Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-NM-111-AD]

Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,

and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Boeing Model 737-

300 and -400 series airplanes, that currently requires either

repetitive leak checks on the forward lavatory service system and

repair as necessary, or draining of the system and placarding the

lavatory inoperative. This action would expand the applicability of the

rule to include all Model 737 series airplanes. It would also add a

requirement to perform leak checks of other lavatory drain systems;

provide for the option of revising the FAA-approved maintenance program

to include a schedule of leak checks; require the installation of a cap

or vacuum break on the flush/fill line; and require either a periodic

replacement of the seal for the cap and tank anti-siphon valve or

periodic maintenance of the

[[Page 55674]]

vacuum break in the flush/fill line. 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 such damage associated with the problems of ``blue

ice.''

DATES: Comments must be received by January 30, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 95-NM-111-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.

The service information referenced in the proposed rule may be

obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

Washington 98124-2207. 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 (206) 227-2778; fax (206) 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 95-NM-111-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-103, Attention: Rules

Docket No. 95-NM-111-AD, 1601 Lind Avenue SW., Renton, Washington

98055-4056.

Discussion of the Existing AD

On May 9, 1989, the FAA issued AD 89-11-03, amendment 39-6223 (54

FR 21933, May 22, 1989), applicable to certain Boeing Model 737-300 and

-400 airplanes, to require repetitive leak checks of the forward

lavatory service system at intervals of 200 hours time-in-service, and

repair, if necessary. That AD also provides operators with an optional

action in lieu of performing these periodic checks, which entails

draining the system, locking the lavatory, and placarding the lavatory

inoperative. That action was prompted by several reports of leakage

from the forward lavatory service system 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 one

incident, ``blue ice'' was ingested into the right engine and resulted

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

flight shutdown of the engine. The requirements of that AD are intended

to prevent such ingestion of ``blue ice'' into the engine, which could

consequently result in damage to the engine and potential separation of

the engine from the airplane.

New Incidents Prompting This Proposed Action

Since the issuance of that AD, the FAA has continued to receive

reports of engine damage on transport category airplanes caused by

``blue ice'' that has formed from leaking lavatory waste systems or

flush/fill lines and is ingested in to the engine(s) of the airplane.

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

damage caused by foreign objects from the forward toilet drain valve

and flush/fill line on certain airplanes. One report was of a dent on

the right horizontal stabilizer leading edge on a 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 of Model

737 series airplanes have stated that leakage from the flush/fill line

is a significant source of the type of ``blue ice'' problems addressed

by the current AD action.

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 system 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 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.''

In light of these continuing incidents and the data received

concerning them, the FAA has determined that the inspections currently

required by AD 89-11-03 are not adequate to positively address the

unsafe condition(s) associated with ``blue ice.'' -

Additionally, since the lavatory systems on Model 737-100, -200,

and -500 series airplanes are similar to those installed on Model 737-

300 and -400 series airplanes (the models currently subject to AD 89-

11-03), the FAA has determined that the potential unsafe condition

exists with regard to all of these models.

Description 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

proposes to issue a new AD to supersede AD 89-11-03. -

Paragraph (a) of the proposed AD would require various repetitive

leak checks of the dump valve and drain valve (either service panel or

in-line drain valve). The intervals for performing these leak checks

would vary from the currently required 200 flight hours to 4,500 flight

hours,

[[Page 55675]]

depending upon the type of valve installed at each location. If any

leak is discovered during a leak check, operators would be required

either to repair the leak, or drain the lavatory system and placard the

lavatory inoperative. -

Proposed paragraph (a) also would require replacement of certain

seals on the toilet tank anti-siphon (check) valve and flush/fill line

cap; and replacement or cleaning of the vacuum break vent line. -

Paragraph (b) of this proposed AD would provide an optional

procedure for complying with the rule, which would entail revising the

FAA-approved maintenance program to incorporate a schedule and

procedure to conduct leak checks of the lavatory drain systems.

However, operators electing to comply with this option would be

required to accomplish the actions required by paragraph (a) of the

proposal until their maintenance program is revised. -

Additionally, operators electing to comply with this option would

be required to obtain approval from the Manager of the FAA's Seattle

Aircraft Certification Office (ACO) for any revision to the leak check

intervals. Requests for such revisions must be accompanied by certain

data when submitted to the ACO [through the appropriate FAA Principal

Maintenance Inspector (PMI)] for approval. In paragraph (c) of the

proposed rule, the FAA proposes a ``data collection format'' for these

requests. Data submitted in accordance with the proposed format, if

favorable to an increase in the leak check interval, will allow the FAA

to justify increasing the leak check interval with assurance that the

valves involved have the required reliability. The data provided also

will be important in assisting the FAA in making future determinations

of appropriate leak check intervals for new valves that have shown

promising, but not conclusive, service data. -

This proposal also includes a process for terminating the leak

checks of waste drain systems for those operators who have installed

in-line drain (ball) valves and elect to comply with the proposed AD

via the ``maintenance program option.'' The FAA has determined that

these types of valves are currently the best solution to the addressed

problems, and provide very reliable operation. In combination with a

normal maintenance program, these valves provide a system that is

superior in reliability to the combination of less reliable valves and

the proposed leak checks. Further, the FAA has been advised that

additional versions of the in-line drain valve may become available for

aft lavatory and flush/fill line applications. This could make it

possible to install in-line drain type valves in all drain systems and

flush/fill line locations. Assuming the new versions are designed,

certified, and found acceptable, based upon the guidelines of NOTE 9 of

the proposed AD, it eventually could be possible to obtain terminating

action for all systems addressed by the AD. -

Paragraph (d) of the proposed AD would require that a lever/lock

cap or a vacuum break be installed for the forward, aft, and executive

lavatories. -

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

operator places an airplane subject to the AD into service, the

operator must establish a schedule for accomplishment of the leak

checks. 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 checks

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 check. Other airplanes would have to

be inspected before an operator could begin operating them or in

accordance with a schedule approved by the FAA PMI, but within a period

not exceeding 200 flight hours.

Related AD's -

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 applicable to Model 737 series

airplanes. In fact, several of the proposed requirements of this action

are based on alternative methods of compliance that the FAA had

previously approved 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.

Economic Impact -

There are approximately 2,410 Model 737 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 1,031

airplanes of U.S. registry and 110 U.S. operators would be affected by

this proposed AD. -

The proposed waste drain system leak check 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

total cost impact on U.S. operators of these proposed requirements of

this AD is estimated to be $371,160, or $360 per airplane, per check/

inspection. -

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

valve installed) may be required to be leak checked as many as 15 times

each year. Certain other airplanes having other valve configurations

would be required to be leak checked as few as 3 times each year. Some

airplanes that have various combinations drain valves installed would

require approximately 2 leak checks of one drain valve and 3 leak

checks of the other drain valve each year. Based on these figures, the

total annual (recurring) cost impact of the required repetitive leak

checks on U.S. operators is estimated to be between $1,080 and $5,400

per airplane per year. -

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 cost of $60 per work hour. As with leak checks, 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 total

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 hour per cap to accomplish, at an average labor rate of

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

There are an average of 2.5 caps per airplane. Based on these figures,

the total cost impact on U.S. operators of these proposed requirements

of this AD is estimated to be $863,463, or $838 per airplane. -

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. -

In addition to the costs discussed above, for those operators who

elect to

[[Page 55676]]

comply with proposed paragraph (b) of this proposed AD action, the FAA

estimates that it would take approximately 40 work hours per operator

to incorporate the lavatory drain system leak check procedures into the

maintenance programs, at an average labor cost of $60 per work hour.

Based on these figures, the total cost impact of the proposed

maintenance revision requirement of this AD action on the 110 U.S.

operators is estimated to be $264,000, or $2,400 per operator.

The total 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 AD.

As a matter of law, in order to be airworthy, an aircraft must conform

to its type design and be in a condition for safe operation. The type

design is approved only after the FAA makes a determination that it

complies with all applicable airworthiness requirements. In adopting

and maintaining those requirements, the FAA has already made the

determination that they establish a level of safety that is cost-

beneficial. When the FAA, as in this AD, makes a finding of an unsafe

condition, this means that the original cost-beneficial level of safety

is no longer being achieved and that the required actions are necessary

to restore that level of safety. Because this level of safety has

already been determined to be cost-beneficial, a full cost-benefit

analysis for this AD would be redundant and unnecessary.

Regulatory Impact

The regulations proposed herein would not have substantial direct

effects on the States, on the relationship between the national

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

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this proposed

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

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

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

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

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

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

regulatory evaluation prepared for this action is contained in the

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

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend

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

follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

Authority: 49 USC 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-6223 (54 FR

21933, May 22, 1989), and by adding a new airworthiness directive (AD),

to read as follows:

Boeing. Docket 95-NM-111-AD. Supersedes AD 89-11-03, Amendment 39-

6223.

Applicability: Boeing Model 737 series 100, 200, 300, 400 and

500 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 use the authority

provided in paragraph (f) of this AD to request approval from the

FAA. This approval may address either no action, if the current

configuration eliminates the unsafe condition; or different actions

necessary to address the unsafe condition described in this AD. Such

a request should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless previously

accomplished.

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

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

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

systems and dislodged from the airplane, accomplish the following:

(a) Except as provided by paragraph (b) of this AD, accomplish

the applicable requirements of paragraphs (a)(1) through (a)(7) 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 check procedures (the one that applies to

the equipment with the longest leak check interval) must be

conducted at each service panel location. The leak check of the in-

line drain valve or service panel drain valve must be performed

while the airplane is pressurized, unless another leak check method

is approved under the provisions of paragraph (f) of this AD.

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

valve installed, Kaiser Electroprecision part number series 2651-

329, 2651-334, or 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)(1)(i) and (a)(1)(ii) of this AD:

(i) Conduct a leak check of the 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 dump valve leak check must

be performed 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) and checking for leakage after

a period of 5 minutes. The in-line drain valve leak check must be

performed with a minimum of 3 pounds per square inch differential

pressure (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.

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

drain valve installed, Kaiser Electroprecision part number series

0218-0032; or Pneudraulics part number series 9527; 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)(2)(i) and (a)(2)(ii) of this AD:

[[Page 55677]]

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

Interval

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Serial numbers of part

number valve approved for

Shaw Waste Drain Valve Part No. 1,000-hour leak check

interval

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

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

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

higher.

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

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

10101000BB2-.............................. 0011 and higher.

10101000B-C-.............................. None.

10101000B-K-.............................. 0007 and higher.

10101000BJ-............................... 0023 and higher.

10101B-577-............................... 0254 and higher.

10101B-577-1.............................. None.

10101B587-................................ 0009 and higher.

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

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

10101000CB-............................... 0061 and higher.

10101000C-G-.............................. None.

10101000C-J-.............................. None.

10101000C-J-2............................. None.

10101000CJ3-.............................. 0014 and higher.

10101000CK-............................... 0317 and higher.

10101000C-M-.............................. 0044 and higher.

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

10101000C-R-.............................. 0191 and higher.

10101C739-................................ 0022 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 for installation on

airplanes other than the airplanes subject to this AD. (Therefore,

being listed in this table does not necessarily mean that a

particular valve is FAA-approved for installation on the Model 737

airplanes subject to this AD.)

(i) Conduct a leak check of the dump valve and drain valve. The

dump valve leak check must be performed 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) and checking for leakage after a period of 5 minutes. The

service panel drain valve leak check 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.

(3) 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)(2) 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)(3)(i) and (a)(3)(ii) of this AD:

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

drain valve. The dump valve leak check must be performed 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) and checking for leakage after a period of 5 minutes.

The service panel drain valve leak check 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.

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

valve that incorporates either ``donut'' assemblies (or substitute

assemblies from another manufacturer) Kaiser Electroprecision part

number 4259-20 or 4259-31, or incorporates Kaiser Roylyn part number

2651-194C, 2651-197C, 2651-216, 2651-219, 2651-235, 2651-256, 2651-

258, 2651-259, 2651-260, 2651-275, 2651-282, 2651-286: Within 200

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

intervals not to exceed 200 flight hours, conduct leak checks of the

dump valve and the service panel drain valve. The dump valve leak

check must be performed 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) and checking

for leakage after a period of 5 minutes. The service panel drain

valve leak check must be performed with a minimum 3 PSID applied

across the valve. Both the donut and the outer cap/door must be leak

checked.

(5) For each lavatory drain system not addressed in paragraph

(a)(1), (a)(2), (a)(3) or (a)(4) 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)(5)(i) and (a)(5)(ii) of this AD:

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

drain valve. The dump valve leak check must be performed 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) and checking for leakage after a period of 5 minutes.

The service panel drain valve leak check 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 flush/fill lines: Within 5,000 flight hours after the

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

5,000 flight hours, perform the requirements of either paragraph

(a)(6)(i) or (a)(6)(ii), as applicable.

(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. Prior to further

flight after replacement, perform a leak check of the toilet tank

anti-siphon (check) valve with a minimum of 3 PSID across the valve.

Note 3: The leak test procedure described in Boeing Service

Letter 737-SL-38-3-A dated March 19, 1990, may be referred to as

guidance for this test.

(ii) If a vacuum break, Monogram part number 3765-175 series or

3765-190 series, is installed on the subject lavatory, replace or

clean the vent line in accordance with the manufacturer's

maintenance manual.

(7) As a result of the leak checks and inspections required by

this paragraph, or if evidence of leakage is found at any other

time, accomplish the requirements of paragraph (a)(7)(i),

(a)(7)(ii), or (a)(7)(iii), as applicable.

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

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

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 4: 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)(7)(i) or (a)(7)(ii): Prior to further fight, drain the affected

lavatory system and placard the lavatory inoperative until repairs

can be accomplished.

(b) As an alternative to the requirements of paragraph (a) of

this AD, operators may revise the FAA-approved maintenance program

to include the requirements specified in paragraphs (b)(1) through

(b)(7) of this AD. However, until the FAA-approved maintenance

program is so revised, operators must accomplish the leak test

requirements of paragraph (a) of this AD. Incorporation of the

requirements specified in paragraphs (b)(1)(i), (b)(2)(i), (b)(4),

(b)(5), (b)(6) and (b)(7) of this AD into the operator's FAA-

approved maintenance program constitutes terminating action for

waste drain systems that incorporate the ball valves specified in

paragraph (b)(1)(i) of this AD. However, the requirements of this AD

that affect flush/fill lines and waste drain systems with valves

different from those listed in paragraph (b)(1)(i) remain in effect.

[[Page 55678]]

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

schedule specified in paragraphs (b)(1)(i) and (b)(1)(ii) of this

AD.

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

valve installed, Kaiser Electroprecision part number series 2651-

329, 2651-334, or 2651-278: Replace the seals within 5,000 flight

hours after revision of the maintenance program in accordance with

paragraph (b) of this AD, and thereafter at intervals not to exceed

48 months.

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

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

revision of the maintenance program in accordance with paragraph (b)

of this AD, and thereafter at intervals not to exceed 18 months. Any

revision to this replacement schedule must be approved by the

Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport

Airplane Directorate.

(2) Conduct periodic leak checks of the lavatory drain systems

in accordance with the applicable schedule specified in paragraphs

(b)(2)(i), (b)(2)(ii), (b)(2)(iii), and (b)(2)(iv) of this AD. Only

one of the waste drain system leak check procedures (the one that

applies to the equipment with the longest leak check interval) must

be conducted at each service panel location. The leak check of the

in-line drain valve or service panel drain valve shall be performed

while the airplane is pressurized, unless another leak check method

is approved under the provisions of paragraph (g) of this AD.

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

valve installed, Kaiser Electroprecision part number series 2651-

329, 2651-334, or 2651-278: Within 5,000 flight hours after the

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

24 months or 5,000 flight hours, whichever occurs later, accomplish

the procedures specified in paragraphs (b)(2)(i)(A) and (b)(2)(i)(B)

of this AD:

(A) Conduct a leak check of the 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 dump valve leak check must

be performed 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) and checking for leakage after

a period of 5 minutes. The in-line drain valve leak check must be

performed with a minimum of 3 pounds per square inch differential

pressure (PSID) applied across the valve.

(B) 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. Any worn or damaged seal must be

replaced, and any damaged seal mating surfaces repaired or replaced,

prior to further flight, in accordance with the valve manufacturer's

maintenance manual.

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

drain valve installed, Kaiser Electroprecision part number series

0218-0032, or Kaiser Electroprecision part number series 0218-0026,

or Shaw Aero Devices part number series 10101000B, 10101000C, 331-

series, 332-series, or Pneudraulics part number series 9527: Within

1,000 flight hours after revising the maintenance program in

accordance with paragraph (b) of this AD, and thereafter at

intervals not to exceed 1,000 flight hours, accomplish the

following:

(A) Conduct leak checks of the dump valve and service panel

drain valve . The dump valve leak check must be performed 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) and checking for leakage after a period of 5 minutes.

The service panel drain valve leak check must be performed with a

minimum of 3 PSID applied across the valve inner door/closure

device. Any revision to this leak check schedule must be approved by

the Manager, Seattle ACO, FAA, Transport Airplane Directorate.

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

mating surface for wear or damage that may cause leakage. Any worn

or damaged seal must be replaced and any damaged seal mating surface

must be repaired or replaced, prior to further flight, in accordance

with the valve manufacturer's maintenance manual.

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

system valve that incorporates either ``donut'' assemblies (or

substitute assemblies from another manufacturer) Kaiser

Electroprecision part number 4259-20 or 4259-31, or incorporates

Kaiser Roylyn part number 2651-194C, 2651-197C, 2651-216, 2651-219,

2651-235, 2651-256, 2651-258, 2651-259, 2651-260, 2651-275, 2651-

282, 2651-286: Within 200 flight hours after revising the

maintenance program in accordance with paragraph (b), and thereafter

at intervals not to exceed 200 flight hours, conduct leak checks of

the dump valve and the service panel drain valve. Both the donut and

the outer cap/door must be leak checked. The dump valve leak check

must be performed 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) and checking for

leakage after a period of 5 minutes. The service panel drain valve

leak check must be performed with a minimum 3 PSID applied across

the valve.

(iv) For each lavatory drain system that incorporates any other

type of approved valves: Within 400 flight hours after revising the

maintenance program in accordance with paragraph (b) of this AD, and

thereafter at intervals not to exceed 400 flight hours, accomplish

the following:

(A) Conduct leak checks of the dump valve and the service panel

drain valve. The dump valve leak check must be performed 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) and checking for leakage after a period of 5 minutes.

The service panel drain valve leak check must be performed with a

minimum 3 PSID applied across the valve. If the service panel drain

valve has an inner door with a second positive seal, only the inner

door must be tested.

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

mating surface for wear or damage that may cause leakage. Any worn

or damaged seal must be replaced and any damaged seal mating surface

must be repaired or replaced, prior to further flight, in accordance

with the valve manufacturer's maintenance manual.

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

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

5,000 flight hours, perform the requirements of either paragraph

(b)(3)(i) or (b)(3)(ii), as applicable.

(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

check of the toilet tank anti-siphon (check) valve with a minimum of

3 PSID across the valve.

Note 5: The leak test procedure of Boeing Service Letter 737-SL-

38-3-A, dated March 19, 1990, May be referred to as guidance for

this test.

(ii) If a vacuum break, Monogram part number 3765-175 series, or

3765-190 series, is installed on the subject lavatory, replace or

clean the vent line in accordance with the manufacturer's

maintenance manual.

(4) Provide procedures for accomplishing visual inspections to

detect leakage, to be conducted by maintenance personnel at

intervals not to exceed 4 calendar days or 45 flight hours, which

ever occurs later.

(5) Provide procedures for reporting leakage. These procedures

shall provide that any ``horizontal blue streak'' findings must be

reported to maintenance and that, prior to further flight, the

leaking system shall either be repaired, or be drained and placarded

inoperative.

(i) For systems incorporating an in-line drain valve, Kaiser

Electroprecision part number series 2651-329, 2651-334 or 2651-278:

The reporting procedures also must include the following:

(A) Provisions for reporting to maintenance any instances of

abnormal operation of the valve handle for the in-line drain valve,

as observed by service personnel during normal servicing.

(B) For instances where abnormal operation of the valve handle

is identified, instructions to accomplish, prior to further flight,

either the in-line drain valve manufacturer's recommended

troubleshooting procedures and correction of the discrepancy; or

drainage of the lavatory system and placarding it inoperative until

the correction of the discrepancy can be accomplished.

(ii) If the drain system also includes an additional service

panel drain valve, Kaiser Electroprecision part number series 0218-

0026 or 0218-0032 or Shaw Aero Devices series 10101000B, series

10101000C, series 331, or series 332, or Pneudraulics part number

series 9527: Indications of abnormal operation of the valve handle

for the in-line drain valve need not be addressed immediately if a

leak check of the service panel drain valve indicates no leakage or

other discrepancy. In these cases, repair of the in-line drain valve

must be accomplished within 1,000 flight hours after the leak check

of the additional service panel drain valve.

(6) Provide training programs for maintenance and servicing

personnel that

[[Page 55679]]

include information on ``Blue Ice Awareness'' and the hazards of blue

ice.

(7) If a leak is discovered during a leak check required by this

paragraph; or if evidence of leakage is found at any other time; or

if repair/replacement of a valve (or valve parts) is required as a

result of a visual inspection required in accordance with this AD;

prior to further flight, accomplish the requirements of paragraph

(b)(7)(i), (b)(7)(ii), or (b)(7)(iii), as applicable.

Note 6: 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.

(i) Repair the leak and, prior to further flight after repair,

perform a leak test. 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.

(ii) Repair or replace the valve or valve parts.

(iii) In lieu of either paragraph (b)(7)(i) or (b)(7)(ii), drain

the affected lavatory system and placard the lavatory inoperative

until repairs can be accomplished.

(c) For operators who elect to comply with paragraph (b) of this

AD: Any revision to (i.e., extension of) the leak check intervals

required by paragraph (b) of this AD must be approved by the

Manager, Seattle ACO, FAA, Transport Airplane Directorate. Requests

for such revisions must be submitted to the Manager of the Seattle

ACO through the FAA Principal Maintenance Inspector (PMI), and must

include the following information:

(1) The operator's name;

(2) A statement verifying that all known cases/indications of

leakage or failed leak tests are included in the submitted material;

(3) The type of valve (make, model, manufacturer, vendor part

number, and serial number);

(4) The period of time covered by the data;

(5) The current FAA leak check interval;

(6) Whether or not seals have been replaced between the seal

replacement intervals required by this AD;

(7) Whether or not leakage has been detected between leak check

intervals required by this AD, and the reason for leakage (i.e.,

worn seals, foreign materials on sealing surface, scratched or

damaged sealing surface or valve, etc.);

(8) Whether or not any cleaning, repairs, or seal changes were

performed on the valve prior to conducting the leak check. [If such

activities have been accomplished prior to conducting the periodic

leak check, that leak check shall be recorded as a ``failure'' for

purposes of the data required for this request submission. The

exception to this is the normally-scheduled seal change in

accordance with paragraph (b)(1) of this AD. Performing this

scheduled seal change prior to a leak check will not cause that leak

check to be recorded as a failure. Debris removal done as part of

normal maintenance for previous flights is also allowable and will

not cause a leak check to be recorded as a failure].

Note 7: Requests for approval of revised leak check intervals

may be submitted in any format, provided the data give the same

level of assurance specified in paragraph (c) above. Results of an

Environmental Quality Analysis (EQA) examination and leak test on a

randomly selected high-flight-hour valve, with seals that have not

been replaced during a period of use at least as long as the desired

interval, may be considered a valuable supplement to the service

history data, reducing the amount of service data that would

otherwise be required.

Note 8: For the purposes of expediting resolution of requests

for revisions to the leak check intervals, the FAA suggests that the

requester summarize the raw data; group the data gathered from

different airplanes (of the same model) and drain systems with the

same kind of valve; and provide a recommendation from pertinent

industry group(s) and/or the manufacturer specifying an appropriate

revised leak check interval.

Note 9: In cases where changes are made to a valve design

approved for an extended leak test interval such that a new valve

dash number or part number is established for the valve, the FAA may

not require extensive service history data to approve the new valve

to the same leak check interval as the previous valve design.

Similarity of design, the nature of the design changes, the nature

and amount of testing, and like factors will be considered by the

FAA to determine the appropriate data requirements and leak check

interval for a new or revised valve based upon an existing design.

Note 10: If other valve designs achieve the reliability (as

demonstrated by equivalent service history and data) of the valves

cited in paragraph (b)(2)(i) of this AD, the FAA may consider

granting terminating action using the same guidelines.

(d) For all airplanes: Unless already accomplished, within 5,000

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

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

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

lines for the forward, aft, and executive lavatories. Or -

(2) Install a vacuum break, Monogram part number 3765-175 series

or 3765-190 series, in the flush/fill lines for the forward, aft,

and executive lavatories. -

(e) 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 checks required by this AD shall be

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

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

once, each subsequent leak check must be performed in accordance

with the new operator's schedule, in accordance with either

paragraph (a) or (b) of this AD as applicable.

(1) For airplanes previously maintained in accordance with this

AD, the first leak check 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 would result in the

earlier accomplishment date for that leak check.

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

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

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

accordance with a schedule approved by the FAA PMI, but within a

period not to exceed 200 flight hours.

(f) Alternative method(s) of compliance with this AD:

(1) 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, FAA, 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.

(2) Alternative methods of compliance previously approved for AD

89-11-03, which permit a 4,500-flight hour interval between leak

checks of the forward waste drain system for those operators

installing the modifications specified in Boeing Service Bulletin

737-38-1028, dated July 18, 1991, and later revisions, are

considered acceptable alternative methods of compliance with the

requirements of only paragraph (a)(1) of this AD. For those

operators, the other requirements of this AD are still required to

be accomplished. All other alternate methods of compliance approved

for AD 89-11-03 are terminated and are no longer in effect.

Note 11: Information concerning the existence of approved

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

obtained from the Seattle ACO.

Note 12: For any valve that is not eligible for the extended

leak check intervals of this AD: To be eligible for the leak check

interval specified in paragraphs (a)(1), (a)(2), (b)(2)(i), and

(b)(2)(ii), the service history data of the valve must be submitted

to the Manager, Seattle ACO, FAA, Transport Airplane Directorate,

with a request for an alternative method of compliance. The request

should include an analysis of known failure modes for the valve, if

it is an existing design, and known failure modes of similar valves,

with an explanation of how design features will preclude these

failure modes, results of qualification tests, and approximately

25,000 flight hours or 25,000 flight cycles of service history data

which include a winter season, collected in accordance with the

requirements of paragraph (c) above, or a similar program. One of

the factors that the FAA will consider in approving alternative

valve designs is whether the valve meets Boeing Specification

S417T105 or 10-62213. However, meeting the Boeing specification is

not a prerequisite for approval of alternative valve designs.

(g) 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.

[[Page 55680]]

Issued in Renton, Washington, on October 26, 1995.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 95-27074 Filed 11-1-95; 8:45 am]

BILLING CODE 4910-13-U