```

[Federal Register Volume 82, Number 51 (Friday, March 17, 2017)]
[Rules and Regulations]
[Pages 14128-14130]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-05331]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-7689; Special Conditions No. 25-645-SC]

Special Conditions: Lufthansa Technik AG; Boeing Model 747-8 
Series Airplanes, Large Non-Structural Glass in the Passenger 
Compartment

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for the Boeing Model 747-8 
airplane. This airplane, as modified by Lufthansa Technik AG 
(Lufthansa), 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 March 8, 2012, Lufthansa Technik AG applied for a supplemental 
type certificate for large, non-structural glass panels in the 
passenger compartment in a Boeing Model 747-8 airplane. 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 
Lufthansa Technik AG, 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

[[Page 14129]]

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, Lufthansa Technik AG 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

    Lufthansa Technik AG 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 augmenting the existing design 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 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 have been known to be 
lethal. Thus the use of glass traditionally has been limited to 
windshields, and instrument and display transparencies. The regulations 
for certification of transport-category airplanes only address, 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:
     Glass panels integrated onto a stairway handrail closeout.
     Glass panels mounted in doors to allow visibility through 
the door when desired.
     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. 25-16-03-SC for Lufthansa 
modifications to the Boeing Model 747-8 airplane was published in the 
Federal Register on February 25, 2016 (81 FR 9363). One comment was 
received.
    By letter no. B-H020-REG-16-TLM-17 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, in Notice no. 25-16-03-SC, 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

[[Page 14130]]

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 Lufthansa. Should 
Lufthansa 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 Lufthansa Technik AG.
    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 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 10, 2017.
Michael Kaszycki,
Assistant Manager, Transport Airplane Directorate, Aircraft 
Certification Service.
[FR Doc. 2017-05331 Filed 3-16-17; 8:45 am]
 BILLING CODE 4910-13-P
```