[Federal Register Volume 76, Number 117 (Friday, June 17, 2011)]
[Rules and Regulations]
[Pages 35324-35327]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-15094]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM458; Special Conditions No. 25-431-SC]
Special Conditions: Boeing Model 787 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 787
series airplane. These airplanes will have a novel or unusual design
feature(s) 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 June 13, 2011.
We must receive your comments by July 18, 2011.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attn: Rules
Docket (ANM-113), Docket No. NM458, 1601 Lind Avenue, SW., Renton,
Washington 98057-3356. You may deliver two copies to the Transport
Airplane Directorate at the above address. You must mark your comments:
Docket No. NM458. You can inspect comments in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Jeff Gardlin, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 227-2136; 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 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
about these special conditions. You can inspect the docket 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 preamble
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal
holidays.
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.
If you want us to acknowledge receipt of your comments on these
special conditions, include with your comments a self-addressed,
stamped postcard on which you have written the docket number. We will
stamp the date on the postcard and mail it back to you.
Background
On March 28, 2003, Boeing Commercial Airplanes applied for an FAA
type certificate for its new Model 787 series airplane (hereafter
referred to as ``787''). Boeing later applied for, and was granted, an
extension of time for the type certificate, which changed the effective
application date to October 1, 2006. The 787 will be an all-new, twin-
engine jet transport airplane with a two-aisle cabin. The maximum
takeoff weight will be 476,000 pounds, with a maximum passenger count
of 381. These airplanes will have a novel or unusual design feature
associated with seats with inflatable lapbelts. 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 airbag, but in this case the
airbag is integrated into the lapbelt, and inflates away from the
seated occupant. While 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, or by
padding. Traditionally, this has required a set back 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 a 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 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
[[Page 35325]]
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 lap belt 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. Boeing 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
787-8 airplane, 25-354-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 lap belt 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 that case when
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. Although specifically prohibited by the FAA
operating regulations, the use of the supplementary loop belt (``belly
belt'') may be required by other civil aviation authorities, and should
also be considered with the end goal of meeting those regulations.
Similarly, if the seat is occupied by a pregnant woman, the
installation needs to 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.
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.
In addition, during the development of the inflatable lap belt 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 meet 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
[[Page 35326]]
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 very 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 state-of-the-art 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. The special
conditions are not an installation approval. Therefore, while the
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 14 CFR 21.17, Boeing Commercial Airplanes
must show that the 787 series airplanes meet the applicable provisions
of part 25, as amended by Amendments 25-1 through 25-120, 25-124, 25-
125, and 25-128 with the following exceptions: Sec. 25.1301 remains at
Amendment 25-119 for cargo fire protection systems.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 25) do not contain adequate or appropriate
safety standards for the 787 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 type certificate for that model be amended
later to include any other model that incorporates 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 787 series airplanes 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; and the FAA must issue a
finding of regulatory adequacy under Sec. 611 of Public Law 92-574,
the ``Noise Control Act of 1972.''.
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. 21.17(a)(2).
Novel or Unusual Design Features
The 787 series airplanes will incorporate the following novel or
unusual design features: Boeing Commercial Airplanes is proposing to
install an inflatable lapbelt on certain seats of 787 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 lap belt 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 787
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 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
787 series airplane. Should Boeing Commercial Airplanes apply at a
later date for a change to the type certificate to include another
model incorporating 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 787 series of airplanes. It is not a rule of general applicability.
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.
[[Page 35327]]
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 787 series airplanes.
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 seatbelts.
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, or
inertial loads resulting from in-flight or ground maneuvers (including
gusts and hard landings), and 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 the certification basis regarding lightning, Sec.
25.1316, and HIRF (special conditions) for the 787-8 airplane, are
incorporated by reference for the purpose of measuring lightning and
HIRF protection.
9. Inflatable lap belts, 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) is 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 part 25, appendix F, part I, paragraph
(b)(5).
Issued in Renton, Washington, on June 13, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 2011-15094 Filed 6-16-11; 8:45 am]
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