[Federal Register Volume 82, Number 51 (Friday, March 17, 2017)]
[Rules and Regulations]
[Pages 14111-14113]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-05330]



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 Rules and Regulations
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  Federal Register / Vol. 82, No. 51 / Friday, March 17, 2017 / Rules 
and Regulations  

[[Page 14111]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-3324; Special Conditions No. 25-650-SC]


Special Conditions: L-3 Communications Integrated Systems; Boeing 
Model 747-8 Series Airplanes, Large Non-Structural Glass in the 
Passenger Compartment

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Model 747-8 
airplane. This airplane, as modified by L-3 Communications Integrated 
Systems (L-3 Communications), will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport-category airplanes. This design 
feature is the installation of large, non-structural glass panels in 
the cabin area of an executive interior occupied by passengers and 
crew. 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 April 17, 2017.

FOR FURTHER INFORMATION CONTACT: Jayson Claar, FAA, Airframe and Cabin 
Safety, ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone 
425-227-2194; facsimile 425-227-1320.

SUPPLEMENTARY INFORMATION:

Background

    On May 10, 2011, L-3 Communications applied for a supplemental type 
certificate for large, non-structural glass panels in the passenger 
compartment in Boeing Model 747-8 airplanes. The Model 747-8 airplane 
is a derivative of the Boeing Model 747-400 airplane approved under 
type certificate no. A20WE. The airplane, as modified by L-3 
Communications, is a four-engine, transport-category airplane that will 
have a maximum takeoff weight of 970,000 lbs, capacity for 24 
crewmembers, and seating for 143 passengers.

Type Certification Basis

    The certification basis for the Boeing Model 747-8 airplane, as 
defined in type certificate no. A20WE, is Title 14, Code of Federal 
Regulations (14 CFR) part 25 as amended by amendments 25-1 through 25-
120, with exceptions for structures and systems that were unchanged 
from the 747-400 design.
    Under the provisions of Sec.  21.101, L-3 Communications must show 
that the Model 747-8 airplane, as changed, continues to meet the 
applicable provisions of the regulations listed in type certificate no. 
A20WE, or the applicable regulations in effect on the date of 
application for the change.
    The certification basis includes certain special conditions, 
exemptions, or later amended sections of the applicable part that are 
not relevant to these special conditions.
    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 Boeing Model 747-8 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 applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design feature, 
these 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 747-8 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.
    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.  21.101.

Novel or Unusual Design Features

    L-3 Communications Integrated Systems is modifying a Boeing Model 
747-8 airplane to install an executive interior. This airplane, as 
modified, will have a novel or unusual design feature that is the 
installation of large, non-structural glass panels in the cabin area of 
an executive interior occupied by passengers and crew. The installation 
of these glass items in the passenger compartment, which can be 
occupied during taxi, takeoff, and landing, is a novel or unusual 
design feature with respect to the material being installed. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature.

Discussion

    No specific regulations address the design and installation of 
large glass components in airplane passenger cabins. Existing 
requirements, such as Sec. Sec.  25.561, 25.562, 25.601, 25.603, 
25.613, 25.775, and 25.789, in the Boeing Model 747-8 airplane 
certification basis applicable to this supplemental type certificate 
project, provide some design standards appropriate for large glass 
component installations. However, additional design standards for non-
structural glass are needed to complement the existing requirements. 
The addition of glass involved in this installation, and the 
potentially unsafe conditions caused by damage to such components from 
external sources, necessitate assuring that adequate safety standards 
are applied to the design and installation of the feature in Boeing 
Model 747-8 airplanes.
    For purposes of these special conditions, a large glass component 
is defined as a glass component weighing 4 kg (9 lbs) or more. 
Groupings of glass items that individually weigh less than 4 kg, but 
collectively weigh 4 kg or more, also would need to be included. These 
special conditions also apply when showing compliance with the 
applicable performance standards in the

[[Page 14112]]

regulations for the installation of these components. For example, 
heat-release and smoke-density testing must not result in fragmentation 
of the component.
    The use of glass has resulted in trade-offs between the one unique 
characteristic of glass--its capability for undistorted or controlled 
light transmittance, or transparency--and the negative aspects of the 
material, such as extreme notch-sensitivity, low fracture resistance, 
low modulus of elasticity, and highly variable properties. While 
reasonably strong, glass is nonetheless not a desirable material for 
traditional airplane applications because it is heavy (about the same 
density as aluminum), and when it fails, it breaks into extremely sharp 
fragments that have the potential for injury and which have been known 
to be lethal. Thus, the use of glass traditionally has been limited to 
windshields, and instrument or display transparencies. The regulations 
only address, and thus only recognize, the use of glass in windshield 
or window applications. These regulations do address the adverse 
properties of glass, but even so, pilots are occasionally injured from 
shattered glass windshields. FAA policy allows glass on instruments and 
display transparencies.
    Other installations of large, non-structural glass items have 
included the following:
    [ballot] Glass panels integrated onto a stairway handrail closeout.
    [ballot] Glass panels mounted in doors to allow visibility through 
the door when desired.
    [ballot] Glass doors on some galley compartments containing small 
amounts of service items.
    These special conditions will reduce the hazards from breakage, or 
from these panels' potential separation from the cabin interior.
    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. 25-16-04-SC, for L-3 
Communications modifications to the Boeing Model 747-8 airplane, was 
published in the Federal Register on February 25, 2016 (81 FR 9365). 
One comment was received.
    By letter no. B-H020-REG-16-TLM-16 dated March 24, 2016, on behalf 
of The Boeing Company (Boeing), Capt. Terry L. McVenes, Director, 
System Safety & Regulatory Affairs, wrote that Boeing provides a

. . . comprehensive set of comments that identify areas of the 
proposed text where changes would be beneficial for better clarity 
and accuracy. [Boeing] consider[s] such clarifications important to 
ensure consistent and standardized interpretation and application of 
the requirements and guidance provided in the document.

    Boeing recommends that proposed special condition no. 1, Material, 
and proposed special condition no. 2, Fragmentation, be revised to 
more-clearly define what each of these special conditions require, and 
how these two requirements are different. We agree that those two 
conditions could be addressed with a single test, so we combined those 
two conditions into a single condition, special condition no. 1, in 
this document, for clarity. The subsequent special conditions have been 
renumbered accordingly.
    Boeing commented that the load conditions in special condition no. 
4, which corresponds to special condition no. 3 in this document, 
should include all flight and landing loads, rather than only emergency 
landing. These special conditions are in addition to the load 
requirements in the certification basis for the glass installation, 
rather than in lieu of the load requirements. Thus, it is not necessary 
to repeat that all of these loads apply to this installation. The 
emergency-landing load condition is not normally applied to 
installations of this type, but for the use of large glass in the 
cabin, we determined that this additional safety standard is necessary. 
We made no changes to special condition number 3 in response to the 
Boeing comments.
    Boeing recommends that the loading conditions in proposed special 
condition no. 3 (which is now special condition no. 2), Strength, and 
proposed special condition no. 4 (which is now special condition no. 
3), Retention, be the same. Proposed special condition no. 3 (which is 
now special condition no. 2), Strength, is required to address the 
unique, extremely notch-sensitive characteristics of the glass as 
having low fracture resistance, low modulus of elasticity, and highly 
variable properties. Special condition no. 3 (which is now special 
condition no. 2) specifically accounts for abuse loads in addition to 
the loads required per subparts C & D of 14 CFR part 25. Special 
condition no. 4 (which is now special condition no. 3) accounts for 
loads encountered during directional loading and rebound resulting from 
emergency landing loads of 14 CFR part 25. We have made minor 
grammatical modifications to the requirements.
    Boeing recommends that, for proposed special condition no. 4 (which 
is now special condition no. 3), Retention, the statement, ``Both the 
directional loading and rebound conditions must be assessed,'' be 
removed, because these both are covered in proposed special condition 
no. 3. As explained above, special condition nos. 3 (which is now 
special condition no. 2) and 4 (which is now special condition no. 3) 
account for different loading conditions. We have made minor 
grammatical modifications to the requirements.

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 747-8 series airplanes as modified by L-3 Communications. 
Should L-3 Communications apply at a later date for a supplemental type 
certificate to modify any other model included on type certificate no. 
A20WE to incorporate the same novel or unusual design feature, these 
special conditions would apply to that model as well.

Conclusion

    This action affects only a certain novel or unusual design feature 
on one model series of airplane. It is not a rule of general 
applicability and affects only the applicant who applied to the FAA for 
approval of this feature on the airplane.

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, for large 
glass components installed in a cabin occupied by passengers or crew 
who are not otherwise protected from the injurious effects of failure 
of the glass installations, as part of the type certification basis for 
Boeing 747-8 airplanes modified by L-3 Communications.
    1. Material Fragmentation--The applicant must use tempered or 
otherwise treated glass to ensure that, when fractured, the glass 
breaks into small pieces with relatively dull edges. The glass 
component installation must retain all glass fragments to minimize the 
danger from flying glass shards or pieces. The applicant must 
demonstrate

[[Page 14113]]

this characteristic by impact and puncture testing, and testing to 
failure. The applicant may conduct this test with or without any glass 
coating that may be utilized in the design.
    2. Strength--In addition to meeting the load requirements for all 
flight and landing loads, including any of the applicable emergency-
landing conditions in subparts C & D of 14 CFR part 25, the glass 
components that are located such that they are not protected from 
contact with cabin occupants must not fail due to abusive loading, such 
as impact from occupants stumbling into, leaning against, sitting on, 
or performing other intentional or unintentional forceful contact with 
the glass component. The applicant must assess the effect of design 
details such as geometric discontinuities or surface finish, including 
but not limited to embossing and etching.
    3. Retention--The glass component, as installed in the airplane, 
must not come free of its restraint or mounting system in the event of 
an emergency landing, considering both the directional loading and 
resulting rebound conditions. The applicant must assess the effect of 
design details such as geometric discontinuities or surface finish, 
including but not limited to embossing and etching.
    4. Instructions for Continued Airworthiness: The instructions for 
continued airworthiness must reflect the method used to fasten the 
panel to the cabin interior, and must ensure the reliability of the 
methods used (e.g., life limit of adhesives, or clamp connection). The 
applicant must define any inspection methods and intervals based upon 
adhesion data from the manufacturer of the adhesive, or upon actual 
adhesion-test data, if necessary.

    Issued in Renton, Washington, on February 14, 2017.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-05330 Filed 3-16-17; 8:45 am]
BILLING CODE 4910-13-P