[Federal Register Volume 72, Number 157 (Wednesday, August 15, 2007)]
[Rules and Regulations]
[Pages 45626-45628]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-16020]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM373; Special Conditions No. 25-360-SC]


Special Conditions: Boeing Model 787-8 Airplane; Composite 
Fuselage In-Flight Fire/Flammability Resistance

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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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. The fuselage of the Boeing 
Model 787-8 series airplane will be made of composite materials rather 
than conventional aluminum. While the regulations include flame 
propagation standards for some materials commonly found in inaccessible 
areas of the airplane, they do not yet incorporate standards for 
materials used to construct the fuselage. Therefore, special conditions 
are needed to address this design feature. 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. Additional special conditions 
will be issued for other novel or unusual design features of the Boeing 
Model 787-8 airplanes.

[[Page 45627]]


DATES: Effective Date: September 14, 2007.

FOR FURTHER INFORMATION CONTACT: Jeff Gardlin, FAA, Airframe/Cabin 
Safety, ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 
telephone (425) 227-2136; 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 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 part 36. The FAA must also issue a finding of regulatory adequacy 
pursuant to section 611 of Public Law 92-574, the ``Noise Control Act 
of 1972.''
    The FAA issues special conditions, as defined in Sec.  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

    In-flight fires have originated in inaccessible areas of aircraft 
where thermal/acoustic insulation located adjacent to the aluminum 
aircraft skin has been the path for flame propagation and fire growth. 
Although these insulation materials were required to comply with the 
basic ``Bunsen burner'' requirements of 14 CFR 25.853(a) and 25.855(d), 
these incidents revealed unexpected flame spread along the insulation 
film covering material of the thermal/acoustic insulation. In all 
cases, the ignition source was relatively modest and, in most cases, 
was electrical in origin (for example an electrical short circuit, 
arcing caused by chafed wiring, or a ruptured ballast case).
    In September 2003, in an effort to limit use of materials that 
sustain or propagate a fire in inaccessible areas, the FAA promulgated 
14 CFR 25.856(a), which requires that thermal/acoustic insulation 
material installed in the fuselage meet newly developed flame 
propagation test requirements. That rule was Amendment 25-111. These 
requirements were developed to address a realistic fire threat. We 
consider that threat generally applicable to the 787.
    Conventional aluminum fuselage material does not contribute to in-
flight fire propagation. As a result, there are no standards that 
address in-flight fire safety of the fuselage structure itself. The 787 
will make extensive use of composite materials in the fabrication of 
the majority of the
     Wing,
     Fuselage skin,
     Stringers,
     Spars, and
     Most other structural elements of all major sub-assemblies 
of the airplane.
    As a result of this extensive use of a new construction material, 
the fuselage cannot be assumed to have the fire resistance previously 
afforded by aluminum during the in-flight fire scenario mentioned 
above. These 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 the 
requirements of Sec.  25.856(a). Resistance to flame propagation must 
be shown, and all products of combustion that may result must be 
evaluated for toxicity and found acceptable.

Discussion of Comments

    Notice of Proposed Special Conditions No. 25-07-09-SC for the 787 
was published in the Federal Register on April 26, 2007 (72 FR 20774). 
Two commenters, the Air Line Pilots Association (ALPA) and an 
individual member of the public, responded to the notice. Both 
commenters concur with the proposed special conditions but have 
additional concerns about composite structures that they feel should be 
addressed.
    Comment 1. A member of the public commented that a post-crash, fuel 
fed fire is a significant hazard that is not addressed in these special 
conditions. This commenter cites research conducted on behalf of the 
Australian Government that documents potential fire hazards associated 
with composite materials--in particular toxicity and smoke. The 
commenter noted that the fire penetration resistance of a composite 
material alone is not sufficient to determine its overall contribution 
to fire safety.
    FAA Response: We agree with the commenter that consideration of 
post-crash fire safety must include all the factors that influence 
survivability, and not just focus on one characteristic. These special 
conditions focus on in-flight fire safety, so any issues related to 
post-crash fire safety go beyond the scope of these special conditions. 
Nonetheless, the FAA is equally concerned with post-crash survivability 
and is addressing this issue through separate criteria. In this case, 
because there are requirements related to post-crash fire safety in 
Sec.  25.856(b), the approach will be via an equivalent level of safety 
finding in accordance with Sec.  21.21(b)(1). A summary of this finding 
will be available in the FAA Regulatory and Guidance Library at http://rgl.faa.gov/.
    Comment 2. ALPA commented that the effects of moisture ingress must 
be addressed for all aspects of composite material integrity.
    FAA Response: From the standpoint of flammability, moisture ingress 
is not an issue, because moisture will tend to reduce the flammability 
of the material. Since these special conditions only concern 
flammability resulting from an in-flight fire, the remainder of the 
issues go beyond the scope of these special conditions. Moisture is 
known to influence properties of composite materials and this concern 
is a well documented environmental condition that Boeing will have to 
address. In fact, the use of composite materials in aviation is not new 
and there is a significant amount of experience with the behavior of 
composites over time in service. Advisory Circular 20-107A, Composite 
Aircraft Structure, also discusses factors that need to be addressed 
when using composite structure.
    Comment 3. ALPA also commented that aluminum structure can 
dissipate heat using the airflow over the skin, but this may not be the 
case for a composite structure because of its different thermal

[[Page 45628]]

conductivity. ALPA believes that this difference must be taken into 
account with any in-flight fire safety assessment.
    FAA Response: We agree that the heat transfer characteristics of 
aluminum influence its response to an in-flight fire, and that a 
composite structure will doubtless behave differently. The goal of 
these special conditions is to enable continued safe flight and landing 
in the event of an in-flight fire that directly impinges on the 
fuselage structure. Since these special conditions require Boeing to 
show that the composite structure is resistant to flame propagation 
resulting from in-flight fire, all the relevant material properties and 
performance characteristics of the composite structure will need to be 
addressed. This requirement is not a comparison with aluminum 
structure. It is a new requirement for composite structure. Since this 
is so, the special conditions as written cover the ALPA concern, and 
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

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.
0
In addition to the requirements of 14 CFR 25.853(a) governing material 
flammability, the following special conditions apply:

    The 787-8 composite fuselage structure must be shown to be 
resistant to flame propagation under the fire threat used to develop 
14 CFR 25.856(a). If products of combustion are observed beyond the 
test heat source, they must be evaluated and found acceptable.

    Issued in Renton, Washington, on August 6, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-16020 Filed 8-14-07; 8:45 am]
BILLING CODE 4910-13-P