[Federal Register Volume 64, Number 92 (Thursday, May 13, 1999)]
[Proposed Rules]
[Pages 25851-25854]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-12057]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM155; Notice No. 25-99-03-SC]
Special Conditions: Boeing Model 767-300 Series Airplanes; Seats
With Inflatable Lapbelts
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for Boeing Model 767-
300 series airplanes. These airplanes as modified by Am-Safe, Inc. will
have novel and unusual design features associated with seats with
inflatable lapbelts. The applicable airworthiness regulations do not
contain adequate or appropriate safety standards for this design
feature. The proposed special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
DATES: Comments must be received on or before June 28, 1999.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Office of the Regional Counsel,
Attention: Rules Docket (ANM-7), Docket No. NM155, 1601 Lind Avenue
SW., Renton, Washington, 98055-4506; or delivered in duplicate to the
Office of the Regional Counsel at the above address. Comments must be
marked: Docket No. NM155. Comments may be inspected in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Jeff Gardlin, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, FAA, 1601 Lind Avenue SW., Renton, Washington,
98055-4056; telephone (206) 227-2136; facsimile (425) 227-1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of
these proposed special conditions by submitting such written data,
views, or arguments as they may desire. Communications should identify
the regulatory docket or notice number and be submitted in duplicate to
the address specified above. All communications
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received on or before the closing date for comments will be considered
by the Administrator. The proposals described in this notice may be
changed in light of the comments received. All comments received will
be available in the Rules Docket for examination by interested persons,
both before and after the closing date for comments. A report
summarizing each substantive public contact with FAA personnel
concerning this rulemaking will be filed in the docket. Persons wishing
the FAA to acknowledge receipt of their comments submitted in response
to this notice must include with those comments a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. NM155.'' The postcard will be date stamped and returned
to the commenter.
Background
On March 8, 1999, Am-Safe Inc. applied for a supplemental type
certificate to install inflatable lapbelts for head injury protection
on certain seats in Boeing Model 767-300 series airplanes. The Model
767-300 series airplane is a swept-wing, conventional-tail, twin-
engine, turbofan-powered transport. 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 deploys 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'' 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 14 CFR part 25, a new standard that quantifies required head
injury protection was created.
Title 14 CFR 25.562 specifies that dynamic tests must be conducted
for each seat type installed in the airplane. In particular, the
regulations require that persons not suffer serious head injury under
the conditions specified in the tests, and that a HIC measurement of
not more than 1,000 units be recorded, should contact with the cabin
interior occur. While the test conditions described in this section are
specific, it is the intent of the requirement that an adequate level of
head injury protection be provided for crash severity up to and
including that specified.
While Amendment 25-64 is not part of the Model 767-300
certification basis, it is recognized that the installation of
inflatable lapbelts will eventually be proposed for airplanes that do
include this requirement. In addition HIC is the only available
quantifiable measure of head injury protection. Therefore, the FAA will
require that a HIC of less than 1000 be demonstrated for occupants of
seats incorporating the inflatable lapbelt.
Because Sec. 25.562 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 essentially
equivalent protection for occupants of all stature, and second, it can
provide significantly greater protection than would be expected with
energy absorbing pads, for example. 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 (FAR). Conversely, airbags 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. These potential advantages must be
balanced against the potential problems in order to develop standards
that will provide an equivalent level of safety to that intended by the
regulations.
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. With this philosophy in mind, the FAA has considered the
following as a basis for the special conditions.
The inflatable lapbelt 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. Am-Safe, Inc. 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 (less than 10-9 per flight
hour). The effect of an inadvertent deployment on a passenger or
crewmember that might be positioned close to the airbag 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 electromagnetic fields (HIRF). Since the sensors that trigger
deployment are electronic, they must be protected from the effects of
these threats. Existing Special Conditions No. 25-ANM-18 regarding
lightning and HIRF are therefore applicable. For the purposes of
compliance with those special conditions, if inadvertent deployment
could cause a hazard to the airplane, the airbag is considered a
critical system; if inadvertent deployment could cause injuries to
persons, the airbag should be considered an essential system. Finally,
the airbag 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 airbag must function
properly and must not introduce any additional hazards to occupants as
a result of its functioning. There are several areas where the airbag
differs from traditional occupant protection systems, and requires
special conditions to ensure adequate performance.
Because the airbag 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
airbag. Since an actual crash is frequently composed of a series of
impacts, this could render the airbag useless if a larger impact
follows the initial impact. This situation does
[[Page 25853]]
not exist with energy absorbing pads or upper torso restraints, which
tend to provide protection proportional to the severity of the impact.
Therefore, the airbag installation should be such that the airbag will
provide protection when it is required, and will not expend its
protection when it is not needed. There is no requirement for the
airbag to provide protection for multiple impacts, where more than one
impact would require protection.
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 buckled.
Since a wide range of occupants could occupy a seat, the inflatable
lapbelt should be effective for a wide range of occupants. The FAA has
historically considered the range from the 5th percentile female to the
95th percentile male as the range of occupants that must be taken into
account. In this case, the FAA is proposing consideration of a larger
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 by 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. The installation needs to address the use of the inflatable
lapbelt by children, 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 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. A separation that
occurs at the location of the inflatable lapbelt would not have to be
considered.
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. In actuality, it is unlikely that an exit would
be prepared this quickly in an accident severe enough to warrant
deployment of the inflatable lapbelt, and the inflatable lapbelt will
likely deflate much quicker than ten seconds.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Am-Safe, Inc. must show that
the Model 767-300 series airplanes, as changed, continue 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 25-45 with exceptions. The U.S. type certification basis for
the Model 767-300 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 Certificate Data Sheet No. A1NM.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25 as amended) do not contain adequate
or appropriate safety standards for Boeing Model 767-300 series
airplanes because of a novel or unusual design feature, special
conditions are prescribed under the provisions of 14 CFR 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Boeing Model 767-300 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 appropriate, are issued in accordance with
14 CFR 11.49 after public notice, as required by 14 CFR 11.28 and
11.29(b), and become part of the type certification basis in accordance
with 14 CFR 21.101(b)(2).
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 under the
provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
The Model 767-300 series airplanes will incorporate the following
novel or unusual design features: Am-Safe, Inc. is proposing to install
an inflatable lapbelt on certain seats of Boeing Model 767-300 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 FAR 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 14 CFR 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 14 CFR 25.785, these special conditions are proposed for the Boeing
Model 767-300 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 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
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to high intensity electromagnetic fields could affect the activation
system.
The following proposed 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 the
Model 767-300 series airplanes. Should Am-Safe, Inc. 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 under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on the Boeing Model 767-300 series airplanes. It is not a rule of
general applicability, and it affects only the applicant who applied to
the FAA for approval of these features on the airplane.
List of Subjects in 14 CFR Part 25
Air transportation, Aircraft, Aviation safety, Safety, Reporting
and recordkeeping requirements.
The authority citation for these proposed special conditions is as
follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the Boeing Model 767-300 series airplanes equipped with inflatable
lapbelts modified by Am-Safe, Inc.
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-nine percentile male. The
inflatable lapbelt must provide a consistent level of energy absorption
throughout that range. 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.
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 buckled (thereby active)
seatbelts.
3. The design must prevent the inflatable lapbelt from being
incorrectly buckled and/or incorrectly installed such that the airbag
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), likely to be experienced in service.
5. The seated occupant must not be injured as a result of the
inflatable lapbelt deployment.
6. It must be shown that the inflatable lapbelt will not be a
hazard to an occupant who is in the brace position when it deploys.
7. It must be shown that an inadvertent deployment, that could
cause injury to a standing or sitting person, is improbable.
8. 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 is extremely improbable.
9. It must be shown that the inflatable lapbelt will not impede
rapid egress of occupants 10 seconds after its deployment.
10. The system must be protected from lightning and HIRF. The
threats specified in Special Condition No. 25-ANM-18 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.
11. The inflatable lapbelt must function properly after loss of
normal aircraft electrical power, and after a transverse separation of
the fuselage at the most critical location.
12. It must be shown that the inflatable lapbelt will not release
hazardous quantities of gas or particulate matter into the cabin.
13. The inflatable lapbelt installation must be protected from the
effects of fire such that no hazard to occupants will result.
14. 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.
Issued in Renton, Washington, on May 3, 1999.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 99-12057 Filed 5-12-99; 8:45 am]
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