[Federal Register Volume 63, Number 114 (Monday, June 15, 1998)]
[Proposed Rules]
[Pages 32624-32628]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-15783]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 63, No. 114 / Monday, June 15, 1998 / 
Proposed Rules  

[[Page 32624]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-325-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, 
and -400F Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 747-100, -200, -
300, -SP, and -400F series airplanes. Among other things, this proposal 
would require repetitive leak checks of the lavatory drain system and 
repair, if necessary; installation of a cap or flush/fill line ball 
valve on the flush/fill line; would require periodic seal changes; and 
replacement of any ``donut'' type valves installed in the waste drain 
system. 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 damage to 
engines, airframes, and property on the ground that is associated with 
the problems of ``blue ice'' that forms from leaking lavatory drain 
systems on transport category airplanes and subsequently dislodges from 
the airplane fuselage.

DATES: Comments must be received by July 30, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-325-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.
    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 (425) 227-2788; fax (425) 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 97-NM-325-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-325-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 populations 
that are at greatest risk of

[[Page 32625]]

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

    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, which is applicable to Model 
747 series airplanes. In fact, several of the proposed requirements of 
this action are based on alternative methods of compliance that the FAA 
had approved previously 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.

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 PSID applied across the valve. If any leak is 
discovered during the leak tests, 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, in lieu of pressure testing of the outer cap seal, operators 
are provided with the option of performing 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.
    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 711 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 201 
airplanes of U.S. registry and 89 U.S. operators would be affected by 
this proposed AD.
    The proposed waste drain system leak test 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 
cost impact on U.S. operators of the waste drain system leak test and 
outer cap inspection is estimated to be $72,360, or $360 per airplane, 
per test/inspection.
    Certain airplanes (i.e., those that have ``donut'' type drain 
valves 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 1 time each year. Based 
on these figures, the annual (recurring) cost impact of the required 
repetitive leak tests on U.S. operators is estimated to be between $360 
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 leak 
tests for an airplane that is flown an average of 3,000 flight hours a 
year is thereby reduced from 15 tests to 3 tests. The cost reduction 
because of the number of tests required is approximately equal to the 
cost of the replacement valve. Therefore, no additional cost would be 
incurred.
    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 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 
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 work 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 4 caps per airplane. Based on these 
figures, the cost impact on U.S. operators of these proposed 
requirements of this AD is estimated to be $269,340, or $1,340 per 
airplane, per replacement cycle.
    The 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 $64,320, 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.

[[Page 32626]]

    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 
proposed 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 proposed 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 proposed 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), 40113, 44701.


Sec. 39.13  [Amended]

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

Boeing: Docket 97-NM-325-AD.

    Applicability: All Model 747-100, -200, -300, -SP, and -400F 
series 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 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 has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    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) Accomplish the applicable requirements of paragraphs (a)(1) 
through (a)(9) 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 test procedures (the one 
that applies to the equipment with the longest leak test interval) 
must be conducted at each service panel location. The waste drain 
system valve leak tests specified in this AD shall be performed in 
accordance with the following requirements: 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 across the valve 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, Seattle Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (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 series 2651-278 
or 2651-357: 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, repeat 
the replacement of 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 of 
the last documented seal change, whichever occurs later. Thereafter, 
repeat the replacement of 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, repeat 
the replacement of 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 part number 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 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.
    (3) For each lavatory drain system that has a service panel 
drain valve installed, Pneudraulics part number series 9527: Within 
2,000 flight hours after the effective date of this AD, accomplish 
the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD. 
Thereafter, repeat the leak tests at intervals not to exceed 2,000 
flight hours.

[[Page 32627]]

    (i) Conduct leak tests 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 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 part number series 
0218-0032 or 2651-357 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)(4)(i) and (a)(4)(ii) of this AD:

   Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Test  
                                Interval                                
------------------------------------------------------------------------
                                                  Serial numbers of part
                                                   number valve approved
       Shaw waste drain valve part number           for 1,000-hour 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.....................................  None.                 
10101000C-A-1...................................  0277 and higher.      
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.''                
------------------------------------------------------------------------

    Note 2: Table 1 is a comprehensive list of all approved Shaw 
valves, including those valves approved by Parts Manufacturer 
Approval (PMA) or Supplemental Type Certificate (STC) for 
installation on Boeing Model 747 series airplanes.

    (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) For each valve, except for Kaiser Electroprecision valve 
part number series 2651-357, 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 part number series 
0218-0026; or Shaw Aero Devices part number 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 requirements of paragraphs (a)(5)(i) and (a)(5)(ii) of this AD:
    (i) Conduct a leak test of the dump valve and the service panel 
drain valve. The leak test of the 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 on 
the airplane. The service panel drain valve leak test 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 each lavatory drain system with a lavatory drain system 
valve that incorporates either ``donut'' plug, Kaiser 
Electroprecision part number 4259-20 or 4259-31; Kaiser Roylyn/
Kaiser Electroprecision cap/flange part numbers 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 
part number 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 part numbers listed above, or a cap/flange which mates 
with the ``donut'' plug part numbers 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 on 
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 the donut valve [part numbers per 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 
requirements of 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 on the airplane. The service panel drain valve leak test 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.
    (8) For flush/fill lines: Within 5,000 flight hours after the 
effective date of this AD, accomplish the requirements of paragraph 
(a)(8)(i) or (a)(8)(ii), as applicable; and paragraph (a)(8)(iii) of 
this AD. Thereafter, repeat the 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.
    (ii) If a flush/fill ball valve, Kaiser Electroprecision part 
number 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.
    (iii) Leak test the toilet tank anti-siphon 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

[[Page 32628]]

occurs in flight. 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.
    (9) As a result of the leak tests and inspections 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), 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 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 fight, 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 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 flush/fill ball valve Kaiser Electroprecision part 
number 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 maintained previously 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 Prinicipal 
Maintenance Inspector (PMI), but within a period not to exceed 200 
flight hours.
    (d) Alternative method(s) of compliance with this AD: 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. Operators shall submit their 
requests through an appropriate FAA PMI, who may add comments and 
then send it to the Manager, Seattle ACO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle 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 June 8, 1998.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-15783 Filed 6-12-98; 8:45 am]
BILLING CODE 4910-13-U