Special Conditions: Airbus Model A380-800 Airplane, Crashworthiness, 48453-48457 [E6-13796]
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Federal Register / Vol. 71, No. 161 / Monday, August 21, 2006 / Rules and Regulations
runs to ensure that it will not be applied
as a minimum threshold for each test
run.
FAA response: Special Condition 2
requires that Airbus demonstrate that
the extendable length escape slide can
achieve an evacuation rate of 45 persons
per minute, but does not specify that
any and every evacuation test must
achieve that rate. Using the average of
tests may be one way to demonstrate the
specified rate, but it is not necessary to
specify that as the only means.
Requested change No. 5: Boeing
further comments that proposed Special
Condition 2 should specify that, ‘‘with
the exception of the sill height and the
required average evacuation rate for this
test series, all the other test conditions
in Technical Standard Order TSC–C69C,
paragraph 5.4, (Basic Test Conditions),
apply.’’
FAA response: This matter is
addressed in Special Condition 1, which
specifies that ‘‘The extendable escape
slide must receive TSO C69c
authorization or the equivalent.’’
Except for the changes discussed
above, the special conditions are
adopted as proposed.
Applicability
2. In addition to the requirements of
§ 25.810(a)(1)(iii) for usability in
conditions of landing gear collapse, the
deployed escape slide in the extended
mode must demonstrate an evacuation
rate of 45 persons per minute per lane
at the sill height corresponding to
activation of the extension.
3. In lieu of the requirements of
§ 25.810(a)(1)(iv), the escape slide must
be capable of being deployed in the
extended mode, and with the assistance
of one person, remain usable in 22 knot
winds directed from the critical angle,
with the airplane on all its landing gear.
4. Pitch sensor tolerances and
accuracy must be taken into account
when demonstrating compliance with
§ 25.1309(a) for the escape slide in both
the extended and unextended modes.
5. There must be a ‘‘slide extension’’
warning such that the cabin crew is
immediately made aware of a non
usable slide (i.e., the main slide has
deployed and the door sill height is
such that the extension should be
deployed but cannot be deployed), even
if this is due to the airplane attitude
changing during the evacuation. The
ability to provide such a warning must
be available for ten minutes after the
airplane is immobilized on the ground.
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 § 21.101.
Issued in Renton, Washington, on July 20,
2006.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E6–13780 Filed 8–18–06; 8:45 am]
Conclusion
DEPARTMENT OF TRANSPORTATION
This action affects only certain novel
or unusual design features of the Airbus
A380–800 airplane. It is not a rule of
general applicability.
Federal Aviation Administration
BILLING CODE 4910–13–P
14 CFR Part 25
List of Subjects in 14 CFR Part 25
[Docket No. NM319; Special Conditions No.
25–321–SC]
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
Special Conditions: Airbus Model
A380–800 Airplane, Crashworthiness
The authority citation for these
special conditions is as follows:
AGENCY:
I
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 the Airbus A380–800 airplane.
In addition to the provisions of 14
CFR part 25, the following special
conditions apply:
1. The extendable escape slide must
receive TSO C69c authorization or the
equivalent.
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I
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Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
SUMMARY: These special conditions are
issued 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
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48453
airworthiness regulations do not contain
adequate or appropriate safety standards
regarding crash survivability. 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. Additional
special conditions will be issued for
other novel or unusual design features
of the Airbus Model A380–800 airplane.
DATES: Effective Date: The effective date
for these special conditions is July 24,
2006.
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:
Background
Airbus applied for FAA certification/
validation of the provisionallydesignated 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 5year 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 had
been moved from May 2005, to January
2006, to match the delivery date of the
first production airplane. In a
subsequent letter (AI/L 810.0223/98
issue 3, dated January 27, 2006), Airbus
stated that its target date for type
certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2),
Airbus chose a new application date of
December 20, 1999, and requested that
the 7-year certification period which
had already been approved be
continued. The FAA has reviewed the
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Federal Register / Vol. 71, No. 161 / Monday, August 21, 2006 / Rules and Regulations
part 25 certification basis for the Model
A380–800 airplane, and no changes are
required based on the new application
date.
The Model A380–800 airplane will be
an all-new, four-engine jet transport
airplane with a full double-deck, twoaisle cabin. The maximum takeoff
weight will be 1.235 million pounds
with a typical three-class layout of 555
passengers.
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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).
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.
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
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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
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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 § 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 § 25.561. Since
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 § 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 § 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. The 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.’’ The 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.
Discussion of Comments
Notice of Proposed Special
Conditions No. 25–05–14–SC,
pertaining to crashworthiness
requirements for the Airbus A380
airplane, was published in the Federal
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Federal Register / Vol. 71, No. 161 / Monday, August 21, 2006 / Rules and Regulations
Register on August 9, 2005 (70 FR
46102). Comments were received from
the Airline Pilots Association (ALPA),
the Association of Flight Attendants
(AFA), and the Boeing Company.
Requested change 1: ALPA addresses
the first sentence in Section b. of the
special conditions which specifies that,
‘‘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
* * * .’’
ALPA states,
‘‘Unless there is a procedure/system
in place in revenue service that prevents
the seat and bin from being loaded in
excess of their rated limit, seats and bins
under the requirements of Section b.
must be tested within the full range of
likely loads, not simply up to their rated
limit. Overhead bins are notorious for
failing in crash scenarios where the
remainder of the cabin remains intact.
In addition, the seat requirements for
testing with only a 50th percentile male
should be reconsidered to evaluate the
full range of occupants, or at least the
5th to 95th percentile of humans.’’
FAA response: Accommodating the
changes requested by ALPA would be
beyond the scope of this rulemaking.
The purpose of the special condition is
to assure that the large size and full
length double deck configuration of the
A380 design do not degrade the
survivability characteristics of the A380
fuselage shell compared to designs for
conventional large transport category
airplanes. The purpose is not to create
a higher safety standard for the A380.
To accomplish a proper comparison,
the mass of items and the weight of
passengers are defined in the same way
as they would be for conventional
airplane designs. Overhead bins are
required to be evaluated for the rated
bin load, and seats are required to be
evaluated for the mass of a 50th
percentile male occupant. To adopt a
procedure to prevent a seat or bin from
being loaded in excess of its rated
design or to adopt a higher passenger
weight for the evaluation of seat
strength would represent a difference
from the certification criteria used for
conventional large transport category
airplane designs.
Since the A380 is not unique or
unusual with regard to these
certification criteria, the requested
changes are considered to be beyond the
scope of this rulemaking. Accordingly,
we have made no changes to the special
conditions, as proposed.
Requested change 2: AFA
recommends deleting Section c. of the
special condition and all reference to
use of the DRI as a measure of
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‘‘physiological limits’’ of a crash.
Instead, AFA suggests relying on
Sections a., b., and d. for
demonstrations of survivability.
AFA supports its recommendation
with a detailed analysis of the
development and use of the DRI and
reaches the following conclusion:
‘‘The DRI is useful, preferably with other
criteria, to predict minor to moderate injury
in ejection seats with occupants who are well
restrained in the vertically seated posture,
and possibly in crashes. The DRI has never
shown the ability to predict survival (or
anything else) in a crash that could cause
severe but not fatal injury.’’
FAA response: The DRI is being used
as a metric to compare the occupant
dynamic response in the Model A380
with that in other airplane designs; it is
not being used as a criterion of injury.
Section c. of the special condition states
that the ‘‘Dynamic Response Index
experienced by the occupants will be no
more severe than that experienced on
conventional large transport airplanes.’’
This comparison does not involve
establishing an injury criterion for DRI.
The FAA considers the DRI to be an
appropriate metric for the comparative
analysis required by the special
condition. Since it is only the vertical
loading that is simulated in the analysis,
the one degree of freedom spring-mass
model on which DRI is based is
acceptable to the FAA. Accordingly, no
change has been made to Section c. of
the special condition, as proposed.
Requested change 3: AFA states, ‘‘The
proposed special condition[s] envision a
simple vertical impact as the
environment to compare the
crashworthiness of the A380–800
airplane with that of ‘conventional large
transport airplanes.’ The ‘conventional
large transport airplane’ is not
specifically designated.’’ 1 AFA suggests
that a simple vertical crash impact is
insufficient to judge crashworthiness
and recommends that, ‘‘The impact
conditions in the Special Conditions
should reflect a representative crash
environment that includes at least both
vertical and longitudinal components.
The conditions used in the Jamshidiat
study (op. cit.) would be appropriate.’’
According to AFA, the impact
conditions studied by Jamshidiat et al.
were much more realistic and severe
than the simple vertical impact
proposed by the special condition.
AFA also discusses the Department of
Defense (DOD) Crash Protection
Handbook, which summarizes critical
findings of past crashworthiness
1 Airbus compared construction of the very large
A380 to that of the ‘‘conventional large’’ A320 and
A340 both of which are currently in production.
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48455
studies. One of those findings is of
particular concern for the A380–800
aircraft:
‘‘For larger aircraft, the earth-scooping
criteria associated with the low angle impact
of Mil–Std–1290 were shown to be
impractical. This conclusion was based on
the fact that the requirement, which was
based on G loading, would impose a severe
weight penalty on large airframes (over
approximately 20,000 pounds). The criteria
described in Mil–Std–1290 were that, ‘The
nose section shall be designed to preclude
any earth plowing and scooping tendency
when the forward 25 percent of the fuselage
has a uniformly applied local upward load of
10g and a rearward load of 4g or the ditching
loads of Mil–A–8865A, whichever is the
greatest.’ ’’
AFA states, ‘‘Because of its size, it is
doubtful if the A380–800 provides
adequate protection against earth
scooping. Earth scooping can disrupt
the continuity of the bottom of the
aircraft (e.g., the British Midlands 737
crash) and result in severe compromise
of living space, and thus of
survivability. It must be considered in
any evaluation of crashworthiness.’’
FAA response: The FAA agrees that a
simple vertical crash impact is
insufficient to judge overall
crashworthiness, because (1) there is no
agreed standard to judge an acceptable
level of crashworthiness, and (2) the
behavior of airplanes during minor
crashes is highly complex and variable.
However, that does not mean that
meaningful crashworthiness evaluations
cannot be made by isolating certain
airplane characteristics that contribute
to post crash survival, such as the
ability of a fuselage to withstand
crushing or collapse due to the vertical
forces resulting from impact with the
ground. This is the effect addressed by
the A380 special condition.
While there are many factors that may
influence the survivability of the
fuselage, the FAA considers the ability
of a fuselage to survive a vertical drop
without crushing or collapse to be a
major factor. In fact, the FAA has
conducted vertical drop testing of actual
fuselage sections for this very purpose,
that is, to determine how current
generation fuselages perform in a minor
crash landing and to identify design
features that affect their performance.
The demonstration required by this
special condition is intended to show
whether the A380, including the full
length upper deck, is able to resist
crushing or floor collapse in a vertical
drop as well as other conventional large
transport airplanes. The requirement to
conduct this demonstration does not
establish a higher level of safety for the
A380. In terms of vertical descent rate,
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it provides for equivalence to the
performance of existing large transport
airplanes.
The FAA does not agree with AFA
that the A380 analysis was overly
unrealistic or has little value, compared
to the study performed by Jamshidiat et
al. The Jamshidiat study was performed
for a different reason than this A380
special condition. Its purpose was to
assess the effect of airplane size on the
longitudinal and transverse acceleration
loads experienced by occupants. The
A380 special condition addresses the
strength of the fuselage shell and its
ability to avoid crushing due to vertical
impact loading. The Jamshidiat study
modeled the fuselage characteristics that
are relevant for evaluating the
longitudinal and transverse acceleration
loads experienced by occupants. The
A380 special condition addresses the
characteristics of the fuselage
construction that are relevant to its
ability to avoid crushing. Therefore, the
A380 special condition and the
Jamshidiat study are complementary. In
fact, the results of the Jamshidiat study
support our assumption that the
§ 25.561 longitudinal accelerations are
adequate for design of the A380 and,
therefore, do not need to be addressed
in the A380 special condition.
Finally, the FAA does not agree that
the DOD crash handbook discussion of
earth plowing/scooping indicates that it
is doubtful that the A380–800 provides
adequate protection against earth
scooping. The comparison the DOD
drew between large airplanes and small
was between 737-size airplanes
(typically greater than 140,000 pounds
gross weight) and business jet or trainer
size airplanes (typically smaller than
20,000 pounds gross weight), not
between 737-size airplanes and A380size airplanes (over 900,000 pounds
gross weight).
We do not believe that any evidence
indicates that the earth plowing/
scooping behavior of an A380-size
airplane will be more severe than for a
747-size airplane. In fact, a conclusion
of the Jamshidiat report cited by AFA
indicates that the opposite is probably
true:
‘‘The longitudinal crash deceleration was a
function of the impact slope, the condition of
the impact surface, the nature of obstacles
and the relative radius of curvature of the
fuselage cross section and the nose planform. The 747–400, with its larger radii of
curvature and greater energy absorption of
the lower fuselage structure has an inherent
advantage over the 737–400 because
obstacles do not follow scaling rules.’’
The FAA agrees with this reasoning
and by extension concludes that the
A380 will have an inherent advantage
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over the 747 and can be expected to
produce lower longitudinal crash
decelerations because of its size.
Requested change 4: The Boeing
Company suggests that the proposed
special conditions be revised or
withdrawn, stating the following:
‘‘A requirement to show equivalency to an
existing airplane is unprecedented and
beyond the scope provided for by FAR 21.16
for Special Conditions. [Section] 21.16 allows
special conditions to be issued ‘to establish
a level of safety equivalent to that established
in the regulations.’ It does not allow the FAA
to issue special conditions to achieve a level
of safety inherent in a past product design
* * * ’’
‘‘Existing Part 25 regulations already
provide for the structural integrity and
crashworthiness of the passenger cabin. To
require the determination and comparison to
other aircraft for the ‘Limit of Reasonable
Survivability’ should be addressed with
general rulemaking, as it is a general upgrade
of the requirements that should apply to all
aircraft types * * *. Since Part 25 already
contains passenger static and dynamic
survivability requirements, the upgrading of
those requirements must come through
general rulemaking and not special
conditions.’’
FAA response: The FAA does not
agree with the commenter that this
special condition is beyond the scope
provided for by 14 CFR 21.16. That
section states that
‘‘If the Administrator finds that the
airworthiness regulations of this subchapter
do not contain adequate or appropriate safety
standards for an aircraft * * * because of a
novel or unusual design feature of the aircraft
* * * he prescribes special conditions and
amendments thereto for the product. The
special conditions * * * contain such safety
standards for the aircraft * * * as the
Administrator finds necessary to establish a
level of safety equivalent to that established
in the regulations.’’
The level of safety established in the
part 25 regulations for transport
category airplanes is evidenced by the
safety record demonstrated in service by
airplanes so certificated. Although an
overall airframe crashworthiness
requirement has never been the subject
of a part 25 regulation, current
generation airplanes certificated under
part 25 have exhibited a level of
crashworthiness that the FAA considers
to be adequate. These airplanes include
those with a single deck and Boeing
Model 747 with an upper deck which is
considerably smaller (in both length and
width) than that of the A380. The
current part 25 regulations have no
doubt contributed to this level of safety,
even though no specific regulation has
addressed the performance of the
airframe in a crash landing, because the
regulations have determined the
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airframe strength, which service
experience has shown to be adequate.
The relevant novel or unusual design
`
features of the A380 vis-a-vis airframe
crashworthiness are its size, gross
weight, and full length double deck
configuration, which are without
precedent in the current commercial
transport airplane fleet. This special
condition requires a demonstration that
the A380 provides a level of crash
survivability equivalent to that of
conventional large transport airplanes.
Therefore, the FAA does not agree with
the Boeing Company that this special
condition is beyond the scope provided
for by § 21.16.
Further, the FAA does not agree that
the part 25 regulations already provide
for the structural integrity and
crashworthiness of the passenger cabin
for the Airbus A380. The existing
regulations address the seats, restraint of
passengers, equipment, cargo and other
large masses contained in the passenger
cabin and their attachment to the
airframe, so as to avoid failure of
structure which would release these
items in the cabin during a minor crash
landing and cause injury or block
emergency escape routes. They do not,
however, address the crashworthiness of
fuselage structure as a whole and its
ability to avoid collapse in a minor
crash landing.
Finally, the FAA does not consider it
necessary to address other airplane
designs with general rulemaking. It is
the unique characteristics of the A380
that motivates this special condition. No
other transport airplane is as large or
heavy as the A380 or has a full length
double deck, and, therefore, there is no
need for general rulemaking.
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 § 21.101.
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.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
I The authority citation for these
special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
E:\FR\FM\21AUR1.SGM
21AUR1
Federal Register / Vol. 71, No. 161 / Monday, August 21, 2006 / Rules and Regulations
rmajette on PROD1PC67 with RULES
The Special Conditions
I Accordingly, pursuant to the authority
delegated to me by the Administrator,
the following special condition is issued
as part of the type certification basis for
the Airbus A380–800 airplane.
In addition to the requirements of
§§ 25.561, 25.562, 25.721, and 25.785,
the following special condition applies:
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 § 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 24,
2006.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E6–13796 Filed 8–18–06; 8:45 am]
BILLING CODE 4910–13–P
VerDate Aug<31>2005
15:07 Aug 18, 2006
Jkt 208001
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM341; Special Conditions No.
25–324–SC]
Special Conditions: Airbus Model
A380–800 Airplane, Loading
Conditions for Multi-leg Landing Gear
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
SUMMARY: These special conditions are
issued 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 loading conditions for multileg landing gear. 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.
Additional special conditions will be
issued for other novel or unusual design
features of the Airbus Model A380–800
airplane.
DATES: Effective Date: The effective date
of these special conditions is July 20,
2006.
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:
Background
Airbus applied for FAA certification/
validation of the provisionallydesignated 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
PO 00000
Frm 00011
Fmt 4700
Sfmt 4700
48457
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 had
been moved from May 2005, to January
2006, to match the delivery date of the
first production airplane. In a
subsequent letter (AI/L 810.0223/98
Issue 3, dated January 27, 2006), Airbus
stated that its target date for type
certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2),
Airbus chose a new application date of
December 20, 1999, and requested that
the 7-year certification period which
had already been approved be
continued. The FAA has reviewed the
part 25 certification basis for the Model
A380–800 airplane, and no changes are
required based on the new application
date.
The Model A380–800 airplane will be
an all-new, four-engine jet transport
airplane with a full double-deck, twoaisle 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.’’
E:\FR\FM\21AUR1.SGM
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]]>Agencies
[Federal Register Volume 71, Number 161 (Monday, August 21, 2006)]
[Rules and Regulations]
[Pages 48453-48457]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-13796]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM319; Special Conditions No. 25-321-SC]
Special Conditions: Airbus Model A380-800 Airplane,
Crashworthiness
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued 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 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: Effective Date: The effective date for these special conditions
is July 24, 2006.
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:
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 had been moved from May 2005, to January 2006, to match the
delivery date of the first production airplane. In a subsequent letter
(AI/L 810.0223/98 issue 3, dated January 27, 2006), Airbus stated that
its target date for type certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2), Airbus chose a new application date
of December 20, 1999, and requested that the 7-year certification
period which had already been approved be continued. The FAA has
reviewed the
[[Page 48454]]
part 25 certification basis for the Model A380-800 airplane, and no
changes are required based on 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).
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.
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 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 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. The 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.'' The
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.
Discussion of Comments
Notice of Proposed Special Conditions No. 25-05-14-SC, pertaining
to crashworthiness requirements for the Airbus A380 airplane, was
published in the Federal
[[Page 48455]]
Register on August 9, 2005 (70 FR 46102). Comments were received from
the Airline Pilots Association (ALPA), the Association of Flight
Attendants (AFA), and the Boeing Company.
Requested change 1: ALPA addresses the first sentence in Section b.
of the special conditions which specifies that, ``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 * * *
.''
ALPA states,
``Unless there is a procedure/system in place in revenue service
that prevents the seat and bin from being loaded in excess of their
rated limit, seats and bins under the requirements of Section b. must
be tested within the full range of likely loads, not simply up to their
rated limit. Overhead bins are notorious for failing in crash scenarios
where the remainder of the cabin remains intact. In addition, the seat
requirements for testing with only a 50th percentile male should be
reconsidered to evaluate the full range of occupants, or at least the
5th to 95th percentile of humans.''
FAA response: Accommodating the changes requested by ALPA would be
beyond the scope of this rulemaking. The purpose of the special
condition is to assure that the large size and full length double deck
configuration of the A380 design do not degrade the survivability
characteristics of the A380 fuselage shell compared to designs for
conventional large transport category airplanes. The purpose is not to
create a higher safety standard for the A380.
To accomplish a proper comparison, the mass of items and the weight
of passengers are defined in the same way as they would be for
conventional airplane designs. Overhead bins are required to be
evaluated for the rated bin load, and seats are required to be
evaluated for the mass of a 50th percentile male occupant. To adopt a
procedure to prevent a seat or bin from being loaded in excess of its
rated design or to adopt a higher passenger weight for the evaluation
of seat strength would represent a difference from the certification
criteria used for conventional large transport category airplane
designs.
Since the A380 is not unique or unusual with regard to these
certification criteria, the requested changes are considered to be
beyond the scope of this rulemaking. Accordingly, we have made no
changes to the special conditions, as proposed.
Requested change 2: AFA recommends deleting Section c. of the
special condition and all reference to use of the DRI as a measure of
``physiological limits'' of a crash. Instead, AFA suggests relying on
Sections a., b., and d. for demonstrations of survivability.
AFA supports its recommendation with a detailed analysis of the
development and use of the DRI and reaches the following conclusion:
``The DRI is useful, preferably with other criteria, to predict
minor to moderate injury in ejection seats with occupants who are
well restrained in the vertically seated posture, and possibly in
crashes. The DRI has never shown the ability to predict survival (or
anything else) in a crash that could cause severe but not fatal
injury.''
FAA response: The DRI is being used as a metric to compare the
occupant dynamic response in the Model A380 with that in other airplane
designs; it is not being used as a criterion of injury. Section c. of
the special condition states that the ``Dynamic Response Index
experienced by the occupants will be no more severe than that
experienced on conventional large transport airplanes.'' This
comparison does not involve establishing an injury criterion for DRI.
The FAA considers the DRI to be an appropriate metric for the
comparative analysis required by the special condition. Since it is
only the vertical loading that is simulated in the analysis, the one
degree of freedom spring-mass model on which DRI is based is acceptable
to the FAA. Accordingly, no change has been made to Section c. of the
special condition, as proposed.
Requested change 3: AFA states, ``The proposed special condition[s]
envision a simple vertical impact as the environment to compare the
crashworthiness of the A380-800 airplane with that of `conventional
large transport airplanes.' The `conventional large transport airplane'
is not specifically designated.'' \1\ AFA suggests that a simple
vertical crash impact is insufficient to judge crashworthiness and
recommends that, ``The impact conditions in the Special Conditions
should reflect a representative crash environment that includes at
least both vertical and longitudinal components. The conditions used in
the Jamshidiat study (op. cit.) would be appropriate.'' According to
AFA, the impact conditions studied by Jamshidiat et al. were much more
realistic and severe than the simple vertical impact proposed by the
special condition.
---------------------------------------------------------------------------
\1\ Airbus compared construction of the very large A380 to that
of the ``conventional large'' A320 and A340 both of which are
currently in production.
---------------------------------------------------------------------------
AFA also discusses the Department of Defense (DOD) Crash Protection
Handbook, which summarizes critical findings of past crashworthiness
studies. One of those findings is of particular concern for the A380-
800 aircraft:
``For larger aircraft, the earth-scooping criteria associated
with the low angle impact of Mil-Std-1290 were shown to be
impractical. This conclusion was based on the fact that the
requirement, which was based on G loading, would impose a severe
weight penalty on large airframes (over approximately 20,000
pounds). The criteria described in Mil-Std-1290 were that, `The nose
section shall be designed to preclude any earth plowing and scooping
tendency when the forward 25 percent of the fuselage has a uniformly
applied local upward load of 10g and a rearward load of 4g or the
ditching loads of Mil-A-8865A, whichever is the greatest.' ''
AFA states, ``Because of its size, it is doubtful if the A380-800
provides adequate protection against earth scooping. Earth scooping can
disrupt the continuity of the bottom of the aircraft (e.g., the British
Midlands 737 crash) and result in severe compromise of living space,
and thus of survivability. It must be considered in any evaluation of
crashworthiness.''
FAA response: The FAA agrees that a simple vertical crash impact is
insufficient to judge overall crashworthiness, because (1) there is no
agreed standard to judge an acceptable level of crashworthiness, and
(2) the behavior of airplanes during minor crashes is highly complex
and variable. However, that does not mean that meaningful
crashworthiness evaluations cannot be made by isolating certain
airplane characteristics that contribute to post crash survival, such
as the ability of a fuselage to withstand crushing or collapse due to
the vertical forces resulting from impact with the ground. This is the
effect addressed by the A380 special condition.
While there are many factors that may influence the survivability
of the fuselage, the FAA considers the ability of a fuselage to survive
a vertical drop without crushing or collapse to be a major factor. In
fact, the FAA has conducted vertical drop testing of actual fuselage
sections for this very purpose, that is, to determine how current
generation fuselages perform in a minor crash landing and to identify
design features that affect their performance.
The demonstration required by this special condition is intended to
show whether the A380, including the full length upper deck, is able to
resist crushing or floor collapse in a vertical drop as well as other
conventional large transport airplanes. The requirement to conduct this
demonstration does not establish a higher level of safety for the A380.
In terms of vertical descent rate,
[[Page 48456]]
it provides for equivalence to the performance of existing large
transport airplanes.
The FAA does not agree with AFA that the A380 analysis was overly
unrealistic or has little value, compared to the study performed by
Jamshidiat et al. The Jamshidiat study was performed for a different
reason than this A380 special condition. Its purpose was to assess the
effect of airplane size on the longitudinal and transverse acceleration
loads experienced by occupants. The A380 special condition addresses
the strength of the fuselage shell and its ability to avoid crushing
due to vertical impact loading. The Jamshidiat study modeled the
fuselage characteristics that are relevant for evaluating the
longitudinal and transverse acceleration loads experienced by
occupants. The A380 special condition addresses the characteristics of
the fuselage construction that are relevant to its ability to avoid
crushing. Therefore, the A380 special condition and the Jamshidiat
study are complementary. In fact, the results of the Jamshidiat study
support our assumption that the Sec. 25.561 longitudinal accelerations
are adequate for design of the A380 and, therefore, do not need to be
addressed in the A380 special condition.
Finally, the FAA does not agree that the DOD crash handbook
discussion of earth plowing/scooping indicates that it is doubtful that
the A380-800 provides adequate protection against earth scooping. The
comparison the DOD drew between large airplanes and small was between
737-size airplanes (typically greater than 140,000 pounds gross weight)
and business jet or trainer size airplanes (typically smaller than
20,000 pounds gross weight), not between 737-size airplanes and A380-
size airplanes (over 900,000 pounds gross weight).
We do not believe that any evidence indicates that the earth
plowing/scooping behavior of an A380-size airplane will be more severe
than for a 747-size airplane. In fact, a conclusion of the Jamshidiat
report cited by AFA indicates that the opposite is probably true:
``The longitudinal crash deceleration was a function of the
impact slope, the condition of the impact surface, the nature of
obstacles and the relative radius of curvature of the fuselage cross
section and the nose plan-form. The 747-400, with its larger radii
of curvature and greater energy absorption of the lower fuselage
structure has an inherent advantage over the 737-400 because
obstacles do not follow scaling rules.''
The FAA agrees with this reasoning and by extension concludes that
the A380 will have an inherent advantage over the 747 and can be
expected to produce lower longitudinal crash decelerations because of
its size.
Requested change 4: The Boeing Company suggests that the proposed
special conditions be revised or withdrawn, stating the following:
``A requirement to show equivalency to an existing airplane is
unprecedented and beyond the scope provided for by FAR 21.16 for
Special Conditions. [Section] 21.16 allows special conditions to be
issued `to establish a level of safety equivalent to that
established in the regulations.' It does not allow the FAA to issue
special conditions to achieve a level of safety inherent in a past
product design * * * ''
``Existing Part 25 regulations already provide for the
structural integrity and crashworthiness of the passenger cabin. To
require the determination and comparison to other aircraft for the
`Limit of Reasonable Survivability' should be addressed with general
rulemaking, as it is a general upgrade of the requirements that
should apply to all aircraft types * * *. Since Part 25 already
contains passenger static and dynamic survivability requirements,
the upgrading of those requirements must come through general
rulemaking and not special conditions.''
FAA response: The FAA does not agree with the commenter that this
special condition is beyond the scope provided for by 14 CFR 21.16.
That section states that
``If the Administrator finds that the airworthiness regulations
of this subchapter do not contain adequate or appropriate safety
standards for an aircraft * * * because of a novel or unusual design
feature of the aircraft * * * he prescribes special conditions and
amendments thereto for the product. The special conditions * * *
contain such safety standards for the aircraft * * * as the
Administrator finds necessary to establish a level of safety
equivalent to that established in the regulations.''
The level of safety established in the part 25 regulations for
transport category airplanes is evidenced by the safety record
demonstrated in service by airplanes so certificated. Although an
overall airframe crashworthiness requirement has never been the subject
of a part 25 regulation, current generation airplanes certificated
under part 25 have exhibited a level of crashworthiness that the FAA
considers to be adequate. These airplanes include those with a single
deck and Boeing Model 747 with an upper deck which is considerably
smaller (in both length and width) than that of the A380. The current
part 25 regulations have no doubt contributed to this level of safety,
even though no specific regulation has addressed the performance of the
airframe in a crash landing, because the regulations have determined
the airframe strength, which service experience has shown to be
adequate.
The relevant novel or unusual design features of the A380 vis-
[agrave]-vis airframe crashworthiness are its size, gross weight, and
full length double deck configuration, which are without precedent in
the current commercial transport airplane fleet. This special condition
requires a demonstration that the A380 provides a level of crash
survivability equivalent to that of conventional large transport
airplanes. Therefore, the FAA does not agree with the Boeing Company
that this special condition is beyond the scope provided for by Sec.
21.16.
Further, the FAA does not agree that the part 25 regulations
already provide for the structural integrity and crashworthiness of the
passenger cabin for the Airbus A380. The existing regulations address
the seats, restraint of passengers, equipment, cargo and other large
masses contained in the passenger cabin and their attachment to the
airframe, so as to avoid failure of structure which would release these
items in the cabin during a minor crash landing and cause injury or
block emergency escape routes. They do not, however, address the
crashworthiness of fuselage structure as a whole and its ability to
avoid collapse in a minor crash landing.
Finally, the FAA does not consider it necessary to address other
airplane designs with general rulemaking. It is the unique
characteristics of the A380 that motivates this special condition. No
other transport airplane is as large or heavy as the A380 or has a full
length double deck, and, therefore, there is no need for general
rulemaking.
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.
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.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
[[Page 48457]]
The Special Conditions
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Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special condition is issued 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 condition applies:
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 24, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E6-13796 Filed 8-18-06; 8:45 am]
BILLING CODE 4910-13-P
