Special Conditions: Boeing Model 787-8 Airplane; Crashworthiness, 54531-54533 [E7-18942]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 72, Number 186 (Wednesday, September 26, 2007)]
[Rules and Regulations]
[Pages 54531-54533]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-18942]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM368 Special Conditions No. 25-362-SC]


Special Conditions: Boeing Model 787-8 Airplane; Crashworthiness

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: The FAA issues these special conditions for the Boeing Model 
787-8 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. These novel 
or unusual design features are associated with carbon fiber reinforced 
plastic used in the construction of the fuselage. For these design 
features, the applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for impact response 
characteristics to ensure survivable crashworthiness. 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 standards. We will issue 
additional special conditions for other novel or unusual design 
features of the Boeing Model 787-8 airplanes.

DATES: Effective Date: October 26, 2007.

FOR FURTHER INFORMATION CONTACT: Ian Won, FAA, Airframe/Cabin Safety, 
ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 
telephone (425) 227-2145; facsimile (425) 227-1320.

SUPPLEMENTARY INFORMATION:

Background

    On March 28, 2003, Boeing applied for an FAA type certificate for 
its new Boeing Model 787-8 passenger airplane. The Boeing Model 787-8 
airplane will be an all-new, two-engine jet transport airplane with a 
two-aisle cabin. The maximum takeoff weight will be 476,000 pounds, 
with a maximum passenger count of 381 passengers.

Type Certification Basis

    Under provisions of Title 14 Code of Federal Regulations (CFR) 
21.17, Boeing must show that Boeing Model 787-8 airplanes (hereafter 
referred to as ``the 787'') meet the applicable provisions of 14 CFR 
part 25, as amended by Amendments 25-1 through 25-117, except 
Sec. Sec.  25.809(a) and 25.812, which will remain at Amendment 25-115. 
If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the 787 because of a novel or unusual design feature, special 
conditions are prescribed under provisions of 14 CFR 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the 787 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. The FAA must also issue a finding of regulatory 
adequacy under section 611 of Public Law 92-574, the ``Noise Control 
Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, 
under Sec.  11.38, and they become part of the type certification basis 
under Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.

Novel or Unusual Design Features

    The 787 airplane will incorporate several novel or unusual design 
features. Because of rapid improvements in airplane technology, the 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. These special 
conditions for the 787 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.
    The 787 fuselage will be fabricated with carbon fiber reinforced 
plastic (CFRP) semi-monocoque construction, consisting of skins with 
co-cured longitudinal stringers and mechanically fastened 
circumferential frames. This is a novel and unusual design feature for 
a large transport category airplane certificated under 14 CFR part 25. 
Structure fabricated from CFRP may behave differently than metallic 
structure because of differences in material ductility, stiffness, 
failure modes, and energy absorption characteristics. Therefore, Boeing 
must evaluate impact response characteristics of the 787 to ensure that 
its survivable crashworthiness characteristics provide approximately 
the same level of safety as those of a similarly sized airplane 
fabricated from traditionally used metallic materials.
    The FAA and industry have been working together for many years to 
understand how to improve transport airplane occupant safety for what 
are considered survivable accidents. This work has involved examining 
airplane accidents, conducting tests to simulate crash conditions, and 
performing analytical modeling of a range of crash conditions, all with 
the purpose of providing further insight into factors that can 
influence occupant safety. Results of this continuing effort have 
enabled specific changes to regulatory standards and design practices 
to improve occupant safety. This evolution is reflected in changes to 
the part 25 Emergency Landing Conditions regulations. For example, 
airplane emergency load factors in Sec.  25.561, General, have been 
increased. We have added passenger seat dynamic load conditions in 
Sec.  25.562, Emergency Landing Dynamic Conditions.
    The seat dynamic conditions were added to the regulations based on 
FAA and industry tests and a review of accidents. These seat dynamic 
conditions reflect the environment for passengers and the airframe 
during a crash event. They are based on data gathered from accidents of 
previously certificated airplanes given conditions that were 
survivable. Tests of previously certificated airplanes showed that 
performance of the airframe was acceptable in a survivable crash event. 
We continually update our requirements as such new information becomes 
available. In the context of this evolution of the regulations, there 
is at present no specific dynamic regulatory requirement for airplane-
level crashworthiness. However, the FAA reviews the design of each new 
airplane model to determine if it incorporates novel or unusual design 
features that may have a significant influence on the crash dynamics of 
the airframe. The Administrator prescribes special conditions for the 
airplane model if the applicable airworthiness regulations do not 
contain adequate or appropriate safety standards because of the novel 
or unusual design feature.
    Because of the novel design features of the 787, Boeing must 
conduct an assessment to ensure that the 787 will not have dynamic 
characteristics that differ significantly from those found in 
previously certificated designs. The nature of this design assessment 
is largely dependent on the similarities and differences between the 
new type design and previously certificated airplanes. Such an 
assessment ensures that the level of safety of the new type

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design is commensurate with that implicitly assumed in the existing 
regulations, and achieved by airplane designs previously certificated. 
If significant trends in industry warrant change to the existing 
regulations, the FAA may use its rulemaking process in collaboration 
with industry to develop an appropriate dynamic regulatory requirement 
for airplane level crashworthiness.
    The FAA and industry have collected a significant amount of 
experimental data as well as data from crashes of transport category 
airplanes that shows a high occupant survival rate at vertical descent 
velocities up to 30 ft/sec. Most of this data was collected on narrow-
body (single aisle) transport category airplanes. Based on this 
information, the FAA finds it appropriate and necessary for an 
assessment of the 787 to span a range of airplane vertical descent 
speeds up to 30 ft/sec.
    The FAA is imposing these special conditions to maintain the level 
of safety envisioned in the existing airworthiness standards under 
foreseeable survivable impact events.

Discussion of Final Special Conditions

    To provide the same level of safety as exists with conventional 
airplane construction, Boeing must show that the 787 has sufficient 
crashworthiness capabilities under foreseeable survivable impact 
events. To show this, Boeing will have to evaluate the impact response 
characteristics of the 787 to ensure that its crashworthiness 
characteristics are not significantly different from those of a 
similarly sized airplane built from traditionally used metals. If the 
evaluation shows that the 787 impact response characteristics are 
significantly different, Boeing will have to make design changes to 
bring the different impact response characteristics in line with those 
of a similarly sized metal construction airplane, or incorporate 
mitigating design features.
    Factors in crash survivability are retention of items of mass, 
maintenance of occupant emergency egress paths, maintenance of 
acceptable acceleration and loads experienced by the occupants, and 
maintenance of a survivable volume. The FAA has reviewed available data 
from accidents, tests simulating crash conditions, and analytical 
modeling of a range of crash conditions. From this information we have 
concluded that airplane performance should be evaluated over a range of 
airplane level vertical impact speeds up to 30 ft/sec.
    If the 787 impact characteristics differ significantly from those 
of a previously certificated wide body transport, this will result in a 
need to meet load factors higher than those defined in 14 CFR 25.561. 
The higher load factors will be necessary in order to maintain the same 
level of safety for the occupants, in terms of retention of items of 
mass. In the case of acceleration and loads experienced by the 
occupants, means would have to be incorporated to reduce load levels 
experienced by those occupants to the injury criteria levels of Sec.  
25.562, or load levels of a previously certificated comparable 
airplane, in order to maintain the same level of safety for the 
occupants.

Discussion of Comments

    Notice of Proposed Special Conditions No. 25-07-05-SC for the 787 
was published in the Federal Register on June 11, 2007 (72 FR 32021). 
Several comments were received from two commenters.
    First Commenter: The commenter, a member of the public, provided 
suggestions and comments related to the subject of crash simulation 
structural analysis as it pertains to the applicant's demonstration of 
compliance to these special conditions. This commenter agreed with the 
intent of the special conditions. However, he suggested that they be 
expanded or new special conditions developed to require a full fuselage 
fuel fed fire test to address possible fire, smoke, and toxicity (FST) 
hazards that may be associated with use of carbon fiber epoxy structure 
on the 787.
    The commenter recommended that the special conditions include a 
requirement for a full scale drop test with a forward velocity vector 
to simulate a condition representative of a wheels-up landing, with the 
resultant vector sum of the vertical and longitudinal velocity 
components being included to assess the loads on the passengers and 
crew.
    FAA Response: We agree that fuselage post-crash fire survivability 
of the 787, including FST hazards that may be associated with use of 
carbon fiber epoxy structure, is an important issue. This issue is 
outside the scope of these special conditions, however. It is being 
addressed in conjunction with the requirements for Sec.  25.856(b) 
relating to fuselage fire penetration protection.
    The FAA considered longitudinal loading conditions as well as 
combined longitudinal and vertical loading conditions of the 787 
airframe under survivable crash conditions and emergency landing 
conditions with various landing gear configurations (wheels up 
configurations). The factors (principally deformation, mass, and 
friction) that govern impact response characteristics in the 
longitudinal direction are not significantly altered with the change 
from metallic to composite fuselage structure. Given the similarity of 
the 787 to the current fleet with respect to these conditions, the FAA 
has determined that these special conditions will be limited to an 
assessment of the 787 for the vertical impact direction.
    With respect to the commenter's suggestions on the specific method 
of compliance, the FAA does not mandate a specific method of compliance 
for the requirements specified. The applicant is responsible for 
demonstrating compliance with these special conditions.
    Second Commenter: This commenter, also a member of the public, 
suggested that the FAA conduct the crash impact testing necessary to 
show that the 787 meets these special conditions. He suggested that 
requirements for demonstrating compliance with the crashworthiness 
special conditions should consist of a drop test of a fuselage section 
of the 787 from a height of 14 feet onto concrete with an impact 
velocity of approximately 30 feet per second. The commenter suggested 
that the criteria of these special conditions should be that the 787 
demonstrate the same level of vertical impact shock-absorption 
capability as demonstrated by an FAA-sponsored drop test of a Boeing 
737 fuselage section conducted in 2000. This commenter also suggested 
that the special conditions be expanded to address post-crash fire 
survivability of the 787 in the post-impact damaged state. He provided 
suggestions and comments related to means of compliance to these 
special conditions, and also some comments on issues outside the scope 
of these special conditions.
    FAA Response: The Administrator prescribes special conditions 
necessary to establish a level of safety equivalent to that established 
by the existing airworthiness standards. The requirements of these 
special conditions were prescribed to ensure that the 787 provides an 
equivalent level of occupant safety and survivability under foreseeable 
survivable impact events to that provided by previously certificated 
wide-body transports of similar size.
    These special conditions do not mandate a specific method of 
compliance for the requirements specified. The applicant is responsible 
for demonstrating compliance with these special conditions. The FAA's 
role is to verify that the special conditions have been complied with, 
rather than to develop a method for compliance. While there are merits 
in conducting a

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full-scale test, there are other approaches using tests and analysis 
that can actually yield more data than would a single test. Thus, we 
consider it more effective to establish the standards and encourage the 
applicant to develop the most effective method of compliance.
    The FAA agrees that fuselage post-crash fire survivability of the 
787, including FST hazards that may be associated with use of carbon 
fiber epoxy structure, is an important issue. This issue is outside the 
scope of these special conditions, however. It is being addressed in 
conjunction with the requirements for Sec.  25.856(b) relating to 
fuselage fire penetration protection.
    These special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
787. Should Boeing apply at a later date for a change to the type 
certificate to include another model on the same type certificate 
incorporating the same novel or unusual design features, these special 
conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
of the 787. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.
    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The 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 Boeing Model 787-8 airplane.
    The Boeing Model 787-8 must provide an equivalent level of occupant 
safety and survivability to that provided by previously certificated 
wide-body transports of similar size under foreseeable survivable 
impact events for the following four criteria. In order to demonstrate 
an equivalent level of occupant safety and survivability, the applicant 
must demonstrate that the Model 787-8 meets the following criteria for 
a range of airplane vertical descent velocities up to 30 ft/sec.
    1. Retention of items of mass. The occupants, i.e., passengers, 
flight attendants, and flightcrew, must be protected during the impact 
event from release of seats, overhead bins, and other items of mass due 
to the impact loads and resultant structural deformation of the 
supporting airframe and floor structures. The applicant must show that 
loads due to the impact event and resultant structural deformation of 
the supporting airframe and floor structure at the interface of the 
airplane structure to seats, overhead bins, and other items of mass are 
comparable to those of previously certificated wide-body transports of 
similar size for the range of descent velocities stated above. The 
attachments of these items need not be designed for static emergency 
landing loads in excess of those defined in Sec.  25.561 if impact 
response characteristics of the Boeing Model 787-8 yield load factors 
at the attach points that are comparable to those for a previously 
certificated wide-body transport category airplane.
    2. Maintenance of acceptable acceleration and loads experienced by 
the occupants. The applicant must show that the impact response 
characteristics of the Boeing Model 787-8, specifically the vertical 
acceleration levels experienced at the seat/floor interface and loads 
experienced by the occupants during the impact events, are consistent 
with those found in Sec.  25.562(b) or with levels expected for a 
previously certificated wide-body transport category airplane for the 
conditions stated above.
    3. Maintenance of a survivable volume. For the conditions stated 
above, the applicant must show that all areas of the airplane occupied 
for takeoff and landing provide a survivable volume comparable to that 
of previously certificated wide-body transports of similar size during 
and after the impact event. This means that structural deformation will 
not result in infringement of the occupants' normal living space so 
that passenger survivability will not be significantly affected.
    4. Maintenance of occupant emergency egress paths. The evacuation 
of occupants must be comparable to that from a previously certificated 
wide-body transport of similar size. To show this, the applicant must 
show that the suitability of the egress paths, as determined following 
the vertical impact events, is comparable to the suitability of the 
egress paths of a comparable, certificated wide-body transport, as 
determined following the same vertical impact events.

    Issued in Renton, Washington, on September 14, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-18942 Filed 9-25-07; 8:45 am]
BILLING CODE 4910-13-P