[Federal Register: January 10, 2006 (Volume 71, Number 6)]
[Rules and Regulations]
[Page 1485-1488]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10ja06-3]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM323; Special Conditions No. 25-311-SC]
Special Conditions: Boeing Model 747-400 Airplane; 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 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 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 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.
Effective Date: January 3, 2006.
FOR FURTHER INFORMATION CONTACT: Alan Sinclair, Airframe/Cabin Safety
Branch, ANM-115, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056;
telephone (425) 227-2195; facsimile (425) 227-1232, e-mail address
alan.sinclair@faa.gov.
SUPPLEMENTARY INFORMATION:
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 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
[[Page 1486]]
(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.
These 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 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 may be
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 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 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.
These 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.
These 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.
These 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:
[[Page 1487]]
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.
Discussion of Comments
Notice of proposed special conditions No. 25-05-08-SC for the
Boeing Model 747-400 series airplanes was published in the Federal
Register on August 11, 2005 (70 FR 46785). One commenter responded to
the notice.
Comment: The commenter expresses concern that the special
conditions neglect to address injuries, especially head injuries to
passengers because of physical movements of the airplane caused by
unexpected disturbances, sudden loss of altitude, disorientation, etc.
FAA Reply: The special conditions do not specifically call out for
the protection of the passenger while moving about the cabin because
the existing regulation, Sec. 25.785(d)(e), already addresses this
requirement. These special conditions are additional requirements to
the existing certification basis of the Boeing Model 747-400.
Comment: The commenter expresses concern that the special
conditions neglect to address injuries caused to passengers by glass
breaking into a large number of small fragments. These small fragments
may have dull edges and fall to the ground causing passengers to slip,
fall, and harm themselves.
FAA Reply: Special conditions 1 and 2 address
this concern by requiring the glass to be tested to failure to
demonstrate that glass pieces must be shown to be non-hazardous.
Comment: The commenter expresses concern that the special
conditions neglect to address disorientation of passengers because of
reflections in mirrored glass panels, or because of intense sunlight
through the windows on clear or mirrored glass panels.
FAA Reply: In this case, glass does not present any additional
hazards over the materials currently used in airplane interiors, such
as polished metals or mirrored acrylics. The FAA is currently unaware
of any instances of these materials causing such disorientation among
the passengers.
Comment: The commenter expresses concern that the special
conditions neglect to address or omit the possible liability incurred
by the carrier, operator, and potential third parties-not excluding the
FAA, which is granting these special conditions. The commenter
expresses concern that the liability incurred could be beyond the
carrier's insurance coverage.
FAA Reply: These special conditions are intended to establish a
level of safety for the use of glass equal to those of the existing
regulations. As such, the liability incurred would be no different than
currently exists in the industry. The aircraft industry requested these
special conditions, and they are required only if the applicant chooses
to install structural glass.
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 change to the supplemental type certificate to include
another model on the same type certificate incorporating 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.
In an effort to address the commenters concerns, and based on the
nature of the intended operation of the affected airplane, the FAA
limits the application of these special conditions to airplanes
operated for private use only. Therefore, the appropriate limitation
has been added to the special conditions.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
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 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. The airplane is not operated for hire or offered for common
carriage. This provision does not preclude the operator from receiving
remuneration to the extent consistent with 14 CFR parts 125 and 91,
subpart F, as applicable.
2. 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 the glass is controlled to reduce
the danger from flying glass shards or
[[Page 1488]]
pieces. This must be demonstrated by testing to failure.
3. 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.
4. 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.
5. 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 January 3, 2006.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate Aircraft Certification
Service.
[FR Doc. 06-200 Filed 1-9-06; 8:45 am]
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