[Federal Register Volume 76, Number 199 (Friday, October 14, 2011)]
[Rules and Regulations]
[Pages 63818-63821]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-26554]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2011-1106; Special Conditions No. 25-448-SC]
Special Conditions: Boeing Model 767-400ER Series Airplanes;
Seats With Inflatable Lapbelts
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Boeing Model 767-
400ER series airplane. These airplanes, as modified by Continental
Airlines, will have a novel or unusual design feature associated with
seats with inflatable lapbelts. 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: The effective date of these special conditions is October 6,
2011. We must receive your comments by November 28, 2011.
ADDRESSES: Send comments identified by docket number FAA-2011-1106
using any of the following methods:
Federal eRegulations Portal: Go to http://www.regulations.gov and follow the online instructions for sending your
comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue, SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery of Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue, SE., Washington, DC, between 8 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without
change, to http://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
Docket: Background documents or comments received may be read at
http://www.regulations.gov at any time. Follow the online instructions
for accessing the docket or go to the Docket Operations in Room W12-140
of the West Building Ground Floor at 1200 New Jersey Avenue, SE.,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: John Shelden, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone 425-227-2785; facsimile 425-227-1149.
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for prior public comment on, these special conditions are
impracticable because these procedures would significantly delay
issuance of the design approval and thus delivery of the affected
aircraft. In addition, the substance of these special conditions has
been subject to the public comment process in several prior instances
with no substantive comments received. The FAA therefore finds that
good cause exists for making these special conditions effective upon
issuance.
Comments Invited
We invite interested people to take part in this rulemaking by
sending 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 will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
we receive.
Background
On March 3, 2011, Continental Airlines applied for a supplemental
type certificate to install inflatable lapbelts for head injury
protection on passenger seats on Boeing Model 767-400ER series
airplanes (hereafter referred to as ``767-400ER''), similar to Special
Condition Numbers 25-431-SC for Boeing Model 787 series airplanes, 25-
386-SC for Boeing Model 737 series airplanes, 25-187A-SC for Boeing
Model 777 series airplanes, and 25-148-SC for Boeing Model 767-300
series airplanes. These special conditions are to allow installation of
inflatable lapbelts for head injury protection on certain seats in
Boeing Model 767-400ER series airplanes.
The inflatable lapbelt is designed to limit occupant forward
excursion in the event of an accident. This will reduce the potential
for head injury, thereby reducing the Head Injury Criteria (HIC)
measurement. The inflatable lapbelt behaves similarly to an automotive
inflatable airbag, but in this case the airbag is integrated into the
lapbelt and inflates away from the seated occupant. While inflatable
airbags are now standard in the automotive industry, the use of an
inflatable lapbelt is novel for commercial aviation.
Title 14, Code of Federal Regulations (14 CFR) 25.785 requires that
occupants be protected from head injury by either the elimination of
any injurious object within the striking radius of the head,
[[Page 63819]]
or by padding. Traditionally, this has required a setback of 35 inches
from any bulkhead or other rigid interior feature or, where not
practical, specified types of padding. The relative effectiveness of
these means of injury protection was not quantified. With the adoption
of Amendment 25-64 to part 25, specifically Sec. 25.562, a new
standard that quantifies required head injury protection was created.
Section 25.562 specifies that each seat type design approved for
crew or passenger occupancy during takeoff and landing must
successfully complete dynamic tests or be shown to be compliant by
rational analysis based on dynamic tests of a similar type seat. In
particular, the regulations require that persons not suffer serious
head injury under the conditions specified in the tests, and that
protection must be provided or the seat be designed so that the head
impact does not exceed an HIC of 1000 units. While the test conditions
described for HIC are detailed and specific, it is the intent of the
requirement that an adequate level of head injury protection be
provided for passengers in a severe crash.
Because Sec. Sec. 25.562 and 25.785 and associated guidance do not
adequately address seats with inflatable lapbelts, the Federal Aviation
Administration (FAA) recognizes that appropriate pass/fail criteria
need to be developed that do fully address the safety concerns specific
to occupants of these seats.
The inflatable lapbelt has two potential advantages over other
means of head impact protection. First, it can provide significantly
greater protection than would be expected with energy-absorbing pads,
and second, it can provide essentially equivalent protection for
occupants of all stature. These are significant advantages from a
safety standpoint, since such devices will likely provide a level of
safety that exceeds the minimum standards of the federal aviation
regulations. Conversely, inflatable lapbelts in general are active
systems and must be relied upon to activate properly when needed, as
opposed to an energy-absorbing pad or upper torso restraint that is
passive, and always available. Therefore, the potential advantages must
be balanced against this and other potential disadvantages in order to
develop standards for this design feature.
The FAA has considered the installation of inflatable lapbelts to
have two primary safety concerns: first, that they perform properly
under foreseeable operating conditions, and second, that they do not
perform in a manner or at such times as would constitute a hazard to
the airplane or occupants. This latter point has the potential to be
the more rigorous of the requirements, owing to the active nature of
the system.
The inflatable lapbelt will rely on electronic sensors for
signaling and a stored gas canister for inflation. These same devices
could be susceptible to inadvertent activation, causing deployment in a
potentially unsafe manner. The consequences of inadvertent deployment,
as well as failure to deploy, must be considered in establishing the
reliability of the system. Continental Airlines must substantiate that
the effects of an inadvertent deployment in flight either would not
cause injuries to occupants, or that such deployment(s) meet the
requirement of Sec. 25.1309(b). The effect of an inadvertent
deployment on a passenger or crewmember that might be positioned close
to the inflatable lapbelt should also be considered. The person could
be either standing or sitting. A minimum reliability level will have to
be established for this case, depending upon the consequences, even if
the effect on the airplane is negligible.
The potential for an inadvertent deployment could be increased as a
result of conditions in service. The installation must take into
account wear and tear so that the likelihood of an inadvertent
deployment is not increased to an unacceptable level. In this context,
an appropriate inspection interval and self-test capability are
considered necessary. Other outside influences are lightning and high
intensity radiated fields (HIRF). Existing regulations regarding
lightning, Sec. 25.1316, and existing HIRF special conditions for the
Boeing Model 767-400ER series aircraft, Special Conditions No. 25-152-
SC, are applicable. Finally, the inflatable lapbelt installation should
be protected from the effects of fire, so that an additional hazard is
not created by, for example, a rupture of the pyrotechnic squib.
In order to be an effective safety system, the inflatable lapbelt
must function properly and must not introduce any additional hazards to
occupants as a result of its functioning. There are several areas where
the inflatable lapbelt differs from traditional occupant protection
systems, and requires special conditions to ensure adequate
performance.
Because the inflatable lapbelt is essentially a single use device,
there is the potential that it could deploy under crash conditions that
are not sufficiently severe as to require head injury protection from
the inflatable lapbelt. Since an actual crash is frequently composed of
a series of impacts before the airplane comes to rest, this could
render the inflatable lapbelt useless if a larger impact follows the
initial impact. This situation does not exist with energy absorbing
pads or upper torso restraints, which tend to provide continuous
protection regardless of severity or number of impacts in a crash
event. Therefore, the inflatable lapbelt installation should provide
protection, when it is required, by not expending its protection during
a less severe impact. Also, it is possible to have several large impact
events during the course of a crash, but there is no requirement for
the inflatable lapbelt to provide protection for multiple impacts.
Since each occupant's restraint system provides protection for that
occupant only, the installation must address seats that are unoccupied.
It will be necessary to show that the required protection is provided
for each occupant regardless of the number of occupied seats, and
considering that unoccupied seats may have lapbelts that are active.
The inflatable lapbelt should be effective for a wide range of
occupants. The FAA has historically considered the range from the fifth
percentile female to the ninety-fifth percentile male as the range of
occupants that must be taken into account. In this case, the FAA is
proposing consideration of a broader range of occupants, due to the
nature of the lapbelt installation and its close proximity to the
occupant. In a similar vein, these persons could have assumed the brace
position, for those accidents where an impact is anticipated. Test data
indicate that occupants in the brace position do not require
supplemental protection, and so it would not be necessary to show that
the inflatable lapbelt will enhance the brace position. However, the
inflatable lapbelt must not introduce a hazard in the case of deploying
into the seated, braced occupant.
Another area of concern is the use of seats, so equipped, by
children whether lap-held, in approved child safety seats, or occupying
the seat directly. Similarly, if the seat is occupied by a pregnant
woman, the installation should address such usage, either by
demonstrating that it will function properly, or by adding appropriate
limitation on usage.
Since the inflatable lapbelt will be electrically powered, there is
the possibility that the system could fail due to a separation in the
fuselage. Since this system is intended as crash/post-crash protection
means, failure to deploy due to fuselage separation is not acceptable.
As with emergency lighting, the system should function properly if such
a separation occurs at any point in the fuselage.
[[Page 63820]]
Since the inflatable lapbelt is likely to have a large volume
displacement, the inflated bag could potentially impede egress of
passengers. Since the bag deflates to absorb energy, it is likely that
an inflatable lapbelt would be deflated at the time that persons would
be trying to leave their seats. Nonetheless, it is considered
appropriate to specify a time interval after which the inflatable
lapbelt may not impede rapid egress. Ten seconds has been chosen as a
reasonable time, since this corresponds to the maximum time allowed for
an exit to be openable (Sec. 25.809). In actuality, it is unlikely
that an exit would be prepared by a flight attendant this quickly in an
accident severe enough to warrant deployment of the inflatable lapbelt,
and the inflatable lapbelt is expected to deflate much quicker than ten
seconds.
The current special conditions for the Boeing Model 777 series
airplanes, Special Conditions No. 25-187A-SC, were amended to address
flammability of the airbag material. During the development of the
inflatable lapbelt, the manufacturer was unable to develop a fabric
that would meet the inflation requirements for the bag and the
flammability requirements of part I(a)(1)(ii) of Appendix F to part 25.
The fabrics that were developed that met the flammability requirement,
did not produce acceptable deployment characteristics. However, the
manufacturer was able to develop a fabric that meets the less stringent
flammability requirements of part I(a)(1)(iv) of Appendix F to part 25
and has acceptable deployment characteristics.
Part I of Appendix F to part 25 specifies the flammability
requirements for interior materials and components. There is no
reference to inflatable restraint systems in Appendix F, because such
devices did not exist at the time the flammability requirements were
written. The existing requirements are based on both material types, as
well as use, and have been specified in light of the state-of-the-art
of materials available to perform a given function. In the absence of a
specific reference, the default requirement would be for the type of
material used to construct the inflatable restraint, which is a fabric
in this case. However, in writing a special condition, the FAA must
also consider the use of the material, and whether the default
requirement is appropriate. In this case, the specialized function of
the inflatable restraint means that highly specialized materials are
needed. The standard normally applied to fabrics is a 12-second
vertical ignition test. However, materials that meet this standard do
not perform adequately as inflatable restraints. Since the safety
benefit of the inflatable restraint is significant, the flammability
standard appropriate for these devices should not screen out suitable
materials, thereby effectively eliminating use of inflatable
restraints. The FAA will need to establish a balance between the safety
benefit of the inflatable restraint, and its flammability performance.
At this time, the 2.5-inch per minute horizontal test is considered to
provide that balance. As the technology in materials progresses (which
is expected), the FAA may change this standard in subsequent special
conditions to account for improved materials.
Finally, it should be noted that the special conditions are
applicable to the inflatable lapbelt system as installed. These special
conditions are not an installation approval. Therefore, while these
special conditions relate to each such system installed, the overall
installation approval is a separate finding and must consider the
combined effects of all such systems installed.
Type Certification Basis
Under the provisions of Title 14 Code of Federal Regulations (14
CFR) 21.101, Continental Airlines must show that the 767-400ER, as
changed, continues to meet the applicable provisions of the regulations
incorporated by reference in Type Certificate No. A1NM 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. A1NM are as follows: Amendments 25-1 through 25-89
with exceptions. The U.S. type certification basis for the Model 767-
400ER is established in accordance with 14 CFR 21.29 and 21.17 and the
type certification application date. The U.S. type certification basis
is listed in Type Certification Data Sheet No. A1NM.
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 767-400ER series airplanes 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,
the special conditions would also apply to the other model.
In addition to the applicable airworthiness regulations and special
conditions, the 767-400ER 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
The 767-400ER will incorporate the following novel or unusual
design feature: Continental Airlines is proposing to install an
inflatable lapbelt on certain seats of the 767-400ER series airplanes
in order to reduce the potential for head injury in the event of an
accident. The inflatable lapbelt works similar to an automotive airbag,
except that the airbag is integrated with the lapbelt of the restraint
system.
The CFR states the performance criteria for head injury protection
in objective terms. However, none of these criteria are adequate to
address the specific issues raised concerning seats with inflatable
lapbelts. The FAA has therefore determined that, in addition to the
requirements of part 25, special conditions are needed to address
requirements particular to installation of seats with inflatable
lapbelts.
Accordingly, in addition to the passenger injury criteria specified
in Sec. 25.785, these special conditions are adopted for the 767-400ER
series airplanes equipped with inflatable lapbelts. Other conditions
may be developed, as needed, based on further FAA review and
discussions with the manufacturer and civil aviation authorities.
Discussion
From the standpoint of a passenger safety system, the inflatable
lapbelt is unique in that it is both an active and entirely autonomous
device. While the automotive industry has good experience with airbags,
the conditions of use and reliance on the inflatable lapbelt as the
sole means of injury protection are quite different. In automobile
installations, the airbag is a supplemental system and works in
conjunction with an upper torso restraint. In addition, the crash event
is more definable and of typically shorter duration, which can simplify
the activation logic. The airplane operating environment is also quite
different from automobiles and includes the potential for greater wear
and tear, and
[[Page 63821]]
unanticipated abuse conditions (due to galley loading, passenger
baggage, etc.). Airplanes also operate where exposure to high intensity
electromagnetic fields could affect the activation system.
The following special conditions can be characterized as addressing
either the safety performance of the system or the system's integrity
against inadvertent activation. Because a crash requiring use of the
inflatable lapbelts is a relatively rare event, and because the
consequences of an inadvertent activation are potentially quite severe,
these latter requirements are probably the more rigorous from a design
standpoint.
Applicability
As discussed above, these special conditions are applicable to the
Continental Airlines 767-400ER series airplane. Should Continental
Airlines apply at a later date for a supplemental type certificate to
modify any other model included on Type Certificate No. A1NM to
incorporate 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 Continental Airlines 767-400ER series of airplanes. It is not a rule
of general applicability and affects only the applicant who applied to
the FAA for approval of these features on the airplane.
The substance of these special conditions has been subjected to the
notice and comment period in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. Therefore, because a delay would
significantly affect the certification of the airplane, which is
imminent, the FAA has determined that prior public notice and comment
are unnecessary and impracticable, and good cause exists for adopting
these special conditions upon issuance. The FAA is requesting comments
to allow interested persons to submit views that may not have been
submitted in response to the prior opportunities for comment described
above.
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 as part of
the type certification basis for Boeing Model 767-400ER series
airplanes modified by Continental Airlines.
1. Seats with Inflatable Lapbelts. It must be shown that the
inflatable lapbelt will deploy and provide protection under crash
conditions where it is necessary to prevent serious head injury. The
means of protection must take into consideration a range of stature
from a two-year-old child to a ninety-fifth percentile male. The
inflatable lapbelt must provide a consistent approach to energy
absorption throughout that range of occupants. In addition, the
following situations must be considered:
a. The seat occupant is holding an infant.
b. The seat occupant is a child in a child restraint device.
c. The seat occupant is a child not using a child restraint device.
d. The seat occupant is a pregnant woman.
2. The inflatable lapbelt must provide adequate protection for each
occupant regardless of the number of occupants of the seat assembly,
considering that unoccupied seats may have active lapbelts.
3. The design must prevent the inflatable lapbelt from being either
incorrectly buckled or incorrectly installed such that the inflatable
lapbelt would not properly deploy. Alternatively, it must be shown that
such deployment is not hazardous to the occupant and will provide the
required head injury protection.
4. It must be shown that the inflatable lapbelt system is not
susceptible to inadvertent deployment as a result of wear and tear,
inertial loads resulting from in-flight or ground maneuvers (including
gusts and hard landings), or other operating and environmental
conditions (vibrations, moisture, etc.) likely to be experienced in
service.
5. Deployment of the inflatable lapbelt must not introduce injury
mechanisms to the seated occupant or result in injuries that could
impede rapid egress. This assessment should include an occupant who is
in the brace position when it deploys and an occupant whose belt is
loosely fastened.
6. It must be shown that inadvertent deployment of the inflatable
lapbelt, during the most critical part of the flight, will either not
cause a hazard to the airplane or its occupants, or it meets the
requirement of Sec. 25.1309(b).
7. It must be shown that the inflatable lapbelt will not impede
rapid egress of occupants 10 seconds after its deployment.
8. The system must be protected from lightning and HIRF. The
threats specified in existing regulations regarding lightning, Sec.
25.1316 and existing HIRF special conditions for the Boeing Model 767-
400ER series aircraft, Special Condition No. 25-152-SC, are
incorporated by reference for the purpose of measuring lightning and
HIRF protection.
9. Inflatable lapbelts, once deployed, must not adversely effect
the emergency lighting system (i.e., block proximity lights to the
extent that the lights no longer meet their intended function).
10. The inflatable lapbelt must function properly after loss of
normal airplane electrical power and after a transverse separation of
the fuselage at the most critical location. A separation at the
location of the lapbelt does not have to be considered.
11. It must be shown that the inflatable lapbelt will not release
hazardous quantities of gas or particulate matter into the cabin.
12. The inflatable lapbelt installation must be protected from the
effects of fire such that no hazard to occupants will result.
13. There must be a means for a crewmember to verify the integrity
of the inflatable lapbelt activation system prior to each flight, or it
must be demonstrated to reliably operate between inspection intervals.
The FAA considers the loss of the airbag system deployment function
alone (i.e., independent of the conditional event that requires the
airbag system deployment) to be a major failure condition.
14. The inflatable material may not have an average burn rate of
greater than 2.5 inches/minute when tested using the horizontal
flammability test as defined in 14 CFR part 25, appendix F, part I,
paragraph (b)(5).
Issued in Renton, Washington, on October 6, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 2011-26554 Filed 10-13-11; 8:45 am]
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