[Federal Register Volume 71, Number 161 (Monday, August 21, 2006)]
[Rules and Regulations]
[Pages 48453-48457]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-13796]


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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.

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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.
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    \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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    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

0
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]
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