99-24792. Special Conditions: Boeing Model 767-300 Series Airplanes; Seats with Inflatable Lapbelts  

  • [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
    
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    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
    
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    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.);
    
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    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,
    
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    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
    
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    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
    
    
    

Document Information

Effective Date:
10/25/1999
Published:
09/23/1999
Department:
Federal Aviation Administration
Entry Type:
Rule
Action:
Final special conditions.
Document Number:
99-24792
Dates:
October 25, 1999.
Pages:
51424-51430 (7 pages)
Docket Numbers:
Docket No. NM155, Special Conditions No. 25-148-SC
PDF File:
99-24792.pdf
CFR: (1)
14 CFR 25