[Federal Register Volume 66, Number 198 (Friday, October 12, 2001)]
[Rules and Regulations]
[Pages 52017-52020]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-25753]



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  Federal Register / Vol. 66, No. 198 / Friday, October 12, 2001 / 
Rules and Regulations  

[[Page 52017]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM198; Special Conditions No. 25-187-SC]


Special Conditions: Boeing Model 777 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 Boeing Model 777 
series airplanes. These airplanes, which are manufactured by Boeing 
Commercial Airplanes, 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. These special conditions contain the 
additional safety standards that the Administrator considers necessary 
to establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: The effective date of these special conditions is October 3, 
2001. Comments must be received on or before November 13, 2001.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration (FAA), Transport Airplane 
Directorate, ANM-113, Attention: Rules Docket No. NM198, 1601 Lind 
Avenue, SW., Renton, Washington 98055-4056, or delivered in duplicate 
to the Transport Airplane Directorate at the above address. All 
comments must be marked: Docket No. NM198. Comments may be inspected in 
the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. 
and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT: Jayson Claar, FAA, Airframe and Cabin 
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98055-
4056; telephone (425) 227-2194; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are unnecessary because 
these special conditions are substantially identical to those that have 
been issued on three previous occasions, and that further new comments 
are unlikely.

Comments Invited

    Interested persons are invited to submit such written data, views, 
or arguments as they may desire. Communications should identify the 
Rules Docket number identified above and be submitted in duplicate to 
the address specified above. All communications received on or before 
the closing date for comments specified above will be considered. The 
special conditions 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 
Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this request must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number NM198.'' The postcard will be date stamped and 
returned to the commenter.

Background

    On April 20, 2001, Boeing Commercial Airplanes, P.O. Box 3707, 
Seattle, Washington 98124, applied for a type certificate design change 
to install inflatable lapbelts for head injury protection on certain 
seats in Boeing Model 777 series airplanes. The Model 777 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 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) Sec. 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 14 CFR part 25, specifically Sec. 25.562, a new standard that 
quantifies required head injury protection was created.
    Section 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 1000 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.
    Amendment 25-64 is part of the Model 777 certification basis. 
Therefore, the seat installation with inflatable lapbelts must meet the 
requirement that a HIC of less than 1000 be demonstrated for occupants 
of seats incorporating the inflatable lapbelt.
    Because Secs. 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, 
for example, and

[[Page 52018]]

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, inflatable lapbelts in general are active systems 
and must be relied upon to activate properly when needed, as opposed to 
an energy-absorbing pad or upper torso restraint that is passive, and 
always available. 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. Boeing Commercial Airplanes 
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 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 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-78 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 inflatable lapbelt is 
considered a critical system; if inadvertent deployment could cause 
injuries to persons, the inflatable lapbelt should be considered an 
essential system. 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 protection 
according to the severity of the impact. Therefore, the inflatable 
lapbelt installation should be such that the inflatable lapbelt will 
provide protection when it is required, and will not expend its 
protection when it is not needed. There is no requirement for the 
inflatable lapbelt 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 inflatable lapbelts that are 
active.
    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 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 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 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. 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 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.
    Finally, it should be noted that the special conditions are 
certification requirements applied to the inflatable lapbelt system as 
installed. The special

[[Page 52019]]

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, Boeing Commercial Airplanes 
must show that the Model 777 series airplanes, as changed, continue to 
meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. T00001SE 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. T00001SE 
are as follows: Amendments 25-1 through 25-82 for the Model 777-200 and 
Amendments 25-1 through 25-86 with exceptions for the Model 777-300. 
The U.S. type certification basis for the Model 777 is established in 
accordance with Secs. 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. T00001SE.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25 as amended) do not contain adequate or 
appropriate safety standards for Boeing Model 777 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, the Boeing Model 777 must comply with the fuel vent and 
exhaust emission requirements of part 34 and the noise certification 
requirements of part 36.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.19 after public notice, as required by Sec. 11.38, and become 
part of the type certification basis in accordance with 
Sec. 21.101(b)(2).
    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 already included on 
the same type certificate be modified 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 777 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 Boeing Model 777 
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 Boeing 
Model 777 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.

Prior Comment

    One comment was received in response to the most recent publication 
of the inflatable lapbelt special conditions (65 FR 60343) which are 
substantially identical to the special condition contained herein. The 
disposition of this comment is contained in Rules Docket No. NM176 and 
is available for examination by interested parties. In our disposition, 
we substantially agreed with the commenter, but noted that the 
substance of the comment was already addressed in the special 
conditions. Therefore, this comment did not result in a change to the 
special conditions.

Applicability

    As discussed above, these special conditions are applicable to the 
Model 777 series airplanes. Should Boeing Commercial Airplanes apply at 
a later date for a change to the type certificate to modify any other 
model included on Type Certificate No. T00001SE 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 777 series airplanes. It is not a rule of general 
applicability, and it affects only Model 777 series airplanes listed on 
TCDS T00001SE.

Immediate Adoption of Special Conditions

    The FAA has determined that notice and opportunity for prior public 
comment hereon are unnecessary because these special conditions are 
substantially identical to those that have been issued on three 
previous occasions, and that further new comments are unlikely.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    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

[[Page 52020]]

conditions are issued as part of the type certification basis for the 
Boeing Model 777 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. 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), 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 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-78 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 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 October 3, 2001.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-25753 Filed 10-11-01; 8:45 am]
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