[Federal Register Volume 70, Number 154 (Thursday, August 11, 2005)]
[Proposed Rules]
[Pages 46785-46788]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-15856]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM323; Notice No. 25-05-18-SC]


Special Conditions: Boeing Model 747-400 Airplane; Large Non-
Structural Glass in the Passenger Compartment

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for a Boeing Model 
747-400 airplane modified by Lufthansa Technik AG. This airplane will 
have a novel or unusual design feature associated with the installation 
of large non-structural glass items in the cabin area of an executive 
interior occupied by passengers and crew. The proposed installation of 
these items in a passenger compartment, which can be occupied during 
taxi, takeoff, and landing, is a novel or unusual design feature with 
respect to the material used. The applicable airworthiness regulations 
do not contain adequate or appropriate safety standards for this design 
feature. These proposed 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: Comments must be received on or before September 12, 2005.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, 
Attention: Rules Docket (ANM-113), Docket No. NM323, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056; or delivered in duplicate to the 
Transport Airplane Directorate at that address. All comments must be 
marked: Docket No. NM323. Comments may be inspected in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Alan Sinclair, Airframe/Cabin Safety 
Branch, ANM-115, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW.,

[[Page 46786]]

Renton, Washington, 98055-4056; telephone (425) 227-2195; facsimile 
(425) 227-1232, e-mail address [email protected].

SUPPLEMENTARY INFORMATION 

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The most 
helpful comments reference a specific portion of the special 
conditions, explain the reason for any recommended change, and include 
supporting data. We ask that you send us two copies of written 
comments.
    We will file in the docket all comments we receive as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these proposed special conditions. The docket is available 
for public inspection before and after the comment closing date. If you 
wish to review the docket in person, go to the address in the ADDRESSES 
section of this notice between 7:30 a.m. and 4 p.m., Monday through 
Friday, except Federal holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late, if it is 
possible to do so without incurring expense or delay. We may change the 
proposed special conditions in light of the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

Background

    On September 8, 2003, Lufthansa Technik AG, Weg beim J[auml]ger 
193, D-22335, Hamburg, Germany, applied for a supplemental type 
certificate (STC) for large non-structural glass items in the cabin 
area of the executive interior occupied by passengers and crew in a 
Boeing Model 747-400 airplane. The Boeing Model 747-400 airplane is 
approved under Type Certificate No. A20WE, and is a large transport 
category airplane with upper and main passenger decks. The airplane is 
limited to 660 passengers or less, depending on the interior 
configuration. This specific Model 747-400 configuration includes 
seating provisions for 105 passengers.

Type Certification Basis

    Under the provisions of Sec.  21.101, Lufthansa Technik must show 
that the Boeing Model 747-400 airplane, as changed, continues to meet 
the applicable provisions of the regulations incorporated by reference 
in Type Certificate No. A20WE or the applicable regulations in effect 
on the date of application for the change. The regulations incorporated 
by reference in the type certificate are commonly referred to as the 
``original type certification basis.'' The regulations incorporated by 
reference in Type Certificate No. A20WE are as follows: Amendments 25-1 
through 25-59 with exceptions for the Boeing Model 747-400. In 
addition, the certification basis includes certain special conditions, 
exemptions, or later amended sections of the applicable part that are 
not relevant to these proposed special conditions. The U.S. type 
certification basis for the Model 747-400 is established in accordance 
with Sec. Sec.  21.17 and 21.29 and the type certification application 
date.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate 
or appropriate safety standards for the Boeing Model 747-400 airplane 
because of a novel or unusual design feature, special conditions are 
prescribed under the provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Boeing Model 747-400 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.
    Special conditions, as defined in Sec.  11.19, are issued in 
accordance with Sec.  11.38 and become part of the type certification 
basis in accordance with Sec.  21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should Lufthansa Technik apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same or similar novel or unusual design 
feature, the special conditions would also apply to the other model 
under the provisions of Sec.  21.101.

Novel or Unusual Design Features

    The Boeing Model 747-400 will incorporate the following novel or 
unusual design feature, the installation of large non-structural glass 
items, typically in the form of glass sheets in the cabin area of an 
executive interior occupied by passengers and crew.
    These installations would be for aesthetic purposes, not for 
safety, in components other than windshields or windows. For these 
special conditions, a large glass item is 4 kg (approximately 10 
pounds) and greater in mass. This limit was established as the mass at 
which a glass component could be expected to potentially cause 
widespread injury if it were to shatter or break free from its 
retention system.
    The proposed special conditions address the novel and unusual 
design features for the use of large non-structural glass in the 
passenger cabin. These large glass items would be installed in occupied 
rooms or areas during taxi, take off, and landing, or rooms or areas 
that occupants do have to enter or pass through to get to any emergency 
exit. The proposed installations of large non-structural glass items 
may include, but are not limited to, the following items:
     Glass partitions.
     Glass attached to the ceiling.
     Wall/door mounted mirrors/glass panels.

Discussion

    The existing part 25 regulations only address the use of glass in 
windshields, instrument or display transparencies, or window 
applications. The regulations treat glass as unique for special 
applications where no other material will serve and address the adverse 
properties of glass.
    Section 25.775, ``Window and windshields,'' provides for the use of 
glass in airplanes, but limits glass to windshields and instrument or 
display transparencies. Furthermore, except for bolted-in windshields, 
there is limited experience with either adhesive or mechanical 
retention methods for large glass objects installed in an airplane 
subject to high loads supported by flexible restraints.
    The regulations provide for the following use of glass in the 
passenger cabin:
    1. Glass items installed in rooms or areas in the cabin that are 
not occupied during taxi, take off, and landing, and occupants do not 
have to enter or pass through the room or area to get to any emergency 
exit.
    2. Glass items integrated into a functional device whose operation 
is dependent upon the characteristics of glass, such as instrument or 
indicator protective transparencies, or monitor screens such as liquid 
crystal display (LCD) or plasma displays. These glass items maybe 
installed in any area in the cabin regardless of occupancy during taxi, 
take-off, and landing. Acceptable means for these items may depend on 
the size and specific location of the device.
    3. Small glass items installed in occupied rooms or areas during 
taxi, take off, and landing, or rooms or areas

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that occupants do have to enter or pass through to get to any emergency 
exit. For the purposes of these special conditions, a small glass item 
is less than 4 kg in mass, or a group of glass items weighing less than 
4 kg in mass.
    The glass items in numbers one, two, and three (above) have been 
restricted to applications where the potential for injury is either 
highly localized (such as instrument faces) or the location is such 
that injury due to failure of the glass is unlikely (e.g., mirrors in 
lavatories). These glass items are subject to the inertia loads 
contained in Sec.  25.561 and maximum positive differential pressure 
for items like monitors, but are not subject to these proposed special 
conditions. They have been found acceptable through project specific 
means of compliance requiring testing to meet the requirement Sec.  
25.785(d), and by adding a protective polycarbonate layer that covers 
the glass exposed to the cabin.
    The use of glass in airplanes utilizes the one unique 
characteristic of glass, its capability for undistorted or controlled 
light transmittance, or transparency. Glass, in its basic form as 
annealed, untreated sheet, plate, or float glass, when compared to 
metals, is extremely notch-sensitive, has a low fracture resistance, 
has a low modulus of elasticity, and can be highly variable in its 
properties. While reasonably strong, it is not a desirable material for 
traditional aircraft applications because, as a solo component, it is 
heavy (about the same density as aluminum). In addition, when glass 
fails, it can break into extremely sharp fragments that have the 
potential for injury above and beyond simple impact, and have been 
known to be lethal.
    The proposed special conditions address installing glass in much 
larger sizes than previously accepted and in a multitude of locations 
and applications, instead of using more traditional aircraft materials. 
In most, if not all cases, the glass will not be covered with a 
polycarbonate layer. Additionally, the retention of glass of this size 
and weight is not amenable to conventional techniques currently 
utilized in airplane cabins.
    The proposed special conditions consider the unusual material 
properties of glass as an interior material that have limited or 
prevented its use in the past, and address the performance standards 
needed to ensure that those properties do not reduce the level of 
safety intended by the regulations. They address the use of large glass 
items installed in occupied rooms or areas during taxi, take off, and 
landing, or rooms or areas that occupants do have to enter or pass 
through to get to any emergency exit.
    The proposed special conditions define a large glass component 
threshold of 4 kg, which is based on an assessment of the mass 
dislodged during a high ``g'' level (as defined in Sec.  25.562) event. 
Groupings of glass components that total more than 4 kg would also need 
to be included. The applicable performance standards in the regulations 
for the installation of these components also apply and should not 
adversely affect the standards provided below. For example, heat 
release and smoke density testing should not result in fragmentation of 
the component.
    For large glass components mounted in a cabin occupied by 
passengers or crew that are not otherwise protected from the injurious 
effects of failure of the glass component, the following apply:
    Material. The glass used must be tempered or otherwise treated to 
ensure that when fractured, it breaks into small pieces with relatively 
dull edges. This must be demonstrated by testing to failure. Tests 
similar to ANSI/SAE Z26.1 section 5.7, Test 7 would be acceptable.
    Fragmentation. The glass component construction must control the 
fragmentation of the glass to minimize the danger from flying glass 
shards or pieces. Impact and puncture testing to failure must 
demonstrate this. Tests similar to ANSI/SAE Z26.1 section 5.9, Test 9 
adjusted to ensure cracking the glass would be acceptable.
    Strength. The glass component, as installed in the airplane, must 
be strong enough to meet the load requirements for all flight and 
landing loads and all of the emergency landing conditions in subparts C 
and D of part 25. In addition, glass components that are located such 
that they are not protected from contact with cabin occupants must be 
designed for abusive loading without failure, such as impact from 
service carts, or occupants stumbling into, leaning against, sitting 
on, or performing other intentional or unintentional forceful contact. 
This must be demonstrated by static structural testing to ultimate load 
except that the critical loading condition must be tested to failure. 
The tested glass component must have all features that affect component 
strength, such as etched surfaces, cut or engraved designs, holes, and 
so forth.
    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. Based on the characteristics of a large glass 
component, dynamic tests should be performed to demonstrate that the 
occupants would be protected up to the load levels required by the 
certification basis of the airplane. A single test for the most 
critical loading for the installed component would be sufficient. This 
may be accomplished by using already accepted methods for dynamic 
testing.
    Analysis may be used in lieu of testing if the applicant has 
validated the strength models and dynamic simulation models used, 
against static tests to failure and dynamic testing to the above 
requirements, and can predict structural failure and dynamic response 
and inertial load. The glass material properties must meet Sec.  
25.613, ``Material strength properties and material design values.'' 
The effect of design details such as geometric discontinuities or 
surface finish must be accounted for in the test/analysis.

Applicability

    As discussed above, these special conditions are applicable to the 
Boeing Model 747-400 airplane. Should Lufthansa Technik apply at a 
later date for a supplemental type certificate to modify any other 
model included on the same 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 certain novel or unusual design features 
on the Boeing Model 747-400 modified by Lufthansa Technik AG. It is not 
a rule of general applicability, and it affects only the applicant who 
applied to the FAA for approval of these features 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 Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the certification basis for the 
Boeing Model 747-400 airplane, modified by Lufthansa Technik AG. For 
these special conditions, a large glass component is 4 kg 
(approximately 10 pounds) and greater in mass, or a grouping of glass 
components that total more than 4 kg.
    1. Material Fragmentation. The glass used to fabricate the 
component must be tempered or treated to ensure that when fractured, it 
breaks into small pieces with relatively dull edges. In addition, it 
must be shown that fragmentation of

[[Page 46788]]

the glass is controlled to reduce the danger from flying glass shards 
or pieces. This must be demonstrated by testing to failure.
    2. Component Strength. The glass component must be strong enough to 
meet the load requirements for all flight and landing loads including 
any of the applicable emergency landing conditions in subparts C & D of 
part 25. Abuse loading without failure, such as impact from occupants 
stumbling into, leaning against, sitting on, or performing other 
intentional or unintentional forceful contact must also be 
demonstrated. This must be demonstrated by static structural testing to 
ultimate load, except that the critical loading condition must be 
tested to failure in the as-installed condition. The tested glass must 
have all features that effect component strength, such as etched 
surfaces, cut or engraved designs, holes, and so forth. Glass pieces 
must be non-hazardous.
    3. Component 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. A test must be performed to demonstrate 
that the occupants would be protected from the effects of the component 
failing or becoming free of restraint under dynamic loading. The 
dynamic loading of Sec.  25.562(b)(2) is considered an acceptable 
dynamic event. The applicant may propose an alternate pulse, however, 
the impulse and peak load may not be less than that of Sec.  
25.562(b)(2). As an alternative to a dynamic test, static testing may 
be used if the loading is assessed as equivalent or more critical than 
a dynamic test, based upon validated dynamic analysis. Both the primary 
directional loading and rebound conditions need to be assessed.
    4. Instruction for Continued Airworthiness. The instruction for 
continued airworthiness will reflect the fastening method used and will 
ensure the reliability of the methods used (e.g., life limit of 
adhesives, or clamp connection). Inspection methods and intervals will 
be defined based upon adhesion data from the manufacturer of the 
adhesive or actual adhesion test data if necessary.

    Issued in Renton, Washington, on August 3, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-15856 Filed 8-10-05; 8:45 am]
BILLING CODE 4910-13-P