[Federal Register: November 20, 2008 (Volume 73, Number 225)]
[Rules and Regulations]
[Page 70257-70261]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr20no08-3]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM394; Special Conditions No. 25-375-SC]
Special Conditions: Airbus A318, A319, A320 and A321 Series
Airplanes; Inflatable Restraints
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 Airbus A318, A319,
A320, and A321 series airplanes. These airplanes will have a novel or
unusual design feature associated with a passenger restraint system
that contains an integrated inflatable airbag installed on passenger
seats. 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 November 12,
2008. We must receive your comments by January 5, 2009.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation
[[Page 70258]]
Administration, Transport Airplane Directorate, Attn: Rules Docket
(ANM-113), Docket No. NM394, 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. NM394. 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: Dan Jacquet, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 227-2676;
facsimile (425) 227-1320.
SUPPLEMENTARY INFORMATION: The FAA has determined that notice and
opportunity for prior public comment hereon 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 will consider comments filed late if it is possible to do
so without incurring expense or delay. We may change these special
conditions based on the comments we receive.
If you want us to let you know we received your comments on these
special conditions, send us 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 2, 2008, Airbus, 1 Rond-Point Maurice Bellonte, 31707
Blagnac, Cedex, France, applied for an amendment to Type Certificate
No. A28NM to install the AmSafe Aviation Inflatable Restraint (AAIR)
for head injury protection on passenger seats on Airbus A318, A319,
A320 and A321 series airplanes. The AAIR is designed to limit passenger
forward excursion in the event of an accident, thus reducing the
potential for head injury (and head entrapment).
The AAIR behaves like an automotive inflatable airbag except that
the airbag is integrated into the passenger restraint system and
inflates away from the seated passenger. While inflatable airbags are
standard in the automotive industry, the use of an inflatable passenger
restraint system is novel for commercial aviation.
Title 14, Code of Federal Regulations (14 CFR) 25.785 requires that
passengers be protected from head injury by either the elimination of
any injurious object within the striking radius of the head or by
padding. Traditionally, compliance has required either a setback of 35
inches from any bulkhead, front seat or other rigid interior feature or
padding where a setback was not practical. The relative effectiveness
of these two means of injury protection was not quantified. The
adoption of Amendment 25-64 to 14 CFR part 25, specifically Sec.
25.562, created a new standard for protection from head injury. Airbus
elected to comply with Sec. 25.562, except for Sec. 25.562(c)(5)
(protection from head injury) and Sec. 25.562(c)(6) (protection from
femur injury), for the Airbus A318, A319, and A321 series airplanes.
The pertinent parts of Sec. 25.562 for these airplanes require that
dynamic tests be conducted for each seat type installed in the
airplane, and that each seat type meets certain performance measures.
Although the head injury protection requirements of Sec. 25.562(e)(5)
are not part of the certification basis for the affected airplanes, it
is relevant for future compliance with Sec. 121.311(j). This
regulation will require full compliance with Sec. 25.562 for airplanes
manufactured on or after October 27, 2009.
Because Sec. Sec. 25.562 and 25.785 do not adequately address
seats with AAIRs, the FAA recognizes that we need to develop
appropriate pass/fail criteria that do address the safety of occupants
of those seats. These special conditions are applicable to inflatable
restraint systems in general. However, because this initial application
is for the AAIR, the following discussion refers specifically to the
AAIR.
The AAIR has two potential advantages over other means of head
impact protection. The first is that it can provide significantly
greater protection than would be expected with energy-absorbing pads;
the second is that 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 part 25 standards.
On the other hand, AAIRs are active systems and must 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 potential disadvantages
in order to develop standards that will provide an equivalent level of
safety to that intended by the regulations.
There are two primary safety concerns with the use of AAIRs: (1)
They perform properly under foreseeable operating conditions, and (2)
they do not perform in a way that 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 AAIR will rely on electronic sensors for signaling and
pyrotechnic charges for activation, so that it is available when
needed. These same devices could be susceptible to inadvertent
activation, causing deployment in a potentially unsafe manner. The
consequences of such deployment must be considered in establishing the
reliability of the system. Airbus must substantiate that the effects of
an inadvertent deployment in flight are either not a hazard to the
airplane or that such deployment is an extremely improbable occurrence
(occurring less than 10-9 per flight hour). The effect of an
inadvertent deployment on a passenger sitting or standing close to the
AAIR must also be considered. 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
necessary.
[[Page 70259]]
Other outside influences are lightning and high intensity radiated
fields (HIRF). Since the sensors that trigger deployment are
electronic, they must be protected from the effects of these threats.
Existing regulations regarding lightning (Sec. 25.1316) and HIRF
(Sec. 25.1317) are applicable in lieu of any other lightning and HIRF
special conditions that have been adopted for the affected airplanes.
For the purposes of compliance, if inadvertent deployment could
cause a hazard to the airplane, the AAIR is considered a critical
system; if inadvertent deployment could cause injuries to persons, the
AAIR is considered an essential system. Finally, the AAIR installation
should be protected from the effects of fire, so that an additional
hazard is not created by, for example, a rupture of a pyrotechnic
squib.
In order to be an effective safety system, the AAIR must function
properly and must not introduce any additional hazards to occupants as
a result of its functioning. There are several areas where the AAIR
differs from traditional occupant protection systems, and requires
special conditions to ensure adequate performance.
Because the AAIR 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 AAIR.
Since an actual crash is frequently composed of a series of impacts
before the airplane comes to rest, this could render the AAIR 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 protection according to the severity of the impact.
Therefore, the AAIR installation should be such that the AAIR will
provide protection when it is required and will not expend its
protection when it is not needed. There is no requirement for the AAIR
to provide protection for multiple impacts, where more than one impact
would require protection.
Since each passenger'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 AAIR that are
active.
Since there is a wide range in the size of passengers, the AAIR
must be effective over the entire range. The FAA has historically
considered the range from the fifth percentile female to the ninety-
fifth percentile male as the range of passengers to take into account.
In this case, the FAA is proposing consideration of an even broader
range of passengers, due to the nature of the AAIR installation and its
close proximity to the passenger. In a similar vein, passengers may
assume the brace position for those accidents where an impact is
anticipated. Test data indicate that passengers in the brace position
do not require supplemental protection, so that it will not be
necessary to show that the AAIR will enhance the brace position.
However, the AAIR must not introduce a hazard in that case by deploying
into the seated, braced passenger.
Another area of concern is the use of seats occupied 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 needs to address such usage, either by demonstrating that
it will function properly, or by adding an appropriate limitation on
usage.
Since the AAIR 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 a means of protection in a
crash or after a crash, failure 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 AAIR 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 AAIR 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 AAIR may not impede rapid egress. Ten seconds has been
chosen as a reasonable time, since it corresponds to the maximum time
allowed for an exit to be openable. In actuality, it is unlikely that
an exit would be prepared this quickly in an accident severe enough to
warrant deployment of the AAIR, and the AAIR will likely deflate much
quicker than ten seconds.
The manufacturers of the inflatable lap belts have been unable thus
far to develop a fabric that meets the inflation requirements for the
bag and the flammability requirements of Part I(a)(1)(ii) of appendix F
of part 25. The fabrics that have been developed that meet the
flammability requirements 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.
Finally, it should be noted that the special conditions are
applicable to the AAIR 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 Sec. 21.101, Airbus must show that the
A318, A319, A320 and A321 series airplanes, as changed, continue to
meet the applicable provisions of the regulations incorporated by
reference in Type Certificate No. A28NM 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 for each individual airplane model are defined within Type
Certificate Data Sheet (TCDS) A28NM.
In addition, the certification basis includes other regulations and
special conditions that are not pertinent to these special conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Airbus A318, A319, A320 and A321
series airplanes, 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, each airplane model 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 Sec. 11.19, under
Sec. 11.38 and they become part of the type certification basis under
Sec. 21.101.
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, or should any other model included on the same
type certificate be modified to incorporate the same novel or unusual
design
[[Page 70260]]
feature, the special conditions would also apply to the other model.
Novel or Unusual Design Features
The Airbus A318, A319, A320 and A321 series airplanes will
incorporate the following novel or unusual design features: These
airplanes as modified by Airbus will have a passenger restraint system
that contains an integrated inflatable airbag device installed on
passenger seats. The AAIR will be installed to reduce the potential for
head injury in the event of an accident. The AAIR works like an
automotive airbag, except that the airbag is integrated with the
passenger restraint system. The AAIR is considered a novel design for
transport category airplanes and was not considered as part of the
original type certification basis.
Section 25.785 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
AAIR. The FAA has therefore determined that, in addition to the
requirements of 14 CFR part 25, special conditions are needed to
address requirements particular to installation of seats with AAIR.
Accordingly, in addition to the passenger injury criteria specified
in Sec. 25.785, these special conditions are adopted for the Airbus
A318, A319, A320 and A321 series airplanes equipped with AAIR. 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 airbag 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 airbag 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
airbags 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
Airbus A318, A319, A320 and A321 series airplanes. Should Airbus apply
at a later date for a change to 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 Airbus A318, A319, A320 and A321 series 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. For this reason and 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 that 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.
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 Airbus A318, A319, A320 and A321
series airplanes, as modified by installation of inflatable restraints.
1. Seats with inflatable restraints. It must be shown that the
inflatable restraints will deploy and provide protection under crash
conditions where it is necessary to prevent serious head injury or head
entrapment. 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 restraints must provide a consistent approach to
energy absorption throughout that range. 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 restraints 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 restraints from being
either incorrectly buckled or incorrectly installed such that the
inflatable restraints 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 restraints 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), likely to be experienced in service.
5. Deployment of the inflatable restraints 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 an inadvertent deployment that could cause
injury to a standing or sitting person is improbable.
7. It must be shown that inadvertent deployment of the inflatable
restraints, during the most critical part of the flight, will either
not cause a hazard to the airplane or is extremely improbable.
8. It must be shown that the inflatable restraints will not impede
rapid egress of occupants 10 seconds after its deployment.
9. If lithium non-rechargeable batteries are used to power the
inflatable restraints, the batteries must be DO-227 and UL compliant.
However, if rechargeable lithium batteries are used,
[[Page 70261]]
additional special conditions may apply.
10. The inflatable restraints 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 lap belt does not have to be considered.
11. It must be shown that the inflatable restraints will not
release hazardous quantities of gas or particulate matter into the
cabin.
12. The inflatable restraints installation must be protected from
the effects of fire such that no hazard to occupants will result.
13. The system must be protected from lightning and HIRF. The
threats specified in Special Conditions No. 25-ANM-23 are incorporated
by reference for the purpose of measuring lightning and HIRF
protection. For the purposes of complying with HIRF requirements, the
inflatable lapbelt system is considered a critical system if its
deployment could have a hazardous effect on the airplane; otherwise it
is considered an essential system.
14. There must be a means for a crewmember to verify the integrity
of the inflatable restraints activation system prior to each flight or
it must be demonstrated to reliably operate between inspection
intervals.
15. 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 November 12, 2008.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-27541 Filed 11-19-08; 8:45 am]
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