[Federal Register Volume 65, Number 60 (Tuesday, March 28, 2000)]
[Rules and Regulations]
[Pages 16305-16309]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-7633]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM167; Special Conditions No. 25-159-SC]


Special Conditions: Boeing Model 777 Series Airplanes; Seats With 
Inflatable Lapbelts

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for Boeing Model 777 
series airplanes. These airplanes as modified by BF Goodrich Aerospace 
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.

EFFECTIVE DATE: April 27, 2000.

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 (425) 227-2136; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:  

Background

    On March 31, 1999, BF Goodrich Aerospace, 3420 South 7th Street, 
Suite 1, Phoenix, Arizona 85040, applied for a supplemental type 
certificate 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

[[Page 16306]]

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.
    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 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 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. BF Goodrich Aerospace 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-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 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 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 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 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.

[[Page 16307]]

    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 applied to the inflatable lapbelt system as installed. 
The special conditions are not an installation approval. Therefore, 
while the special conditions relate to each such system installed, the 
overall installation approval is a separate finding, and must consider 
the combined effects of all such systems installed.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, BF Goodrich Aerospace 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 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. T00001SE.
    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 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 14 CFR part 34 and the noise 
certification requirements of 14 CFR part 36.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49 after public notice, as required by Secs. 11.28 and 
11.29(b), 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 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 777 series airplanes will incorporate the following novel 
or unusual design features: BF Goodrich 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 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 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 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.

Discussion of Comments

    Notice of proposed special conditions No. 25-99-10-SC for the 
Boeing Model 777 series airplanes was published in the Federal Register 
on December 13, 1999 (64 FR 69425). Three comments were received. One 
commenter concurred with the special conditions as proposed.
    One commenter states that the requirement of condition #4 was 
vague, and that ``wear and tear'' needed further definition. The 
commenter suggests that the special condition be specific as to the 
level of wear and tear that must be addressed. The commenter indicates 
that operational inspections would be difficult and require changes to 
manufacturers' manuals. The commenter notes that the special condition 
seems to be focused on

[[Page 16308]]

pyrotechnically operated designs, and that this might not always be the 
case.
    The FAA agrees that the term ``wear and tear'' is not particularly 
specific, 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 
that 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.
    One commenter felt that special conditions #4 and #7 should also 
address the storage and transportation of the unit or its components, 
relative to inadvertent deployment. While this is a legitimate concern, 
it is not relevant to these special conditions, since it is not an 
issue for approval of the inflatable lapbelt on an airplane. Existing 
regulations in Title 49 of CFR address storage and transportation of 
hazardous materials.
    One commenter states that the requirement of condition #5 was 
impractical as stated, since no injury severity level was specified. 
One commenter points out that a bruise or rash could be considered an 
injury under the current wording, and would therefore make the 
inflatable lapbelt unacceptable. The commenter suggests that the 
requirement should be stated as a performance criterion. For example, a 
requirement that deployment of the inflatable lapbelt should not cause 
an injury that would adversely affect the ability to egress the 
airplane.
    Another commenter notes that in promotional literature the 
inflatable lapbelt appears to deploy from between the occupant and the 
seatbelt, and is characterized as a pre-tensioning device. The 
commenter considers that this could introduce new injury mechanisms 
that should be considered. In addition, the commenter questions whether 
this type of deployment could alter the position of the seatbelt 
itself, so that it bears on soft tissue, rather than the hips.
    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. Bruises or friction injuries would not be considered new 
injury mechanisms. However, there could be other injury mechanisms that 
might not have a direct impact on rapid egress, but could still be 
debilitating. The special condition requires that the inflatable 
lapbelt not introduce injury mechanisms and that rapid egress not be 
affected. With regard to the manner in which the airbag deploys, the 
FAA agrees that this should be considered as part of the special 
conditions. In fact, the concern expressed by the commenter is 
precisely the sort of thing the special conditions are intended to 
address, i.e., the introduction of injury mechanisms.
    One commenter states that consideration should be given to 
potential injury resulting from an airbag that appears not to provide 
full coverage to the head. It is not clear what change to the special 
conditions the commenter intended as a result of this suggestion. The 
performance of the inflatable lapbelt must be assessed by actual test. 
Therefore, whether or not the airbag provides full coverage to the head 
will be evident from tests and, of course, the acceptability of this 
must be assessed. No change is made to the special conditions.
    One commenter questioned the origin of the 10-second standard 
proposed in condition #8, and whether that standard applied equally to 
accidents that consisted of single and multiple impacts. The commenter 
also states that this requirement must be related to other time 
critical requirements in the regulations, such as those for exit 
opening, escape slide deployment and overall airplane evacuation time.
    The requirement as written was intended to address 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 
considering the time from impact until an airplane comes to rest, 
coupled with the time needed to prepare exits and escape slides for 
evacuation. Therefore, whether an accident consists of a single impact 
or several, 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. There is no need to 
further correlate this requirement to other evacuation time-related 
requirements, since there is no conflict or incompatibility.
    One commenter notes that promotional literature implies that the 
inflatable lapbelt will have an end release buckle. The commenter 
questions whether this is appropriate in an aviation application and 
whether an injured person would be able to release such a buckle.
    The FAA considers the utility and functionality of the buckle 
itself as not requiring special conditions. Any restraint system buckle 
must be demonstrated to be in compliance with the applicable 
requirements, whether it releases from the center or the end. 
Therefore, the fact that this restraint system is also equipped with an 
airbag device has no bearing on the buckle position assessment, other 
than as it relates to egress. Egress issues are already covered in 
condition #8.

Applicability

    As discussed above, these special conditions are applicable to the 
Model 777 series airplanes. Should BF Goodrich apply at a later date 
for a supplemental 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 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 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 777 series airplanes 
modified by BF Goodrich Aerospace by installing inflatable lapbelts.

[[Page 16309]]

    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 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 March 20, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 00-7633 Filed 3-27-00; 8:45 am]
BILLING CODE 4910-13-U