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

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