[Federal Register Volume 64, Number 184 (Thursday, September 23, 1999)]
[Rules and Regulations]
[Pages 51424-51430]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-24792]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM155; Special Conditions No. 25-148-SC]
Special Conditions: Boeing Model 767-300 Series Airplanes; Seats
with Inflatable Lapbelts
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for Boeing Model 767-300
series airplanes. These airplanes as modified by Am-Safe, Inc. will
have novel and
[[Page 51425]]
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. These special
conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
EFFECTIVE DATE: October 25, 1999.
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:
Background
On March 8, 1999, Am-Safe Inc. 240 North 48th Avenue, Phoenix,
Arizona, 85043, 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 the
fixed mounted 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 1,000 be demonstrated for occupants of
seats incorporating the inflatable lapbelt.
Because 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 significantly
greater protection than would be expected with energy absorbing pads,
for example, 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 (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 disadvantages 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 before the airplane
[[Page 51426]]
comes to rest, this could render the airbag 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
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 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 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 may 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 if it
deploys 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 the 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 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 similarly to a fixed
mounted 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 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 adopted 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.);
[[Page 51427]]
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.
Discussion of Comments
Notice of proposed special conditions, Notice No. 25-99-03-SC, for
the Boeing Model 767-300 series airplanes; equipped with inflatable
lapbelts was published in the Federal Register on May 13, 1999 (64 FR
2581). Eight commenters responded to the Notice.
Six commenters addressed special condition #1, concerning the range
of occupants and conditions of occupancy that must be considered when
qualifying the inflatable lapbelt. One commenter felt that pregnant
women should be added to the occupants considered. Other commenters
stated that the range of occupant statures specified was not
substantiated, and that there were existing accepted ranges that were
applicable to this installation that should be used. Some commenters
inferred from the wording of condition #1 that ``consideration'' of the
scenarios specified meant that occupant protection must be demonstrated
for those scenarios. Another commenter pointed out that occupant
stature was very important to the performance of the inflatable
lapbelt, considering that the occupant's lap and lower limbs were
likely to provide the bearing surface for the airbag. A commenter also
noted that, once deployed, the airbag will absorb energy based upon its
size, pressure and vent area, and to require a ``consistent'' level of
energy absorption for all occupant sizes is virtually impossible.
After further consideration, the FAA has concluded that the
established range of occupant stature, inclusive of the ninety-fifth
percentile male is sufficient to address the performance of the
inflatable lapbelt. Consideration of larger occupants, while desirable,
is not specifically unique to this installation, and therefore should
not be made an additional criterion by special condition. The FAA does,
however, continue to maintain that small children should be
accommodated by the inflatable lapbelt, and should not be subject to
any hazards associated with its deployment. There were no adverse
comments to this aspect of the proposal.
With respect to consideration of occupancy conditions given in
conditions #1.a., b., and c., it was not the FAA's intent that the
lapbelt be shown to accommodate all of these conditions. The intent of
the condition was to cause each case to be addressed, and either
demonstrated to be acceptable, or prohibited from occurring by
operational limitations. Thus, if the inflatable lapbelt cannot
accommodate a child restraint device, it would be acceptable to
prohibit use of child restraint devices in seats so equipped. The same
is true for the other conditions.
With respect to the requirement that the inflatable lapbelt provide
a ``consistent level of energy absorption'' the FAA agrees that the
amount of energy absorbed is dependent on the amount of energy input,
and that will vary according to occupant size. The use of the word
consistent may be confusing in this case. The intent of the requirement
is to ensure that the range of occupants under consideration is
presented with a consistent approach to injury protection, such that
all occupants are afforded protection by the same mechanisms. This
requirement has the effect of both establishing a consistent approach
to injury protection for the range of occupants, as well as permitting
demonstration with the fiftieth percentile anthropomorphic test dummy
(ATD) to show compliance for the extremes of the ranges.
With respect to pregnant women, the FAA agrees that there should be
some instruction provided regarding use of the seat with an inflatable
lapbelt. This requirement is added as condition #1.d., which would
enable the applicant to either demonstrate or restrict such occupancy.
It is clear that the performance of the inflatable lapbelt will
depend to a large extent on the bearing surface, whether it is the
person occupying the seat themselves or it is the airplane interior
structure. The FAA considers this to be part of the basic qualification
of the system, and however the system performs, it must be shown to do
so reliably and consistently for the range of occupants.
Two commenters addressed condition #2 regarding the number of
seated occupants to be considered. Both commenters stated that the
wording of the condition implies that the buckles must have switches,
and that a buckle is required for firing. Both commenters request
clarification of the term ``adequate protection''. One commenter
suggested alternative wording.
In this case, the design incorporates switches in the buckle
assembly, and so the special condition addresses that design. Other
designs might be addressed differently, but the main issue is to
consider the effect on occupants of a partially occupied seat assembly,
if all of the airbags activate. In that instance, the inflatable
lapbelt should still perform its safety function for each occupant, and
there should be no hazard (either as a result of the deployment, or to
egress) from inflatable lapbelts that might activate in unoccupied seat
places. In order to account for possible design changes, the wording is
adjusted slightly to remove the word ``buckled'' and simply state that
the unoccupied seats may have ``active'' inflatable lapbelts.
One commenter stated that condition #3 is subjective, and the
stiffness of the belt should suffice to satisfy the requirement.
Another commenter pointed out that a person could properly fasten the
belt, and then twist the whole assembly so as to invert the buckle with
respect to its proper position. The same commenter also noted that a
loosely fastened belt should be considered.
The intent of this requirement is to make improper use of the belt
unlikely. While there may be some subjectivity in this determination,
there are practical design measures that will effectively eliminate the
chance that a person would inadvertently misuse the lapbelt. The
situation where a person deliberately inverts the buckle is different,
and the intent of the special condition was not to account for such
situations. Nonetheless, the measures taken to address inadvertent
misuse will also likely be effective in preventing or minimizing
deliberate misuse. With respect to a loosely fastened belt, this is
something that no doubt occurs on standard seatbelts and reduces their
effectiveness. The FAA agrees that a loosely fastened belt should not
result in any greater risk to the occupant than on a standard belt, but
cannot require that the inflatable belt be demonstrated to perform as
well in this condition as when it is properly fastened. This provision
is added to condition #5, which addresses occupants in the brace
position.
Four commenters felt that the requirement of condition #4 was
vague, and that ``wear and tear'' needed further definition. Some
commenters felt that this requirement could be linked to inspection and
instructions for continued airworthiness, which are required anyway.
One commenter indicated that the condition is directed at pyrotechnic
devices, which may not be typical.
The FAA agrees that the term ``wear and tear'' is not particularly
specific,
[[Page 51428]]
and this was intentional. Depending on where certain components of the
system are installed, their susceptibility to in-service wear and tear
will vary. It is the intent of this requirement that the inflatable
lapbelt will not deploy as a result of foreseeable in-service
conditions, including interaction with passengers, if applicable, use
of service carts, if applicable, and so on. There are regulatory
requirements for instructions for continued airworthiness, which
continue to apply and are not a substitute for these special
conditions. The device in question is pyrotechnically activated and,
therefore, this condition was written with that in mind. Other designs
that might require a different condition, or might not require a
similar consideration, are not the subject of this special condition.
No change is made to the special condition.
Four commenters felt that the requirement of condition #5 was
impractical as stated, since no injury severity level was specified.
One commenter pointed out that a bruise could be considered an injury
under the current wording, and would therefore make the inflatable
lapbelt unacceptable. Commenters point out that a person sitting in a
fully compliant standard seat is likely to suffer some injuries as a
result of an accident of the severity addressed by the regulations, and
that the requirement should be that their ability to egress the
airplane not be adversely affected.
The FAA agrees that the proposed wording could have unintended
consequences. The intent of the requirement is to prevent the
introduction of injury mechanisms that did not exist previously, or
would not be present on a seat that complied with the regulations
directly. In this regard, injuries that would affect rapid egress are
certainly of concern. However, there could be other injury mechanisms
that might not have a direct impact on rapid egress, but could still be
debilitating. In order to clarify the requirement, the wording is
changed to require that the inflatable lapbelt not introduce injury
mechanisms and that rapid egress not be affected.
Three commenters addressed the issue of brace position. Comments
concerned establishing what is an acceptable brace position and on what
basis an injury assessment should be made.
For the purposes of this special condition, the brace position is
considered to be that shown on the operators' safety information card.
The FAA does not expect that different approaches to the brace
positions are feasible for seats with and without the inflatable
lapbelt (for example considering the seated, upright position as the
``brace'' position for these seats). It is recognized that the current
approach to brace position does result in a different position for
seats that are closely spaced, versus those that aren't. In both of
those cases, however, the approach is to assume a position bending as
far forward as possible. Considering the modifications made to
condition #5, this requirement will be combined with that one as a
consideration to be addressed when determining injury potential. (Note:
The special conditions are renumbered due to the combining of Notice
conditions #5 and #6).
There was one comment regarding condition #6 (condition #7 of
Notice), the need to demonstrate that inadvertent deployment that could
cause injury to a sitting or standing person is improbable
(10-5/flt-hour). The commenter felt that this requirement
could be open-ended unless inadvertent deployment was shown to be
extremely improbable (10-9/flt-hour). The FAA does not
agree. Demonstration of reliability at the improbable level is
sufficient to satisfy the objective of the requirement.
Two commenters addressed the requirement that an inadvertent
deployment that could cause a hazard to continued safe flight and
landing be extremely improbable. Both commenters agree with the
requirement, however, one commenter believes it is unnecessary, since
the commenter feels the inflatable lapbelt cannot cause such a hazard.
While the FAA agrees that the design as it is currently understood is
unlikely to constitute a direct hazard to safe flight, this requirement
is fundamental to the acceptability of such a system. Thus, while the
system may, in practice, not constitute a hazard, the possibility
cannot be ruled out, and criteria are needed in that event.
Four commenters questioned the proposed requirement addressing
impediment to rapid egress. One commenter stated that some ground rules
are necessary to make an objective assessment. Another commenter
questioned the origin of the 10 second standard proposed, and whether
that standard applied equally to accidents that consisted of single and
multiple impacts. One commenter stated that the deflated airbag should
also be considered. Another commenter noted that the deflation of the
airbag is dependent on vent size and the impact occuring to the bag
itself. If there is no impact, the bag will vent naturally, and
typically more slowly than if it were impacted.
The requirement as written was intended to address both the
inflated and deflated conditions, as well as a representative accident
scenario, from initial impact until the airplane comes to rest. The
reason that a specific time interval was chosen was in consideration of
the fact that an evacuation cannot take place simultaneously with the
accident. The 10 second interval was established based on FAA review of
both test and accident data concerning the time from impact until an
airplane comes to rest, coupled with the time needed to prepare exits
and escape slides for evacuation. Therefore, 10 seconds after the
device deploys, it should not impede rapid egress of occupants. This
includes occupants of seats adjacent to deployed devices, as well as
occupants of the seat in which the device deploys. No change is made to
this provision.
One commenter questioned the need to address lightning and high
intensity radiated fields (HIRF), considering the potential hazard. The
FAA regards this as a necessary requirement since the failure to
address it potentially increases the hazards present. If the inflatable
lapbelt were not protected from HIRF and lightning effects the
potential for inadvertent deployment increases dramatically, and the
associated risk would increase accordingly. Therefore, the requirement
remains as written.
One commenter noted that, in the preamble discussion regarding
condition #10 (condition #11 of Notice), a transverse separation
occurring at the location of the inflatable lapbelt is excluded from
consideration. The commenter suggests that this provision be included
in condition #10 (condition #11 of Notice) itself. This has been done.
Two commenters believe that condition #11 (condition #12 of Notice)
is too vague, and that no standards are provided to determine what
constitutes a ``hazardous quantity'' of gas. One commenter questions
whether the hazard extends to the effect on visibility from release of
any gases.
This requirement was left intentionally general, since there are so
many different approaches to inflation systems and the gases used.
Since the bag is vented to the cabin, it is assumed that occupants will
be exposed to the gases used. To large extent, then, this requirement
will dictate the gases that are used. The FAA considers it appropriate
to allow the applicant to demonstrate that that the gases released do
not pose a safety hazard, and there are several options for doing this.
There was no intent to address visibility as part of this condition,
although it theoretically could be an issue as part of
[[Page 51429]]
condition #8 (condition #9 of Notice). This isn't expected to be the
case, however.
Two commenters responded to the requirement that the inflatable
lapbelt be protected from the effects of fire. Both commenters agree
with the intent of the requirement. One commenter proposes alternative
wording to clarify that the effects of the fire are applicable to the
most critical component of the system, and the other commenter proposes
that the standards currently used for chemical oxygen generators should
be adequate.
Again, this requirement was intentionally general, since the system
design and installation will dictate the fire threat, as well as the
consequences of the threat. For example, an installation that isolated
any pyrotechnic devices or pressure vessels from the occupants might
not be as critical as one where those items are inside the passenger
cabin. In terms of the standards to be used, there are existing
standards for pressure vessels, gas generators and other components
that could be applied to this device/installation. The FAA expects the
applicant to propose standards that are applicable in this case.
There was one comment regarding the provisions of condition #13
(condition #14 of Notice). This condition requires that there be means
to enable a crewmember to determine whether the system is operable, or
that the system has been shown to be reliable over a specified
inspection interval. The commenter notes that readiness indicators can
add complexity to the system and actually reduce reliability. The
commenter clarifies the understanding that an inspection interval based
on reliability data is an acceptable method of compliance.
As noted above, the special condition allows more than one method
of verifying system integrity. Either of the approaches is acceptable,
but the FAA considers it necessary to minimize the possibility that the
system could experience an undetected failure.
One commenter had several general comments regarding the wisdom of
incorporating such a device on an airplane, considering the potential
for inadvertent deployments or misuse, versus the probability of having
an accident in the first place. The commenter contends that the risk of
the former outweighs the risk of the latter. The FAA agrees that this
could be an issue, considering the very low accident rate, however,
this is one of the main issues of the special conditions. The special
conditions are written to prevent the inadvertent deployments or show
that such deployments are not a hazard. If the special conditions are
met, the FAA considers that this is not an issue.
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 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 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 the Boeing Model 767-300 series
airplanes modified by Am-Safe, Inc. by installing inflatable lapbelts.
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. 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 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. 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 occupants 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
lapbelt, 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 lapbelt will not impede
rapid egress of occupants 10 seconds after its deployment.
9. 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.
10. 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. 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
[[Page 51430]]
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 September 15, 1999.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 99-24792 Filed 9-22-99; 8:45 am]
BILLING CODE 4910-13-P