[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