[Federal Register Volume 63, Number 131 (Thursday, July 9, 1998)]
[Proposed Rules]
[Pages 37074-37078]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18158]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket 97-NM-242-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-8 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Model DC-8 series 
airplanes. Among other things, this proposal would require repetitive 
leak tests of the lavatory drain systems and repair, if necessary; 
installation of a lever lock cap, vacuum breaker check valve or flush/
fill line ball valve on the flush/fill line; periodic seal changes; and 
replacement of ``donut'' type waste drain valves installed in the waste 
drain system. This proposal is prompted by continuing reports of damage 
to engines, airframes, and 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 August 24, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-242-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.

FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California 
90712-4317; telephone (562) 627-5336; fax (562) 627-5210.

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 97-NM-242-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-114, Attention: Rules 
Docket No. 97-NM-242-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Over the past several years, the FAA has received numerous reports 
of leakage from the lavatory service systems 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 several 
of these incidents, the ingestion of ``blue ice'' into an engine 
resulted in the loss of an engine fan blade, severe engine damage, and 
the inflight shutdown of the engine. In two cases, the loads created by 
the ``blue ice'' being ingested into the engine resulted in the engine 
being physically torn from the airplane. Damage to an engine, or the 
separation of an engine from the airplane, could result in reduced 
controllability of the airplane.
    The FAA also has received reports of at least three incidents of 
damage to the airframe of various models of transport category 
airplanes that was caused by foreign objects dislodged from the forward 
toilet drain valve and flush/fill line. One report was of a dent on the 
right horizontal stabilizer leading edge on a Boeing 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 have 
stated that leakage from the flush/fill line is a significant source of 
problems associated with ``blue ice.'' Such damage caused by ``blue 
ice'' could adversely affect the integrity of the fuselage skin or 
surface structures.
    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 systems 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

[[Page 37075]]

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.''

Current Rules

    In response to these incidents, the FAA has issued several AD's 
applicable to various transport category airplanes, and is currently 
considering additional rulemaking to address the problems associated 
with ``blue ice'' on other transport category airplanes.

Discussion 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 is 
proposing this AD, which would require the following actions:
    Paragraph (a) of the proposed AD would require periodic replacement 
of the valve seals of each lavatory drain system with new valve seals. 
This paragraph also would require repetitive leak tests of the lavatory 
dump valve and drain valve (either service panel or in-line drain 
valve). The leak test of panel valves would be required to be performed 
with a minimum of 3 pounds per square inch differential pressure (PSID) 
applied across the valve. If any leak is discovered during the leak 
checks, operators would be required either to repair the leak and 
retest it, or drain the lavatory system and placard it inoperative 
until repairs can be made.
    In cases where the panel valve has both an inner seal and an outer 
cap seal, perform a visual inspection for damage or wear of the outer 
cap seal and seal surface. Any damaged parts detected would be required 
to be repaired or replaced prior to further flight, or the lavatory 
drained and placarded inoperative until repairs can be made.
    Paragraph (a) of the proposed AD also requires replacement of all 
donut type drain system valves with another type of FAA-approved valve.
    Additionally, the flush/fill line anti-siphon valve would be 
required to be leak checked. Seals of the anti-siphon (check) valve, 
flush/fill line cap, or flush/fill line ball valve would be required to 
be replaced periodically.
    Paragraph (b) of the proposed AD would require that all operators 
install a lever lock cap on the flush/fill lines for all service 
panels, or install a flush/fill ball valve Kaiser Electroprecision part 
number series 0062-0009 on the flush/fill lines for all lavatories.
    Paragraph (c) of the proposed AD would require that, before an 
operator places an airplane into service, a schedule for accomplishment 
of the leak tests required by this AD shall be established. 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 tests 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 test. Other airplanes would have to 
be inspected before an operator could begin operating them or in 
accordance with a schedule approved by the FAA Principal Maintenance 
Inspector (PMI), but within a period not to exceed 200 flight hours.

Economic Impact

    There are approximately 306 Model DC-8 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 229 
airplanes of U.S. Registry and 26 U.S. operators would be affected by 
this proposed AD.
    The proposed waste drain system leak test and outer cap inspections 
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 
cost impact on U.S. operators of the waste drain system leak test and 
outer cap inspection is estimated to be $82,440, or $360 per airplane, 
per test/inspection.
    Certain airplanes (i.e., those that have ``donut'' type drain valve 
installed) may be required to be leak tested as many as 15 times each 
year. Certain other airplanes having other valve configurations would 
be required to be leak tested as few as 3 times each year. Based on 
these figures, the cost impact of this proposed requirement is 
estimated to be between $1,080 and $5,400 per airplane per year.
    With regard to replacement of ``donut'' type drain valves, the cost 
of a new valve is approximately $1,200. However, the number of leakage 
tests for an airplane that flies an average of 3,000 flight hours a 
year is reduced from 15 tests to 3 tests, which essentially pays for 
the cost of the replacement valve, so that no additional net cost is 
incurred because of this change.
    The FAA estimates that it would take approximately 1 work hour per 
airplane to accomplish a visual inspection of the service panel drain 
valve cap/door seal and seal mating surfaces, at an average labor rate 
of $60 per work hour. As with leak tests, 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 cost impact of the 
proposed repetitive visual inspections 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 cost impact on U.S. operators of these proposed requirements is 
estimated to be $171,178, or $748 per airplane.
    The proposed seal replacements of the drain valves required by 
paragraph (a) of this AD would require approximately 2 work hours to 
accomplish, at an average labor cost of $60 per hour. The cost of 
required parts would be $200 per each seal change. Based on these 
figures, the cost impact on U.S. operators of these proposed 
requirements of this AD is estimated to be $73,280, or approximately 
$320 per airplane, per replacement.
    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.
    The 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

[[Page 37076]]

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 U.S.C. 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 97-NM-242-AD.

    Applicability: Model DC-8 series airplanes equipped with a lavatory 
drainage system; 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 request approval for an 
alternative method of compliance in accordance with paragraph (d) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition as not been 
eliminated, the request should include specific proposed actions to 
address it.

    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 
system and dislodged from the airplane, accomplish the following:
    (a) Accomplish the applicable requirements of paragraphs (a)(1) 
through (a)(9) of this AD at the time specified in each paragraph. 
For the waste drain system of any lavatory that incorporates more 
than one type of valve, only one of the waste drain system leak test 
procedures (the one that applies to the equipment with the longest 
leak test interval) must be conducted at each service panel 
location. During the performance of the waste drain system valve 
leak tests specified in this AD, fluid shall completely cover the 
upstream end of the valve being tested. The direction of the 3 
pounds per square inch differential pressure (PSID) shall be applied 
in the same direction as occurs in flight; the other waste drain 
system valves shall be open, and the minimum time to maintain the 
differential pressure shall be 5 minutes. Any revision of the seal 
change intervals or leak test intervals must be approved by the 
Manager, Los Angeles Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate.

    Note 2: Inclusion of a valve in this AD does not mean that the 
valve has been certified for installation in DC-8 series airplanes. 
Certification of the valve for installation in the airplane must be 
accomplished by means acceptable to the FAA, if the valve has not 
been previously certified.

    (1) Replace the valve seals with new valve seals in accordance 
with the applicable schedule specified in paragraphs (a)(1)(i), 
(a)(1)(ii), and (a)(1)(iii) of this AD.
    (i) For each lavatory drain system that has an in-line drain 
valve installed, Kaiser Electroprecision part number (p/n) series 
2651-278: Replace the seals within 5,000 flight hours after the 
effective date of this AD, or within 48 months after the last 
documented seal change, whichever occurs later. Thereafter, replace 
the seals at intervals not to exceed 48 months.
    (ii) For each lavatory drain system that has a Pneudraulics part 
number series 9527 valve: Replace the seals within 5,000 flight 
hours after the effective date of this AD, or within 18 months after 
the last documented seal change, whichever occurs later. Thereafter, 
replace the seals at intervals not to exceed 18 months or 6,000 
flight hours, whichever occurs later.
    (iii) For each lavatory drain system that has any other type of 
drain valve: Replace the seals within 5,000 flight hours after the 
effective date of this AD, or within 18 months after the last 
documented seal change, whichever occurs later. Thereafter, replace 
the seals at intervals not to exceed 18 months.
    (2) For each lavatory drain system that has an in-line drain 
valve installed, Kaiser Electroprecision p/n series 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)(2)(i) and (a)(2)(ii) of 
this AD.
    (i) Conduct a leak test of the toilet tank 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 toilet tank dump 
valve leak test must be performed by filling the toilet tank with a 
minimum of 10 gallons of water/rinsing fluid and testing for leakage 
after a period of 5 minutes. Take precautions to avoid overfilling 
the tank and spilling fluid into the airplane. The in-line drain 
valve leak test must be performed with a minimum of 3 PSID applied 
across the valve.
    (ii) If a service panel valve or cap is installed, perform a 
visual inspection to detect wear or damage that may allow leakage 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.
    (3) For each lavatory drain system that has a service panel 
drain valve installed, Pneudraulics p/n series 9527: Within 2,000 
flight hours after the effective date of this AD, and thereafter at 
intervals not to exceed 2,000 flight hours, accomplish the 
procedures specified in paragraphs (a)(3)(i) and (a)(3)(ii) of this 
AD.
    (i) Conduct a leak test of the toilet tank dump valve and the 
service panel drain

[[Page 37077]]

valve. The toilet tank dump valve leak test must be performed by 
filling the toilet tank with a minimum of 10 gallons of water/
rinsing fluid and testing for leakage after a period of 5 minutes. 
Take precautions to avoid overfilling the tank and spilling fluid 
into the airplane. The leak test of the service panel drain valve 
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.
    (4) For each lavatory drain system that has a service panel 
drain valve installed, Kaiser Electroprecision p/n series 0218-0032, 
or Shaw Aero Devices 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 procedures specified in paragraphs (a)(4)(i) 
and (a)(4)(ii) of this AD.

                  Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Test Interval                  
----------------------------------------------------------------------------------------------------------------
                                                           Serial No. of part No. Valve approved for 1,000-hour 
            Shaw waste drain valve part No.                                 leak test interval                  
----------------------------------------------------------------------------------------------------------------
331 Series, 332 Series.................................  All.                                                   
10101000B-A............................................  None.                                                  
10101000B-A-1..........................................  0207-0212, 0219, 0226 and higher.                      
10101000BA2............................................  0130 and higher.                                       
10101000C-A-1..........................................  0277 and higher.                                       
10101000C-J............................................  None.                                                  
10101000C-J-2..........................................  None.                                                  
10101000CN OR C-N......................................  3649 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''. 
----------------------------------------------------------------------------------------------------------------

    (i) Conduct a leak test of the toilet tank dump valve and 
service panel drain valve. The toilet tank dump valve leak test must 
be performed by filling the toilet tank with a minimum of 10 gallons 
of water/rinsing fluid and testing for leakage after a period of 5 
minutes. Take precautions to avoid overfilling the tank and spilling 
fluid into the airplane. The service panel drain valve leak test 
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.
    (5) For each lavatory drain system that has a service panel 
drain valve installed, Kaiser Electroprecision p/n series 0218-0026; 
or Shaw Aero Devices p/n series 10101000B or 10101000C [except as 
specified in paragraph (a)(4) 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 procedures specified in 
paragraphs (a)(5)(i) and (a)(5)(ii) of this AD.
    (i) Conduct a leak test of the toilet tank dump valve and the 
service panel drain valve. The leak test of the toilet tank dump 
valve must be performed by filling the toilet tank with a minimum of 
10 gallons of water/rinsing fluid and testing for leakage after a 
period of 5 minutes. Take precautions to avoid overfilling the tank 
and spilling fluid into the airplane. The service panel drain valve 
leak test 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.
    (6) For each lavatory drain system with a lavatory drain system 
valve that incorporates either ``donut'' plug, Kaiser 
Electroprecision p/n's 4259-20 or 4259-31; Kaiser Roylyn/Kaiser 
Electroprecision cap/flange p/n's 2651-194C, 2651-197C, 2651-216, 
2651-219, 2651-235, 2651-256, 2651-258, 2651-259, 2651-260, 2651-
275, 2651-282, 2651-286; Shaw Aero Devices assembly p/n 0008-100; or 
other FAA-approved equivalent parts; accomplish the requirements of 
paragraphs (a)(6)(i), (a)(6)(ii), and (a)(6)(iii) of this AD at the 
times specified in those paragraphs. For the purposes of this 
paragraph [(a)(6)], ``FAA-approved equivalent part'' means either a 
``donut'' plug which mates with the cap/flange p/n's listed above, 
or a cap/flange which mates with the ``donut'' plug p/n's listed 
above, such that the cap/flange and ``donut'' plug are used together 
as an assembled valve.
    (i) Within 200 flight hours after the effective date of this AD, 
and thereafter at intervals not to exceed 200 flight hours, conduct 
leak tests of the toilet tank dump valve and the service panel drain 
valve. The leak test of the toilet tank dump valve must be performed 
by filling the toilet tank with a minimum of 10 gallons of water/
rinsing fluid and testing for leakage after a period of 5 minutes. 
Take precautions to avoid overfilling the tank and spilling fluid 
into the airplane. The service panel drain valve leak test must be 
performed with a minimum 3 PSID applied across the valve.
    (ii) Perform a visual inspection of the outer door/cap and seal 
mating surface for wear or damage that may cause leakage. This 
inspection shall be accomplished in conjunction with the leak tests 
of paragraph (a)(6)(i).
    (iii) Within 5,000 flight hours after the effective date of this 
AD, replace all the ``donut'' valves identified in paragraph (a)(6) 
of this AD with another type of FAA-approved valve. Following 
installation of the replacement valve, perform the appropriate leak 
tests and seal replacements at the intervals specified for that 
replacement valve, as applicable.
    (7) For each lavatory drain system not addressed in paragraphs 
(a)(2), (a)(3), (a)(4), (a)(5), and (a)(6) 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 procedures 
specified in paragraphs (a)(7)(i) and (a)(7)(ii) of this AD.
    (i) Conduct a leak test of the toilet tank dump valve and the 
service panel drain valve. The toilet tank dump valve leak test must 
be performed by filling the toilet tank with a minimum of 10 gallons 
of water/rinsing fluid and testing for leakage after a period of 5 
minutes. Take precautions to avoid overfilling the tank and spilling 
fluid into the airplane. The leak test of the service panel drain 
valve 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.
    (8) For flush/fill lines: Within 5,000 flight hours after the 
effective date of this AD, perform the requirements of paragraph 
(a)(8)(i) or (a)(8)(ii), as applicable; and paragraph (a)(8)(iii) of 
this AD. Thereafter, repeat these requirements at intervals not to 
exceed 5,000 flight hours, or 48 months after the last documented 
seal change, whichever occurs later.
    (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 
test of the toilet tank anti-siphon (check) valve with a minimum of 
3 PSID across the valve, in accordance with the applicable portions 
of paragraph (a)(8)(ii)(A) of this AD.
    (ii) If a vacuum breaker check valve, Monogram p/n series 3765-
190, or Shaw Aero Devices p/n series 301-0009-01 is installed on the 
subject lavatory, replace the seals/o-rings in the valve. Perform a 
leak test of the vacuum breaker check valve and verify proper 
operation of the vent line vacuum breaker, in accordance with 
paragraphs (a)(8)(ii)(A) and (a)(8)(ii)(B) of this AD.

[[Page 37078]]

    (A) Leak test the toilet tank anti-siphon (check) valve or the 
vacuum breaker check valve 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). Apply 3 PSID 
across the valve in the same direction as occurs in flight. The vent 
line vacuum breaker on vacuum breaker check valves must be pinched 
closed or plugged for this leak test. If there is a cap/valve at the 
flush/fill line port, the cap/valve must be removed/open during the 
test. Check for leakage at the flush/fill line port for a period of 
5 minutes.
    (B) Verify proper operation of the vent line vacuum breaker by 
filling the tank and checking at the fill line port for back 
drainage after disconnecting the fluid source from the flush/fill 
line port. If back drainage does not occur, replace the vent line 
vacuum breaker or repair the vacuum breaker check valve, in 
accordance with the component maintenance manual to obtain proper 
back drainage. As an alternative to the test technique specified 
above, verify proper operation of the vent line vacuum breaker in 
accordance with the procedures of the applicable component 
maintenance manual.
    (iii) If a flush/fill ball valve, Kaiser Electroprecision p/n 
series 0062-0009, is installed on the flush/fill line of the subject 
lavatory, replace the seals in the flush/fill ball valve and the 
toilet tank anti-siphon valve. Perform a leak test of the toilet 
tank anti-siphon valve with a minimum of 3 PSID across the valve, in 
accordance with paragraph (a)(8)(ii)(A) of this AD.
    (9) If leakage is discovered during any leak test or inspection 
required by paragraph (a) of this AD, or if evidence of leakage is 
found at any other time, accomplish the requirements of paragraph 
(a)(9)(i), (a)(9)(ii), or (a)(9)(iii) of this AD, as applicable.
    (i) If a leak is discovered, prior to further flight, repair the 
leak. Prior to further flight after repair, perform the appropriate 
leak test as specified in paragraph (a) of this AD, as applicable. 
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 3: 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)(9)(i) or (a)(9)(ii): Prior to further flight, drain the affected 
lavatory system and placard the lavatory inoperative until repairs 
can be accomplished.
    (b) For all airplanes: Unless accomplished previously, within 
5,000 flight hours after the effective date of this AD, perform the 
actions specified in either paragraph (b)(1) or (b)(2) of this AD:
    (1) Install an FAA-approved lever lock cap on the flush/fill 
lines for all lavatories. Or
    (2) Install a vacuum break, Monogram p/n series 3765-190, or 
Shaw Aero Devices p/n series 301-0009-01, in the flush/fill lines 
for all lavatories. Or
    (3) Install a flush/fill ball valve, Kaiser Electroprecision p/n 
series 0062-0009 on the flush/fill lines for all lavatories.
    (c) 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 tests required by this AD shall be 
established in accordance with either paragraph (c)(1) or (c)(2) of 
this AD, as applicable. After each leak test has been performed 
once, each subsequent leak test must be performed in accordance with 
the new operator's schedule, in accordance with paragraph (a) of 
this AD.
    (1) For airplanes that have been maintained previously in 
accordance with this AD, the first leak test 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 
results in the earlier accomplishment date for that leak test.
    (2) For airplanes that have not been previously maintained in 
accordance with this AD, the first leak test to be performed by the 
new operator must be accomplished prior to further flight, or in 
accordance with a schedule approved by the FAA Principal Maintenance 
Inspector (PMI), but within a period not to exceed 200 flight hours.
    (d) 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, Los Angeles ACO. Operators shall 
submit their requests through an appropriate FAA PMI, who may add 
comments and then send it to the Manager, Los Angeles ACO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (e) 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.

    Issued in Renton, Washington, on July 1, 1998.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-18158 Filed 7-8-98; 8:45 am]
BILLING CODE 4910-13-U