[Federal Register Volume 64, Number 69 (Monday, April 12, 1999)]
[Rules and Regulations]
[Pages 17514-17522]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-8686]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-325-AD; Amendment 39-11116; AD 99-08-10]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts 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 amendment requires repetitive leak tests 
of the lavatory drain system and repair, if necessary; installation of 
a cap or flush/fill line ball valve on the flush/fill line; periodic 
seal changes; and replacement of any ``donut'' type valves installed in 
the waste drain system. This amendment is prompted by continuing 
reports of damage to airframes 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 AD are intended to 
prevent damage to 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: Effective May 17, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 17, 1999.

ADDRESSES: This information may be examined at the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, Rules Docket, 
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to all Boeing Model 747-100, -200, -
300, -SP, and -400F series airplanes was published in the Federal 
Register on June 15, 1998 (63 FR 32624). That action proposed to 
require repetitive leak tests of the lavatory drain system and repair, 
if necessary; installation of a cap or flush/fill line ball valve on 
the flush/fill line; periodic seal changes; and replacement of any 
``donut'' type valves installed in the waste drain system.
    The actions specified in that proposal are intended to prevent 
damage to 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.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

1. Support for the Proposal

    Two commenters support the proposed rule.

2. Request To Revise the Unsafe Condition

    One commenter, the airplane manufacturer, requests that the 
proposed rule be revised to remove reference to ``engine damage'' in 
the description of the unsafe condition. The airplane manufacturer 
bases this request on the fact that it is not aware of any in-service 
reports of engine damage due to ``blue ice'' on Model 747 series 
airplanes.
    The FAA concurs. Since the FAA has not received any reports of 
engine damage due to ``blue ice'' on Model 747 series airplanes, 
reference to ``engine damage'' in the description of the unsafe 
condition has been removed from the AD.

3. Request To Extend Leak Test Intervals for Model 747 Series 
Airplanes

    One commenter requests that the leak test intervals be specified in 
flight cycles rather than flight hours as proposed in the Notice of 
Proposed Rulemaking (NPRM). The commenter also requests that, if the 
intervals are retained as flight hours, all of the intervals should be 
extended. The commenter points out that a typical ``C'' check on Model 
747 series airplanes is between 5,000 and 6,000 flight hours, as 
compared to typical ``C'' checks of Models 727 and 737 series 
airplanes, which are generally between 3,000 and 4,000 flight hours. 
Since most of the wear and damage is caused by opening and closing the 
valve, which happens during a flight cycle, and is not directly related 
to the number of flight hours, flight cycles are more critical than 
flight hours with regard to the potential for leakage. Because Model 
747 series airplanes have a low number of flight cycles per hour, the 
fleet should be allowed a greater leak test interval than the interval 
specified for Models 727 and 737 series airplanes.
    The FAA does not concur that the leak test intervals should be 
specified in flight cycles rather than flight hours. The commenter did 
not provide any specific data that correlated the number of flight 
hours to the number of flight cycles for the Boeing Model 747 fleet and 
the Boeing 727 and 737 fleets. Additionally, existing ``blue ice'' 
Airworthiness Directives for other airplanes presently specify the leak 
test intervals in terms of flight hours. To change the leak test 
intervals from flight hours to flight cycles could result in an 
operator having some airplanes operating under flight hours intervals 
and other airplanes operating under flight cycle intervals, which may 
be burdensome for the operator.
    However, the FAA does concur that certain leak test intervals can 
be extended somewhat for Model 747 series airplanes for the reasons the 
commenter suggested. Specific extensions of leak tests for certain 
valves are discussed later in this disposition of comments.

4. Requests To Extend PneuDraulics Leak Test Intervals

    One commenter requests that the leak test interval for the 
PneuDraulics service panel drain valve be revised from 2,000 to 4,000 
flight hours. The commenter advises that the PneuDraulics service panel 
drain valve specified in paragraph

[[Page 17515]]

(a) of the proposal has had in excess of 800,000 flight hours of 
service history documented by operators in FAA-approved maintenance 
programs with only two leakage events reported.
    The FAA concurs that, for the reasons provided by the commenter, 
extension of the leak test interval from 2,000 flight hours to 4,000 
flight hours for those PneuDraulics valves is justified. Since that 
service history was obtained when the operators were using FAA-approved 
maintenance programs that required reporting of any leakage, the FAA 
has high confidence that this data is representative of the actual 
leakage rates. Paragraph (a)(3) of the final rule has been revised to 
reflect the 4,000 flight hour leak test interval.

5. Request To Extend Leak Test Interval for Certain Shaw Aero 
Valves

    The commenter requests that the leak test interval for certain Shaw 
Aero service panel drain valves be extended from 1,000 flight hours to 
2,000 flight hours. The commenter states that data submitted previously 
to the FAA indicates that there are nearly 8,000 Shaw Aero service 
panel drain valves on airplanes that have accumulated in excess of 50 
million flight hours over the past 10 years. The commenter points out 
that, on all of the airplanes on which Shaw Aero service panel drain 
valves were installed during production, there were less than ten 
reports of leakage during that time that could have been attributed to 
a Shaw Aero Devices service panel drain valve.
    In addition, the commenter states that Boeing has presented data to 
the FAA showing that the Shaw Aero service panel drain valve has been 
the baseline unit installed on Model 737 series airplanes since January 
1991, and on Model 757 series airplanes since July 1992. All Boeing 
service data available through February 1996 indicates that all 
versions of the Shaw service panel drain valves can be attributed to 
less than 0.60 percent of the reports of leakage on Model 737 and 757 
series airplanes.
    The commenter states that the data presented shows ample evidence 
to support a leak test interval equal to the PneuDraulics valve, which 
was granted a leak test interval extension based on only 412 valves 
installed on aircraft flown over a much shorter interval than the 10 
year period cited for the Shaw valves. Additionally, the commenter 
points out that industry experience clearly indicates that the main 
problems occur after two years of residue build-up on the sealing 
surfaces of any valve, irrespective of the design features. The 
commenter points out that meaningful data must be gathered over a 
period of at least two years.
    Additionally, the commenter advises that several airlines have 
collected, or are in the process of collecting, data in order to submit 
a request for extended leak test intervals for their fleets. In fact, 
the commenter states that it has attached a copy of one such draft 
request that indicates that there have been only two cases reported of 
any evidence of leakage on a fleet of 163 Boeing Model 727 series 
airplanes that have accumulated 325,678 flight hours on Shaw Aero 
Devices 332 series valves.
    The FAA concurs with the commenter's request to extend certain 
interval times based on the general extension of intervals given to 
Model 747 series airplanes explained previously. Those intervals have 
been extended for certain Shaw Aero service panel drain valves from 
1,000 to 1,500 flight hours. The leak test interval for certain other 
Shaw Aero service panel drain valves has been increased from 600 to 800 
flight hours. The FAA has revised certain sub-paragraphs of paragraph 
(a) of the final rule to reflect those extensions of the leak test 
intervals.
    This commenter also states that in over 50 million flight hours on 
8,000 valves only four instances of leakage have been reported. 
However, data the FAA has received indicates that most instances of 
leakage are not reported. Leakage from a service panel drain valve is 
not a reportable event as required by Part 21.3 of the Federal Aviation 
Regulations (14 CFR part 21.3). The service history data was not 
collected as part of an FAA-approved maintenance program that requires 
reporting of service panel drain valve leakage. Therefore, the FAA does 
not have a high level of confidence that the reported leakage rates are 
necessarily representative of the actual leakage rate in service. As an 
example, a Boeing report cited by the commenter listed 157 total 
reports of leakage for 662 Boeing Model 747 series airplanes for the 
history of the fleet up until April of 1996, when the data was 
collected. However, the FAA recently received a copy of a report 
regarding ice on certain airplanes arriving at Narita Airport in Japan 
during a two-week period in February 1998. For 562 arrivals of Boeing 
Model 747 series airplanes that were inspected during the two-week 
period, there were 14 instances of ice found at lavatory service 
panels. While some of those instances were caused by leakage from the 
flush/fill lines instead of the waste drain valve, the fact remains 
that a two-week period of actual inspection at one airport revealed 14 
instances of leakage compared to 157 cases of leakage reported by 
operators to Boeing for the entire operating history of the Model 747 
fleet until 1996. Clearly, the amount of actual leakage is not 
reflected in the number reported by operators to Boeing.
    In regard to the commenter's statement that several operators are 
in the process of gathering data regarding performing leak checks, the 
FAA has not received that data as of this date. Without reviewing the 
actual data and information, the FAA cannot provide a decision to 
extend the leak test interval. Therefore, no change is necessary to the 
final rule in this regard.

6. Request To Extend the Leak Test Interval for Certain Service 
Panel Ball Valves

    The same commenter requests that the leak test interval (currently 
1,000 flight hours) be extended for Kaiser Electroprecision service 
panel ball valves, Part Number (P/N) 2651-357. The commenter contends 
that the Kaiser Electroprecision service panel ball valve is designed 
considerably different than the other valves that are subject to the 
proposed 1,000-flight-hour intervals for valves. The commenter notes 
that the Kaiser ``Expander'' valve, P/N 0218-0032, and Shaw Aero 
``Posi-Lift'' valve, P/N 10101000C( ), are subject to the proposed 
1,000-flight-hour intervals also. The commenter points out that Kaiser 
P/N 2651-357 is considered a ball valve. The commenter questions that 
if the FAA considers similarity of valves in determining an appropriate 
leak test interval, Kaiser P/N 2651-357 is at least equivalent to a 
PneuDraulics P/N 9527 series valve. The commenter points out that P/N 
9527 series valves are essentially only a half-ball valve. Since Kaiser 
makes the in-line ball valve, P/N 2651-278, which has a 4,500-flight-
hour leak test interval, Kaiser's experience in manufacturing 
reliability should be considered when setting an initial leak test 
interval for the panel ball valve, P/N 2651-357. The commenter 
concludes that a new valve such as this should not receive a 
``generic'' 1,000-flight-hour leak test, but rather should be 
considered for an extension of the leak test interval based on its 
design and similarity to other valves.
    The FAA concurs that Kaiser Electoprecision panel ball valve, P/N 
2651-357( ) series can be extended from the proposed 1,000-flight-hour 
interval. In fact, the FAA has recently approved the leak test interval 
for that panel ball valve to be extended from 1,000 to 2,000 flight 
hours. The FAA based this extension on similarity to the Kaiser

[[Page 17516]]

Electroprecision in-line drain valve, the service history of over 20 
panel ball valves with an average of over 2,000 flight hours per valve 
and with no reports of leakage, and other data and analysis. The FAA 
considers similarity of valves, the manufacturer's experience, and 
manufacturing reliability in setting the initial leak test interval for 
a particular valve. These factors are also considered in determining 
the amount of in-service monitoring by operators that is required for 
an extension of the leak test interval. The intent of requiring service 
experience in addition to similarity analysis is to make sure that 
there are no unforeseen design deficiencies in a valve for which 
similarity is claimed. Similarity can be used to reduce the amount of 
in-service experience needed for a particular valve to receive an 
extension of the leak test interval. Therefore, paragraph (a)(4) of the 
final rule specifies the 2,000-flight-hour interval for the Kaiser 
Electoprecision panel ball valve, P/N 2651-357( ) series.

7. Request To Use Optional Method

    One commenter requests that the proposal be revised to allow use of 
Monogram P/N 4803-76 or P/N 4803-96 series vacuum breaker check valve 
as an option to the installation of a lever lock cap on the flush/fill 
line or a ball valve on the flush/fill line. Another commenter requests 
that the proposal be revised to allow use of either a vacuum breaker 
check valve or an automatic shut-off valve as an option to installing a 
lever lock cap on the flush/fill line or a ball valve on the flush/fill 
line. The commenters point out that such an option to installing flush/
fill line ball valves was permitted in the ``blue ice'' AD for 
McDonnell Douglas Model DC-10 series airplanes [AD 96-12-18, amendment 
39-9661 (61 FR 29009, June 7, 1996)].
    The FAA concurs with the commenter's request. Vacuum breaker check 
valves, Monogram P/N 4803-86, installed on McDonnell Douglas Model DC-
10 series airplanes, and Monogram P/N 4803-76 and -96 installed on 
Boeing Model 747 series airplanes are similar to each other in design 
and function. The FAA has determined that those valves are adequate to 
install as an alternative to installing a lever lock cap of the flush/
fill line or a ball valve on the flush/fill line. The FAA also has 
determined that installation of an automatic shut-off valve is an 
adequate method to prevent leakage from the flush/fill line. Certain 
paragraphs of this AD [(a), (b)(3), and (a)(9)(ii)] have been revised 
to add provisions to install vacuum breaker valves as an option to 
installing a lever lock cap or ball valve on the flush/fill line. 
Additionally, the final rule has been revised to add provisions in 
paragraphs (b)(3) and (a)(9)(iv) of this AD to install and test a shut-
off valve per Boeing specification number 60B50341 as an option to 
installing a lever lock cap or flush/fill line ball valve on the flush/
fill line.
    In addition to listing optional valves for the flush/fill line, the 
FAA also added vacuum leak test procedures as discussed in comment 10 
below, and reorganized the seal change and leak test requirements 
previously contained in paragraph (a)(8) of the NPRM, and moved them 
into paragraphs (a)(9) and (a)(10) of the final rule.

8. Request To Revise Specifications of the Leak Test of the Toilet 
Tank Dump Valve

    The commenter, the airplane manufacturer, points out that the 
proposal specifies that the toilet tank be filled with a ``minimum of 
10 gallons of water/rinsing fluid'' prior to performing the leak test 
of the toilet tank dump valve. The commenter requests that the 
specifications for the leak test be changed to require ``a minimum of 
10 gallons of water/rinsing fluid for tanks with less than 30 gallons 
capacity, and a minimum of 20 gallons of water/rinsing fluid for tanks 
with more than 30 gallons capacity.'' The commenter states that due to 
the wide variation in toilet tank sizes on the Model 747 fleet, 10 
gallons may not be adequate in some cases to properly conduct a leak 
test.
    The FAA concurs that the amount of fluid in the tank should be 
sufficient to test for leakage of the toilet tank dump valve, and that 
the specifications for conducting the leak test should be revised. The 
intent of specifying that the leak test be performed with ``a minimum 
of 10 gallons'' was to indicate that sufficient fluid be used to 
perform a valid leak test, without having to completely fill the tank 
and risk a spill of fluid inside the airplane. Since some Model 747 
series airplanes are equipped with toilet tanks that are considerably 
larger than tanks in other airplanes, an increase in the minimum amount 
of fluid used to perform the test is considered necessary for airplanes 
with the larger tanks. The FAA has revised the final rule to specify 
the requested revision.

9. Request To Revise Table 1 of the Proposal

    The commenter requests that Table 1 of the proposal be revised to 
correct the serial numbers of 10101000B-A-1 valves and to add 
10101000C-R and 10101000C-G valves to Table 1.
    The FAA concurs with the request to correct the serial numbers for 
10101000B-A-1 valves and has revised Table 1 accordingly. However, the 
FAA does not concur with the commenter's request to add the two 
additional valves to Table 1. The FAA has determined that those valves 
are not used on the airplanes affected by this AD. Further, the FAA has 
removed certain other part numbers of valves (10101000B-A and 
10101000C-A) listed in Table 1 of the proposal since they are not 
eligible for the 1,000-flight-hour leak test interval. Additionally, 
Note 2 of the AD has been revised to specify that Table 1 of the AD 
contains only valves that are eligible for a leak check interval of 
1,500 hours.

10. Request To Use Vacuum Tool

    One commenter requests that the proposal be revised to allow 
testing of the inner seal of the service panel valve with a vacuum tool 
for a period of one minute without any fluid upstream of the valve. 
This same commenter states that testing with air (vacuum tool) is more 
stringent than testing with water. The commenter points out that when 
testing with air, a leak path is detected readily within one minute 
because the pressure gauge will move indicating a loss of vacuum. The 
commenter also points out that previous AD's have permitted leak 
testing with a vacuum tool. A second commenter states that by allowing 
a leak test without requiring that the inner door of the service panel 
be covered with fluid, the likelihood of ``blue showers'' (i.e., 
uncontrolled leakage of waste tank drain line inside the airplane) 
would be reduced.
    The FAA concurs with the request to allow a vacuum leak test 
procedure for the reasons the commenter provided. The FAA has revised 
paragraphs (a), (a)(10)(ii), and Note 3 of the final rule to add 
provisions and instructions for the use of vacuum leak test procedures. 
However, the FAA does not concur with the request to establish a period 
of one minute for the vacuum leak test. The commenter did not provide 
sufficient evidence to support reducing the leak test period from five 
minutes to one minute. Therefore, no change is necessary to the final 
rule regarding the time period required for the leak test.

11. Request To Revise ``Dump Valve'' Terminology

    One commenter requests that paragraph (a)(5)(i) of the proposal be 
revised to change the current wording of ``dump valve'' to the correct 
terminology of ``toilet tank dump valve.'' The commenter points out 
that changing the terminology in that particular paragraph would make 
the

[[Page 17517]]

use of the term ``toilet tank dump valve'' consistent throughout the 
proposal. The FAA concurs and has revised the final rule accordingly.

12. Request To Clarify Seal Replacement Interval

    One commenter requests that the compliance time for replacement of 
seals be revised to clarify that the seal replacement interval would 
begin when the new valve is installed or a new airplane is delivered.
    The FAA concurs. Installation of a new valve or delivery of a new 
airplane would also mean that a new seal is in place. Therefore, the 
FAA considers that a new valve installation or delivery of a new 
airplane constitutes the ``last documented seal change.'' The FAA has 
revised paragraphs (a)(1) and (a)(9) of the final rule to reflect this 
change. The FAA points out that, for the purposes of this AD, a ``new'' 
airplane is one that has accumulated less than 100 total flight hours 
or 30 calendar days, whichever occurs later, since the issuance of the 
original airworthiness certificate.

13. Request To Correct a Part Number

    One commenter requests that paragraphs (a)(8)(ii) and (b)(2) of the 
proposal be revised to reflect the correct part number for the flush/
fill ball valve. The commenter advises that the correct part number is 
Kaiser Electroprecision part number series 0062-0010, not ``0062-
0009,'' as specified in the proposal. The FAA concurs with the 
commenter's request, and has revised paragraphs (a)(9)(iii) and (b)(2) 
of the final rule to reflect the correct part numbers.

14. Request To Extend the Seal Change Interval

    One commenter requests that paragraph (a)(1)(ii) of the proposal be 
revised to reduce the seal change interval from 6,000 to 5,000 flight 
hours for the PneuDraulics valve. The commenter states that the seal in 
a ball-valve or half-ball valve located at the service panel is 
subjected to a significantly greater dynamic action than that of a seal 
in a flapper-type valve. The distance that the ball or half-ball drags 
across the seal subjects the seal to considerably more wear that the 
wear experienced by an O-ring seal in a flapper-type valve as it moves 
from a sealed to an unsealed position. The plastic seals used in the 
ball or half-ball valves are much less forgiving and less compressible 
than elastomer type seals used in flapper-type valves. Therefore, the 
ball or half-ball valves are more susceptible to being damaged by 
foreign objects and consequent leakage. The potential for ice, hardened 
debris, and ``black tar'' to build up on the ball at the service panel 
makes the seals more susceptible to damage by service and maintenance 
personnel than the seals of an in-line ball valve. Additionally, the 
commenter contends that the performance of the seals in the in-line 
ball valve cannot be replicated in-service on ball or half-ball valves 
used at the service panel. Service panel components also experience 
greater temperature fluctuations (-65 degrees Fahrenheit to +130 
degrees Fahrenheit) than those experienced by components upstream.
    The FAA does not concur with the commenter's request to reduce the 
seal change interval for the PneuDraulics valve. The commenter did not 
provide any specific data to demonstrate that ball valve seals or half-
ball valve seals actually do have greater failure rates than flapper 
type valves. The FAA established the seal change interval for the 
PneuDraulics valve based on data submitted by an operator and the valve 
manufacturer. No change is necessary to the final rule.

15. Request To Standardize the Requirements for Extension of the 
Leak Test

    One commenter, a valve manufacturer, requests that the proposal be 
revised to require ``equivalent'' criteria for extending the leak tests 
of all valves. The manufacturer states that certain criteria were 
required to obtain leak test extensions for its product, but that other 
valves were not subjected to the same stringent criteria. The commenter 
notes that valves with components prone to multiple failure and easily 
damaged seals will leak if exposed to the hourly usage schedules (as 
proposed in the NPRM). The commenter contends that a valve with exposed 
soft seals can leak immediately after successfully passing a test if 
damaged by ice, tools, or loss of the donut plug. The commenter further 
contends that the valves should have a primary seal and a secondary 
seal as required by the specifications of the airplane manufacturer for 
panel valves.
    The FAA does not concur that the final rule should be revised in 
regard to establishing ``equivalent'' criteria for extending the leak 
test intervals. The FAA has required all operators requesting an 
extension to provide service history and data to support any extensions 
of leak test intervals. Previous service experience, similarity to 
existing valves, and the quality of the data are considered in 
determining an appropriate extension of the leak check interval for 
each valve. No change is necessary to the final rule.

16. Request To Establish Consistent Testing Intervals for 
Components

    One commenter, the airplane manufacturer, states that it is 
concerned that test and maintenance intervals for a particular part 
number component may not be consistent across all models. The commenter 
requests that any increased intervals for a specific component be 
applied to all models using that component.
    The FAA does not concur. As explained in a previous disposition of 
comment (number 3), the flight cycles per flight hours are different on 
various airplane models. Therefore, the cyclic wear on various 
components differs according to the airplane model on which the 
component is installed. Consequently, the FAA cannot approve consistent 
flight hour intervals for leak checks on specific components that apply 
to all airplane models.
    Operators who wish to take advantage of the increase in leak test 
intervals may request information concerning the existence of approved 
alternative methods of compliance, in accordance with Note 5 of this 
AD. Additionally, paragraph (d) of this AD provides for any operator to 
request approval of an alternative method of compliance that provides 
an acceptable level of safety.

17. Request To Provide a Maintenance Option

    One commenter, the airplane manufacturer, requests that the FAA add 
a maintenance option to the AD that would permit operators to revise 
their FAA-approved maintenance program to include the requirements 
specified in the proposal. The commenter points out that such a 
revision would permit operators to justify extending leak test 
intervals to intervals that are consistent with their regularly 
scheduled maintenance.
    The FAA does not concur. The FAA did not provide the maintenance 
option in this AD based on information it received that few operators 
were inclined to revise their maintenance program to incorporate the 
requirements of this AD. Additionally, comments submitted regarding 
previous ``blue ice'' AD's that did contain the maintenance option 
stated that the proposed AD's were ``too long, and hard to 
understand.'' The FAA's intent by not specifying the maintenance option 
in this AD is to simplify and clarify the requirements of this AD. No 
change to the final rule is necessary in that regard. However, if an 
operator wishes to request approval for revision of its

[[Page 17518]]

maintenance program, a request should be submitted to the FAA in 
accordance with the provisions of paragraph (d) of this AD.

18. Request To Include Terminating Action in the AD

    One commenter, the airplane manufacturer, requests that a provision 
for terminating action be included in the AD. The commenter agrees that 
incorporation of the proposed AD requirements such as ``donut'' lug 
removal, seal replacement, rinse system upgrade, and installation of 
improved drain valves will result in reduced incidences of ``blue 
ice.'' However, if an operator incorporates the requirements of the 
proposed AD, and revises its maintenance program to include seal 
replacement and/or seal visual inspections, the commenter considers 
those actions to be sufficient to provide terminating action.
    The FAA does not concur. The FAA finds that previous requests for 
terminating action based on the installation of certain valves have 
been unsuccessful. Accomplishment of the requirements of this AD will 
ensure that an effective and uniform program to prevent incidents of 
``blue ice'' is in effect for the entire fleet. Therefore, no change to 
the final rule is necessary in that regard.

19. Request To Remove the Requirement to Replace ``Donut'' Valves

    One commenter, an airline operator, requests that the proposal be 
revised to remove the requirement ``to replace `donut' valves with 
another FAA-approved valves within 5,000 flight hours.'' The commenter 
points out that other AD's concerning ``blue ice'' have not required 
replacement of ``donut'' valves. Further, the commenter contends that 
the repetitive leak test intervals specified in the proposal will 
address the safety considerations. The commenter states that, based on 
financial considerations, the replacement of ``donut'' valves should be 
an option for operators.
    The FAA does not concur with the request to remove the requirement 
to replace ``donut valves.'' The FAA finds that several incidents of 
``blue ice'' were caused by ``donut'' valve leakage on airplanes, 
despite a required leak test at intervals of 200 hours. Additionally, 
the largest and most potentially dangerous pieces of ``blue ice'' have 
been associated with ``donut'' valves. Based on the continued problems 
associated with the use of ``donut'' valves, the FAA has determined 
that those valves must be replaced. No change to the final rule is 
necessary in that regard. Regarding current AD's addressing ``blue 
ice,'' continuing to require the leak test intervals for the ``donut'' 
valves may motivate operators to replace the ``donut'' valves. However, 
if the FAA finds that ``donut'' valves continue to be a source of 
``blue ice,'' additional rulemaking may be considered.

20. Request To Call Out Part Numbers by Name

    One commenter requests that lever/lock caps manufactured in 
accordance with an FAA-Parts Manufacturer Approval granted to Shaw Aero 
Devices be called out by part number the same way the Kaiser flush/fill 
ball valve part number is called out in the proposal. The commenter did 
not provide an explicit reason for this request.
    The FAA does not concur. Reference to lever lock caps as ``FAA-
approved lever lock caps'' rather than specific part numbers that are 
called out has been the standard practice in the development of the 
``blue ice'' AD's. Therefore, the Shaw Aero Devices lever lock cap, 
part number 580-116, is encompassed in the final rule as an ``FAA-
approved lever lock cap.'' However, the Kaiser flush/fill line ball is 
not a lever lock cap and would not be encompassed by the phrase ``FAA-
approved lever lock caps.'' Consequently, the Kaiser valve part number 
is specifically called out in the final rule. No change is necessary to 
the final rule in that regard.

21. Requests To Revise the Cost Impact Information

    One commenter, a parts manufacturer, requests that the cost impact 
information, below, be revised to reflect an optional use of a hand 
held vacuum pump as the most cost effective method to perform the leak 
tests. The commenter points out that a hand held vacuum pump takes less 
time and does not require fuel to power-up the airplane.
    The FAA does not concur with the commenter's request. The cost 
impact figures provided in an AD are intended to provide an approximate 
cost of performing required tasks. The FAA has no way of determining 
the specific cost figures of each possible method of accomplishing a 
required task. The cost estimates, as provided, are simply estimates 
based on the best information the FAA has available at the time the 
rule is developed. No change is necessary to the final rule in that 
regard.
    Another commenter states that the work hours necessary to install 
the flush/fill line cap is estimated in the proposal to be 1 work hour 
per cap. The commenter requests that the work hour estimate be revised 
to include heating the flush/fill line to prevent ice build-up within 
the line behind the cap. The commenter provided no work hour figures 
that would include heating of the flush/fill line.
    The FAA does not concur. Heating for the line behind the flush/fill 
cap may be considered a good practice and possibly the most practical 
solution where flush/fill lines take a long time to drain. The FAA 
typically provides cost estimates only for those actions that are 
required to be accomplished. In this case, heating of the line behind 
the flush/fill cap is not necessary when operators allow the flush/fill 
line to drain before closing the cap. The FAA considers it to be the 
operator's choice to allow the flush/fill line to drain after 
servicing, or to install heating for the flush/fill line. Therefore, no 
change is necessary to the final rule.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost 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 will be affected by 
this AD.
    The waste drain system leak test and outer cap inspection will 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 
will 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

[[Page 17519]]

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 will 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 will 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 installation of the flush/fill line cap will take approximately 
1 work hour per cap to accomplish, at an average labor rate of $60 per 
work hour. The cost of required parts will 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 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 will require approximately 2 work hours to accomplish, at an 
average labor cost of $60 per hour. The cost of required parts will be 
$200 per each seal change. Based on these figures, the cost impact on 
U.S. operators of these 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 of this AD will 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 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 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 adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:
    Compliance: Required as indicated, unless accomplished previously.

99-08-10 Boeing: Amendment 39-11116. 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 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)(11) 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: The toilet tank dump 
valve leak test must be performed by filling the toilet tank with 
water/rinsing fluid to fill the toilet tank to a level that 
submerges the toilet

[[Page 17520]]

tank dump valve seals with sufficient fluid to perform a valid test, 
and testing for leakage after a period of five minutes. For 
guidance, a minimum of 10 gallons is considered sufficient for a 
tank of 30 gallons or less capacity, and 20 gallons of fluid is 
considered sufficient for a tank with more than 30 gallons capacity. 
For tests of service panel drain valves, unless otherwise specified 
by 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 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. As an alternative to the 
above test procedure for the service panel drain valves and in-line 
drain valves, a vacuum test may be done in accordance with Shaw Aero 
Devices Document ILS-193, Operation Instructions for the Waste Drain 
Valve Inner Flapper and Lavatory Rinse/Fill Valve Leak Test Tool, 
dated November 17, 1998, using a minimum of 3 PSID across the in-
line drain valve or waste drains system service panel valve inner 
door for a period of 5 minutes. Any movement of the needle of the 
pressure gauge during the test period constitutes failure of the 
test. Other leak test tools may by used for this test if approved 
per paragraph (d) of this AD. 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. For purposes of determining 
seal replacement times specified in this AD: If a new valve is 
installed or a ``new airplane'' is delivered, it is considered that 
the new valve installation or airplane delivery constitutes the 
``last documented seal change.'' A ``new airplane'' for the purposes 
of this AD is an airplane that has accumulated less than 100 total 
flight hours or 30 calendar days, whichever occurs later, since the 
issuance of the original airworthiness certificate.
    (i) For each lavatory drain system that has an in-line drain 
valve installed, Kaiser Electroprecision part number series 2651-278 
or a Kaiser Electroprecision service panel ball valve, part number 
series 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 6,000 flight hours after the effective date of this AD, 
and thereafter at intervals not to exceed 6,000 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. 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 
4,000 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 4,000 
flight hours.
    (i) Conduct leak tests of the toilet tank dump valve and service 
panel drain valve. 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 
2651-357-(2) or higher -() (dash number): Within 2,000 flight hours 
after the effective date of this AD, and thereafter at intervals not 
to exceed 2,000 flight hours, conduct a leak test of the toilet tank 
dump valve and service panel drain valve. 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.
    (5) For each lavatory drain system that has a service panel 
drain valve installed, Kaiser Electroprecision part number series 
0218-0032 or Shaw Aero part number/serial number as listed in Table 
1 of this AD: Within 1,500 flight hours after the effective date of 
this AD, and thereafter at intervals not to exceed 1,500 flight 
hours, accomplish the requirements of paragraphs (a)(5)(i) and 
(a)(5)(ii) of this AD:

   Table 1.--Shaw Aero Valves Approved for 1,500 Flight Hour Leak Test
                                Interval
------------------------------------------------------------------------
                                          Serial numbers of part number
   Shaw waste drain valve part number     valve approved for 1,500 hour
                                                leak test interval
------------------------------------------------------------------------
331 Series, 332 Series.................  All.
10101000B-A-1..........................  0201 and higher.
10101000BA2............................  0130 and higher.
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 list of approved Shaw valves that are 
eligible for a 1,500 hour leak test, including those valves approved 
by Parts Manufacturer Approval (PMA) or Supplemental Type 
Certificate (STC) for installation on Boeing Model 747 series 
airplanes that are subject to this AD.
    (i) Conduct a leak test of the toilet tank dump valve and 
service panel drain valve. 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, perform a visual inspection of the outer 
cap/door and seal mating surface for any wear or damage that may 
cause leakage.

[[Page 17521]]

    (6) 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 800 flight hours after the effective date of this AD, and 
thereafter at intervals not to exceed 800 flight hours, accomplish 
the requirements of paragraphs (a)(6)(i) and (a)(6)(ii) of this AD:
    (i) Conduct a leak test of the toilet tank dump valve and the 
service panel drain valve. 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.
    (7) 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)(7)(i), (a)(7)(ii), and 
(a)(7)(iii) of this AD at the times specified in those paragraphs. 
For the purposes of this paragraph [(a)(7)], ``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 250 flight hours after the effective date of this AD, 
and thereafter at intervals not to exceed 250 flight hours, conduct 
leak tests of the toilet tank dump valve and the service panel drain 
valve. 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)(7)(i).
    (iii) Within 5,000 flight hours after the effective date of this 
AD, replace the donut valve [part numbers per paragraph (a)(7) 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.
    (8) For each lavatory drain system not addressed in paragraphs 
(a)(2), (a)(3), (a)(4), (a)(5), (a)(6), or (a)(7) of this AD: Within 
250 flight hours after the effective date of this AD, and thereafter 
at intervals not to exceed 250 flight hours, accomplish the 
requirements of paragraphs (a)(8)(i) and (a)(8)(ii) of this AD:
    (i) Conduct a leak test of the toilet tank dump valve and the 
service panel drain valve. 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.
    (9) For flush/fill lines: Within 5,000 flight hours after the 
effective date of this AD, perform the requirements of paragraph 
(a)(9)(i), (a)(9)(ii), (a)(9)(iii), or (a)(9)(iv) of this AD, as 
applicable. 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. For the purpose of determining 
seal replacement times required by this AD: If a new valve has been 
installed or a new airplane has been delivered, the new valve 
installation or airplane delivery may be considered to constitute 
the ``last documented seal change.'' For the purposes of this AD, a 
``new airplane'' is defined as an airplane that has accumulated less 
than 100 total flight hours or 30 calendar days, whichever occurs 
later, since the issuance of the original airworthiness certificate.
    (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 paragraph (a)(10)(i) or 
(a)(10(ii), or (a)(10)(iii) of this AD, as applicable.
    (ii) If a vacuum breaker check valve having Monogram part number 
series 4803-76 or 4803-96 is installed on the subject lavatory, 
prior to further flight, replace the seals/o-rings in the vacuum 
breaker check valve. Perform a leak test of the vacuum breaker check 
valve in accordance with paragraph (a)(10)(i) or (a)(10)(ii) of this 
AD, as applicable. Verify proper operation of the vent line vacuum 
breaker in accordance with paragraph (a)(10)(iii) of this AD.
    (iii) If a flush/fill ball valve having Kaiser Electroprecision 
part number series 0062-0010 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)(10)(i) or (a)(10)(ii) of 
this AD, as applicable.
    (iv) If a shut-off valve having Boeing Specification #SCD 
60B50341 is installed on the flush/fill line of the subject 
lavatory, replace the seals in the shut-off valve. Perform a leak 
test of the shut-off valve with a minimum of 3 PSID across the 
valve, in accordance with paragraph (a)(10)(ii) of this AD. At the 
time the test is performed, ground handling bus power must be 
removed from the shutoff valve and level sensor. This can be 
accomplished by de-energizing the ground handling bus completely 
(refer to Boeing Maintenance Manual 38-32-00/1 and 24-22-00/201 as 
an additional source of service information) or by removing ground 
handling bus supplied power to only the shutoff valve and waste 
level sensor. To remove ground handling bus supplied power to the 
shutoff valve and waste level sensor, open the ground service 
lavatory lights circuit breaker supplying 115V AC to the shutoff 
valve and the lavatory tank fill control circuit breaker supplying 
28 V DC to the level sensor. These circuit breakers are located on 
panel P14 of Model 747-100, -200, -300 and SP airplanes, and on 
panel P414 of Model 747-400F series airplanes.
    (10) Perform the tests specified in paragraph (a)(9) of this AD 
in accordance with the instructions of paragraph (a)(10)(i), 
(a)(10)(ii), or (a)(10)(iii) of this AD, as applicable.
    (i) Leak test the toilet tank anti-siphon valve or the vacuum 
breaker check valve by filling the bowl above the toilet tank 
approximately half-full with water/rinsing fluid (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 or opened during the test. Test for 
leakage at the flush/fill line port for a period of 5 minutes.

    Note 3: The leak test may be accomplished by pressurizing the 
airplane or by performing the leak test using Boeing vacuum test rig 
described in Boeing Maintenance Manual, 38-32-00/501, which is 
considered to be an additional source of service information for 
this test, if the toilet tank is filled to the level specified in 
paragraph (a)(10)(i) of this AD.

    (ii) As an alternative to the leak tests of the flush/fill line 
valve specified in paragraph (a)(10)(i) of this AD, a vacuum test 
may be done using a minimum of 3 PSID across the anti-siphon valve, 
vacuum breaker valve, or shut-off valve in the flush/fill line for a 
period of 5 minutes, in accordance with Shaw Aero Devices Document 
ILS-193 (Operation Instructions for the waste Drain Valve Inner 
Flapper and Lavatory Rinse/Fill Valve Leak Test Tool) dated November 
17, 1998. 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. Any movement of the needle of the 
pressure gauge during the test period constitutes failure of the 
test and shall be considered evidence of leakage. Other leak test 
tools may by used for this test if approved in accordance with 
paragraph (d) of this AD.
    (iii) Verify proper operation of the vent line vacuum breaker by 
filling the tank and testing at the fill line port for back drainage 
after disconnecting the fluid source from the flush/fill line port. 
As an alternative to the above test technique, verify proper 
operation of the vent line vacuum breaker in accordance with the 
procedures of the applicable component maintenance manual. If back 
drainage does not occur, prior to further flight, replace the vent 
line vacuum breaker or repair the vacuum breaker check valve in 
accordance with the appropriate component maintenance manual to 
obtain proper back drainage.

[[Page 17522]]

    (11) If evidence of leakage or valve damage that may cause 
leakage is found during the leak tests and inspections required by 
paragraph (a) of this AD or at any other time: Accomplish the 
requirements of paragraph (a)(11)(i), (a)(11)(ii), or (a)(11)(iii) 
of this AD, as applicable.
    (i) If any leakage is discovered, prior to further flight, 
perform the requirements of paragraphs (a)(11)(i)(A) and 
(a)(11)(i)(B) of this AD.
    (A) Repair the leakage in accordance with the applicable 
component repair or maintenance manual.
    (B) Perform the appropriate leak test, as specified in paragraph 
(a) of this AD; thoroughly clean the surfaces adjacent to any 
leakage to remove any horizontal fluid residue streaking. Cleaning 
must be to the extent that any future appearance of a horizontal 
fluid residue streak would indicate that the system is leaking.

    Note 4: For purposes of this AD, ``leakage'' is defined as any 
visible leakage, if observed during a leak test. At any time other 
than during a leak test, ``leakage'' is defined as the presence of 
ice in the service panel, horizontal fluid residue streaks, or 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 and that wear or damage could result in 
a leak, 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)(11)(i) or (a)(11)(ii) of this AD: Prior to further flight, drain 
the affected lavatory system and placard the lavatory inoperative 
until repairs are accomplished.
    (b) For all airplanes: Unless accomplished previously, within 
5,000 flight hours after the effective date of this AD, install one 
of the caps/valves specified in paragraph (b)(1), (b)(2), (b)(3), or 
(b)(4) of this AD on each flush/fill line of all lavatories.
    (1) Install an FAA-approved lever/lock cap on the flush/fill 
line. Or
    (2) Install a flush/fill ball valve Kaiser Electroprecision part 
number series 0062-0010 on the flush/fill line. Or
    (3) Install a vacuum breaker valve, Monogram part number series 
4803-76 or 4803-96 on the flush/fill line. Or
    (4) Install a shut-off valve, Boeing specification number 
60B50341, on the flush/fill line.
    (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 according to 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 Principal Maintenance 
Inspector (PMI), but within a period not to exceed 250 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, Seattle Aircraft Certification 
Office, 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.

    Note 5: 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.
    (f) Except as provided in paragraph (a) of this AD, the vacuum 
leak tests of the service panel drain valves and in-line drain 
valves, and vacuum leak tests of the service panel drain valves and 
flush/fill line valves, if accomplished, shall be done in accordance 
with Shaw Aero Devices, Doc. ILS-193, Operation Instructions for the 
Waste Drain Valve Inner Flapper and Lavatory Rinse/Fill Valve Leak 
Test Tool, dated November 1998. This incorporation by reference was 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Shaw 
Aero Devices, Inc., 12291 Towne Lake Drive, Ft. Myers, Florida 
33913. Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (g) This amendment becomes effective on May 17, 1999.

    Issued in Renton, Washington, on April 1, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-8686 Filed 4-9-99; 8:45 am]
BILLING CODE 4910-13-P