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[Federal Register Volume 79, Number 143 (Friday, July 25, 2014)]
[Rules and Regulations]
[Pages 43232-43233]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-17518]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2014-0067; Special Conditions No. 25-556-SC]

Special Conditions: Learjet Inc., Model LJ-200-1A10 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 Learjet Inc. Model 
LJ-200-1A10 airplane. This airplane will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. The fuselage 
of the Model LJ-200-1A10 will be made of composite materials rather 
than conventional aluminum, which may affect fire propagation during an 
in-flight fire. The applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for 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 airworthiness standards.

DATES: Effective Date: August 25, 2014.

FOR FURTHER INFORMATION CONTACT: Alan Sinclair, FAA, Airframe and Cabin 
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98057-
3356; telephone 425-227-2195; facsimile 425-227-1232.

SUPPLEMENTARY INFORMATION:

Background

    On February 9, 2009, Learjet Inc. applied for a type certificate 
for their new Model LJ-200-1A10 airplane (hereafter referred to as the 
``Model LJ-200''). The Model LJ-200 is a business class airplane 
powered by two high-bypass turbine engines with an estimated maximum 
takeoff weight of 35,550 pounds and an interior configuration for up to 
10 passengers.
    The Model LJ-200 is the first composite fuselage airplane design 
manufactured by Learjet Inc. A fuselage manufactured from composite 
material is considered a novel or unusual design with respect to 
existing regulations for this type of aircraft. The performance of 
aircraft consisting of a conventional

[[Page 43233]]

aluminum fuselage in an inaccessible in-flight fire scenario is 
understood based on service history and extensive intermediate and 
large-scale fire testing. The fuselage itself does not contribute to 
in-flight fire propagation. This may not be the case for an all-
composite fuselage. The existing regulations do not adequately address 
protection against an in-flight fire for an all-composite fuselage. 
These special conditions are necessary to ensure a level of safety 
equivalent to that provided by existing regulations.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Learjet Inc. must show that the Model LJ-200 airplane meets 
the applicable provisions of part 25, as amended by Amendments 25-1 
through 25-127, and 14 CFR part 26, as amended by Amendment 26-1 
through 26-2.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Model LJ-200 airplane because of a 
novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    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.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model LJ-200 airplane must comply with the fuel vent 
and exhaust emission requirements of 14 CFR part 34 and the noise 
certification requirements of 14 CFR part 36, and the FAA must issue a 
finding of regulatory adequacy under Sec.  611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Model LJ-200 airplane will incorporate the following novel or 
unusual design features: The fuselage will be fabricated using 
composite materials instead of conventional aluminum.

Discussion

    The Model LJ-200 airplane 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. Despite the major change from aluminum 
to composite material for the fuselage, the Model LJ-200 airplane must 
have in-flight survivability such that the composite fuselage does not 
propagate a fire. A methodology for assessing the in-flight fire 
survivability of an all-composite fuselage is therefore needed.
    The FAA believes that one way to assess the survivability within 
the cabin of the Model LJ-200 airplane is to conduct large-scale tests. 
These large-scale tests would use a mock-up of a Model LJ-200 airplane 
fuselage skin/structure section of sufficient size to assess any 
tendency for fire propagation. The fire threat used to represent the 
realistic ignition source in the airplane would consist of a 4'' x 4'' 
x 9'' polyurethane foam block and 10 ml of Heptane. This ignition 
source provides approximately three minutes of flame time and would be 
positioned at various points and orientations within the mocked up 
installation to impinge on those areas of the fuselage considered to be 
most crucial.
    This fire threat was established based on an assessment of a range 
of potential ignition sources, coupled with possible contamination of 
materials. The FAA considers this a severe fire threat, encompassing a 
variety of scenarios. However, should ignition or fire sources of a 
greater severity be identified, these special conditions or the method 
of compliance would need to be modified in order to take the more 
severe threat into account.
    Despite the major change from aluminum to composite material for 
the fuselage, the Model LJ-200 must have in-flight fire survivability 
such that the composite fuselage is no worse than that of a similar 
aluminum structure.
    These special conditions contain the additional safety standards 
that the Administrator considers necessary to establish a level of 
safety equivalent to that established by the existing airworthiness 
standards.

Discussion of Comments

    Notice of proposed special conditions No. 25-14-01-SC for the 
Learjet Inc. Model LJ-200-1A10 airplane was published in the Federal 
Register on February 7, 2014 (79 FR 7406). No comments were received, 
and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Model LJ-200 airplane. Should Learjet Inc. apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, the special conditions would 
apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplanes. 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 Learjet Inc. Model LJ-200-1A10 
airplane.
    Composite Fuselage In-Flight Fire/Flammability Resistance. The 
Learjet Inc. Model LJ-200 composite fuselage structure must be shown to 
be resistant to flame propagation under the fire threat used to develop 
Sec.  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 June 6, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-17518 Filed 7-24-14; 8:45 am]
BILLING CODE 4910-13-P
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