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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

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

RIN 2120-AA64

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

and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of

comment period.

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

SUMMARY: This document revises an earlier proposed airworthiness

directive (AD), applicable to all Boeing Model 737-100, -200, -300, -

400, and -500 series airplanes, which would have superseded an existing

AD that currently requires either leak tests of the forward lavatory

service system, and repair, as necessary; or draining the system and

placarding the lavatory inoperative. That proposed AD would have

provided an option for accomplishing terminating action for certain

leak tests. It would have required leak tests of other lavatory drain

systems; installation of a cap or vacuum break on the flush/fill line;

and either periodic replacement of the seal for the cap and tank anti-

siphon valve or periodic maintenance of the vacuum break in the flush/

fill line. This action revises the proposed AD by removing the

terminating action; requiring periodic changing of the seals of certain

lavatory drain systems; replacing ``donut valves'' with other FAA-

approved valves; revising certain leak test intervals; and revising the

pressurization and fluid level requirements for testing. 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 January 5, 1998.

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 (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 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 supplemental 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

A proposal to amend part 39 of the Federal Aviation Regulations (14

CFR part 39) to add an airworthiness directive (AD), applicable to all

Boeing Model 737-100, -200, -300, -400, and -500 series airplanes, was

published as a notice of proposed rulemaking (NPRM) in the Federal

Register on November 2, 1995 (60 FR 55673). That NPRM proposed to

supersede AD 89-11-03, amendment 39-6223 (54 FR 21933, May 22, 1989),

applicable to certain Boeing Model 737-300 and -400 series airplanes.

That proposal would have continued to require either repetitive leak

tests on the forward lavatory service system, and repair, as necessary;

or draining of the system and placarding the lavatory inoperative. It

would have also added a requirement to

[[Page 62709]]

perform leak tests of other lavatory drain systems; provided for the

option of revising the FAA-approved maintenance program to include a

schedule of leak tests; required the installation of a cap or vacuum

break on the flush/fill line; and required either a periodic

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

periodic maintenance of the vacuum break in the flush/fill line. That

proposal also would have expanded the applicability of the rule to

include all Model 737 series airplanes.

That NPRM was 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. Such formation and dislodging of

``blue ice,'' if not corrected, could result in damage to the engine

and potential separation of the engine from the airplane.

Actions Since the Issuance of Previous NPRM

Since the issuance of that previous NPRM, the FAA has received

reports indicating that leakage of certain in-line valves of the

lavatory waste drain systems has been detected. In consideration of

this and other factors (a more detailed discussion of the other factors

is presented later in this supplemental NPRM), the FAA has determined

that the terminating action provided by the previous NPRM must be

removed from this supplemental NPRM. In addition, the FAA has

determined that certain additional changes to the previous NPRM are

necessary.

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, which is 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 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.

General Changes to the Proposal: Revision of Optional Maintenance

Program

As discussed previously, the FAA has received recent reports of

leakage in certain in-line drain (ball) valves. In order to ensure that

leak check results are uniformly reviewed before any extension of leak

check intervals, the FAA has determined that the previously proposed

optional terminating action provided for in paragraph (b) of the

previous NPRM must be removed from this supplemental NPRM in order to

maintain an adequate level of safety. The 5,000-hour leak test interval

remains unchanged.

General Changes to the Proposal: Revised Leak Test Intervals for

Certain Valves

Based on recently received new data submitted by various operators,

the supplemental NPRM would revise the previously proposed leak test

intervals for certain valves. These changes have been added to

paragraphs (a) and (b) of this supplemental NPRM. (A more detailed

discussion of those proposed changes in the leak test intervals is

presented later in the preamble.)

General Changes to the Proposal: Requirement To Change Seals

One comment submitted to the Rules Docket in response to the

previously issued NPRM, requests that a requirement to change the valve

seals be added to paragraph (a) of the proposal. The commenter points

out that if the seals are not changed periodically, they could fail and

leak in between leak testing. The FAA concurs with the request, and has

added a requirement to paragraph (a) of this supplemental NPRM to

change the seals of valves at intervals similar to the proposed

requirements of the valve seal changes in paragraph (b) of this

supplemental NPRM.

General Changes to the Proposal: Requirement To Remove ``Donut''

Valves

Another comment submitted to the Rules Docket in response to the

previously issued NPRM, requests that the FAA mandate the removal of

``donut'' style valves from the airplane and require replacement with

one of the three service panel valves, as specified in the proposed

rule. The commenter states that the ``donut'' valves have a long

history of poor performance.

The FAA concurs that the ``donut'' style valves should be removed.

``Donut'' style valves have been involved in more cases of leakage and

consequent formation of ``blue ice'' than any other valve design. In

addition, cases of leakage of ``donut'' style valves that have been

leak tested (as required by previous AD's) are still being reported.

Therefore, the FAA has determined that the ``donut'' style valves

should be removed.

However, the FAA finds that, rather than require replacement of the

``donut'' style valves with one of the three service panel valves

listed in the previous NPRM, a requirement to replace the ``donut''

valves with ``an FAA-approved valve'' is more appropriate. This leaves

an opportunity for operators to choose valves that may be ``FAA-

approved,'' but that may not be specified in the rule. Paragraphs

(a)(6)(iii) and (b)(2)(iv)(C) of this supplemental NPRM have been

revised to reflect this change.

General Changes to the Proposal: Revised Pressurization

Requirements

Several comments submitted to the Rules Docket in response to the

previously issued NPRM included requests to revise the requirement to

pressurize the airplane while performing leak tests to verify the

integrity of in-line drain valves or service panel drain valves. The

commenters state that applying a minimum pressure of 3 pounds per

square inch differential pressure (PSID) across the line by using a

leak test tool, such as a hand-held vacuum pump, would be just as

effective as pressurizing the airplane, yet would provide a more

economical method of accomplishing the leak test. Additionally, the

commenters point out that using a 3 PSID differential pressure is

consistent with the ``blue ice'' AD requirements for Boeing Model 727

series airplanes.

The FAA concurs. Paragraphs (a) and (b) of this supplemental NPRM

have been revised to require the tests while applying a minimum 3 PSID

differential pressure in the same direction as would occur during

flight.

General Changes to the Proposal: Revised Requirement of Fluid Level

Several comments submitted to the Rules Docket in response to the

previously issued NPRM included requests that the FAA revise the

proposed leak test procedure to empty and refill the lavatory to within

two inches of overflowing. The commenters state that the difference

between that specified level of fluid and actual overflowing of the

fluid is approximately only one gallon. Since overflow of the lavatory

could cause damage to the airplane, the commenters consider that any

fluid above normal level (10 gallons) is unnecessary.

[[Page 62710]]

Therefore, the commenters request that the required fluid level be

reduced.

The FAA concurs that a lower fluid level is acceptable, except in

the case of testing the anti-siphon valve. The FAA finds that fluid at

the 10-gallon level is too low to result in fluid contacting the seals

during the test of the anti-siphon valve; the lack of contact of the

fluid with the seals would invalidate the test. Therefore, this

supplemental NPRM has been revised to require that the lavatory be

filled with a minimum of 10 gallons of fluid, except when testing the

anti-siphon valve. However, operators should take precautions to ensure

that the tank is not overfilled; a statement to this effect has been

added to this supplemental NPRM.

Conclusion

Since the changes described above expand the scope of the

previously issued proposed rule, the FAA has determined that it is

necessary to reopen the comment period to provide additional

opportunity for public comment.

Comments Received

Due consideration has been given to the comments received in

response to the NPRM issued previously.

Support for the Proposal

One commenter supports the proposed rule.

Request To Withdraw the Proposal: Risk of Injury From ``Blue Ice''

Is Extremely Remote

The Air Transport Association (ATA) of America, on behalf of its

members, requests that the proposed rule be withdrawn. The commenter

considers that, from a statistical standpoint, the risk of injury to

persons on the ground from falling ``blue ice'' is extremely remote.

The FAA does not concur that the proposed rule should be withdrawn.

The FAA has responded to the commenter on this issue during previous

rulemaking concerning ``blue ice'' on Boeing Model 727 series

airplanes. As stated in the preamble of that final rule, the FAA

pointed out that 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 aft lavatory drain systems are

detected and corrected in a timely manner, ``blue ice'' incidents would

go untested and eventually someone would be struck, perhaps fatally, by

falling ``blue ice.'' To discount the unsafe condition to persons on

the ground presented by falling ``blue ice'' would be a gross breach of

the FAA's safety obligations and commitment to the public.

Request To Withdraw the Proposal: Issue an Advisory Circular in

Lieu of an AD

This same commenter suggests that, if some type of action must be

taken, a more manageable alternative to issuing an AD should be

considered. The commenter suggests that such an alternative could be

the development of an Advisory Circular (AC).

The FAA does not concur that issuance of an AC would provide a

``more manageable'' method of addressing the ``blue ice'' safety issue.

In certain cases, the issuance of an AC is an appropriate first step to

address a concern at a more informal level than an AD. In line with

this approach, Advisory Circular 120-39, ``Hazards of Waste Water Ice

Accumulation Separating from Aircraft in Flight,'' was issued on

October 31, 1980. Paragraph 3. of that AC states, ``Each operator

should initiate and accomplish inspections and maintenance of waste

drain valves, caps, and heater systems to the extent necessary to

ensure that these systems remain airworthy and function as designed, to

prevent ice build-up from leaking waste water, and the resultant

separation from the aircraft.'' The FAA concludes that the time elapsed

since the issuance of that AC has given industry sufficient opportunity

to make this approach work. The continuing problems with ``blue ice,''

however, demonstrate the need for a more definitive solution; this

proposed rule is an appropriate approach.

Request To Revise Rulemaking Criteria To Ensure Level of Safety Is

Cost Beneficial

The ATA requests that the FAA redefine the criteria used to

determine an ``unsafe condition'' so that the cost of rulemaking

(airworthiness directives) is commensurate with the risks associated

with not correcting the identified safety concern. Additionally, the

commenter states that in meetings between the ATA and FAA management,

participants agreed to a definition of ``airworthiness.'' The ATA would

like to see that definition adopted for use in determining the need for

an airworthiness directive. ATA states that without specific criteria

and definitions of these terms, the FAA's determination of an unsafe

condition and compliance period for adoption of the proposed rule must

be viewed as subjective and, therefore, deficient as rulemaking.

The FAA does not concur with the commenter's assertion that

``without further guidance, the FAA's determination of an unsafe

condition must be viewed as subjective and, therefore, deficient as

rulemaking.'' The legal question is whether the FAA has identified an

unsafe condition that may exist or develop in other products of the

same type design. The FAA's determination on this issue is legally

appropriate (and the rulemaking is not ``deficient'') as long as the

FAA has a reasonable basis for that determination. In this supplemental

proposed rule, the FAA finds that there is an unsafe condition based on

reports of 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. Although these

reasons may be characterized as ``subjective'' because they are

qualitative rather than quantitative, the FAA considers them to be

appropriate and sufficient to establish the reasonableness of this

proposed action.

Request To Consider the Cost Impact to Airline Operators

One commenter states that in order to standardize leak testing

intervals at 1,000 and 4,500 flight hours, it will have to install a

part in the aft drain system on its entire fleet, and in the forward

drain system on airplanes that do not have Kaiser in-line ball valves

installed in the forward drain system. The commenter requests that,

since the annual cost for this will be $8,064, the FAA should

reconsider that requirement.

Another commenter asserts that compliance with the proposed rule

will force airlines with good maintenance programs and high levels of

``blue ice'' awareness to spend money accomplishing repetitive leak

tests that will not add any additional levels of safety to the aircraft

or to people on the ground. The commenter further states that the

additional ground time required to perform these tests will also

complicate scheduling and hamper efforts to increase aircraft

utilization. The FAA infers that the commenter is requesting that the

FAA reconsider the cost impact of the proposed action.

The FAA acknowledges that the obligation to maintain aircraft in an

airworthy condition is vital, but sometimes expensive. ``Blue ice''

[[Page 62711]]

frequently is not traceable to the particular airplane, operator, and

waste system that produced it. Incidents of leakage usually are not

reported; only the relatively serious leakage incidents become known to

the FAA. Previous attempts to rely solely upon increased maintenance

while using lower reliability hardware have not proven to be

successful. Therefore, a system to prevent incidents of ``blue ice'' in

the fleet must be based upon reduction of the number of incidents of

leakage by encouraging the use of more reliable equipment, and

requiring that, if an incident of leakage does occur, it is detected

and corrected in a timely manner.

In addition, 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 proposal is unrealistic because, in the interest of

maintaining safe aircraft, prudent operators would accomplish the

proposed actions even if they were not required to do so.

Request To Distinguish Risks Associated With Forward and Aft

Lavatories Drain Systems

Two commenters note that the compliance times of the NPRM do not

reflect a difference between risks associated with leakage from the

forward lavatory drain system and the risks associated with leakage

from the aft drain. One of the commenters asserts that operators who

upgraded their forward lavatory systems to address the more significant

safety concern over ice ingestion in engines would still be subject to

the more stringent leak test intervals of the aft lavatory drain

systems because of difficulties in redesigning and implementing

retrofit of the aft lavatory drain systems. The commenters assert that

the differences between the risks of leakage from the forward lavatory

should be reflected by an adjustment to the proposed compliance times.

The FAA does not concur that the risks associated with either the

forward or aft lavatories should be distinguished by an adjustment to

the proposed compliance times of the NPRM. As discussed previously,

``blue ice'' detaching from the forward lavatory could cause damage to

the engine and airframe, as well as present a hazard to persons on the

ground; ``blue ice'' detaching from the aft lavatory presents a hazard

to persons on the ground. Regardless of whether the formation of ``blue

ice'' occurs on the forward or aft lavatory drain system, the resultant

unsafe condition would exist. Even if the formation of ``blue ice'' on

the aft lavatory drain systems may appear to be a less ``significant''

safety concern than the forward systems, a safety concern for those

persons on the ground, nevertheless, still exists.

Request To Involve Principal Maintenance Inspectors (PMI)

This same commenter, in reference to paragraph (b) of the previous

NPRM, contends that it is more appropriate for the PMI, rather than the

Seattle Aircraft Certification Office (ACO) engineering staff, to

approve subsequent changes to the maintenance program once the program

has been approved. The commenter considers that the PMI is more

qualified than the ACO staff to approve tasks on training, reporting,

and adjustment to the leak test intervals based upon reliability

program recommendations. The commenter points out that the subject

matter of the rule is clearly maintenance-related, and the ACO staff is

not equipped to effectively respond to requests for maintenance

interval changes that may occur. The commenter states that paragraph

(b) of the proposal should be revised to include a statement that the

AD is no longer applicable once a revision to the FAA-approved

maintenance program is implemented.

The FAA does not concur. Although the FAA agrees that the PMI

should have oversight of most of the requirements of the proposed

alternative maintenance program provision of the rule, the FAA does not

agree that the PMI should be tasked with approving certain adjustments

of the program. Failure threshold criteria and definitive leak/failure

rate data do not exist for the majority of the subject valves;

therefore, a PMI would have no data on which to base the approval of an

extension of a leak test interval for many valves with the assurance

that the valve would not fail within the adjusted interval. In light of

this, it is essential that the FAA, at the ACO level, have feedback as

to the leak and failure rates experienced in the field. Although the

PMI's serve as the FAA's critical link with the operators (and the PMI

oversight responsibilities will not be minimized by this AD action), it

is the staff of the ACO that provides the engineering support necessary

to evaluate whether increases in leak test intervals will maintain an

acceptable level of safety.

Further, the FAA considers it essential that any adjustment of the

required leak test intervals, seal change intervals, and data reporting

procedures should be approved in a uniform manner to ensure that the

program is administered uniformly (and appropriately) fleetwide. The

staff of the Seattle ACO is in the best position to ensure that this is

accomplished. Additionally, given that possible new relevant issues

might be revealed during the approval process, it is imperative that

the engineering staff at the ACO have such feedback. In any case, the

ACO staff will work closely with the cognizant PMI to ensure that any

approved revisions to this aspect of the maintenance program are

appropriate and workable for the applicable airline.

Request To Increase Leak Test Intervals for Pneudraulics Drain

Valves

Several commenters request that the leak test interval for

Pneudraulics drain valve having part number (P/N) 9527-1 be increased

from the proposed 1,000 flight hours. Two of the commenters requested

the interval be increased to 2,000 flight hours; and one of the

commenters, the valve manufacturer, requests that the interval be

increased to 4,500 flight hours.

The FAA concurs partially. Since the issuance of the NPRM, the FAA

has received new data regarding the in-service performance of the

Pneudraulics 9527 series drain valve. The data was obtained in

accordance with procedures similar to those of paragraphs (b) and (c)

of this supplemental NPRM. This data revealed that, only two leak tests

failures were detected during a total time of 847,927 hours on 412

Pneudraulics valves. In consideration of this data, the FAA finds that,

for those operators who choose to comply with the requirements of

paragraph (a) of the AD, this information justifies an increase of the

leak test interval of Pneudraulics valves having P/N 9527 series from

1,000 hours to 2,000 hours. Additionally, the FAA finds that, for

operators who choose to comply with the maintenance option of paragraph

(b) of the AD, this information justifies an increase of the leak test

interval of the Pneudraulics valves P/N 9527 series from 1,000 hours to

4,000 hours. Paragraphs (a) and (b) of this supplemental NPRM have been

revised accordingly. However, if following the requirements of

paragraphs (b) and (c) of this supplemental NPRM, similar data is

gathered by a number of operators and are submitted to the FAA in

support of an extension of the leak check interval for another type of

valve, the FAA will consider extension of the leak check intervals for

that valve for all operators using the valve.

[[Page 62712]]

Request To Increase Leak Test Intervals of Certain Other Shaw

Valves

One commenter states that its fleet has a mixture of valves that

have been modified in accordance with Shaw Service Bulletin SB

10101000B-38-1, and valves that have not been modified in accordance

with that service bulletin. The operator requests that the currently

proposed leak test interval of 600 flight hours (for the valves that

have not been modified in accordance with the service bulletin) be

increased to equal the 1,000 flight hour leak test interval of the

valves modified in accordance with that service bulletin. Because of

the operator's high level of awareness, it sees no safety compromise in

requiring the unmodified valves to be leak tested at 1,000 flight

hours.

The FAA does not concur. The modifications described by the subject

service bulletin were designed to make the valves less likely to leak.

Therefore, the leak test interval is permitted to be increased only for

those valves that have been modified in accordance with Shaw Service

Bulletin SB 1010000B-38-1.

Request To Increase Leak Test Interval for Other Shaw Valves

One commenter, a valve manufacturer, requests that the leak test

interval for certain Shaw valves be extended from 1,000 flight hours to

2,000 flight hours when the maintenance procedures have been revised

and data have been submitted to substantiate the increased interval.

The FAA concurs that when maintenance procedures have been revised

and data have been submitted to substantiate the increased interval,

approval may be granted to increase the leak test intervals. Under the

provisions of this supplemental NPRM, an operator has the option of

proposing a change to its maintenance program, gathering data, and

making a request for extension of the leak test interval. Operators

interested in this option should contact the Seattle Aircraft

Certification Office to discuss implementation of this option before

submitting the request to extend the leak test intervals. If a number

of operators successfully follow this procedure and provide data

similar to that provided for the Pneudraulics P/N 9527 series valve,

the FAA will consider an ``across the board'' increase for extension of

the leak check interval for the valve that they are using. This

procedure is applicable to valve manufacturers as well.

Request To Increase Interval of Replacement of Pneudraulics Valve

Seals

One commenter, an operator, requests that the replacements of the

seals of the Pneudraulics valves be extended from the proposed ``prior

to 5,000 flight hours after the effective date of the AD, and

thereafter at intervals not to exceed 18 months,'' to replacement of

the seal ``every third leak test of the drain system, or every 6,000

flight hours.'' The commenter states that implementation of the revised

compliance times would provide a scheduling convenience, and would

still maintain an acceptable level of safety.

The FAA concurs that the intervals for the repetitive replacements

can be extended somewhat. Since the Pneudraulics valve seals are

similar to those used in the in-line drain valves and replacement of

those seals are approved for longer replacement intervals, the FAA has

revised paragraphs (a)(1)(ii) and (b)(1)(ii) of this supplemental NPRM

to require accomplishment of repetitive seal replacements at intervals

not to exceed 18 months or 6,000 flight hours, whichever occurs later.

Request To Revise Compliance Times for Certain Seal Changes

One commenter, the airplane manufacturer, requests that the

proposed rule be revised to provide for an alternative repetitive

interval for accomplishment of the seal changes. Specifically, the

commenter requests that, ``or within 48 months after the last

documented seal change'' be added after the proposed repetitive

interval of ``5,000 flight hours'' in paragraph (b)(1)(i) of the

proposed rule. The commenter states that this alternative repetitive

interval would prevent unnecessary seal changes for operators that have

recently performed the seal change.

The FAA concurs that the requested alternative repetitive interval

would prevent unnecessary seal changes for operators that have recently

performed the seal change. The FAA considers that those alternative

repetitive intervals provide an equivalent level of safety. Therefore,

the FAA has revised paragraph (b)(3) of this supplemental NPRM (which

appeared as paragraph (b)(1) of the previous proposal). The FAA also

has made a corresponding change to paragraph (a)(8) of this

supplemental NPRM since it is similar to the requirements of paragraph

(b)(3) of the supplemental NPRM.

Request To Delete Certain Seal Part Numbers

One commenter, the airplane manufacturer, requests that valve seal

part numbers 2651-329, 2651-334, 10101000C-G, 10101000C-M, and

1010000C-R be deleted from the proposal. The commenter considers that

part numbers that have not been installed, either in production or

retrofit, on Boeing Model 737 series airplanes should not be cited in

the NPRM. The FAA concurs with the commenter's remarks, and has removed

all references to those parts numbers from this supplemental NPRM.

Request To Mandate Leak Testing of All Seals in the Lavatory System

One commenter notes that, while the previous NPRM proposes leak

testing of the dump valve seal and the inner seal of the drain valve of

the service panel, no testing of the outer cap/door seal is required.

The commenter states that since the outer cap/door seal is the ``last

resort'' in preventing leakage of ``blue ice,'' leak testing should be

required of the outer cap/door.

The FAA does not concur. Some valve designs are such that the valve

must be partially disassembled (removing the inner seal, interlocking

inner plugs, etc.) to allow the outer door to be tested, which would

invalidate the test of the inner seal. Additionally, different valve

designs may require valve disassembly and reassembly as part of the

test procedure with different test procedures for different valve

designs. These factors complicate the specification of a usable test of

both inner and outer doors for all existing valve designs. Therefore,

the FAA finds that the requirement to apply 3 PSID across the valve

inner door and to visually inspect the outer door seal for damage that

could cause leakage on all service panel valves to be adequate and

appropriate. However, if an operator prefers to test the outer door and

inspect the inner door, the FAA will consider requests for an

alternative method of compliance as provided in paragraph (f) of this

proposed AD.

Request To Require a Lever Lock Cap and a Vacuum Breaker Check

Valve

One commenter states that, instead of permitting a vacuum breaker

check valve to be used as an alternative to the installation of a lever

lock cap, the FAA should require both of them. The commenter states

that a long history of poor performance of check valves and lever lock

caps indicates that a redundant system requiring both the valve and cap

would have greater reliability.

[[Page 62713]]

The FAA does not concur in this case. The FAA acknowledges that

redundant systems generally provide a higher level of safety; however,

in this case, redundancy to the check valve function is provided by the

vacuum breaker. In the case of a check valve alone, the lever lock cap

provides redundancy to the check valve. There are insufficient data to

show which combination is more reliable.

However, service history information indicates that vacuum breaker

check valves with poppet check valves (rather than mushroom check

valves) have a greater reliability record. Therefore, the FAA has

removed reference to Monogram Part Number 3765-175 (mushroom type) from

paragraphs (a) and (b) of this supplemental NPRM. By requiring repair

of leaking components when ``blue streaks'' are observed, the FAA

intends that operators, through their own experience, will determine

which combination of valves works the best to avoid leakage. However,

if the FAA receives data indicating service problems or unreliability

with vacuum breaker check valves using poppet checks, the FAA may

consider further rulemaking action.

Request To Revise Approvals of Certain Vacuum Breakers

Two commenters request that the approval of vacuum breakers, as

referenced in the proposed rule, be revised. One commenter requests

that reference to all Monogram part number series 3765-175 or 3765-190

series be deleted, and replaced with ``* * * an FAA-approved check

valve with a vacuum breaker * * *,'' or replaced with a specific

reference to valves having Shaw part number 301-0009-01. This commenter

states that the vacuum breaker check valves leaked, and should not be

provided as an alternative to installation of a lever lock cap on the

flush/fill line. The other commenter requests that instead of

specifying particular part numbers, the approval reference should be to

``* * * an FAA-approved vacuum break in the * * *.'' This commenter

considers that this would cover all vacuum breaker manufacturers.

The FAA concurs partially. The FAA has reviewed available service

history data and concluded that vacuum breaker check valves of the

poppet type (such as Monogram part number series 3765-190) have fewer

reports of leakage than the vacuum breaker test valves of the mushroom

type (such as Monogram part number 3765-175). Therefore, as stated

previously, the FAA has removed reference to Monogram part number 3765-

175 as an approved valve from this supplemental NPRM.

The FAA also has reviewed the design of Shaw part number 301-0009-

01, which is a vacuum breaker check valve of the poppet type, and has

added it as an acceptable part number in paragraphs (a)(8)(ii) and

(b)(3)(ii) of this supplemental NPRM.

Additionally, since the issuance of the previous NPRM, another

acceptable valve for the flush/fill line has been certified. The

installation of Kaiser Electroprecision flush/fill ball valve part

number series 0062-0009 has been added to paragraphs (a)(8)(iii),

(b)(3)(iii), and (d)(3) of this supplemental NPRM as an alternative

method of preventing leakage from the flush/fill line.

Request To Shorten Leak Test Intervals of Flush/Fill Caps

The commenter states that there is no discussion in the proposal of

what would prompt an airline to ensure flush/fill caps are installed in

all positions prior to each flight. The commenter contends that it is

common practice for caps to be removed from airplanes due to their

nuisance value. The commenter also states that the flush/fill caps, as

well as the lever lock caps, are difficult to operate and commonly have

the seals removed, which render them inoperable on the airplane. The

commenter considers the ease with which the seal is removed is a design

flaw of the valve itself. Therefore, the commenter requests that

another device be considered instead of the flush/fill caps that is not

on the exterior of the aircraft and cannot be tampered with by ground

maintenance personnel. The commenter notes that a device incorporated

further upstream with positive shut-off and anti-siphon features would

eliminate the ``blue ice'' that occurs at the flush/fill port.

Therefore, the commenter requests that, until such a device can be

developed and FAA-approved, the leak tests and inspections of this area

should be performed more frequently.

The FAA does not concur with the commenter's request. The FAA does

not consider it necessary to require an additional inspection to ensure

installation of the flush/fill caps when they are installed in

accordance with an AD. If, as the commenter asserts, cases of

uninstalled flush/fill caps commonly occur, the FAA does not find that

reason to assume that operators would continue that practice in the

future if operation without the flush/fill caps would be a violation of

an AD. Further, lever lock caps are specified by this supplemental NPRM

precisely because they must be in the closed position to allow the

service panel door to be closed. In addition, this supplemental NPRM

specifies that if there is evidence of leakage, the leaking device must

be corrected, or the lavatory drained and placarded inoperative.

Therefore, if seals or caps are removed and result in leakage, this

provision will ensure that the system is repaired before the lavatory

is returned to service.

Additionally, the FAA notes that the vacuum break poppet type check

valves specified in the previous NPRM can be used as an alternative to

using lever lock caps. The FAA is not aware of any data, presently,

that supports an increase or decrease in the leak test intervals of the

devices on the flush/fill line. Consequently, this supplemental NPRM

contains neither an increase nor a decrease in the leak test intervals

of these devices. However, if such data becomes available that supports

a decrease in the leak test intervals, the FAA may consider additional

rulemaking.

Request To Revise the Leak Test of the Inner Door of the Service

Panel Drain Valve

Several commenters request that the leak test of the inner door of

the service panel drain be revised to require the test to be run with

the outer door open when using a vacuum box so that the 3 PSID

differential is applied across the inner door. One of these commenters,

the airplane manufacturer, points out that if the outer door seal is

good, the inner door seal will not reflect a pressure differential. For

this reason, the FAA concurs. The FAA has revised the supplemental NPRM

to specify that the test be run with the outer door open when using a

vacuum box.

Request To Revise Testing of Drain Panel Valves

One commenter requests that testing of the drain valves cover both

the inner door of the valve and the outer door/cap of the valve. The

commenter also notes that some valves have their primary seals on the

outer doors, not the inner doors, so that omitting the test of the

outer door, as proposed in the NPRM, results in the primary seal of the

valve being untested.

The FAA does not concur. As discussed previously in the request to

mandate leak testing of all seals in the lavatory system, the FAA has

revised the requirements of the leak testing of the drain valves of

service panels to require applying 3 PSID across the valve inner door

and visually inspecting the outer door seal for damage. This approach

should adequately test valves with inner and outer doors. However, if

[[Page 62714]]

an operator elects to test the outer door and visually inspect the

inner door, that operator should apply for approval of an alternative

method of compliance under the provisions of paragraph (f) of this

supplemental NPRM.

Request To Require Visual Inspection of the Outer Cap/Door

Two commenters request that paragraphs (a)(4) and (b)(2)(iii) of

the proposal be revised to delete the requirement to perform a leak

test of the outer door of ``donut'' type valves, and add a visual

inspection of the outer doors instead. The commenters state that the

``donut'' valves are similar to other valves in that they provide two

sealing surfaces. The commenters note that for those other valves, the

proposal would require only a test of the inner door or the sealing

surface.

The FAA concurs and has revised paragraphs (a)(4) and (b)(2)(iii)

of this supplemental NPRM accordingly. In light of the fact that this

supplemental NPRM would require eventually removing all ``donut''

valves and replacing them with FAA-approved valves, the FAA finds that,

in the interim, a visual inspection of the outer doors, rather than a

leak test, will ensure an acceptable level of safety.

Request To Require a Leak Test of the Outer Door of the Service

Panel Drain

Another commenter states that since the FAA required it to perform

the leak test of the outer door, the rules for testing the service

panel drain should not be changed at this time. The commenter states

that by requiring leak tests only of the inner door, the proposal

provides an unfair competitive advantage in favor of its competitors

because some valves have their primary seals on the outer doors instead

of the inner doors. In addition, by not requiring a leak test of the

outer door, the actual primary seal of the valve would not be tested.

The FAA does not concur with the request to require leak tests of

the outer door seal. The FAA finds that performing a leak test of the

inner door and visual inspections of the outer door provide an

acceptable level of safety. However, if an operator chooses to test the

outer door and visually inspect the inner door, under the provisions of

paragraph (f) of this supplemental NPRM, that operator may request

approval of an adjustment of this requirement if data are submitted to

substantiate that such an adjustment would provide an acceptable level

of safety.

Request To Extend Leak Test Intervals in Paragraph (b) of the

Proposal

Several commenters state that the leak test intervals specified in

paragraph (b) of the proposal should be relaxed so that operators would

be encouraged to select it as an alternative to the accomplishment of

the requirements of paragraph (a) of the proposal. One of the

commenters states that this same request was made in response to the

proposed rule concerning ``blue ice'' for Boeing Model 727 series

airplanes, and that the FAA did not respond to that request. Several

commenters assert that paragraph (b) of the proposal should

additionally provide terminating action once an operator's FAA-approved

maintenance plan has been incorporated.

The FAA does not concur with the commenters' request to increase

the leak test intervals specified in paragraph (b) simply in order to

encourage operators to choose that option. For the reasons specified

previously under the ``General Changes to the Proposal: Revision of

Optional Maintenance Program'' section of this supplemental NPRM, the

FAA finds that the previously proposed terminating action must be

deleted. Further, the expansion of leak test intervals that are

included in paragraph (b) of this supplemental NPRM is primarily

related to the reliability of the waste drain valves involved. The

additional requirements of paragraph (b) provide assurance that

expansion of the intervals will not result in significant leakage

events in the time between the leak tests. The FAA included paragraph

(b) of this supplemental NPRM not only because it does contain certain

``attractive'' features, but also to provide a format for verifiable

empirical data to serve as a reliability indicator for the waste drain

valves. To date, three operators have opted to follow requirements

similar to those provided in paragraph (b) of this supplemental NPRM.

The FAA concludes, therefore, that compliance with the optional

provisions of paragraph (b) of this supplemental NPRM is of value to

some operators.

Additionally, in reviewing the preamble of AD 94-23-10 (applicable

to Boeing Model 727 series airplanes), the FAA finds that the

commenter's request regarding the leak test intervals of paragraph (b)

of that AD was specifically addressed in the final rule. The FAA's

response noted the revision of several requirements of paragraph (b) of

that final rule to make it more ``attractive'' to operators; certain of

those revised requirements included extended leak test intervals for

some valves.

Request To Revise Leak Test Intervals for Service Panel Drain

Valves

The airplane manufacturer requests that paragraph (b)(2)(ii) of the

proposal be revised to increase the replacement interval of the service

panel drain valves from 1,000 flight hours to 2,000 flight hours. The

commenter states that increasing this interval would not decrease the

level of safety because of other requirements of paragraph (b) of the

proposal. Further, the commenter notes that two alternative methods of

compliance have been granted to increase the interval to 2,000 flight

hours.

The FAA does not concur with the commenter's request to increase

the leak test interval ``across the board'' for service panel drain

valves at this time. However, if data are submitted for specific

service panel drain valves in accordance with the data gathering

requirements of paragraph (b) of this supplemental NPRM, the FAA will

review the data and may consider extending the leak test intervals

accordingly. If a number of operators have successfully accomplished

such programs, the FAA will evaluate all the data submitted for a

particular valve and consider an ``across the board'' extension of the

leak test interval.

Request for Clarification of Compliance Times

The airplane manufacturer requests that compliance times in

paragraph (b)(4) of the proposal be revised. That proposed compliance

time is currently specified as ``* * * at intervals not to exceed 4

calendar days or 45 flight hours, whichever occurs later.'' The

commenter requests that the phrase ``not to exceed'' be deleted and

replaced with the word ``of.'' The manufacturer states that the phrase

``not to exceed'' appears to be in conflict with the phrase ``* * *

whichever occurs later.'' Therefore, the manufacturer suggests revising

the compliance time to read ``at intervals of 4 calendar days or 45

flight hours, whichever occurs later.''

The FAA does not concur that the phrases are in conflict with each

other. The phrases ``at intervals not to exceed 4 calendar days or 45

flight hours, whichever occurs later'' are standard phrasing the FAA

uses routinely in providing certain compliance times. The phrase, ``not

to exceed,'' allows accomplishment of the required action at

frequencies less than the specified intervals. The phrase, ``whichever

occurs later,'' allows an operator to select the means of measuring the

[[Page 62715]]

interval that results in less frequent accomplishment of the required

actions, depending upon the operator's individual utilization rates.

Therefore, no change of compliance time is required to paragraph (b)(4)

of the supplemental NPRM.

Request To Incorporate Paragraph (b) Into Paragraph (f) of the

Proposal

One commenter considers that the provisions in paragraph (b) of the

NPRM are merely guidelines for submitting alternative methods of

compliance. Therefore, the commenter requests that paragraph (b) of the

proposal be incorporated into the paragraph that specifically addresses

alternative methods of compliance [paragraph (f) of the proposal].

The FAA does not concur. The maintenance option provided by

paragraph (b) of this supplemental NPRM provides for the acquisition of

data that are required to justify extending leak test intervals.

Compliance with paragraph (b) of the supplemental NPRM is an approved

method of establishing empirical data on valve reliability. The FAA

sees no added value in changing the paragraph numbering of the

proposal. Moreover, the FAA considers that a change in the numbering of

the paragraphs would have the potential for added confusion since an

existing AD for the Boeing Model 727 series airplanes concerning ``blue

ice'' also has paragraph (b) designated as the maintenance option.

Request To Revise Test Requirements for Flush/Fill Line Anti-Siphon

Valves

The airplane manufacturer requests that paragraph (b)(3) of the

proposal be revised from ``Thereafter, repeat the requirements at

intervals not to exceed 5,000 flight hours'' to ``Thereafter, repeat

the requirements at intervals not to exceed 5,000 flight hours or 24

months.'' The commenter notes that the paragraph would then be

consistent with the test requirements of the in-line drain valve in

paragraph (b)(2)(i) of the proposal.

The FAA does not concur. The compliance times for testing the in-

line drain valves specified in paragraph (b)(2)(i) of the supplemental

NPRM were based on supportive data to justify those times. The FAA has

not received data justifying a similar compliance time for the flush/

fill line anti-siphon valve.

Request To Clarify Table 1 of the Proposal

One commenter, a valve manufacturer, requests that specific Shaw

Aero valves approved for a leak test interval of 1,000 flight hours be

clarified. The FAA has revised Table 1 of this supplemental NPRM to

clarify specifically which Shaw valves have been approved for use on

Boeing Model 737 series airplanes.

Request To Base Leak Test Intervals for Valves on Valve Quality

One commenter states that it is more important to use a quality

valve than a ``maintenance program'' to ensure reliability. The

commenter asserts that maintenance programs should be required of all

airlines, so that leak test intervals would be based on the quality and

performance of the hardware.

The FAA does not concur that claims of valve quality should be the

only basis for determining leak test intervals, or that all operators

should be required to follow the requirements of the optional

maintenance program [paragraph (b) of the supplemental NPRM]. Extension

of the leak test interval is based primarily upon hardware reliability,

as stated elsewhere in this supplemental NPRM. However, verification of

the actual reliability of the hardware is difficult to determine.

Review of maintenance data that is obtained through the maintenance

program and verified by FAA Flight Standards plays a major role in

determining the extension of leak test intervals. Although valve

manufacturers and some operators claim that the hardware and systems

currently in service are providing adequate levels of safety, incidents

of ``blue ice'' continue to occur.

Since leakage from the waste system is not a reportable event

according to part 21 of the Federal Aviation Regulations (14 CFR part

21), the FAA included the provisions of paragraph (b) of the proposal

to make leakage from the waste system a reportable event. Those

operators who choose to compile that data will have documented

information to submit to the FAA as a basis for increasing leak test

intervals. As stated earlier, the FAA has already used this program to

extend the leak test interval for a certain valve.

With regard to the commenter's statement that all operators should

be required to follow a maintenance program, the FAA has incorporated

requirements to periodically change valve seals and correct any leakage

found in accordance with paragraph (a) of this supplemental NPRM. The

more extensive requirements of the maintenance program specified in

paragraph (b) of the supplemental NPRM provide assurance that

significant leakage will not occur during the expanded leak test

intervals.

Request To Increase Certain Leak Test Intervals

The ATA asserts that leak test intervals of every 200 flight hours

for certain drain system valves cannot be justified based on safety

concerns with ``blue ice.'' The ATA requests that those leak test

intervals be extended.

The FAA does not concur. The current leak test interval for certain

drain system valves is every 200 flight hours, as required by AD 89-11-

03. Nevertheless, the FAA has continued to receive reports of damage to

airplanes. The FAA intends to increase the leak test interval only for

those valves documented to be reliable, in accordance with the proposed

requirements of this supplemental NPRM.

Request for Definition of ``Vent Line''

Another operator requests that the term ``vent line'' be defined

specifically. The commenter questions if ``vent line'' as cited in the

proposed AD refers only to the portion of the line shown on the

Monogram check valve.

The FAA acknowledges that clarification is necessary. The vent line

vacuum breaker is that portion of the valve and vent line that

functions as a vacuum breaker, as opposed to the part of the valve

performing a ``check valve'' function. The intent of the previous NPRM

was to perform maintenance on the vacuum breaker check valve and ensure

that the vacuum break feature operates correctly. For clarification

purposes, reference to the term ``vent line'' has been removed from

this supplemental NPRM, and the applicable paragraphs have been revised

to reference a ``vent line vacuum breaker.''

Request To Revise Reference to Service Information

The airplane manufacturer advised that the correct service

bulletins that should be cited in paragraph (f)(2) of the proposal are

Boeing Service Bulletins 737-38-1026 (lavatory A), and 737-38-1031

(lavatory F). Those service bulletins describe alternative methods of

compliance with the requirements of only paragraph (a)(2) of the

supplemental NPRM. The FAA inadvertently cited an incorrect service

bulletin in the previous NPRM; the supplemental NPRM has been revised

to cite the correct service bulletins.

Request To Change Reference to Certain Drain System Valves

One commenter requests that the description of the ``donut'' valves

in paragraphs (a)(4) and (b)(2)(iii) of the NPRM be expanded to read,

``For each lavatory drain system that incorporates

[[Page 62716]]

``donut'' plugs (Kaiser Electroprecision, part number 4259-20 or 4259-

31), or FAA-approved equivalent, or incorporates Kaiser

Electroprecision cap/flange, part numbers * * *.'' The FAA concurs, and

has revised paragraphs (a)(6) and (b)(2)(iv) of this supplemental NPRM

[which appeared as paragraphs (a)(4) and (b)(2)(iii), respectively, of

the previous NPRM] to provide clarification concerning the specific

``donut'' valves, as suggested by the commenter.

Request To Revise Notes 3 and 5 of the Proposal

The airplane manufacturer requests that Notes 3 and 5 of the NPRM

be corrected to reference Boeing Maintenance Manual Section 38-32-00/

501 instead of the currently referenced Boeing service letter.

The FAA acknowledges that Boeing Maintenance Manual Section 38-32-

00/501 is the appropriate guidance for the testing, and has revised

Note 3 of this supplemental NPRM accordingly. However, since reference

to guidance for performing leak tests specifically addressed in Note 5

of the previous NPRM is no longer necessary or applicable, it has been

removed from this supplemental NPRM. (Note 5 of this supplemental NPRM

now contains information unrelated to NOTE 5 of the previous NPRM.)

Request To Delete Reference to Development of Future In-Line Drain

Valves

One commenter, a valve manufacturer, requests that reference to the

development of future in-line drain valves that would provide for

possible terminating action be deleted from the proposal since that

statement may mislead airlines and other interested parties to think

that development and approval of those valves is currently in progress.

The commenter states that the NPRM is a place for facts, not

supposition of what might be. The commenter further states that it

believes it has been ``damaged'' by mention of a future valve,

specifically when the FAA has not considered existing in-service data

concerning the reliability of this manufacturer's valves.

The FAA acknowledges the commenter's request. The FAA has removed

reference to current in-line drain valves, as well as possible future

development of those valves, from consideration as terminating action

for certain requirements of this supplemental NPRM. As discussed

previously in the preamble of this supplemental NPRM, the FAA has

determined that terminating action for the leak testing of the in-line

valves under an approved maintenance program is no longer appropriate,

based on recent reports of leakage of drain systems with in-line drain

valves installed.

In addition, it is common practice for the FAA to provide

information in NPRM's concerning possible development and approval of

various corrective actions. For example, in certain cases, compliance

times for corrective actions are based on a time frame that is

determined to be adequate in order to develop, approve, and install

such corrective actions, e.g., repair, parts, or modifications.

Establishment of a reasonable compliance time enables the manufacturer

to plan its schedules and resources so that the corrective action is

made available to the airlines well within the compliance time

established by an AD. For these reasons, the FAA finds that the

development and approval of future parts, repair, or modifications are

not only relevant to discussions in proposed rules, they are, in

certain cases, inherent to the discussion itself.

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 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 these proposed requirements of this AD

is estimated to be $371,160, 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 3 times each year. Some

airplanes that have various combinations drain valves installed would

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

of the other drain valve 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 $1,080 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 is

incurred because of this change.

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 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 2.5 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 $863,463, or $838 per

airplane.

The addition of the seal change requirement to paragraph (a) will

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 $329,920,

or approximately $320 per airplane per year.

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 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 test procedures

into the maintenance programs, at an average

[[Page 62717]]

labor cost of $60 per work hour. Based on these figures, the 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 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 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 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: All 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

otherwise 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 (f) 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) Except as provided by paragraph (b) of this AD, 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 (SACO), FAA,

Transport Airplane Directorate.

(1) Replace the 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: 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

[[Page 62718]]

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.

(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 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 Nos. of part number

Shaw waste drain valve part no. valve approved 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-1.......................... 0277 and higher.

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

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

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 737 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) 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; or other FAA-approved

equivalent parts; accomplish the requirements at the specified times

of paragraphs (a)(6)(i), (a)(6)(ii), and (a)(6)(iii) of this AD. For

the purposes of this paragraph [(a)(6)], ``equivalent part'' means

either a ``donut'' plug that mates with the cap/flange having part

numbers listed in this paragraph, or a cap/flange that mates with

the ``donut'' plug having part numbers listed in this paragraph,

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 paragraph

(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.

[[Page 62719]]

(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, perform the requirements of paragraph

(a)(8)(i), (a)(8)(ii), or (a)(8)(iii) 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.

(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)(8)(ii)(A)

of this AD, as applicable.

Note 3: The leak test procedure described in Boeing Maintenance

Manual, 38-32-00/501, may be referred to as guidance for this test

if the toilet tank is filled to the level specified in paragraph

(a)(8)(ii)(A) of this AD.

(ii) If a vacuum breaker check valve, Monogram part number

series 3765-190, or Shaw Aero Devises part number series 301-0009-01

is installed on the subject lavatory, replace the seals/o-rings in

the valve. Perform a leak test of the vacuum breaker check valve and

verify proper operation of the vent line vacuum breaker in

accordance with paragraphs (a)(8)(ii)(A) and (a)(8)(ii)(B) of this

AD.

(A) Leak test the toilet tank anti-siphon valve or the vacuum

breaker check 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 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/open during the test.

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

minutes.

(B) 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.

If back drainage does not occur, replace the vent line vacuum

breaker or repair the vacuum breaker check valve in accordance with

the component maintenance manual to obtain proper back drainage. 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.

(iii) 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. 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)(8)(ii)(A) of this AD.

(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 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)(9)(i) or (a)(9)(ii): Prior to further flight, 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 requirements of

paragraph (a) of this AD. 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 ACO.

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

schedule specified in paragraphs (b)(1)(i), (b)(1)(ii), or

(b)(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: Replace the seals within 5,000 flight hours after the effective

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

documented seal change, whichever occurs later. Thereafter, repeat

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

(2) Conduct periodic leak tests of the lavatory drain systems in

accordance with the applicable schedule specified in paragraphs

(b)(2)(i), (b)(2)(ii), (b)(2)(iii), (b)(2)(iv), and (b)(2)(v) of

this AD. 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.

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

valve installed, Kaiser Electroprecision part number series 2651-

278: Within 5,000 flight hours after the effective date of this AD,

or within 5,000 hours of the last documented leak test, whichever

occurs later, accomplish the procedures specified in paragraphs

(b)(2)(i)(A) and (b)(2)(i)(B) of this AD. Thereafter repeat the

procedures at intervals not to exceed 24 months or 5,000 flight

hours, whichever occurs later.

(A) Conduct a leak test 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 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 in-line drain valve

leak test must be performed with a minimum of 3 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.

(ii) 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, or within

4,000 flight hours of the last documented leak test, whichever

occurs later, accomplish the requirements of paragraph (b)(2)(ii)(A)

and (b)(2)(ii)(B) of this AD. Thereafter, repeat the requirements at

intervals not to exceed 4,000 flight hours.

(A) 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 on 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.

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

mating surface for wear or damage that may cause leakage.

[[Page 62720]]

(iii) 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: Within 1,000 flight hours after the effective

date of this AD, or within 1,000 flight hours of the last documented

leak test, whichever occurs later, accomplish the requirements of

paragraphs (b)(2)(iii)(A) and (b)(2)(iii)(B) of this AD. Thereafter,

repeat the requirements at intervals not to exceed 1,000 flight

hours.

(A) 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 on 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.

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

mating surface for wear or damage that may cause leakage.

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

valve that incorporates either ``donut'' plugs Kaiser

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

Kaiser Electroprecision cap/flange 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; or other FAA-approved equivalent

part; accomplish the requirements at the times specified in

paragraphs (b)(2)(iv)(A), (b)(2)(iv)(B), and (b)(2)(iv)(C) of this

AD. For the purposes of this paragraph [(b)(2)(iv)], ``FAA-approved

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

cap/flange having part numbers listed in this paragraph, or a cap/

flange that mates with the ``donut'' plug having part numbers listed

in this paragraph, such that the cap/flange and ``donut'' plug are

used together as an assembled valve.

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

or within 200 flight hours after the last documented leak test,

whichever occurs later, conduct leak tests of the dump valve and the

service panel drain valve. Thereafter, repeat the tests at intervals

not to exceed 200 flight hours. The 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.

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

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

this inspection in conjunction with the leak tests specified in

paragraph (b)(2)(iv)(A).

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

AD, replace the donut valve with another type of FAA-approved valve.

Following replacement of the valve, perform the subsequent leak

tests and seal replacements at the intervals specified for the new

valve.

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

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

date of this AD, or within 400 flight hours of the last documented

leak test, whichever occurs later, accomplish the requirements of

paragraph (b)(2)(v)(A) and (b)(2)(v)(B) of this AD. Thereafter,

repeat the requirements at intervals not to exceed 400 flight hours.

(A) Conduct leak tests 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. 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.

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

effective date of this AD, perform the requirements of paragraph

(b)(3)(i), (b)(3)(ii), or (b)(3)(iii), 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.

(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 as specified in paragraph (b)(3)(ii)(A) of

this AD.

(ii) If a vacuum breaker check valve, Monogram part number

series 3765-190 or Shaw Aero Devises part number series 301-0009-01,

is installed on the subject lavatory; replace the seals/o-rings in

the valve. Prior to further flight, leak test the vacuum breaker

check valve, and test for proper operation of the vent line vacuum

breaker as specified in paragraphs (b)(3)(ii)(A) and (b)(3)(ii)(B)

of this AD.

(A) Leak test the toilet tank anti-siphon valve or the vacuum

breaker check 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). Pressurize the

airplane to 3 PSID. 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/opened during the test. Test for leakage at the

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

Note 5: The leak test procedure in the appropriate section of

Boeing Maintenance Manual 38-32-00 may be used as guidance for this

test if the toilet tank is filled approximately half full (at least

2 inches above the flapper in the bowl).

(B) 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.

If back drainage does not occur, replace the vent line vacuum

breaker or repair the vacuum breaker check valve in accordance with

the component maintenance manual as required to obtain proper back

drainage.

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

number series 0062-009 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 in accordance with paragraph (b)(3)(ii))(A)

of this AD.

(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 placard

inoperative.

(6) Provide training programs for maintenance and servicing

personnel that include information on ``Blue Ice Awareness'' and the

hazards of ``blue ice''.

(7) If a leak is discovered during a leak test required by

paragraph (b) of this AD; 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 test 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;

[[Page 62721]]

(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 test interval;

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

replacement intervals required by this AD;

(7) Whether or not a service panel drain valve is installed

downstream of an in-line drain valve, Kaiser Electroprecision part

number series 2651-278: Data on a service panel valve installed

downstream of an in-line drain valve will not be considered as an

indicator of the reliability of the service panel drain valve

because the in-line valve prevents potential leakage from reaching

the service panel drain valve.

(8) Whether or not leakage has been detected between leak test

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

worn seals, foreign materials on sealing surface, scratched or

damaged sealing surface on valve, etc.);

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

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

activities have been accomplished prior to conducting the periodic

leak test, that leak test 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 test will not cause that leak

test to be recorded as a failure. Debris removal of major blockages

done as part of normal maintenance for previous flights is also

allowable and will not cause a leak test to be recorded as a

failure. Minor debris removal that is not commonly removed during

the normal ground maintenance test should not be removed prior to

the leak test.]

Note 7: Requests for approval of revised leak test 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 test 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 test 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 test 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 test

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

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

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

actions specified in paragraph (d)(1), (d)(2), or (d)(3) of this AD:

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

lines for all lavatories. Or

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

190, or Shaw Aero Devises part number series 301-0009-01, in the

flush/fill lines for all lavatories. Or

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

number series 0062-0009 on the flush/fill lines for all 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 tests 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 test has been performed

once, each subsequent leak test 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 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 would result in the

earlier accomplishment date for that leak test.

(2) For airplanes that have not been previously maintained 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 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

tests of the forward waste drain system for those operators

installing the modifications specified in Boeing Service Bulletin

737-38-1026, Revision 2, dated May 4, 1995, or Boeing Service

Bulletin 737-38-1031, Revision 1, dated April 20, 1995, and later

FAA-approved revisions, are considered acceptable alternative

methods of compliance with the requirements of only paragraph (a)(2)

of this AD. For those operators, the other requirements of this AD

are still required to be accomplished. All other alternative methods

of compliance approved for AD 89-11-03 are terminated and are no

longer in effect.

Note 10: Information concerning the existence of approved

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

obtained from the Seattle ACO.

Note 11: For any valve that is not eligible for the extended

leak test intervals of this AD: To be eligible for the extended leak

test intervals specified in paragraph (b) of this AD, 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

Secs. 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 November 18, 1997.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 97-30855 Filed 11-24-97; 8:45 am]

BILLING CODE 4910-13-U