Special Conditions: Boeing Model 787-8 Airplane; Composite Wing and Fuel Tank Structure-Fire Protection Requirements, 57844-57848 [E7-20031]
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Federal Register / Vol. 72, No. 196 / Thursday, October 11, 2007 / Rules and Regulations
• ALPA Comment re Special
Condition (8): Finally, ALPA
commented on monitoring and warning
features that will indicate when the
state-of-charge of the batteries has fallen
below levels considered acceptable for
dispatch of the airplane. The commenter
suggested that the special conditions
address the location of the warning
indication; whether it is displayed to
the captain, the crew, or both; and the
training to be incorporated in the crew
training programs.
FAA Response: Flight deck warning
indicators associated with the state-ofcharge of the lithium ion battery and
appropriate training of the crew will be
addressed during certification as part of
the flight deck evaluation. As required
by § 25.1309(c), this evaluation will
ensure that the warning indication is
effective and appropriate for the hazard.
We made no change as a result of this
comment.
These special conditions are issued 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.
In lieu of the requirements of 14 CFR
25.1353(c)(1) through (c)(4), the
following special conditions apply.
Lithium ion batteries on the Boeing
Model 787–8 airplane must be designed
and installed as follows:
(1) Safe cell temperatures and
pressures must be maintained during
any foreseeable charging or discharging
condition and during any failure of the
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I
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charging or battery monitoring system
not shown to be extremely remote. The
lithium ion battery installation must
preclude explosion in the event of those
failures.
(2) Design of the lithium ion batteries
must preclude the occurrence of selfsustaining, uncontrolled increases in
temperature or pressure.
(3) No explosive or toxic gases
emitted by any lithium ion battery in
normal operation, or as the result of any
failure of the battery charging system,
monitoring system, or battery
installation not shown to be extremely
remote, may accumulate in hazardous
quantities within the airplane.
(4) Installations of lithium ion
batteries must meet the requirements of
14 CFR 25.863(a) through (d).
(5) No corrosive fluids or gases that
may escape from any lithium ion battery
may damage surrounding structure or
any adjacent systems, equipment, or
electrical wiring of the airplane in such
a way as to cause a major or more severe
failure condition, in accordance with 14
CFR 25.1309(b) and applicable
regulatory guidance.
(6) Each lithium ion battery
installation must have provisions to
prevent any hazardous effect on
structure or essential systems caused by
the maximum amount of heat the
battery can generate during a short
circuit of the battery or of its individual
cells.
(7) Lithium ion battery installations
must have a system to control the
charging rate of the battery
automatically, so as to prevent battery
overheating or overcharging, and,
(i) A battery temperature sensing and
over-temperature warning system with a
means for automatically disconnecting
the battery from its charging source in
the event of an over-temperature
condition, or,
(ii) A battery failure sensing and
warning system with a means for
automatically disconnecting the battery
from its charging source in the event of
battery failure.
(8) Any lithium ion battery
installation whose function is required
for safe operation of the airplane must
incorporate a monitoring and warning
feature that will provide an indication
to the appropriate flight crewmembers
whenever the state-of-charge of the
batteries has fallen below levels
considered acceptable for dispatch of
the airplane.
(9) The Instructions for Continued
Airworthiness required by 14 CFR
25.1529 must contain maintenance
requirements for measurements of
battery capacity at appropriate intervals
to ensure that batteries whose function
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is required for safe operation of the
airplane will perform their intended
function as long as the battery is
installed in the airplane. The
Instructions for Continued
Airworthiness must also contain
procedures for the maintenance of
lithium ion batteries in spares storage to
prevent the replacement of batteries
whose function is required for safe
operation of the airplane with batteries
that have experienced degraded charge
retention ability or other damage due to
prolonged storage at a low state of
charge.
Note: These special conditions are not
intended to replace 14 CFR 25.1353(c) in the
certification basis of the Boeing 787–8
airplane. These special conditions apply only
to lithium ion batteries and their
installations. The requirements of 14 CFR
25.1353(c) remain in effect for batteries and
battery installations of the Boeing 787–8
airplane that do not use lithium ion batteries.
Issued in Renton, Washington, on
September 28, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E7–19980 Filed 10–10–07; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM366 Special Conditions No.
25–348–SC]
Special Conditions: Boeing Model 787–
8 Airplane; Composite Wing and Fuel
Tank Structure—Fire Protection
Requirements
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
SUMMARY: These special conditions are
issued 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
composite materials chosen for the
construction of the fuel tank skin and
structure. For these design features, the
applicable airworthiness regulations do
not contain adequate or appropriate
safety standards for wing and fuel tank
structure with respect to postcrash fire
safety. These special conditions contain
the additional safety standards that the
Administrator considers necessary to
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Federal Register / Vol. 72, No. 196 / Thursday, October 11, 2007 / Rules and Regulations
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: November 13,
2007.
FOR FURTHER INFORMATION CONTACT:
Mike Dostert, FAA, Propulsion/
Mechanical Systems, ANM–112,
Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind
Avenue, SW., Renton, Washington
98057–3356; telephone (425) 227–2132;
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.
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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 §§ 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 § 11.38,
and they become part of the type
certification basis under § 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
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conditions would also apply to the other
model under § 21.101.
Novel or Unusual Design Features
The 787 will incorporate a number of
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 will be the first large
transport category airplane not built
mainly with aluminum materials for the
fuel tank structure. Instead it will use
chiefly composite materials for the
structural elements and skin of the
wings and fuel tanks. Conventional
airplanes with aluminum skin and
structure provide a well understood
level of safety during postcrash fires
with respect to fuel tanks. This is based
on service history and extensive fullscale fire testing. Composites may or
may not have capabilities equivalent to
aluminum, and current regulations do
not provide objective performance
requirements for wing and fuel tank
structure with respect to postcrash fire
safety. Use of composite structure is
new and novel compared to the designs
envisioned when the applicable
regulations were written. Because of
this, Boeing must present additional
confirmation by test and analysis that
the 787 provides an acceptable level of
safety with respect to the performance
of the wings and fuel tanks during an
external fuel-fed fire.
Although the FAA has previously
approved fuel tanks made of composite
materials that are located in the
horizontal stabilizer of some airplanes,
the composite wing structure of the 787
will introduce a new fuel tank
construction into service. Advisory
Circular (AC) 20–107A, Composite
Aircraft Structure, under the topic of
flammability, states: ‘‘The existing
requirements for flammability and fire
protection of aircraft structure attempt
to minimize the hazard to the occupants
in the event ignition of flammable fluids
or vapors occurs. The use of composite
structure should not decrease this
existing level of safety.’’ The relevance
to the wing structure is that postcrash
fire passenger survivability is dependent
on the time available for passenger
evacuation before fuel tank breach or
structural failure. Structural failure can
be a result of degradation in loadcarrying capability in the upper or lower
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57845
wing surface caused by a fuel-fed
ground fire. Structural failure can also
be a result of over-pressurization caused
by ignition of fuel vapors in the fuel
tank.
The FAA has historically developed
rules with the assumption that the
material of construction for wing and
fuselage would be aluminum. As a
representative case, § 25.963 was
developed because of a large fuel-fed
fire following the failures of fuel tank
access doors caused by uncontained
engine failures. During the subsequent
Aviation Rulemaking Advisory
Committee (ARAC) harmonization
process with the JAA,1 the structures
group tried to harmonize the
requirements of § 25.963 for impact and
fire resistance of fuel tank access panels.
Both authorities recognized that existing
aluminum wing structure provided an
acceptable level of safety. Further
rulemaking has not yet been pursued.
As with previous Boeing airplane
designs with underwing mounted
engines, the wing tanks and center tanks
are located in proximity to the
passengers and near the engines.
Experience indicates postcrash
survivability is greatly influenced by the
size and intensity of any fire that occurs.
The ability of aluminum wing surfaces
wetted by fuel on their interior surface
to withstand postcrash fire conditions
has been shown by tests conducted at
the FAA Technical Center. These tests
have verified adequate dissipation of
heat across wetted aluminum fuel tank
surfaces so that localized hot spots do
not occur, thus minimizing the threat of
explosion. This inherent capability of
aluminum to dissipate heat also allows
the wing lower surface to retain its load
carrying characteristics during a fuel-fed
ground fire. It significantly delays wing
collapse or burn-through for a time
interval that usually exceeds evacuation
times. In addition, as an aluminum fuel
tank is heated with significant
quantities of fuel inside, fuel vapor
accumulates in the ullage space,
exceeding the upper flammability limit
relatively quickly and thus reducing the
threat of a fuel tank explosion prior to
fuel tank burn-through. Service history
of conventional aluminum airplanes has
shown that fuel tank explosions caused
1 The JAA is the Joint Aviation Authority of
Europe and the JAR is its Joint Aviation
Requirements, the equivalent of our Federal
Aviation Regulations. In 2003, the European
Aviation Safety Agency (EASA) was formed, and
EASA is now the principal aviation regulatory
agency in Europe. We intend to work with EASA
to ensure that our rules are also harmonized with
its Certification Specifications (CS). But since these
efforts in developing harmonization of § 25.963
occurred before EASA was formed, it was the JAA
that was involved with them.
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by ground fires have been rare on
airplanes configured with flame
arrestors in the fuel tank vent lines. Fuel
tanks constructed with composite
materials may or may not have
equivalent capability.
Current regulations were developed
and have evolved under the assumption
that wing construction would be of
aluminum materials, which provide
inherent properties. Current regulations
may not be adequate when applied to
airplanes constructed of different
materials.
Aluminum has the following
properties with respect to fuel tanks and
fuel-fed external fires.
• Aluminum is highly thermally
conductive. It readily transmits the heat
of a fuel-fed external fire to fuel in the
tank. This has the benefit of rapidly
driving the fuel tank ullage to exceed
the upper flammability limit prior to
burn-through of the fuel tank skin or
heating of the wing upper surface above
the auto-ignition temperature. This
greatly reduces the threat of fuel tank
explosion.
• Aluminum panels at thicknesses
previously used in wing lower surfaces
of large transport category airplanes
have been fire resistant as defined in 14
CFR part 1 and AC 20–135.
• The heat absorption capacity of
aluminum and fuel will prevent burnthrough or wing collapse for a time
interval that will generally exceed the
passenger evacuation time.
The extensive use of composite
materials in the design of the 787 wing
and fuel tank structure is considered a
major change from conventional and
traditional methods of construction.
This will be the first large transport
category airplane to be certificated with
this level of composite material for these
purposes. The applicable airworthiness
regulations do not contain specific
standards for postcrash fire safety
performance of wing and fuel tank skin
or structure.
Discussion of Special Conditions
In order to provide the same level of
safety as exists with conventional
airplane construction, Boeing must
demonstrate that the 787 has sufficient
postcrash survivability to enable
occupants to safely evacuate in the
event that the wings are exposed to a
large fuel-fed fire. Factors in fuel tank
survivability are the structural integrity
of the wing and tank, flammability of
the tank, burn-through resistance of the
wing skin, and the presence of autoignition threats during exposure to a
fire. The FAA assessed postcrash
survival time during the adoption of
Amendment 25–111 for fuselage burn-
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through protection. Studies conducted
by and on behalf of the FAA indicated
that, following a survivable accident,
prevention of fuselage burn-through for
approximately 5 minutes can
significantly enhance survivability. (See
report numbers DOT/FAA/AR–99/57
and DOT/FAA/AR–02/49.) There is
little benefit in requiring the design to
prevent wing skin burn-through beyond
five minutes, due to the effects of the
fuel fire itself on the rest of the airplane.
That assessment was carried out based
on accidents involving airplanes with
conventional fuel tanks, and
considering the ability of ground
personnel to rescue occupants. In
addition, AC 20–135 indicates that,
when aluminum is used for fuel tanks,
the tank should withstand the effects of
fire for 5 minutes without failure.
Therefore, to be consistent with existing
capability and related requirements, the
787 fuel tanks must be capable of
resisting a postcrash fire for at least 5
minutes. In demonstrating compliance,
Boeing must address a range of fuel
loads from minimum to maximum, as
well as any other critical fuel load.
Discussion of Comments
Notice of Proposed Special
Conditions No. 25–07–03–SC for the
787 was published in the Federal
Register on April 9, 2007 (72 FR 17441).
Two comments were received from the
Air Line Pilots Association,
International (ALPA), two from Airbus,
and several from members of the public.
Comment 1—Air Line Pilots
Association (ALPA). The Air Line Pilots
Association, International questioned
whether the 787 will be required to
comply with any and all rules related to
fuel tank inerting/flammability
requirements of 14 CFR parts 25 and
121 and the guidance in Advisory
Circular 25.981–2A.
FAA Response. The 787 will be
required to meet the current
requirements for the certification basis
of the airplane that include fuel vapor
flammability standards, and we will be
proposing additional requirements
within special conditions for a nitrogen
inerting system. The certification basis
for the 787 includes Amendment 25–
102, which includes the § 25.981(c)
requirement for minimization of fuel
tank flammability. In the preamble to
Amendment 25–102 we described the
intended level of flammability to be
equivalent to an unheated aluminum
wing fuel tank. The composite fuel tank
structure of the 787 does not inherently
meet this flammability standard because
of the difference in thermal conductivity
between composite materials and
aluminum. Boeing has proposed a
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design that includes a nitrogen inerting
system to meet the flammability
standard. Because of this novel and
unique feature that provides nitrogen
enriched air to all fuel tanks, we will be
publishing proposed special conditions
for public comment.
We have made no changes to these
special conditions as a result of this
comment.
Comment 2—ALPA. ALPA also
commented that it is important to
determine the characteristics of
composites after prolonged exposure to
moisture of any kind (humidity, liquid,
deicing fluid, fuel etc.) and stated that
the FAA must conduct or endorse
research to determine whether
composite materials are susceptible to
absorbing liquids during prolonged
exposure. The commenter also stated
that research must be done to determine
effects of water (or other liquid)
intrusion on the aircraft weight,
controllability, flammability, and
survivability.
FAA Response. The FAA concurs
with the concerns of the commenter and
has discussed these items with the
applicant. The existing airworthiness
regulations for certification require that
all parts and components be qualified
for all foreseeable environmental
conditions as installed on the airplane.
Therefore, as part of the material
certification and approval, the
composite material is required to be
subjected to accelerated environmental
exposure to all liquids anticipated to be
in contact with the material for the life
of the aircraft. This includes but is not
limited to water, salt spray, fuel,
hydraulic fluid, and de-icing fluids. Any
material effects due to this exposure
testing will have to be considered in
showing the material’s ability to
perform its intended function, including
consideration for the life and
performance of the material. These
environmental qualifications are
required by existing airworthiness
regulations and are therefore not
required to be included in the special
conditions for composite structure. We
have made no changes to these special
conditions as a result of this comment.
Comment 3—Airbus. Airbus noted a
reference in the proposed special
conditions to testing conducted at the
FAA Technical Center that
demonstrated aluminum fuel tank
performance under postcrash fire
conditions. The commenter requested
access to the documentation for review
of the test data to understand the
applied conditions and parameters of
the test.
FAA Response. The noted reports are
available to the public via the FAA
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Technical Center Website for Fire Safety
at https://www.fire.tc.faa.gov/. The
document we were referring to in the
proposed special conditions was
document FAA–RD–75–119,
Investigation of Aircraft Fuel Tank
Explosions and Nitrogen Inerting
Requirements During Ground Fires. We
have made no changes to these special
conditions as a result of this comment.
Comment 4—Airbus. Airbus also
requested clarification of the following
statement on page 17443 of the Federal
Register, under the heading ‘‘Discussion
of Proposed Special Conditions:’’ * * *
AC 20–135 indicates that, when
aluminum is used for fuel tanks, the
tank should withstand the effects of fire
for 5 minutes without failure.’’ Airbus
said this statement needed clarification,
because the actual language in the AC
discusses fire resistance of a number of
elements, but does not consider the fuel
tank as a whole.
FAA Response. The commenter is
correct that AC 20–135 does not
specifically refer to demonstrating that
the fuel tank as a whole is fire resistant.
In the past fuel tanks have typically
been constructed of aluminum, which is
considered to be fire resistant. AC 20–
135 provides general guidance on how
materials can be shown to be fire
resistant if they can withstand the
effects of fire for 5 minutes. These
special conditions require that the fuel
tank be shown to meet fire resistance
standards and one means of showing a
material meets these standards is
described in the AC. Since the fuel tank
is constructed of composite materials,
we consider the guidance in the AC to
be applicable to the fuel tank as a
whole. We’ve made no change to these
special conditions as a result of this
comment.
The following four comments,
received from the public, were outside
the scope of these special conditions.
Comment 5. One commenter
requested that the FAA and foreign
authorities pursue rulemaking activities
to develop specific rules related to use
of composite materials for basic airframe
structure.
FAA Response. Although this
comment does not address the context
of these special conditions, we agree
that current transport category rules do
not adequately address the unique
aspects of composite structure. These
special conditions, and others for the
787 and other certification projects
involving composite structure, are the
first steps in establishing new
airworthiness standards. We anticipate
that these special conditions will be
followed by rulemaking activity to
establish similar standards in the
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applicable sub-parts of part 25. The
FAA cannot comment on the position of
other foreign authorities in this regard.
No change to the special conditions is
required.
Comment 6. This commenter also
requested that the scope of the special
conditions be expanded to include
evaluation of the fuselage, wing, and
fuel tank to simulate actual survivable
crash conditions during a fuel fed fire
with respect to fire, smoke, and toxicity
and passenger survivability. The
commenter requested that the special
conditions address fire, smoke, and
toxicity environments within the
fuselage interior during an external fuel
fed fire.
FAA Response. While we agree with
the commenter that these are important
considerations, the FAA has determined
that this comment is outside the scope
of these special conditions because they
are limited to performance of the wing
and fuel tank structure during a
postcrash ground fire. The performance
of the fuselage barrel and interiors
during a fuel-fed fire is already
addressed by existing regulations
(reference 14 CFR 25.853, 25.855, and
25.856 and Appendix F for current
standards for airplane interior fire
safety). We have determined that
existing regulations for a fuel-fed
external fire are adequate to address
cabin interiors, including those issues
suggested by the commenter, and
special conditions are not warranted. In
addition, while full scale fire tests of the
wing and fuselage were considered by
the FAA, we determined that requiring
a large scale fire test could be overly
prescriptive. The means of complying
with the objectives of these special
conditions will be reviewed and
approved by the FAA. In addition,
although the performance standards for
the wing and fuselage were developed
independently, they have a common
objective of preserving the current level
of safety provided by aluminum
airplanes. After reviewing this
comment, we have determined that no
change to the special conditions is
required.
Comment 7. This commenter has
noted that burn-through tests at the
component level do not address high
lateral fire burning rates or fire and
smoke ingress into the cabin. The
commenter suggested testing should be
expanded to include a full scale fire test
of a fuselage barrel section with all exits
opened and slides deployed throughout
the test.
FAA Response. The FAA has
determined that the requirements for the
smoke, toxicity, and fire resistance of
the fuselage materials are adequately
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57847
addressed by the current regulations
and, therefore, inclusion in these special
conditions is unwarranted. The intent
and scope of these special conditions
was to ensure that the wing and fuel
tank structure will not pose an
additional hazard to passengers and
crew during postcrash fire scenarios
because of the introduction of
composite materials. Cabin safety
special conditions have been developed
and published for comment in Special
Conditions No. 25–07–09–SC, Docket
No. NM373, published April 26, 2007
(72 FR 20774). Those special conditions
require that the 787 provide the same
level of in-flight survivability as a
conventional aluminum fuselage
airplane. This includes its thermal/
acoustic insulation meeting
requirements of § 25.856(a). Those
special conditions state that resistance
to flame propagation must be shown,
and all products of combustion that may
result must be evaluated for toxicity and
found acceptable.
We have made no changes to these
special conditions as a result of this
comment.
Comment 8. Another commenter
provided extensive background
information on the current level of
safety provided by the crashworthiness
of aluminum transport category
airframes. This commenter expressed
concern that the introduction of a
composite fuselage will reduce the
crashworthiness of transport airplanes.
The commenter further requested that
we impose a fuselage drop test for the
787 to ensure that the current level of
safety provided by an aluminum
fuselage is provided by the composite
materials used in the construction of the
787 fuselage.
FAA Response: We would like to note
that the scope of these special
conditions is limited to the fire safety
provisions of the fuel tanks and wing
structure during a fuel-fed ground fire.
These special conditions are not
intended to address the structural
crashworthiness of the airframe. We
have considered the impact of
composites on airframe crashworthiness
and have proposed Special Conditions
25–07–05–SC, published on June 11,
2007, in the Federal Register (72 FR
32021). As stated in those special
conditions, ‘‘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
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Model 787–8 meets the following
criteria for a range of airplane vertical
descent velocities up to 30 ft/sec * * *’’
The FAA considers that proposed
Special Conditions 25–07–05–SC
adequately addresses the commenter’s
concerns for crashworthiness and we
note that the commenter had
opportunity to submit comments to that
proposal as well. We have made no
changes to these special conditions as a
result of this comment.
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.
I The authority citation for these
special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
The Special Conditions
I 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.
ebenthall on PRODPC61 with RULES
In addition to complying with 14 CFR part
25 regulations governing the fire-safety
performance of the fuel tanks, wings, and
nacelle, the Boeing Model 787–8 must
demonstrate acceptable postcrash
survivability in the event the wings are
exposed to a large fuel-fed ground fire.
Boeing must demonstrate that the wing and
fuel tank design can endure an external fuelfed pool fire for at least 5 minutes. This shall
be demonstrated for minimum fuel loads (not
less than reserve fuel levels) and maximum
fuel loads (maximum range fuel quantities),
and other identified critical fuel loads.
Considerations shall include fuel tank
flammability, burn-through resistance, wing
structural strength retention properties, and
auto-ignition threats during a ground fire
event for the required time duration.
Issued in Renton, Washington, on
September 28, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E7–20031 Filed 10–10–07; 8:45 am]
BILLING CODE 4910–13–P
VerDate Aug<31>2005
14:49 Oct 10, 2007
Jkt 211001
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2007–28172; Directorate
Identifier 2007–NE–23–AD; Amendment 39–
15224; AD 2007–21–06]
RIN 2120–AA64
Airworthiness Directives; General
Electric Company (GE) CF6–80C2A5F
Turbofan Engines
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule.
AGENCY:
SUMMARY: The FAA is adopting a new
airworthiness directive (AD) for GE
CF6–80C2A5F turbofan engines
installed on, but not limited to, Airbus
A300F4–605R airplanes. This AD
requires removing previous software
versions from the engine electronic
control unit (ECU). Engines with new
version software will have increased
margin to flameout. This AD results
from reports of engine flameout events
during flight, including reports of events
where all engines simultaneously
experienced a flameout or other adverse
operation. Although the root cause
investigation is not yet complete, we
believe that exposure to ice crystals
during flight is associated with these
flameout events. We are issuing this AD
to minimize the potential of an allengine flameout event caused by ice
accretion and shedding during flight.
DATES: This AD becomes effective
November 15, 2007.
ADDRESSES: You can get the service
information identified in this AD from
General Electric Company via Lockheed
Martin Technology Services, 10525
Chester Road, Suite C, Cincinnati, Ohio
45215, telephone (513) 672–8400, fax
(513) 672–8422.
The Docket Operations office is
located at U.S. Department of
Transportation, Docket Operations, M–
30, West Building Ground Floor, Room
W12–140, 1200 New Jersey Avenue, SE.,
Washington, DC 20590–0001.
FOR FURTHER INFORMATION CONTACT: John
Golinski, Aerospace Engineer, Engine
Certification Office, FAA, Engine and
Propeller Directorate, 12 New England
Executive Park, Burlington, MA 01803;
e-mail: john.golinski@faa.gov;
telephone: (781) 238–7135, fax: (781)
238–7199.
SUPPLEMENTARY INFORMATION: The FAA
proposed to amend 14 CFR part 39 with
a proposed AD. The proposed AD
applies to GE CF6–80C2A5F turbofan
PO 00000
Frm 00010
Fmt 4700
Sfmt 4700
engines installed on Airbus A300 series
airplanes. We published the proposed
AD in the Federal Register on June 28,
2007 (72 FR 35366). That action
proposed to require removing previous
software versions from the engine ECU.
Engines with new version software will
have increased margin to flameout.
Examining the AD Docket
You may examine the AD docket on
the Internet at https://
www.regulations.gov or in person at the
Docket Operations office between 9 a.m.
and 5 p.m., Monday through Friday,
except Federal holidays. Follow the
online instructions for accessing the
docket. The AD docket contains this
AD, the regulatory evaluation, any
comments received, and other
information. The street address for the
Docket Operations office (telephone
(800) 647–5527) is provided in the
ADDRESSES section. Comments will be
available in the AD docket shortly after
receipt.
Comments
We provided the public the
opportunity to participate in the
development of this AD. We have
considered the comments received.
Applicability Clarification
One commenter, Airbus, points out
that CF6–80C2A5F engines are installed
on Airbus A300–600 series airplanes,
and not on Airbus A300 series
airplanes, as we stated in the proposed
AD. We agree that the applicability
needs clarification. However, to be more
accurate, we changed the AD to state
that the CF6–80C2A5F engines are
installed on, but not limited to, Airbus
A300F4–605R airplanes.
Request To Exclude Airplanes
Airbus requests that we exclude
airplanes that have incorporated
modification number (No.) 13270, from
the AD applicability. Airbus did not
provide any technical rationale,
information, or explanation regarding
the content of modification No. 13270,
or why airplanes with modification No.
13270 should be excluded from the AD.
We do not agree. We believe that
modification No. 13270 might be an
Airbus design change for removing
previous versions of software from
engines and incorporating new software.
We state in the AD that the actions are
required unless previously done. Airbus
airplanes that have previously
incorporated the actions of this AD by
following the GE Service Bulletin, or
any other document, such as Airbus
modification No. 13270, have satisfied
the requirements of this AD, and no
E:\FR\FM\11OCR1.SGM
11OCR1
]]>Agencies
[Federal Register Volume 72, Number 196 (Thursday, October 11, 2007)]
[Rules and Regulations]
[Pages 57844-57848]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-20031]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM366 Special Conditions No. 25-348-SC]
Special Conditions: Boeing Model 787-8 Airplane; Composite Wing
and Fuel Tank Structure--Fire Protection Requirements
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued 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 composite materials chosen for the
construction of the fuel tank skin and structure. For these design
features, the applicable airworthiness regulations do not contain
adequate or appropriate safety standards for wing and fuel tank
structure with respect to postcrash fire safety. These special
conditions contain the additional safety standards that the
Administrator considers necessary to
[[Page 57845]]
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: November 13, 2007.
FOR FURTHER INFORMATION CONTACT: Mike Dostert, FAA, Propulsion/
Mechanical Systems, ANM-112, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 227-2132; 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 will incorporate a number of 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 will be the first large transport category airplane not
built mainly with aluminum materials for the fuel tank structure.
Instead it will use chiefly composite materials for the structural
elements and skin of the wings and fuel tanks. Conventional airplanes
with aluminum skin and structure provide a well understood level of
safety during postcrash fires with respect to fuel tanks. This is based
on service history and extensive full-scale fire testing. Composites
may or may not have capabilities equivalent to aluminum, and current
regulations do not provide objective performance requirements for wing
and fuel tank structure with respect to postcrash fire safety. Use of
composite structure is new and novel compared to the designs envisioned
when the applicable regulations were written. Because of this, Boeing
must present additional confirmation by test and analysis that the 787
provides an acceptable level of safety with respect to the performance
of the wings and fuel tanks during an external fuel-fed fire.
Although the FAA has previously approved fuel tanks made of
composite materials that are located in the horizontal stabilizer of
some airplanes, the composite wing structure of the 787 will introduce
a new fuel tank construction into service. Advisory Circular (AC) 20-
107A, Composite Aircraft Structure, under the topic of flammability,
states: ``The existing requirements for flammability and fire
protection of aircraft structure attempt to minimize the hazard to the
occupants in the event ignition of flammable fluids or vapors occurs.
The use of composite structure should not decrease this existing level
of safety.'' The relevance to the wing structure is that postcrash fire
passenger survivability is dependent on the time available for
passenger evacuation before fuel tank breach or structural failure.
Structural failure can be a result of degradation in load-carrying
capability in the upper or lower wing surface caused by a fuel-fed
ground fire. Structural failure can also be a result of over-
pressurization caused by ignition of fuel vapors in the fuel tank.
The FAA has historically developed rules with the assumption that
the material of construction for wing and fuselage would be aluminum.
As a representative case, Sec. 25.963 was developed because of a large
fuel-fed fire following the failures of fuel tank access doors caused
by uncontained engine failures. During the subsequent Aviation
Rulemaking Advisory Committee (ARAC) harmonization process with the
JAA,\1\ the structures group tried to harmonize the requirements of
Sec. 25.963 for impact and fire resistance of fuel tank access panels.
Both authorities recognized that existing aluminum wing structure
provided an acceptable level of safety. Further rulemaking has not yet
been pursued.
---------------------------------------------------------------------------
\1\ The JAA is the Joint Aviation Authority of Europe and the
JAR is its Joint Aviation Requirements, the equivalent of our
Federal Aviation Regulations. In 2003, the European Aviation Safety
Agency (EASA) was formed, and EASA is now the principal aviation
regulatory agency in Europe. We intend to work with EASA to ensure
that our rules are also harmonized with its Certification
Specifications (CS). But since these efforts in developing
harmonization of Sec. 25.963 occurred before EASA was formed, it
was the JAA that was involved with them.
---------------------------------------------------------------------------
As with previous Boeing airplane designs with underwing mounted
engines, the wing tanks and center tanks are located in proximity to
the passengers and near the engines. Experience indicates postcrash
survivability is greatly influenced by the size and intensity of any
fire that occurs. The ability of aluminum wing surfaces wetted by fuel
on their interior surface to withstand postcrash fire conditions has
been shown by tests conducted at the FAA Technical Center. These tests
have verified adequate dissipation of heat across wetted aluminum fuel
tank surfaces so that localized hot spots do not occur, thus minimizing
the threat of explosion. This inherent capability of aluminum to
dissipate heat also allows the wing lower surface to retain its load
carrying characteristics during a fuel-fed ground fire. It
significantly delays wing collapse or burn-through for a time interval
that usually exceeds evacuation times. In addition, as an aluminum fuel
tank is heated with significant quantities of fuel inside, fuel vapor
accumulates in the ullage space, exceeding the upper flammability limit
relatively quickly and thus reducing the threat of a fuel tank
explosion prior to fuel tank burn-through. Service history of
conventional aluminum airplanes has shown that fuel tank explosions
caused
[[Page 57846]]
by ground fires have been rare on airplanes configured with flame
arrestors in the fuel tank vent lines. Fuel tanks constructed with
composite materials may or may not have equivalent capability.
Current regulations were developed and have evolved under the
assumption that wing construction would be of aluminum materials, which
provide inherent properties. Current regulations may not be adequate
when applied to airplanes constructed of different materials.
Aluminum has the following properties with respect to fuel tanks
and fuel-fed external fires.
Aluminum is highly thermally conductive. It readily
transmits the heat of a fuel-fed external fire to fuel in the tank.
This has the benefit of rapidly driving the fuel tank ullage to exceed
the upper flammability limit prior to burn-through of the fuel tank
skin or heating of the wing upper surface above the auto-ignition
temperature. This greatly reduces the threat of fuel tank explosion.
Aluminum panels at thicknesses previously used in wing
lower surfaces of large transport category airplanes have been fire
resistant as defined in 14 CFR part 1 and AC 20-135.
The heat absorption capacity of aluminum and fuel will
prevent burn-through or wing collapse for a time interval that will
generally exceed the passenger evacuation time.
The extensive use of composite materials in the design of the 787
wing and fuel tank structure is considered a major change from
conventional and traditional methods of construction. This will be the
first large transport category airplane to be certificated with this
level of composite material for these purposes. The applicable
airworthiness regulations do not contain specific standards for
postcrash fire safety performance of wing and fuel tank skin or
structure.
Discussion of Special Conditions
In order to provide the same level of safety as exists with
conventional airplane construction, Boeing must demonstrate that the
787 has sufficient postcrash survivability to enable occupants to
safely evacuate in the event that the wings are exposed to a large
fuel-fed fire. Factors in fuel tank survivability are the structural
integrity of the wing and tank, flammability of the tank, burn-through
resistance of the wing skin, and the presence of auto-ignition threats
during exposure to a fire. The FAA assessed postcrash survival time
during the adoption of Amendment 25-111 for fuselage burn-through
protection. Studies conducted by and on behalf of the FAA indicated
that, following a survivable accident, prevention of fuselage burn-
through for approximately 5 minutes can significantly enhance
survivability. (See report numbers DOT/FAA/AR-99/57 and DOT/FAA/AR-02/
49.) There is little benefit in requiring the design to prevent wing
skin burn-through beyond five minutes, due to the effects of the fuel
fire itself on the rest of the airplane. That assessment was carried
out based on accidents involving airplanes with conventional fuel
tanks, and considering the ability of ground personnel to rescue
occupants. In addition, AC 20-135 indicates that, when aluminum is used
for fuel tanks, the tank should withstand the effects of fire for 5
minutes without failure. Therefore, to be consistent with existing
capability and related requirements, the 787 fuel tanks must be capable
of resisting a postcrash fire for at least 5 minutes. In demonstrating
compliance, Boeing must address a range of fuel loads from minimum to
maximum, as well as any other critical fuel load.
Discussion of Comments
Notice of Proposed Special Conditions No. 25-07-03-SC for the 787
was published in the Federal Register on April 9, 2007 (72 FR 17441).
Two comments were received from the Air Line Pilots Association,
International (ALPA), two from Airbus, and several from members of the
public.
Comment 1--Air Line Pilots Association (ALPA). The Air Line Pilots
Association, International questioned whether the 787 will be required
to comply with any and all rules related to fuel tank inerting/
flammability requirements of 14 CFR parts 25 and 121 and the guidance
in Advisory Circular 25.981-2A.
FAA Response. The 787 will be required to meet the current
requirements for the certification basis of the airplane that include
fuel vapor flammability standards, and we will be proposing additional
requirements within special conditions for a nitrogen inerting system.
The certification basis for the 787 includes Amendment 25-102, which
includes the Sec. 25.981(c) requirement for minimization of fuel tank
flammability. In the preamble to Amendment 25-102 we described the
intended level of flammability to be equivalent to an unheated aluminum
wing fuel tank. The composite fuel tank structure of the 787 does not
inherently meet this flammability standard because of the difference in
thermal conductivity between composite materials and aluminum. Boeing
has proposed a design that includes a nitrogen inerting system to meet
the flammability standard. Because of this novel and unique feature
that provides nitrogen enriched air to all fuel tanks, we will be
publishing proposed special conditions for public comment.
We have made no changes to these special conditions as a result of
this comment.
Comment 2--ALPA. ALPA also commented that it is important to
determine the characteristics of composites after prolonged exposure to
moisture of any kind (humidity, liquid, deicing fluid, fuel etc.) and
stated that the FAA must conduct or endorse research to determine
whether composite materials are susceptible to absorbing liquids during
prolonged exposure. The commenter also stated that research must be
done to determine effects of water (or other liquid) intrusion on the
aircraft weight, controllability, flammability, and survivability.
FAA Response. The FAA concurs with the concerns of the commenter
and has discussed these items with the applicant. The existing
airworthiness regulations for certification require that all parts and
components be qualified for all foreseeable environmental conditions as
installed on the airplane. Therefore, as part of the material
certification and approval, the composite material is required to be
subjected to accelerated environmental exposure to all liquids
anticipated to be in contact with the material for the life of the
aircraft. This includes but is not limited to water, salt spray, fuel,
hydraulic fluid, and de-icing fluids. Any material effects due to this
exposure testing will have to be considered in showing the material's
ability to perform its intended function, including consideration for
the life and performance of the material. These environmental
qualifications are required by existing airworthiness regulations and
are therefore not required to be included in the special conditions for
composite structure. We have made no changes to these special
conditions as a result of this comment.
Comment 3--Airbus. Airbus noted a reference in the proposed special
conditions to testing conducted at the FAA Technical Center that
demonstrated aluminum fuel tank performance under postcrash fire
conditions. The commenter requested access to the documentation for
review of the test data to understand the applied conditions and
parameters of the test.
FAA Response. The noted reports are available to the public via the
FAA
[[Page 57847]]
Technical Center Website for Fire Safety at https://www.fire.tc.faa.gov/
. The document we were referring to in the proposed special conditions
was document FAA-RD-75-119, Investigation of Aircraft Fuel Tank
Explosions and Nitrogen Inerting Requirements During Ground Fires. We
have made no changes to these special conditions as a result of this
comment.
Comment 4--Airbus. Airbus also requested clarification of the
following statement on page 17443 of the Federal Register, under the
heading ``Discussion of Proposed Special Conditions:'' * * * AC 20-135
indicates that, when aluminum is used for fuel tanks, the tank should
withstand the effects of fire for 5 minutes without failure.'' Airbus
said this statement needed clarification, because the actual language
in the AC discusses fire resistance of a number of elements, but does
not consider the fuel tank as a whole.
FAA Response. The commenter is correct that AC 20-135 does not
specifically refer to demonstrating that the fuel tank as a whole is
fire resistant. In the past fuel tanks have typically been constructed
of aluminum, which is considered to be fire resistant. AC 20-135
provides general guidance on how materials can be shown to be fire
resistant if they can withstand the effects of fire for 5 minutes.
These special conditions require that the fuel tank be shown to meet
fire resistance standards and one means of showing a material meets
these standards is described in the AC. Since the fuel tank is
constructed of composite materials, we consider the guidance in the AC
to be applicable to the fuel tank as a whole. We've made no change to
these special conditions as a result of this comment.
The following four comments, received from the public, were outside
the scope of these special conditions.
Comment 5. One commenter requested that the FAA and foreign
authorities pursue rulemaking activities to develop specific rules
related to use of composite materials for basic airframe structure.
FAA Response. Although this comment does not address the context of
these special conditions, we agree that current transport category
rules do not adequately address the unique aspects of composite
structure. These special conditions, and others for the 787 and other
certification projects involving composite structure, are the first
steps in establishing new airworthiness standards. We anticipate that
these special conditions will be followed by rulemaking activity to
establish similar standards in the applicable sub-parts of part 25. The
FAA cannot comment on the position of other foreign authorities in this
regard. No change to the special conditions is required.
Comment 6. This commenter also requested that the scope of the
special conditions be expanded to include evaluation of the fuselage,
wing, and fuel tank to simulate actual survivable crash conditions
during a fuel fed fire with respect to fire, smoke, and toxicity and
passenger survivability. The commenter requested that the special
conditions address fire, smoke, and toxicity environments within the
fuselage interior during an external fuel fed fire.
FAA Response. While we agree with the commenter that these are
important considerations, the FAA has determined that this comment is
outside the scope of these special conditions because they are limited
to performance of the wing and fuel tank structure during a postcrash
ground fire. The performance of the fuselage barrel and interiors
during a fuel-fed fire is already addressed by existing regulations
(reference 14 CFR 25.853, 25.855, and 25.856 and Appendix F for current
standards for airplane interior fire safety). We have determined that
existing regulations for a fuel-fed external fire are adequate to
address cabin interiors, including those issues suggested by the
commenter, and special conditions are not warranted. In addition, while
full scale fire tests of the wing and fuselage were considered by the
FAA, we determined that requiring a large scale fire test could be
overly prescriptive. The means of complying with the objectives of
these special conditions will be reviewed and approved by the FAA. In
addition, although the performance standards for the wing and fuselage
were developed independently, they have a common objective of
preserving the current level of safety provided by aluminum airplanes.
After reviewing this comment, we have determined that no change to the
special conditions is required.
Comment 7. This commenter has noted that burn-through tests at the
component level do not address high lateral fire burning rates or fire
and smoke ingress into the cabin. The commenter suggested testing
should be expanded to include a full scale fire test of a fuselage
barrel section with all exits opened and slides deployed throughout the
test.
FAA Response. The FAA has determined that the requirements for the
smoke, toxicity, and fire resistance of the fuselage materials are
adequately addressed by the current regulations and, therefore,
inclusion in these special conditions is unwarranted. The intent and
scope of these special conditions was to ensure that the wing and fuel
tank structure will not pose an additional hazard to passengers and
crew during postcrash fire scenarios because of the introduction of
composite materials. Cabin safety special conditions have been
developed and published for comment in Special Conditions No. 25-07-09-
SC, Docket No. NM373, published April 26, 2007 (72 FR 20774). Those
special conditions require that the 787 provide the same level of in-
flight survivability as a conventional aluminum fuselage airplane. This
includes its thermal/acoustic insulation meeting requirements of Sec.
25.856(a). Those special conditions state that resistance to flame
propagation must be shown, and all products of combustion that may
result must be evaluated for toxicity and found acceptable.
We have made no changes to these special conditions as a result of
this comment.
Comment 8. Another commenter provided extensive background
information on the current level of safety provided by the
crashworthiness of aluminum transport category airframes. This
commenter expressed concern that the introduction of a composite
fuselage will reduce the crashworthiness of transport airplanes. The
commenter further requested that we impose a fuselage drop test for the
787 to ensure that the current level of safety provided by an aluminum
fuselage is provided by the composite materials used in the
construction of the 787 fuselage.
FAA Response: We would like to note that the scope of these special
conditions is limited to the fire safety provisions of the fuel tanks
and wing structure during a fuel-fed ground fire. These special
conditions are not intended to address the structural crashworthiness
of the airframe. We have considered the impact of composites on
airframe crashworthiness and have proposed Special Conditions 25-07-05-
SC, published on June 11, 2007, in the Federal Register (72 FR 32021).
As stated in those special conditions, ``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
[[Page 57848]]
Model 787-8 meets the following criteria for a range of airplane
vertical descent velocities up to 30 ft/sec * * *'' The FAA considers
that proposed Special Conditions 25-07-05-SC adequately addresses the
commenter's concerns for crashworthiness and we note that the commenter
had opportunity to submit comments to that proposal as well. We have
made no changes to these special conditions as a result of this
comment.
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.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
0
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.
In addition to complying with 14 CFR part 25 regulations
governing the fire-safety performance of the fuel tanks, wings, and
nacelle, the Boeing Model 787-8 must demonstrate acceptable
postcrash survivability in the event the wings are exposed to a
large fuel-fed ground fire. Boeing must demonstrate that the wing
and fuel tank design can endure an external fuel-fed pool fire for
at least 5 minutes. This shall be demonstrated for minimum fuel
loads (not less than reserve fuel levels) and maximum fuel loads
(maximum range fuel quantities), and other identified critical fuel
loads. Considerations shall include fuel tank flammability, burn-
through resistance, wing structural strength retention properties,
and auto-ignition threats during a ground fire event for the
required time duration.
Issued in Renton, Washington, on September 28, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-20031 Filed 10-10-07; 8:45 am]
BILLING CODE 4910-13-P
