95-27074. Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes  

  • [Federal Register Volume 60, Number 212 (Thursday, November 2, 1995)]
    [Proposed Rules]
    [Pages 55673-55680]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 95-27074]
    
    
    
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    DEPARTMENT OF TRANSPORTATION
    14 CFR Part 39
    
    [Docket No. 95-NM-111-AD]
    
    
    Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
    and -500 Series Airplanes
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Notice of proposed rulemaking (NPRM).
    
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    SUMMARY: This document proposes the supersedure of an existing 
    airworthiness directive (AD), applicable to certain Boeing Model 737-
    300 and -400 series airplanes, that currently requires either 
    repetitive leak checks on the forward lavatory service system and 
    repair as necessary, or draining of the system and placarding the 
    lavatory inoperative. This action would expand the applicability of the 
    rule to include all Model 737 series airplanes. It would also add a 
    requirement to perform leak checks of other lavatory drain systems; 
    provide for the option of revising the FAA-approved maintenance program 
    to include a schedule of leak checks; require the installation of a cap 
    or vacuum break on the flush/fill line; and require either a periodic 
    replacement of the seal for the cap and tank anti-siphon valve or 
    periodic maintenance of the 
    
    [[Page 55674]]
    vacuum break in the flush/fill line. This proposal is prompted by 
    continuing reports of damage to engines and airframes, separation of 
    engines from airplanes, and damage to property on the ground, caused by 
    ``blue ice'' that forms from leaking lavatory drain systems on 
    transport category airplanes and subsequently dislodges from the 
    airplane fuselage. The actions specified by this proposed AD are 
    intended to prevent such damage associated with the problems of ``blue 
    ice.''
    
    DATES: Comments must be received by January 30, 1996.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), Transport Airplane Directorate, ANM-103, 
    Attention: Rules Docket No. 95-NM-111-AD, 1601 Lind Avenue SW., Renton, 
    Washington 98055-4056. Comments may be inspected at this location 
    between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
    holidays.
        The service information referenced in the proposed rule may be 
    obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
    Washington 98124-2207. This information may be examined at the FAA, 
    Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, 
    Washington.
    
    FOR FURTHER INFORMATION CONTACT:
    Don Eiford, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 
    FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., 
    Renton, Washington; telephone (206) 227-2778; fax (206) 227-1181.
    
    SUPPLEMENTARY INFORMATION:
    
    Comments Invited
    
        Interested persons are invited to participate in the making of the 
    proposed rule by submitting such written data, views, or arguments as 
    they may desire. Communications shall identify the Rules Docket number 
    and be submitted in triplicate to the address specified above. All 
    communications received on or before the closing date for comments, 
    specified above, will be considered before taking action on the 
    proposed rule. The proposals contained in this notice may be changed in 
    light of the comments received.
        Comments are specifically invited on the overall regulatory, 
    economic, environmental, and energy aspects of the proposed rule. All 
    comments submitted will be available, both before and after the closing 
    date for comments, in the Rules Docket for examination by interested 
    persons. A report summarizing each FAA-public contact concerned with 
    the substance of this proposal will be filed in the Rules Docket.
        Commenters wishing the FAA to acknowledge receipt of their comments 
    submitted in response to this notice must submit a self-addressed, 
    stamped postcard on which the following statement is made: ``Comments 
    to Docket Number 95-NM-111-AD.'' The postcard will be date stamped and 
    returned to the commenter.
    
    Availability of NPRMs
    
        Any person may obtain a copy of this NPRM by submitting a request 
    to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
    Docket No. 95-NM-111-AD, 1601 Lind Avenue SW., Renton, Washington 
    98055-4056.
    
    Discussion of the Existing AD
    
        On May 9, 1989, the FAA issued AD 89-11-03, amendment 39-6223 (54 
    FR 21933, May 22, 1989), applicable to certain Boeing Model 737-300 and 
    -400 airplanes, to require repetitive leak checks of the forward 
    lavatory service system at intervals of 200 hours time-in-service, and 
    repair, if necessary. That AD also provides operators with an optional 
    action in lieu of performing these periodic checks, which entails 
    draining the system, locking the lavatory, and placarding the lavatory 
    inoperative. That action was prompted by several reports of leakage 
    from the forward lavatory service system on in-service transport 
    category airplanes that resulted in the formation of ``blue ice'' on 
    the fuselage. In some instances, the ``blue ice'' subsequently 
    dislodged from the fuselage and was ingested into an engine. In one 
    incident, ``blue ice'' was ingested into the right engine and resulted 
    in the loss of an engine fan blade, severe engine damage, and an in-
    flight shutdown of the engine. The requirements of that AD are intended 
    to prevent such ingestion of ``blue ice'' into the engine, which could 
    consequently result in damage to the engine and potential separation of 
    the engine from the airplane.
    
    New Incidents Prompting This Proposed Action
    
        Since the issuance of that AD, the FAA has continued to receive 
    reports of engine damage on transport category airplanes caused by 
    ``blue ice'' that has formed from leaking lavatory waste systems or 
    flush/fill lines and is ingested in to the engine(s) of the airplane.
        The FAA also has received reports of at least three incidents of 
    damage caused by foreign objects from the forward toilet drain valve 
    and flush/fill line on certain airplanes. One report was of a dent on 
    the right horizontal stabilizer leading edge on a Model 737 series 
    airplane that was caused by ``blue ice'' that had formed from leakage 
    through a flush/fill line; in this case, the flush/fill cap was missing 
    from the line at the forward service panel. Numerous operators of Model 
    737 series airplanes have stated that leakage from the flush/fill line 
    is a significant source of the type of ``blue ice'' problems addressed 
    by the current AD action.
        Additionally, there have been numerous reports of ``blue ice'' 
    dislodging from airplanes and striking houses, cars, buildings, and 
    other occupied areas on the ground. Although there have been no reports 
    of any person being struck by ``blue ice,'' the FAA considers that the 
    large number of reported cases of ``blue ice'' falling from lavatory 
    drain system is sufficient to support the conclusion that ``blue ice'' 
    presents an unsafe condition to people on the ground. Demographic 
    studies have shown that population density has increased around 
    airports, and probably will continue to increase. These are populations 
    that are at greatest risk of damage and injury due to ``blue ice'' 
    dislodging from an airplane during descent. Without actions to ensure 
    that leaks from the lavatory drain systems are detected and corrected 
    in a timely manner, ``blue ice'' incidents could go unchecked and 
    eventually someone may be struck, perhaps fatally, by falling ``blue 
    ice.''
        In light of these continuing incidents and the data received 
    concerning them, the FAA has determined that the inspections currently 
    required by AD 89-11-03 are not adequate to positively address the 
    unsafe condition(s) associated with ``blue ice.'' -
        Additionally, since the lavatory systems on Model 737-100, -200, 
    and -500 series airplanes are similar to those installed on Model 737-
    300 and -400 series airplanes (the models currently subject to AD 89-
    11-03), the FAA has determined that the potential unsafe condition 
    exists with regard to all of these models.
    
    Description of the Proposed Rule -
    
        Since an unsafe condition has been identified that is likely to 
    exist or develop on other products of this same type design, the FAA 
    proposes to issue a new AD to supersede AD 89-11-03. -
        Paragraph (a) of the proposed AD would require various repetitive 
    leak checks of the dump valve and drain valve (either service panel or 
    in-line drain valve). The intervals for performing these leak checks 
    would vary from the currently required 200 flight hours to 4,500 flight 
    hours, 
    
    [[Page 55675]]
    depending upon the type of valve installed at each location. If any 
    leak is discovered during a leak check, operators would be required 
    either to repair the leak, or drain the lavatory system and placard the 
    lavatory inoperative. -
        Proposed paragraph (a) also would require replacement of certain 
    seals on the toilet tank anti-siphon (check) valve and flush/fill line 
    cap; and replacement or cleaning of the vacuum break vent line. -
        Paragraph (b) of this proposed AD would provide an optional 
    procedure for complying with the rule, which would entail revising the 
    FAA-approved maintenance program to incorporate a schedule and 
    procedure to conduct leak checks of the lavatory drain systems. 
    However, operators electing to comply with this option would be 
    required to accomplish the actions required by paragraph (a) of the 
    proposal until their maintenance program is revised. -
        Additionally, operators electing to comply with this option would 
    be required to obtain approval from the Manager of the FAA's Seattle 
    Aircraft Certification Office (ACO) for any revision to the leak check 
    intervals. Requests for such revisions must be accompanied by certain 
    data when submitted to the ACO [through the appropriate FAA Principal 
    Maintenance Inspector (PMI)] for approval. In paragraph (c) of the 
    proposed rule, the FAA proposes a ``data collection format'' for these 
    requests. Data submitted in accordance with the proposed format, if 
    favorable to an increase in the leak check interval, will allow the FAA 
    to justify increasing the leak check interval with assurance that the 
    valves involved have the required reliability. The data provided also 
    will be important in assisting the FAA in making future determinations 
    of appropriate leak check intervals for new valves that have shown 
    promising, but not conclusive, service data. -
        This proposal also includes a process for terminating the leak 
    checks of waste drain systems for those operators who have installed 
    in-line drain (ball) valves and elect to comply with the proposed AD 
    via the ``maintenance program option.'' The FAA has determined that 
    these types of valves are currently the best solution to the addressed 
    problems, and provide very reliable operation. In combination with a 
    normal maintenance program, these valves provide a system that is 
    superior in reliability to the combination of less reliable valves and 
    the proposed leak checks. Further, the FAA has been advised that 
    additional versions of the in-line drain valve may become available for 
    aft lavatory and flush/fill line applications. This could make it 
    possible to install in-line drain type valves in all drain systems and 
    flush/fill line locations. Assuming the new versions are designed, 
    certified, and found acceptable, based upon the guidelines of NOTE 9 of 
    the proposed AD, it eventually could be possible to obtain terminating 
    action for all systems addressed by the AD. -
        Paragraph (d) of the proposed AD would require that a lever/lock 
    cap or a vacuum break be installed for the forward, aft, and executive 
    lavatories. -
        Paragraph (e) of the proposed AD would require that, before an 
    operator places an airplane subject to the AD into service, the 
    operator must establish a schedule for accomplishment of the leak 
    checks. This provision is intended to ensure that transferred airplanes 
    are inspected in accordance with the AD on the same basis as if there 
    were continuity in ownership, and that scheduling of the leak checks 
    for each airplane is not delayed or postponed due to a transfer of 
    ownership. Airplanes that have previously been subject to the AD would 
    have to be checked in accordance with either the previous operator's or 
    the new operator's schedule, whichever would result in the earlier 
    accomplishment date for that leak check. Other airplanes would have to 
    be inspected before an operator could begin operating them or in 
    accordance with a schedule approved by the FAA PMI, but within a period 
    not exceeding 200 flight hours.
    
    Related AD's -
    
        On November 9, 1994, the FAA issued AD 94-23-10, amendment 39-9073 
    (59 FR 59124, November 16, 1994), which is applicable to Boeing Model 
    727 series airplanes. That AD contains numerous requirements that are 
    similar to those proposed in this action applicable to Model 737 series 
    airplanes. In fact, several of the proposed requirements of this action 
    are based on alternative methods of compliance that the FAA had 
    previously approved for compliance with AD 94-23-10. -
        The FAA is currently considering additional rulemaking to address 
    the problems associated with ``blue ice'' on other transport category 
    airplanes.
    
    Economic Impact -
    
        There are approximately 2,410 Model 737 series airplanes of the 
    affected design in the worldwide fleet. The FAA estimates that 1,031 
    airplanes of U.S. registry and 110 U.S. operators would be affected by 
    this proposed AD. -
        The proposed waste drain system leak check and outer cap inspection 
    would take approximately 6 work hours per airplane to accomplish, at an 
    average labor rate of $60 per work hour. Based on these figures, the 
    total cost impact on U.S. operators of these proposed requirements of 
    this AD is estimated to be $371,160, or $360 per airplane, per check/
    inspection. -
        Certain airplanes (i.e., those that have ``donut'' type of drain 
    valve installed) may be required to be leak checked as many as 15 times 
    each year. Certain other airplanes having other valve configurations 
    would be required to be leak checked as few as 3 times each year. Some 
    airplanes that have various combinations drain valves installed would 
    require approximately 2 leak checks of one drain valve and 3 leak 
    checks of the other drain valve each year. Based on these figures, the 
    total annual (recurring) cost impact of the required repetitive leak 
    checks on U.S. operators is estimated to be between $1,080 and $5,400 
    per airplane per year. -
        The FAA estimates that it would take approximately 1 work hour per 
    airplane lavatory drain to accomplish a visual inspection of the 
    service panel drain valve cap/door seal and seal mating surfaces, at an 
    average labor cost of $60 per work hour. As with leak checks, certain 
    airplanes would be required to be visually inspected as many as 15 
    times or as few as 3 times each year. Based on these figures, the total 
    annual (recurring) cost impact of the required repetitive visual 
    inspections on U.S. operators is estimated to be between $180 and $900 
    per airplane per year. -
        The proposed installation of the flush/fill line cap would take 
    approximately 1 hour per cap to accomplish, at an average labor rate of 
    $60 per work hour. The cost of required parts would be $275 per cap. 
    There are an average of 2.5 caps per airplane. Based on these figures, 
    the total cost impact on U.S. operators of these proposed requirements 
    of this AD is estimated to be $863,463, or $838 per airplane. -
        The number of required work hours, as indicated above, is presented 
    as if the accomplishment of the actions proposed in this AD were to be 
    conducted as ``stand alone'' actions. However, in actual practice, 
    these actions could be accomplished coincidentally or in combination 
    with normally scheduled airplane inspections and other maintenance 
    program tasks. Therefore, the actual number of necessary ``additional'' 
    work hours would be minimal in many instances. Additionally, any costs 
    associated with special airplane scheduling should be minimal. -
        In addition to the costs discussed above, for those operators who 
    elect to 
    
    [[Page 55676]]
    comply with proposed paragraph (b) of this proposed AD action, the FAA 
    estimates that it would take approximately 40 work hours per operator 
    to incorporate the lavatory drain system leak check procedures into the 
    maintenance programs, at an average labor cost of $60 per work hour. 
    Based on these figures, the total cost impact of the proposed 
    maintenance revision requirement of this AD action on the 110 U.S. 
    operators is estimated to be $264,000, or $2,400 per operator.
        The total cost impact figures discussed above are based on 
    assumptions that no operator has yet accomplished any of the current or 
    proposed requirements of this AD action, and that no operator would 
    accomplish those actions in the future if this AD were not adopted.
        The FAA recognizes that the obligation to maintain aircraft in an 
    airworthy condition is vital, but sometimes expensive. Because AD's 
    require specific actions to address specific unsafe conditions, they 
    appear to impose costs that would not otherwise be borne by operators. 
    However, because of the general obligation of operators to maintain 
    aircraft in an airworthy condition, this appearance is deceptive. 
    Attributing those costs solely to the issuance of this AD is 
    unrealistic because, in the interest of maintaining safe aircraft, 
    prudent operators would accomplish the required actions even if they 
    were not required to do so by the AD.
        A full cost-benefit analysis has not been accomplished for this AD. 
    As a matter of law, in order to be airworthy, an aircraft must conform 
    to its type design and be in a condition for safe operation. The type 
    design is approved only after the FAA makes a determination that it 
    complies with all applicable airworthiness requirements. In adopting 
    and maintaining those requirements, the FAA has already made the 
    determination that they establish a level of safety that is cost-
    beneficial. When the FAA, as in this AD, makes a finding of an unsafe 
    condition, this means that the original cost-beneficial level of safety 
    is no longer being achieved and that the required actions are necessary 
    to restore that level of safety. Because this level of safety has 
    already been determined to be cost-beneficial, a full cost-benefit 
    analysis for this AD would be redundant and unnecessary.
    
    Regulatory Impact
    
        The regulations proposed herein would not have substantial direct 
    effects on the States, on the relationship between the national 
    government and the States, or on the distribution of power and 
    responsibilities among the various levels of government. Therefore, in 
    accordance with Executive Order 12612, it is determined that this 
    proposal would not have sufficient federalism implications to warrant 
    the preparation of a Federalism Assessment.
        For the reasons discussed above, I certify that this proposed 
    regulation (1) is not a ``significant regulatory action'' under 
    Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
    Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
    and (3) if promulgated, will not have a significant economic impact, 
    positive or negative, on a substantial number of small entities under 
    the criteria of the Regulatory Flexibility Act. A copy of the draft 
    regulatory evaluation prepared for this action is contained in the 
    Rules Docket. A copy of it may be obtained by contacting the Rules 
    Docket at the location provided under the caption ADDRESSES.
    
    List of Subjects in 14 CFR Part 39
    
        Air transportation, Aircraft, Aviation safety, Safety.
    
    The Proposed Amendment
    
        Accordingly, pursuant to the authority delegated to me by the 
    Administrator, the Federal Aviation Administration proposes to amend 
    part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
    follows:
    
    PART 39--AIRWORTHINESS DIRECTIVES
    
        1. The authority citation for part 39 continues to read as follows:
        Authority: 49 USC 106(g), 40101, 40113, 44701.
    
    
    Sec. 39.13  [Amended]
    
        2. Section 39.13 is amended by removing amendment 39-6223 (54 FR 
    21933, May 22, 1989), and by adding a new airworthiness directive (AD), 
    to read as follows:
    
    Boeing. Docket 95-NM-111-AD. Supersedes AD 89-11-03, Amendment 39-
    6223.
    
        Applicability: Boeing Model 737 series 100, 200, 300, 400 and 
    500 airplanes, certificated in any category.
    
        Note 1: This AD applies to each airplane identified in the 
    preceding applicability provision, regardless of whether it has been 
    modified, altered, or repaired in the area subject to the 
    requirements of this AD. For airplanes that have been modified, 
    altered, or repaired so that the performance of the requirements of 
    this AD is affected, the owner/operator must use the authority 
    provided in paragraph (f) of this AD to request approval from the 
    FAA. This approval may address either no action, if the current 
    configuration eliminates the unsafe condition; or different actions 
    necessary to address the unsafe condition described in this AD. Such 
    a request should include an assessment of the effect of the changed 
    configuration on the unsafe condition addressed by this AD. In no 
    case does the presence of any modification, alteration, or repair 
    remove any airplane from the applicability of this AD.
    
        Compliance: Required as indicated, unless previously 
    accomplished.
        To prevent engine damage, airframe damage, and/or hazard to 
    persons or property on the ground as a result of ``blue ice'' that 
    has formed from leakage of the lavatory drain system or flush/fill 
    systems and dislodged from the airplane, accomplish the following:
        (a) Except as provided by paragraph (b) of this AD, accomplish 
    the applicable requirements of paragraphs (a)(1) through (a)(7) of 
    this AD at the time specified in each paragraph. If the waste drain 
    system incorporates more than one type of valve, only one of the 
    waste drain system leak check procedures (the one that applies to 
    the equipment with the longest leak check interval) must be 
    conducted at each service panel location. The leak check of the in-
    line drain valve or service panel drain valve must be performed 
    while the airplane is pressurized, unless another leak check method 
    is approved under the provisions of paragraph (f) of this AD.
        (1) For each lavatory drain system that has an in-line drain 
    valve installed, Kaiser Electroprecision part number series 2651-
    329, 2651-334, or 2651-278: Within 4,500 flight hours after the 
    effective date of this AD, and thereafter at intervals not to exceed 
    4,500 flight hours, accomplish the procedures specified in 
    paragraphs (a)(1)(i) and (a)(1)(ii) of this AD:
        (i) Conduct a leak check of the dump valve (in-tank valve that 
    is spring loaded closed and operable by a T-handle at the service 
    panel) and the in-line drain valve. The dump valve leak check must 
    be performed by filling the toilet tank with water/rinsing fluid to 
    a level such that the bowl is approximately half full (at least 2 
    inches above the flapper in the bowl) and checking for leakage after 
    a period of 5 minutes. The in-line drain valve leak check must be 
    performed with a minimum of 3 pounds per square inch differential 
    pressure (PSID) applied across the valve.
        (ii) If a service panel valve or cap is installed, perform a 
    visual inspection of the service panel drain valve outer cap/door 
    seal and the inner seal (if the valve has an inner door with a 
    second positive seal), and the seal mating surfaces, for wear or 
    damage that may allow leakage.
        (2) For each lavatory drain system that has a service panel 
    drain valve installed, Kaiser Electroprecision part number series 
    0218-0032; or Pneudraulics part number series 9527; or Shaw Aero 
    part number/serial number as listed in Table 1 of this AD: Within 
    1,000 flight hours after the effective date of this AD, and 
    thereafter at intervals not to exceed 1,000 flight hours, accomplish 
    the requirements of paragraphs (a)(2)(i) and (a)(2)(ii) of this AD:
    
                                                                            
    
    [[Page 55677]]
      Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Check  
                                    Interval                                
    ------------------------------------------------------------------------
                                                   Serial numbers of part   
                                                  number valve approved for 
          Shaw Waste Drain Valve Part No.           1,000-hour leak check   
                                                          interval          
    ------------------------------------------------------------------------
    331 Series, 332 Series....................  All.                        
    10101000B-A-..............................  None.                       
    10101000B-A-1.............................  0207-0212, 0219, 0226 and   
                                                 higher.                    
    10101000BA2-..............................  0130 and higher.            
    10101000B-B-..............................  None.                       
    10101000BB2-..............................  0011 and higher.            
    10101000B-C-..............................  None.                       
    10101000B-K-..............................  0007 and higher.            
    10101000BJ-...............................  0023 and higher.            
    10101B-577-...............................  0254 and higher.            
    10101B-577-1..............................  None.                       
    10101B587-................................  0009 and higher.            
    10101000C-A-..............................  None.                       
    10101000C-A-1.............................  0277 and higher.            
    10101000CB-...............................  0061 and higher.            
    10101000C-G-..............................  None.                       
    10101000C-J-..............................  None.                       
    10101000C-J-2.............................  None.                       
    10101000CJ3-..............................  0014 and higher.            
    10101000CK-...............................  0317 and higher.            
    10101000C-M-..............................  0044 and higher.            
    10101000CN OR C-N-........................  3649 and higher.            
    10101000C-R-..............................  0191 and higher.            
    10101C739-................................  0022 and higher.            
    Certain 10101000B valves-.................  Any of these ``B'' series   
                                                 valves that incorporate the
                                                 improvements of Shaw       
                                                 Service Bulletin 10101000B-
                                                 38-1, dated October 7,     
                                                 1994, and are marked       
                                                 ``SBB38-1-58''.            
    Certain 10101000C valves..................  Any of these ``C'' series   
                                                 valves that -incorporate   
                                                 the improvements of Shaw   
                                                 Service Bulletin 10101000C-
                                                 38-2 dated October 7, 1994,
                                                 and are marked ``SBC38-2-  
                                                 58''.                      
    ------------------------------------------------------------------------
    
    
    
        Note 2: Table 1 is a comprehensive list of all approved Shaw 
    Valves, including those valves approved for installation on 
    airplanes other than the airplanes subject to this AD. (Therefore, 
    being listed in this table does not necessarily mean that a 
    particular valve is FAA-approved for installation on the Model 737 
    airplanes subject to this AD.)
    
        (i) Conduct a leak check of the dump valve and drain valve. The 
    dump valve leak check must be performed by filling the toilet tank 
    with water/rinsing fluid to a level such that the bowl is 
    approximately half full (at least 2 inches above the flapper in the 
    bowl) and checking for leakage after a period of 5 minutes. The 
    service panel drain valve leak check must be performed with a 
    minimum of 3 PSID applied across the valve inner door/closure 
    device.
        (ii) Perform a visual inspection of the outer cap/door and seal 
    mating surface for wear or damage that may cause leakage.
        (3) For each lavatory drain system that has a service panel 
    drain valve installed, Kaiser Electroprecision part number series 
    0218-0026; or Shaw Aero Devices part number series 10101000B or 
    10101000C [except as specified in paragraph (a)(2) of this AD]: 
    Within 600 flight hours after the effective date of this AD, and 
    thereafter at intervals not to exceed 600 flight hours, accomplish 
    the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD:
        (i) Conduct a leak check of the dump valve and the service panel 
    drain valve. The dump valve leak check must be performed by filling 
    the toilet tank with water/rinsing fluid to a level such that the 
    bowl is approximately half full (at least 2 inches above the flapper 
    in the bowl) and checking for leakage after a period of 5 minutes. 
    The service panel drain valve leak check must be performed with a 
    minimum 3 PSID applied across the valve inner door/closure device.
        (ii) Perform a visual inspection of the outer cap/door and seal 
    mating surface for wear or damage that may cause leakage.
        (4) For each lavatory drain system with a lavatory drain system 
    valve that incorporates either ``donut'' assemblies (or substitute 
    assemblies from another manufacturer) Kaiser Electroprecision part 
    number 4259-20 or 4259-31, or incorporates Kaiser Roylyn part number 
    2651-194C, 2651-197C, 2651-216, 2651-219, 2651-235, 2651-256, 2651-
    258, 2651-259, 2651-260, 2651-275, 2651-282, 2651-286: Within 200 
    flight hours after the effective date of this AD, and thereafter at 
    intervals not to exceed 200 flight hours, conduct leak checks of the 
    dump valve and the service panel drain valve. The dump valve leak 
    check must be performed by filling the toilet tank with water/
    rinsing fluid to a level such that the bowl is approximately half 
    full (at least 2 inches above the flapper in the bowl) and checking 
    for leakage after a period of 5 minutes. The service panel drain 
    valve leak check must be performed with a minimum 3 PSID applied 
    across the valve. Both the donut and the outer cap/door must be leak 
    checked.
        (5) For each lavatory drain system not addressed in paragraph 
    (a)(1), (a)(2), (a)(3) or (a)(4) of this AD: Within 200 flight hours 
    after the effective date of this AD, and thereafter at intervals not 
    to exceed 200 flight hours, accomplish the requirements of 
    paragraphs (a)(5)(i) and (a)(5)(ii) of this AD:
        (i) Conduct a leak check of the dump valve and the service panel 
    drain valve. The dump valve leak check must be performed by filling 
    the toilet tank with water/rinsing fluid to a level such that the 
    bowl is approximately half full (at least 2 inches above the flapper 
    in the bowl) and checking for leakage after a period of 5 minutes. 
    The service panel drain valve leak check must be performed with a 
    minimum 3 PSID applied across the valve inner door/closure device.
        (ii) Perform a visual inspection of the outer cap/door and seal 
    mating surface for wear or damage that may cause leakage.
        (6) For flush/fill lines: Within 5,000 flight hours after the 
    effective date of this AD, and thereafter at intervals not to exceed 
    5,000 flight hours, perform the requirements of either paragraph 
    (a)(6)(i) or (a)(6)(ii), as applicable.
        (i) If a lever lock cap is installed on the flush/fill line of 
    the subject lavatory, replace the seals on the toilet tank anti-
    siphon (check) valve and the flush/fill line cap. Prior to further 
    flight after replacement, perform a leak check of the toilet tank 
    anti-siphon (check) valve with a minimum of 3 PSID across the valve.
    
        Note 3: The leak test procedure described in Boeing Service 
    Letter 737-SL-38-3-A dated March 19, 1990, may be referred to as 
    guidance for this test.
    
        (ii) If a vacuum break, Monogram part number 3765-175 series or 
    3765-190 series, is installed on the subject lavatory, replace or 
    clean the vent line in accordance with the manufacturer's 
    maintenance manual.
        (7) As a result of the leak checks and inspections required by 
    this paragraph, or if evidence of leakage is found at any other 
    time, accomplish the requirements of paragraph (a)(7)(i), 
    (a)(7)(ii), or (a)(7)(iii), as applicable.
        (i) If a leak is discovered, prior to further flight, repair the 
    leak. Prior to further flight after repair, perform the leak test. 
    Additionally, prior to returning the airplane to service, clean the 
    surfaces adjacent to where the leakage occurred to clear them of any 
    horizontal fluid residue streaks; such cleaning must be to the 
    extent that any future appearance of a horizontal fluid residue 
    streak will be taken to mean that the system is leaking again.
    
        Note 4: For purposes of this AD, ``leakage'' is defined as any 
    visible leakage, if observed during a leak test. At any other time 
    (than during a leak test), ``leakage'' is defined as the presence of 
    ice in the service panel, or horizontal fluid residue streaks/ice 
    trails originating at the service panel. The fluid residue is 
    usually, but not necessarily, blue in color.
    
        (ii) If any worn or damaged seal is found, or if any damaged 
    seal mating surface is found, prior to further flight, repair or 
    replace it in accordance with the valve manufacturer's maintenance 
    manual.
        (iii) In lieu of performing the requirements of paragraph 
    (a)(7)(i) or (a)(7)(ii): Prior to further fight, drain the affected 
    lavatory system and placard the lavatory inoperative until repairs 
    can be accomplished.
        (b) As an alternative to the requirements of paragraph (a) of 
    this AD, operators may revise the FAA-approved maintenance program 
    to include the requirements specified in paragraphs (b)(1) through 
    (b)(7) of this AD. However, until the FAA-approved maintenance 
    program is so revised, operators must accomplish the leak test 
    requirements of paragraph (a) of this AD. Incorporation of the 
    requirements specified in paragraphs (b)(1)(i), (b)(2)(i), (b)(4), 
    (b)(5), (b)(6) and (b)(7) of this AD into the operator's FAA-
    approved maintenance program constitutes terminating action for 
    waste drain systems that incorporate the ball valves specified in 
    paragraph (b)(1)(i) of this AD. However, the requirements of this AD 
    that affect flush/fill lines and waste drain systems with valves 
    different from those listed in paragraph (b)(1)(i) remain in effect. 
    
    
    [[Page 55678]]
    
        (1) Replace the valve seals in accordance with the applicable 
    schedule specified in paragraphs (b)(1)(i) and (b)(1)(ii) of this 
    AD.
        (i) For each lavatory drain system that has an in-line drain 
    valve installed, Kaiser Electroprecision part number series 2651-
    329, 2651-334, or 2651-278: Replace the seals within 5,000 flight 
    hours after revision of the maintenance program in accordance with 
    paragraph (b) of this AD, and thereafter at intervals not to exceed 
    48 months.
        (ii) For each lavatory drain system that has any other type of 
    drain valve: Replace the seals within 5,000 flight hours after 
    revision of the maintenance program in accordance with paragraph (b) 
    of this AD, and thereafter at intervals not to exceed 18 months. Any 
    revision to this replacement schedule must be approved by the 
    Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport 
    Airplane Directorate.
        (2) Conduct periodic leak checks of the lavatory drain systems 
    in accordance with the applicable schedule specified in paragraphs 
    (b)(2)(i), (b)(2)(ii), (b)(2)(iii), and (b)(2)(iv) of this AD. Only 
    one of the waste drain system leak check procedures (the one that 
    applies to the equipment with the longest leak check interval) must 
    be conducted at each service panel location. The leak check of the 
    in-line drain valve or service panel drain valve shall be performed 
    while the airplane is pressurized, unless another leak check method 
    is approved under the provisions of paragraph (g) of this AD.
        (i) For each lavatory drain system, that has an in-line drain 
    valve installed, Kaiser Electroprecision part number series 2651-
    329, 2651-334, or 2651-278: Within 5,000 flight hours after the 
    effective date of this AD, and thereafter at intervals not to exceed 
    24 months or 5,000 flight hours, whichever occurs later, accomplish 
    the procedures specified in paragraphs (b)(2)(i)(A) and (b)(2)(i)(B) 
    of this AD:
        (A) Conduct a leak check of the dump valve (in-tank valve that 
    is spring loaded closed and operable by a T-handle at the service 
    panel) and the in-line drain valve. The dump valve leak check must 
    be performed by filling the toilet tank with water/rinsing fluid to 
    a level such that the bowl is approximately half full (at least 2 
    inches above the flapper in the bowl) and checking for leakage after 
    a period of 5 minutes. The in-line drain valve leak check must be 
    performed with a minimum of 3 pounds per square inch differential 
    pressure (PSID) applied across the valve.
        (B) If a service panel valve or cap is installed, perform a 
    visual inspection of the service panel drain valve outer cap/door 
    seal and the inner seal (if the valve has an inner door with a 
    second positive seal), and the seal mating surfaces, for wear or 
    damage that may allow leakage. Any worn or damaged seal must be 
    replaced, and any damaged seal mating surfaces repaired or replaced, 
    prior to further flight, in accordance with the valve manufacturer's 
    maintenance manual.
        (ii) For each lavatory drain system that has a service panel 
    drain valve installed, Kaiser Electroprecision part number series 
    0218-0032, or Kaiser Electroprecision part number series 0218-0026, 
    or Shaw Aero Devices part number series 10101000B, 10101000C, 331-
    series, 332-series, or Pneudraulics part number series 9527: Within 
    1,000 flight hours after revising the maintenance program in 
    accordance with paragraph (b) of this AD, and thereafter at 
    intervals not to exceed 1,000 flight hours, accomplish the 
    following:
        (A) Conduct leak checks of the dump valve and service panel 
    drain valve . The dump valve leak check must be performed by filling 
    the toilet tank with water/rinsing fluid to a level such that the 
    bowl is approximately half full (at least 2 inches above the flapper 
    in the bowl) and checking for leakage after a period of 5 minutes. 
    The service panel drain valve leak check must be performed with a 
    minimum of 3 PSID applied across the valve inner door/closure 
    device. Any revision to this leak check schedule must be approved by 
    the Manager, Seattle ACO, FAA, Transport Airplane Directorate.
        (B) Perform a visual inspection of the outer cap/door and seal 
    mating surface for wear or damage that may cause leakage. Any worn 
    or damaged seal must be replaced and any damaged seal mating surface 
    must be repaired or replaced, prior to further flight, in accordance 
    with the valve manufacturer's maintenance manual.
        (iii) For each lavatory drain system with a lavatory drain 
    system valve that incorporates either ``donut'' assemblies (or 
    substitute assemblies from another manufacturer) Kaiser 
    Electroprecision part number 4259-20 or 4259-31, or incorporates 
    Kaiser Roylyn part number 2651-194C, 2651-197C, 2651-216, 2651-219, 
    2651-235, 2651-256, 2651-258, 2651-259, 2651-260, 2651-275, 2651-
    282, 2651-286: Within 200 flight hours after revising the 
    maintenance program in accordance with paragraph (b), and thereafter 
    at intervals not to exceed 200 flight hours, conduct leak checks of 
    the dump valve and the service panel drain valve. Both the donut and 
    the outer cap/door must be leak checked. The dump valve leak check 
    must be performed by filling the toilet tank with water/rinsing 
    fluid to a level such that the bowl is approximately half full (at 
    least 2 inches above the flapper in the bowl) and checking for 
    leakage after a period of 5 minutes. The service panel drain valve 
    leak check must be performed with a minimum 3 PSID applied across 
    the valve.
        (iv) For each lavatory drain system that incorporates any other 
    type of approved valves: Within 400 flight hours after revising the 
    maintenance program in accordance with paragraph (b) of this AD, and 
    thereafter at intervals not to exceed 400 flight hours, accomplish 
    the following:
        (A) Conduct leak checks of the dump valve and the service panel 
    drain valve. The dump valve leak check must be performed by filling 
    the toilet tank with water/rinsing fluid to a level such that the 
    bowl is approximately half full (at least 2 inches above the flapper 
    in the bowl) and checking for leakage after a period of 5 minutes. 
    The service panel drain valve leak check must be performed with a 
    minimum 3 PSID applied across the valve. If the service panel drain 
    valve has an inner door with a second positive seal, only the inner 
    door must be tested.
        (B) Perform a visual inspection of the outer cap/door and seal 
    mating surface for wear or damage that may cause leakage. Any worn 
    or damaged seal must be replaced and any damaged seal mating surface 
    must be repaired or replaced, prior to further flight, in accordance 
    with the valve manufacturer's maintenance manual.
        (3) For flush/fill lines: Within 5,000 flight hours after the 
    effective date of this AD, and thereafter at intervals not to exceed 
    5,000 flight hours, perform the requirements of either paragraph 
    (b)(3)(i) or (b)(3)(ii), as applicable.
        (i) If a lever lock cap is installed on the flush/fill line of 
    the subject lavatory, replace the seals on the toilet tank anti-
    siphon (check) valve and the flush/fill line cap. Perform a leak 
    check of the toilet tank anti-siphon (check) valve with a minimum of 
    3 PSID across the valve.
    
        Note 5: The leak test procedure of Boeing Service Letter 737-SL-
    38-3-A, dated March 19, 1990, May be referred to as guidance for 
    this test.
    
        (ii) If a vacuum break, Monogram part number 3765-175 series, or 
    3765-190 series, is installed on the subject lavatory, replace or 
    clean the vent line in accordance with the manufacturer's 
    maintenance manual.
        (4) Provide procedures for accomplishing visual inspections to 
    detect leakage, to be conducted by maintenance personnel at 
    intervals not to exceed 4 calendar days or 45 flight hours, which 
    ever occurs later.
        (5) Provide procedures for reporting leakage. These procedures 
    shall provide that any ``horizontal blue streak'' findings must be 
    reported to maintenance and that, prior to further flight, the 
    leaking system shall either be repaired, or be drained and placarded 
    inoperative.
        (i) For systems incorporating an in-line drain valve, Kaiser 
    Electroprecision part number series 2651-329, 2651-334 or 2651-278: 
    The reporting procedures also must include the following:
        (A) Provisions for reporting to maintenance any instances of 
    abnormal operation of the valve handle for the in-line drain valve, 
    as observed by service personnel during normal servicing.
        (B) For instances where abnormal operation of the valve handle 
    is identified, instructions to accomplish, prior to further flight, 
    either the in-line drain valve manufacturer's recommended 
    troubleshooting procedures and correction of the discrepancy; or 
    drainage of the lavatory system and placarding it inoperative until 
    the correction of the discrepancy can be accomplished.
        (ii) If the drain system also includes an additional service 
    panel drain valve, Kaiser Electroprecision part number series 0218-
    0026 or 0218-0032 or Shaw Aero Devices series 10101000B, series 
    10101000C, series 331, or series 332, or Pneudraulics part number 
    series 9527: Indications of abnormal operation of the valve handle 
    for the in-line drain valve need not be addressed immediately if a 
    leak check of the service panel drain valve indicates no leakage or 
    other discrepancy. In these cases, repair of the in-line drain valve 
    must be accomplished within 1,000 flight hours after the leak check 
    of the additional service panel drain valve.
        (6) Provide training programs for maintenance and servicing 
    personnel that 
    
    [[Page 55679]]
    include information on ``Blue Ice Awareness'' and the hazards of blue 
    ice.
        (7) If a leak is discovered during a leak check required by this 
    paragraph; or if evidence of leakage is found at any other time; or 
    if repair/replacement of a valve (or valve parts) is required as a 
    result of a visual inspection required in accordance with this AD; 
    prior to further flight, accomplish the requirements of paragraph 
    (b)(7)(i), (b)(7)(ii), or (b)(7)(iii), as applicable.
    
        Note 6: For purposes of this AD, ``leakage'' is defined as any 
    visible leakage, if observed during a leak test. At any other time 
    (than during a leak test), ``leakage'' is defined as the presence of 
    ice in the service panel, or horizontal fluid residue streaks/ice 
    trails originating at the service panel. The fluid residue is 
    usually, but not necessarily, blue in color.
    
        (i) Repair the leak and, prior to further flight after repair, 
    perform a leak test. Additionally, prior to returning the airplane 
    to service, clean the surfaces adjacent to where the leakage 
    occurred to clear them of any horizontal fluid residue streaks; such 
    cleaning must be to the extent that any future appearance of a 
    horizontal fluid residue streak will be taken to mean that the 
    system is leaking again.
        (ii) Repair or replace the valve or valve parts.
        (iii) In lieu of either paragraph (b)(7)(i) or (b)(7)(ii), drain 
    the affected lavatory system and placard the lavatory inoperative 
    until repairs can be accomplished.
        (c) For operators who elect to comply with paragraph (b) of this 
    AD: Any revision to (i.e., extension of) the leak check intervals 
    required by paragraph (b) of this AD must be approved by the 
    Manager, Seattle ACO, FAA, Transport Airplane Directorate. Requests 
    for such revisions must be submitted to the Manager of the Seattle 
    ACO through the FAA Principal Maintenance Inspector (PMI), and must 
    include the following information:
        (1) The operator's name;
        (2) A statement verifying that all known cases/indications of 
    leakage or failed leak tests are included in the submitted material;
        (3) The type of valve (make, model, manufacturer, vendor part 
    number, and serial number);
        (4) The period of time covered by the data;
        (5) The current FAA leak check interval;
        (6) Whether or not seals have been replaced between the seal 
    replacement intervals required by this AD;
        (7) Whether or not leakage has been detected between leak check 
    intervals required by this AD, and the reason for leakage (i.e., 
    worn seals, foreign materials on sealing surface, scratched or 
    damaged sealing surface or valve, etc.);
        (8) Whether or not any cleaning, repairs, or seal changes were 
    performed on the valve prior to conducting the leak check. [If such 
    activities have been accomplished prior to conducting the periodic 
    leak check, that leak check shall be recorded as a ``failure'' for 
    purposes of the data required for this request submission. The 
    exception to this is the normally-scheduled seal change in 
    accordance with paragraph (b)(1) of this AD. Performing this 
    scheduled seal change prior to a leak check will not cause that leak 
    check to be recorded as a failure. Debris removal done as part of 
    normal maintenance for previous flights is also allowable and will 
    not cause a leak check to be recorded as a failure].
    
        Note 7: Requests for approval of revised leak check intervals 
    may be submitted in any format, provided the data give the same 
    level of assurance specified in paragraph (c) above. Results of an 
    Environmental Quality Analysis (EQA) examination and leak test on a 
    randomly selected high-flight-hour valve, with seals that have not 
    been replaced during a period of use at least as long as the desired 
    interval, may be considered a valuable supplement to the service 
    history data, reducing the amount of service data that would 
    otherwise be required.
        Note 8: For the purposes of expediting resolution of requests 
    for revisions to the leak check intervals, the FAA suggests that the 
    requester summarize the raw data; group the data gathered from 
    different airplanes (of the same model) and drain systems with the 
    same kind of valve; and provide a recommendation from pertinent 
    industry group(s) and/or the manufacturer specifying an appropriate 
    revised leak check interval.
        Note 9: In cases where changes are made to a valve design 
    approved for an extended leak test interval such that a new valve 
    dash number or part number is established for the valve, the FAA may 
    not require extensive service history data to approve the new valve 
    to the same leak check interval as the previous valve design. 
    Similarity of design, the nature of the design changes, the nature 
    and amount of testing, and like factors will be considered by the 
    FAA to determine the appropriate data requirements and leak check 
    interval for a new or revised valve based upon an existing design.
        Note 10: If other valve designs achieve the reliability (as 
    demonstrated by equivalent service history and data) of the valves 
    cited in paragraph (b)(2)(i) of this AD, the FAA may consider 
    granting terminating action using the same guidelines.
    
        (d) For all airplanes: Unless already accomplished, within 5,000 
    flight hours after the effective date of this AD, perform the 
    actions specified in either paragraph (d)(1) or (d)(2) of this AD:
        (1) Install a FAA approved lever/lock cap on the flush/fill 
    lines for the forward, aft, and executive lavatories. Or -
        (2) Install a vacuum break, Monogram part number 3765-175 series 
    or 3765-190 series, in the flush/fill lines for the forward, aft, 
    and executive lavatories. -
        (e) For any affected airplane acquired after the effective date 
    of this AD: Before any operator places into service any airplane 
    subject to the requirements of this AD, a schedule for the 
    accomplishment of the leak checks required by this AD shall be 
    established in accordance with either paragraph (e)(1) or (e)(2) of 
    this AD, as applicable. After each leak check has been performed 
    once, each subsequent leak check must be performed in accordance 
    with the new operator's schedule, in accordance with either 
    paragraph (a) or (b) of this AD as applicable.
        (1) For airplanes previously maintained in accordance with this 
    AD, the first leak check to be performed by the new operator must be 
    accomplished in accordance with the previous operator's schedule or 
    with the new operator's schedule, whichever would result in the 
    earlier accomplishment date for that leak check.
        (2) For airplanes that have not been previously maintained in 
    accordance with this AD, the first leak check to be performed by the 
    new operator must be accomplished prior to further flight, or in 
    accordance with a schedule approved by the FAA PMI, but within a 
    period not to exceed 200 flight hours.
        (f) Alternative method(s) of compliance with this AD:
        (1) An alternative method of compliance or adjustment of the 
    compliance time that provides an acceptable level of safety may be 
    used if approved by the Manager, Seattle ACO, FAA, Transport 
    Airplane Directorate. Operators shall submit their requests through 
    an appropriate FAA PMI, who may add comments and then send it to the 
    Manager, Seattle ACO.
        (2) Alternative methods of compliance previously approved for AD 
    89-11-03, which permit a 4,500-flight hour interval between leak 
    checks of the forward waste drain system for those operators 
    installing the modifications specified in Boeing Service Bulletin 
    737-38-1028, dated July 18, 1991, and later revisions, are 
    considered acceptable alternative methods of compliance with the 
    requirements of only paragraph (a)(1) of this AD. For those 
    operators, the other requirements of this AD are still required to 
    be accomplished. All other alternate methods of compliance approved 
    for AD 89-11-03 are terminated and are no longer in effect.
    
        Note 11: Information concerning the existence of approved 
    alternative methods of compliance with this AD, if any, may be 
    obtained from the Seattle ACO.
        Note 12: For any valve that is not eligible for the extended 
    leak check intervals of this AD: To be eligible for the leak check 
    interval specified in paragraphs (a)(1), (a)(2), (b)(2)(i), and 
    (b)(2)(ii), the service history data of the valve must be submitted 
    to the Manager, Seattle ACO, FAA, Transport Airplane Directorate, 
    with a request for an alternative method of compliance. The request 
    should include an analysis of known failure modes for the valve, if 
    it is an existing design, and known failure modes of similar valves, 
    with an explanation of how design features will preclude these 
    failure modes, results of qualification tests, and approximately 
    25,000 flight hours or 25,000 flight cycles of service history data 
    which include a winter season, collected in accordance with the 
    requirements of paragraph (c) above, or a similar program. One of 
    the factors that the FAA will consider in approving alternative 
    valve designs is whether the valve meets Boeing Specification 
    S417T105 or 10-62213. However, meeting the Boeing specification is 
    not a prerequisite for approval of alternative valve designs.
    
        (g) Special flight permits may be issued in accordance with 
    sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
    CFR 21.197 and 21.199) to operate the airplane to a location where 
    the requirements of this AD can be accomplished. 
    
    [[Page 55680]]
    
        Issued in Renton, Washington, on October 26, 1995.
    Darrell M. Pederson,
    Acting Manager, Transport Airplane Directorate, Aircraft Certification 
    Service.
    [FR Doc. 95-27074 Filed 11-1-95; 8:45 am]
    BILLING CODE 4910-13-U
    
    

Document Information

Published:
11/02/1995
Department:
Transportation Department
Entry Type:
Proposed Rule
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
95-27074
Dates:
Comments must be received by January 30, 1996.
Pages:
55673-55680 (8 pages)
Docket Numbers:
Docket No. 95-NM-111-AD
PDF File:
95-27074.pdf
CFR: (1)
14 CFR 39.13