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]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP,

and -400F Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to all Boeing Model 747-100, -200, -

300, -SP, and -400F series airplanes. Among other things, this proposal

would require repetitive leak checks of the lavatory drain system and

repair, if necessary; installation of a cap or flush/fill line ball

valve on the flush/fill line; would require periodic seal changes; and

replacement of any ``donut'' type valves installed in the waste drain

system. This proposal is prompted by continuing reports of damage to

engines and airframes, separation of engines from airplanes, and damage

to property on the ground, caused by ``blue ice'' that forms from

leaking lavatory drain systems on transport category airplanes and

subsequently dislodges from the airplane fuselage. The actions

specified by this proposed AD are intended to prevent damage to

engines, airframes, and property on the ground that is associated with

the problems of ``blue ice'' that forms from leaking lavatory drain

systems on transport category airplanes and subsequently dislodges from

the airplane fuselage.

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

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 97-NM-325-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. Comments may be inspected at this

location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except

Federal holidays.

This information may be examined at the FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer,

Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft

Certification Office, 1601 Lind Avenue, SW., Renton, Washington;

telephone (425) 227-2788; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed rule by submitting such written data, views, or arguments as

they may desire. Communications shall identify the Rules Docket number

and be submitted in triplicate to the address specified above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed rule. All

comments submitted will be available, both before and after the closing

date for comments, in the Rules Docket for examination by interested

persons. A report summarizing each FAA-public contact concerned with

the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 97-NM-325-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules

Docket No. 97-NM-325-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

Over the past several years, the FAA has received numerous reports

of leakage from the lavatory service systems on in-service transport

category airplanes that resulted in the formation of ``blue ice'' on

the fuselage. In some instances, the ``blue ice'' subsequently

dislodged from the fuselage and was ingested into an engine. In several

of these incidents, the ingestion of blue ice into an engine resulted

in the loss of an engine fan blade, severe engine damage, and the

inflight shutdown of the engine. In two cases, the loads created by the

``blue ice'' being ingested into the engine resulted in the engine

being physically torn from the airplane. Damage to an engine, or the

separation of an engine from the airplane, could result in reduced

controllability of the airplane.

The FAA also has received reports of at least three incidents of

damage to the airframe of various models of transport category

airplanes that was caused by foreign objects dislodged from the forward

toilet drain valve and flush/fill line. One report was of a dent on the

right horizontal stabilizer leading edge on a Boeing Model 737 series

airplane that was caused by ``blue ice'' that had formed from leakage

through a flush/fill line; in this case, the flush/fill cap was missing

from the line at the forward service panel. Numerous operators have

stated that leakage from the flush/fill line is a significant source of

problems associated with ``blue ice.'' Such damage caused by ``blue

ice'' could adversely affect the integrity of the fuselage skin or

surface structures.

Additionally, there have been numerous reports of ``blue ice''

dislodging from airplanes and striking houses, cars, buildings, and

other occupied areas on the ground. Although there have been no reports

of any person being struck by ``blue ice,'' the FAA considers that the

large number of reported cases of ``blue ice'' falling from lavatory

drain systems is sufficient to support the conclusion that ``blue ice''

presents an unsafe condition to people on the ground. Demographic

studies have shown that population density has increased around

airports, and probably will continue to increase. These are populations

that are at greatest risk of

[[Page 32625]]

damage and injury due to ``blue ice'' dislodging from an airplane

during descent. Without actions to ensure that leaks from the lavatory

drain systems are detected and corrected in a timely manner, ``blue

ice'' incidents could go unchecked and eventually someone may be

struck, perhaps fatally, by falling ``blue ice.''

Current Rules

On November 9, 1994, the FAA issued AD 94-23-10, amendment 39-9073

(59 FR 59124, November 16, 1994), which is applicable to Boeing Model

727 series airplanes. That AD contains numerous requirements that are

similar to those proposed in this action, which is applicable to Model

747 series airplanes. In fact, several of the proposed requirements of

this action are based on alternative methods of compliance that the FAA

had approved previously for compliance with AD 94-23-10.

The FAA is currently considering additional rulemaking to address

the problems associated with ``blue ice'' on other transport category

airplanes.

Discussion of the Proposed Rule

Since an unsafe condition has been identified that is likely to

exist or develop on other products of this same type design, the FAA is

proposing this AD, which would require the following actions:

Paragraph (a) of the proposed AD would require periodic replacement

of the valve seals of each lavatory drain system with new valve seals.

This paragraph also would require repetitive leak tests of the lavatory

dump valve and drain valve (either service panel or in-line drain

valve). The leak test of panel valves would be required to be performed

with a minimum of 3 PSID applied across the valve. If any leak is

discovered during the leak tests, operators would be required either to

repair the leak and retest it, or drain the lavatory system and placard

it inoperative until repairs can be made.

In cases where the panel valve has both an inner seal and an outer

cap seal, in lieu of pressure testing of the outer cap seal, operators

are provided with the option of performing a visual inspection for

damage or wear of the outer cap seal and seal surface. Any damaged

parts detected would be required to be repaired or replaced prior to

further flight, or the lavatory drained and placarded inoperative until

repairs can be made.

Additionally, the flush/fill line anti-siphon valve would be

required to be leak checked. Seals of the anti-siphon (check) valve,

flush/fill line cap, or flush/fill line ball valve would be required to

be replaced periodically.

Paragraph (b) of the proposed AD would require that all operators

install a lever/lock cap on the flush/fill lines for all service

panels, or install a flush/fill ball valve Kaiser Electroprecision part

number series 0062-0009 on the flush/fill lines for all lavatories.

Paragraph (c) of the proposed AD would require that, before an

operator places an airplane into service, a schedule for accomplishment

of the leak tests required by this AD shall be established. This

provision is intended to ensure that transferred airplanes are

inspected in accordance with the AD on the same basis as if there were

continuity in ownership, and that scheduling of the leak tests for each

airplane is not delayed or postponed due to a transfer of ownership.

Airplanes that have previously been subject to the AD would have to be

checked in accordance with either the previous operator's or the new

operator's schedule, whichever would result in the earlier

accomplishment date for that leak test. Other airplanes would have to

be inspected before an operator could begin operating them or in

accordance with a schedule approved by the FAA Principal Maintenance

Inspector (PMI), but within a period not to exceed 200 flight hours.

Economic Impact

There are approximately 711 Model 747 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 201

airplanes of U.S. registry and 89 U.S. operators would be affected by

this proposed AD.

The proposed waste drain system leak test and outer cap inspection

would take approximately 6 work hours per airplane to accomplish, at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact on U.S. operators of the waste drain system leak test and

outer cap inspection is estimated to be $72,360, or $360 per airplane,

per test/inspection.

Certain airplanes (i.e., those that have ``donut'' type drain

valves installed) may be required to be leak tested as many as 15 times

each year. Certain other airplanes having other valve configurations

would be required to be leak tested as few as 1 time each year. Based

on these figures, the annual (recurring) cost impact of the required

repetitive leak tests on U.S. operators is estimated to be between $360

and $5,400 per airplane per year.

With regard to replacement of ``donut'' type drain valves, the cost

of a new valve is approximately $1,200. However, the number of leak

tests for an airplane that is flown an average of 3,000 flight hours a

year is thereby reduced from 15 tests to 3 tests. The cost reduction

because of the number of tests required is approximately equal to the

cost of the replacement valve. Therefore, no additional cost would be

incurred.

The FAA estimates that it would take approximately 1 work hour per

airplane lavatory drain to accomplish a visual inspection of the

service panel drain valve cap/door seal and seal mating surfaces, at an

average labor rate of $60 per work hour. As with leak tests, certain

airplanes would be required to be visually inspected as many as 15

times or as few as 3 times each year. Based on these figures, the

annual (recurring) cost impact of the required repetitive visual

inspections on U.S. operators is estimated to be between $180 and $900

per airplane per year.

The proposed installation of the flush/fill line cap would take

approximately 1 work hour per cap to accomplish, at an average labor

rate of $60 per work hour. The cost of required parts would be $275 per

cap. There are an average of 4 caps per airplane. Based on these

figures, the cost impact on U.S. operators of these proposed

requirements of this AD is estimated to be $269,340, or $1,340 per

airplane, per replacement cycle.

The seal replacements of the drain valves required by paragraph (a)

of this AD would require approximately 2 work hours to accomplish, at

an average labor cost of $60 per hour. The cost of required parts would

be $200 per each seal change. Based on these figures, the cost impact

on U.S. operators of these proposed requirements of this AD is

estimated to be $64,320, or approximately $320 per airplane per

replacement.

The number of required work hours, as indicated above, is presented

as if the accomplishment of the actions proposed in this AD were to be

conducted as ``stand alone'' actions. However, in actual practice,

these actions could be accomplished coincidentally or in combination

with normally scheduled airplane inspections and other maintenance

program tasks. Therefore, the actual number of necessary ``additional''

work hours would be minimal in many instances. Additionally, any costs

associated with special airplane scheduling should be minimal.

The cost impact figures discussed above are based on assumptions

that no operator has yet accomplished any of the current or proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

[[Page 32626]]

The FAA recognizes that the obligation to maintain aircraft in an

airworthy condition is vital, but sometimes expensive. Because AD's

require specific actions to address specific unsafe conditions, they

appear to impose costs that would not otherwise be borne by operators.

However, because of the general obligation of operators to maintain

aircraft in an airworthy condition, this appearance is deceptive.

Attributing those costs solely to the issuance of this AD is

unrealistic because, in the interest of maintaining safe aircraft,

prudent operators would accomplish the required actions even if they

were not required to do so by the AD.

A full cost-benefit analysis has not been accomplished for this

proposed AD. As a matter of law, in order to be airworthy, an aircraft

must conform to its type design and be in a condition for safe

operation. The type design is approved only after the FAA makes a

determination that it complies with all applicable airworthiness

requirements. In adopting and maintaining those requirements, the FAA

has already made the determination that they establish a level of

safety that is cost-beneficial. When the FAA, as in this proposed AD,

makes a finding of an unsafe condition, this means that the original

cost-beneficial level of safety is no longer being achieved and that

the required actions are necessary to restore that level of safety.

Because this level of safety has already been determined to be cost-

beneficial, a full cost-benefit analysis for this proposed AD would be

redundant and unnecessary.

Regulatory Impact

The regulations proposed herein would not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this proposed

regulation (1) is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the DOT

Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);

and (3) if promulgated, will not have a significant economic impact,

positive or negative, on a substantial number of small entities under

the criteria of the Regulatory Flexibility Act. A copy of the draft

regulatory evaluation prepared for this action is contained in the

Rules Docket. A copy of it may be obtained by contacting the Rules

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend

part 39 of the Federal Aviation Regulations (14 CFR part 39) as

follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Boeing: Docket 97-NM-325-AD.

Applicability: All Model 747-100, -200, -300, -SP, and -400F

series airplanes, certificated in any category.

Note 1: This AD applies to each airplane identified in the

preceding applicability provision, regardless of whether it has been

modified, altered, or repaired in the area subject to the

requirements of this AD. For airplanes that have been modified,

altered, or repaired so that the performance of the requirements of

this AD is affected, the owner/operator must request approval for an

alternative method of compliance in accordance with paragraph (d) of

this AD. The request should include an assessment of the effect of

the modification, alteration, or repair on the unsafe condition

addressed by this AD; and, if the unsafe condition has not been

eliminated, the request should include specific proposed actions to

address it.

Compliance: Required as indicated, unless accomplished

previously.

To prevent engine damage, airframe damage, and/or hazard to

persons or property on the ground as a result of ``blue ice'' that

has formed from leakage of the lavatory drain system or flush/fill

systems and dislodged from the airplane, accomplish the following:

(a) Accomplish the applicable requirements of paragraphs (a)(1)

through (a)(9) of this AD at the time specified in each paragraph.

If the waste drain system incorporates more than one type of valve,

only one of the waste drain system leak test procedures (the one

that applies to the equipment with the longest leak test interval)

must be conducted at each service panel location. The waste drain

system valve leak tests specified in this AD shall be performed in

accordance with the following requirements: Fluid shall completely

cover the upstream end of the valve being tested; the direction of

the 3 pounds per square inch differential pressure (PSID) shall be

applied across the valve in the same direction as occurs in flight;

the other waste drain system valves shall be open; and the minimum

time to maintain the differential pressure shall be 5 minutes. Any

revision of the seal change intervals or leak test intervals must be

approved by the Manager, Seattle Aircraft Certification Office

(ACO), FAA, Transport Airplane Directorate.

(1) Replace the valve seals with new valve seals in accordance

with the applicable schedule specified in paragraphs (a)(1)(i),

(a)(1)(ii), and (a)(1)(iii) of this AD.

(i) For each lavatory drain system that has an in-line drain

valve installed, Kaiser Electroprecision part number series 2651-278

or 2651-357: Replace the seals within 5,000 flight hours after the

effective date of this AD, or within 48 months after the last

documented seal change, whichever occurs later. Thereafter, repeat

the replacement of the seals at intervals not to exceed 48 months.

(ii) For each lavatory drain system that has a Pneudraulics part

number series 9527 valve: Replace the seals within 5,000 flight

hours after the effective date of this AD, or within 18 months of

the last documented seal change, whichever occurs later. Thereafter,

repeat the replacement of the seals at intervals not to exceed 18

months or 6,000 flight hours, whichever occurs later.

(iii) For each lavatory drain system that has any other type of

drain valve: Replace the seals within 5,000 flight hours after the

effective date of this AD, or within 18 months after the last

documented seal change, whichever occurs later. Thereafter, repeat

the replacement of the seals at intervals not to exceed 18 months.

(2) For each lavatory drain system that has an in-line drain

valve installed, Kaiser Electroprecision part number series 2651-

278: Within 4,500 flight hours after the effective date of this AD,

and thereafter at intervals not to exceed 4,500 flight hours,

accomplish the procedures specified in paragraphs (a)(2)(i) and

(a)(2)(ii) of this AD:

(i) Conduct a leak test of the toilet tank dump valve (in-tank

valve that is spring loaded closed and operable by a T-handle at the

service panel) and the in-line drain valve. The toilet tank dump

valve leak test must be performed by filling the toilet tank with a

minimum of 10 gallons of water/rinsing fluid and testing for leakage

after a period of 5 minutes. Take precautions to avoid overfilling

the tank and spilling fluid into the airplane. The in-line drain

valve leak test must be performed with a minimum of 3 PSID applied

across the valve.

(ii) If a service panel valve or cap is installed, perform a

visual inspection of the service panel drain valve outer cap/door

seal and the inner seal (if the valve has an inner door with a

second positive seal), and the seal mating surfaces for wear or

damage that may allow leakage.

(3) For each lavatory drain system that has a service panel

drain valve installed, Pneudraulics part number series 9527: Within

2,000 flight hours after the effective date of this AD, accomplish

the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD.

Thereafter, repeat the leak tests at intervals not to exceed 2,000

flight hours.

[[Page 32627]]

(i) Conduct leak tests of the toilet tank dump valve and service

panel drain valve. The toilet tank dump valve leak test must be

performed by filling the toilet tank with a minimum of 10 gallons of

water/rinsing fluid and testing for leakage after a period of 5

minutes. Take precautions to avoid overfilling the tank and spilling

fluid into the airplane. The leak test of the service panel drain

valve must be performed with a minimum of 3 PSID applied across the

valve inner door/closure device.

(ii) Perform a visual inspection of the outer cap/door and seal

mating surface for wear or damage that may cause leakage.

(4) For each lavatory drain system that has a service panel

drain valve installed, Kaiser Electroprecision part number series

0218-0032 or 2651-357 or Shaw Aero part number/serial number as

listed in Table 1 of this AD: Within 1,000 flight hours after the

effective date of this AD, and thereafter at intervals not to exceed

1,000 flight hours, accomplish the requirements of paragraphs

(a)(4)(i) and (a)(4)(ii) of this AD:

Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Test

Interval

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

Serial numbers of part

number valve approved

Shaw waste drain valve part number for 1,000-hour leak

test interval

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

331 Series, 332 Series.......................... All.

10101000B-A..................................... None.

10101000B-A-1................................... 0207-0212, 0219, 0226

and higher.

10101000BA2..................................... 0130 and higher.

10101000C-A..................................... None.

10101000C-A-1................................... 0277 and higher.

10101000CN OR C-N............................... 3649 and higher.

Certain 10101000B valves........................ Any of these ``B''

series valves that

incorporate the

improvements of Shaw

Service Bulletin

10101000B-38-1, dated

October 7, 1994, and

are marked ``SBB38-1-

58.''

Certain 10101000C valves........................ Any of these ``C''

series valves that

incorporate the

improvements of Shaw

Service Bulletin

10101000C-38-2 dated

October 7, 1994, and

are marked ``SBC38-2-

58.''

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

Note 2: Table 1 is a comprehensive list of all approved Shaw

valves, including those valves approved by Parts Manufacturer

Approval (PMA) or Supplemental Type Certificate (STC) for

installation on Boeing Model 747 series airplanes.

(i) Conduct a leak test of the toilet tank dump valve and

service panel drain valve. The toilet tank dump valve leak test must

be performed by filling the toilet tank with a minimum of 10 gallons

of water/rinsing fluid and testing for leakage after a period of 5

minutes. Take precautions to avoid overfilling the tank and spilling

fluid into the airplane. The service panel drain valve leak test

must be performed with a minimum of 3 PSID applied across the valve

inner door/closure device.

(ii) For each valve, except for Kaiser Electroprecision valve

part number series 2651-357, perform a visual inspection of the

outer cap/door and seal mating surface for wear or damage that may

cause leakage.

(5) For each lavatory drain system that has a service panel

drain valve installed, Kaiser Electroprecision part number series

0218-0026; or Shaw Aero Devices part number series 10101000B or

10101000C [except as specified in paragraph (a)(4) of this AD]:

Within 600 flight hours after the effective date of this AD, and

thereafter at intervals not to exceed 600 flight hours, accomplish

the requirements of paragraphs (a)(5)(i) and (a)(5)(ii) of this AD:

(i) Conduct a leak test of the dump valve and the service panel

drain valve. The leak test of the dump valve must be performed by

filling the toilet tank with a minimum of 10 gallons of water/

rinsing fluid and testing for leakage after a period of 5 minutes.

Take precautions to avoid overfilling the tank and spilling fluid on

the airplane. The service panel drain valve leak test must be

performed with a minimum 3 PSID applied across the valve inner door/

closure device.

(ii) Perform a visual inspection of the outer cap/door and seal

mating surface for wear or damage that may cause leakage.

(6) For each lavatory drain system with a lavatory drain system

valve that incorporates either ``donut'' plug, Kaiser

Electroprecision part number 4259-20 or 4259-31; Kaiser Roylyn/

Kaiser Electroprecision cap/flange part numbers 2651-194C, 2651-

197C, 2651-216, 2651-219, 2651-235, 2651-256, 2651-258, 2651-259,

2651-260, 2651-275, 2651-282, 2651-286; Shaw Aero Devices assembly

part number 0008-100; or other FAA-approved equivalent parts;

accomplish the requirements of paragraphs (a)(6)(i), (a)(6)(ii), and

(a)(6)(iii) of this AD at the times specified in those paragraphs.

For the purposes of this paragraph [(a)(6)], ``FAA-approved

equivalent part'' means either a ``donut'' plug which mates with the

cap/flange part numbers listed above, or a cap/flange which mates

with the ``donut'' plug part numbers listed above, such that the

cap/flange and ``donut'' plug are used together as an assembled

valve.

(i) Within 200 flight hours after the effective date of this AD,

and thereafter at intervals not to exceed 200 flight hours, conduct

leak tests of the toilet tank dump valve and the service panel drain

valve. The leak test of the toilet tank dump valve must be performed

by filling the toilet tank with a minimum of 10 gallons of water/

rinsing fluid and testing for leakage after a period of 5 minutes.

Take precautions to avoid overfilling the tank and spilling fluid on

the airplane. The service panel drain valve leak test must be

performed with a minimum 3 PSID applied across the valve.

(ii) Perform a visual inspection of the outer door/cap and seal

mating surface for wear or damage that may cause leakage. This

inspection shall be accomplished in conjunction with the leak tests

of paragraph (a)(6)(i).

(iii) Within 5,000 flight hours after the effective date of this

AD, replace the donut valve [part numbers per paragraph (a)(6) of

this AD] with another type of FAA-approved valve. Following

installation of the replacement valve, perform the appropriate leak

tests and seal replacements at the intervals specified for that

replacement valve, as applicable.

(7) For each lavatory drain system not addressed in paragraphs

(a)(2), (a)(3), (a)(4), (a)(5), and (a)(6) of this AD: Within 200

flight hours after the effective date of this AD, and thereafter at

intervals not to exceed 200 flight hours, accomplish the

requirements of paragraphs (a)(7)(i) and (a)(7)(ii) of this AD:

(i) Conduct a leak test of the toilet tank dump valve and the

service panel drain valve. The toilet tank dump valve leak test must

be performed by filling the toilet tank with a minimum of 10 gallons

of water/rinsing fluid and testing for leakage after a period of 5

minutes. Take precautions to avoid overfilling the tank and spilling

fluid on the airplane. The service panel drain valve leak test must

be performed with a minimum 3 PSID applied across the valve inner

door/closure device.

(ii) Perform a visual inspection of the outer cap/door and seal

mating surface for wear or damage that may cause leakage.

(8) For flush/fill lines: Within 5,000 flight hours after the

effective date of this AD, accomplish the requirements of paragraph

(a)(8)(i) or (a)(8)(ii), as applicable; and paragraph (a)(8)(iii) of

this AD. Thereafter, repeat the requirements at intervals not to

exceed 5,000 flight hours, or 48 months after the last documented

seal change, whichever occurs later.

(i) If a lever lock cap is installed on the flush/fill line of

the subject lavatory, replace the seals on the toilet tank anti-

siphon (check) valve and the flush/fill line cap.

(ii) If a flush/fill ball valve, Kaiser Electroprecision part

number series 0062-0009, is installed on the flush/fill line of the

subject lavatory, replace the seals in the flush/fill ball valve and

the toilet tank anti-siphon valve.

(iii) Leak test the toilet tank anti-siphon valve by filling the

toilet tank with water/rinsing fluid to a level such that the bowl

is approximately half full (at least 2 inches above the flapper in

the bowl.) Apply 3 PSID across the valve in the same direction as

[[Page 32628]]

occurs in flight. If there is a cap/valve at the flush/fill line

port, the cap/valve must be removed/open during the test. Check for

leakage at the flush/fill line port for a period of 5 minutes.

(9) As a result of the leak tests and inspections required by

paragraph (a) of this AD, or if evidence of leakage is found at any

other time, accomplish the requirements of paragraph (a)(9)(i),

(a)(9)(ii), or (a)(9)(iii), as applicable.

(i) If a leak is discovered, prior to further flight, repair the

leak. Prior to further flight after repair, perform the appropriate

leak test, as applicable. Additionally, prior to returning the

airplane to service, clean the surfaces adjacent to where the

leakage occurred to clear them of any horizontal fluid residue

streaks; such cleaning must be to the extent that any future

appearance of a horizontal fluid residue streak will be taken to

mean that the system is leaking again.

Note 3: For purposes of this AD, ``leakage'' is defined as any

visible leakage, if observed during a leak test. At any other time

(than during a leak test), ``leakage'' is defined as the presence of

ice in the service panel, or horizontal fluid residue streaks/ice

trails originating at the service panel. The fluid residue is

usually, but not necessarily, blue in color.

(ii) If any worn or damaged seal is found, or if any damaged

seal mating surface is found, prior to further flight, repair or

replace it in accordance with the valve manufacturer's maintenance

manual.

(iii) In lieu of performing the requirements of paragraph

(a)(9)(i) or (a)(9)(ii): Prior to further fight, drain the affected

lavatory system and placard the lavatory inoperative until repairs

can be accomplished.

(b) For all airplanes: Unless accomplished previously, within

5,000 flight hours after the effective date of this AD, perform the

actions specified in paragraph (b)(1) or (b)(2) of this AD:

(1) Install an FAA-approved lever/lock cap on the flush/fill

lines for all lavatories. Or

(2) Install a flush/fill ball valve Kaiser Electroprecision part

number series 0062-0009 on the flush/fill lines for all lavatories.

(c) For any affected airplane acquired after the effective date

of this AD: Before any operator places into service any airplane

subject to the requirements of this AD, a schedule for the

accomplishment of the leak tests required by this AD shall be

established in accordance with either paragraph (c)(1) or (c)(2) of

this AD, as applicable. After each leak test has been performed

once, each subsequent leak test must be performed in accordance with

the new operator's schedule, in accordance with paragraph (a) of

this AD.

(1) For airplanes that have been maintained previously in

accordance with this AD, the first leak test to be performed by the

new operator must be accomplished in accordance with the previous

operator's schedule or with the new operator's schedule, whichever

results in the earlier accomplishment date for that leak test.

(2) For airplanes that have not been maintained previously in

accordance with this AD, the first leak test to be performed by the

new operator must be accomplished prior to further flight, or in

accordance with a schedule approved by the FAA Prinicipal

Maintenance Inspector (PMI), but within a period not to exceed 200

flight hours.

(d) Alternative method(s) of compliance with this AD: An

alternative method of compliance or adjustment of the compliance

time that provides an acceptable level of safety may be used if

approved by the Manager, Seattle ACO. Operators shall submit their

requests through an appropriate FAA PMI, who may add comments and

then send it to the Manager, Seattle ACO.

Note 4: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(e) Special flight permits may be issued in accordance with

sections 21.197 and 21.199 of the Federal Aviation Regulations (14

CFR 21.197 and 21.199) to operate the airplane to a location where

the requirements of this AD can be accomplished.

Issued in Renton, Washington, on June 8, 1998.

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 98-15783 Filed 6-12-98; 8:45 am]

BILLING CODE 4910-13-U