 
the supporting structure. That is, the supporting structure must be 
able to support the loads imposed by these items of mass, assuming that 
they remain attached during the impact event, and the floor structure 
must deform in a way that would allow them to remain attached. However, 
the attachments of these items need not be designed for static 
emergency landing loads in excess of those specified in Sec.  25.561.
    c. The Dynamic Response Index experienced by the occupants will not 
be more severe than that experienced on conventional large transport 
airplanes. (The Dynamic Response Index is described in USAA VSCOM TR 
89-D-22B, ``Aircraft Crash Survival Design Guide, Volume II, Aircraft 
Design Crash Impact Conditions and Human Tolerance.'')
    d. Cargo loading of the fuselage for this evaluation accounts for 
variations that could have a deleterious effect on structural 
performance.

    Issued in Renton, Washington on July 25, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-15649 Filed 8-8-05; 8:45 am]
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