Airworthiness Directives; Boeing Model 727 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 90-NM-265-AD; Amendment 39-9073; AD 94-23-10]

Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing AD that currently

requires periodic leak checks of the forward lavatory drain system and

provides for the installation of a new drain valve as terminating

action. This action continues to require various leak checks, but

deletes a previously provided terminating action; adds requirements for

leak checks of other lavatory drain systems; provides for the option of

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

leak checks; requires the installation of a cap on the flush/fill line;

and requires either a periodic leak check of the flush/fill line cap or

replacement of the seals on both that cap and the toilet tank anti-

siphon (check) valve. This amendment 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 had formed from leaking forward lavatory drain systems and

subsequently had dislodged from the airplane. The actions specified by

this AD are intended to prevent such damage associated with the

problems of ``blue ice.''

EFFECTIVE DATE: December 16, 1994.

ADDRESSES: The service information referenced in this AD may be

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

Washington 98124-2207. This information may be examined at the Federal

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

103, Attention: Rules Docket No. 90-NM-265-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.

FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer,

Seattle Aircraft Certification Office, Systems and Equipment Branch,

ANM-130S, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056; telephone (206) 227-2788; fax (206) 227-

1811.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to add an airworthiness directive (AD), applicable

to Boeing Model 727 series airplanes, was published as a supplemental

notice of proposed rulemaking (NPRM) in the Federal Register on March

18, 1994 (59 FR 12865). That supplemental NPRM proposed to supersede AD

86-05-07, amendment 39-5250 (51 FR 7767, March 6, 1986). That AD

currently requires periodic leak checks of the forward lavatory drain

system and provides for the installation of a new drain valve as

terminating action.

Among other things, the supplemental NPRM proposed to:

1. Delete the existing provision for terminating action;

2. Require repetitive leak checks of both the forward and the aft

lavatory drain systems;

3. Provide an optional procedure for complying with the rule, which

would entail revising the FAA-approved maintenance program to

incorporate a schedule and procedure to conduct leak checks of the

lavatory drain systems; and

4. Require the installation of a lever lock cap on flush/fill

lines, and periodic leak check of the flush/fill line.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Personal Injury Risk of Blue Ice

Several commenters request that all actions applicable to the aft

lavatory drainage systems be deleted from the proposed rule, since the

risk of injury caused by ``blue ice'' forming at an aft lavatory,

dislodging from an airplane, and striking a person on the ground is

extremely remote. As justification for their request, these commenters

cite an analysis that was performed in 1990 to determine the

probability of personal injury. This analysis concludes that such

probability is on the order of 1 x 10-9 per flight.

The FAA does not concur with these commenters' request. The

criteria of a probability of injury being on the order of 1 x

10-9 per flight hour is relevant when an aircraft system is

originally certified. However, once an unsafe condition becomes known

to the FAA, an analysis is not necessarily sufficient to refute the

unsafe condition. The FAA considers that the numerous reported cases of

``blue ice'' striking and damaging houses, cars, and populated areas is

sufficient to support the conclusion that ``blue ice'' falling from aft

lavatory drain systems presents an unsafe condition.

Moreover, the FAA does not find the analysis submitted by the

commenters to be conclusive. That particular analysis was based on

several assumptions whose adequacy the FAA questions. Among them are:

1. The analysis assumed that a piece of ``blue ice'' falls to the

ground once every two weeks in the United States. These figures were

based upon language that appeared in a newspaper article and are

apparently anecdotal data. The FAA points out that the cases addressed

in the newspaper article (and, therefore, in the analysis) may be only

the ``reported'' cases; however, the vast majority of cases go

unreported, and are likely to be on the order of many magnitudes

greater than the number reported.

2. Additionally, the crux of the analysis is based on assumptions

that the size of a shadow of a person on the ground is two square feet.

This appears to assume that the person is standing up, the ice comes

straight down, the ice falls as a single projectile, and the ice does

not break into smaller pieces as it comes through a roof and ceiling.

None of these assumptions are proven or representative of a typical

scenario.

Further, the FAA points 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 unchecked 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.

Reliability Targets for Leak Check Intervals

One commenter requests that the FAA provide reliability targets so

that operators would know what data were necessary to obtain FAA

approval of any request for an extension of a leak check interval. The

FAA cannot concur with the commenter's request. The FAA has not

provided such a ``reliability target'' because of the difficulty

involved in specifying a target that would be applicable to and

appropriate for all or most operators. While the FAA recognizes that

larger operators are more likely to be able to provide a statistically

significant data package, it considers that the approach to the

development of ``reliability targets'' must also allow smaller

operators to participate. For these reasons, and until a universal

reliability target program can be developed, the FAA will review

individual requests on a case-by-case basis. Paragraph (c) of the final

rule provides for the submission of data to be considered for the

approval of extensions to leak check intervals; these data can be

summarized and accompanied by recommendations from industry groups.

Data From Boeing Model 737's

One commenter requests that the FAA consider data from Boeing Model

737 airplanes, in conjunction with data from Boeing Model 727

airplanes, when reviewing requests to extend the leak check interval.

The FAA points out that, even though the design of the Model 727 and

Model 737 are not similar in many aspects, the functioning of the

lavatory drain systems on both models may be similar due to the

similarity of the hardware used. Therefore, the FAA will consider data

from similar drain systems of different airplane models when reviewing

requests received to extend leak check intervals; however, in

accordance with the data gathering requirements of paragraph (c) of

this final rule, any data submitted must reflect which airplanes and

which drain valves the data represent.

Boeing Specifications vs. Brand Name Valves

Several commenters request that the proposed rule be revised so

that affected hardware is identified by Boeing Specification number,

rather than by vendor part numbers. These commenters are concerned that

certain parts may not qualify for longer inspection intervals because

they have dash numbers not called out specifically in the proposed

rule. They consider that this is not only confusing, but inequitable,

since many later hardware configurations will fall into the ``any other

type valve'' category that provides for a leak check interval of only

400 flight hours. The commenters consider that requesting ``alternative

methods of compliance'' will become the norm, unless the rule is

revised to refer to hardware specification numbers. One commenter, a

manufacturer of valves, is concerned that it will be unable to market

its equipment because the proposed rule provides no performance

standards under which its valves can qualify.

On the other hand one commenter objects to the FAA's statement in

the preamble to the supplemental NPRM that indicated, ``* * * 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.'' This commenter interprets the phrase to be a requirement for

Boeing approval of any alternative valve only to the Boeing

specifications.

The FAA does not concur with the commenters' requests to call out

valves by Boeing specification only. Boeing specifications were not

referenced in this final rule because the FAA does not consider it

appropriate for Boeing to screen and potentially disapprove, for

purposes of this AD, alternative valves that may not qualify to

Boeing's specifications. This would have the effect of delegating to

Boeing, through its specification qualification procedure, the

authority to approve or disapprove alternative methods of compliance

with this AD. Approval under a Boeing specification is not a

requirement for a valve design under this rule; it is only a factor to

be considered. Other factors may be taken into account as well, such as

having extensive service history data. Review and approval of

alternative valve designs is a function of the FAA through the

``alternative methods of compliance'' procedures provided by paragraph

(f) of the final rule. The wording of the NOTE 7 following paragraph

(f) of the final rule has been revised to clarify this point.

Qualifying For 1,000 Flight Hour Leak Check Interval

Several operators request that the proposed rule be revised to

include a provision that would allow any service panel drain valve,

manufactured by any manufacturer, to become qualified for the 1,000-

flight hour leak check interval. These commenters state that, by

restricting the 1,000-flight hour interval to only certain brand name

valves, the FAA restricts competition that could lead eventually to the

development of better valves.

The FAA does not agree that the 1,000 flight hour leak check

interval should be allowed unequivocally for all service panel drain

valves. Current service history data indicate that some valves are more

reliable than others; those valves that have demonstrated such

reliability in service so far are the valves identified (by brand name)

in this rule. The FAA does not consider that a design review and

qualification test are sufficient to determine how well a valve will

perform in actual service. This has been clearly demonstrated by the

history of this specific AD action: the installation of any of several

valves was designated previously as terminating action for the required

leak check, but those valves were later found to be subject to leakage.

However, the FAA does agree that requirements for service history data

should not be so rigid as to preclude competition by valve

manufacturers with new designs. Therefore, the FAA will consider

requests for inclusion in the 1,000-flight hour leak check category any

valve for which the design, qualification test, and service history

data are provided. The request should include an analysis of known

failure modes for the valve and failure modes of similar valves; an

explanation should be included as to how the design features of the

valve will preclude these failure modes. Also included should be the

results of qualification tests, and service history data covering

approximately 25,000 flight hours or 25,000 flight cycles (including a

winter season), collected in accordance with the requirements of

paragraph (c) of the final rule, or a similar program. The final rule

has been revised to include a new NOTE 7 to specify the request for

this information. -

Further, the FAA notes that one operator and a manufacturer,

Pneudraulics, already have provided these data to the FAA, and the

final rule has been revised to add certain Pneudraulics valves to the

category of valves subject to a 1,000-flight hour leak check interval.

(Without the submission and approval of this data, these valves would

have been required to be leak checked at the 200-flight hour interval.)

Differences Between Paragraphs (a) and (b) of the Rule

One commenter maintains that the FAA's safety objective in

addressing the ``blue ice'' issue should be to ensure that each and

every operator has a comprehensive lavatory drain service program in

place. The commenter points out that the FAA attempted this approach

under the provisions of proposed paragraph (b), but made the conditions

of compliance more stringent than those of proposed paragraph (a), such

that no operator would elect to comply with paragraph (b). The

commenter considers this unfortunate since it will result in a less

effective ``blue ice'' prevention program fleetwide.

The FAA acknowledges that a difference exists between the

provisions of paragraphs (a) and (b), both in the supplemental NPRM and

in this final rule. However, as explained elsewhere in this preamble,

the FAA has revised several requirements of paragraph (b) of the final

rule to make it more ``attractive'' to operators. Certain of these

revised requirements include extended leak check intervals for some

valves. The FAA does consider that revising the maintenance program to

include the procedures specified in paragraph (b) will be more

effective overall in addressing ``blue ice'' as an on-going issue. The

provisions of paragraph (b) are more comprehensive in approach: they

include requirements not only for leak checks of the valves, but

replacement of valve seals, repetitive visual inspections for leakage,

procedures for reporting leakage, and training programs to inform

pertinent personnel on ``blue ice'' awareness.

The FAA considers that it is appropriate to maintain the provisions

of paragraph (a) as an option, so that operators without an FAA-

approved maintenance program will have some means to comply with the

rule.

Along this same line, another commenter points out other

differences between the provisions of paragraphs (a) and (b). The

commenter indicates that any valve service history data that is

gathered by an operator complying with paragraph (a) may not be as

valuable as data gathered by an operator complying with paragraph (b).

Unless there is a specific, scheduled maintenance program, there is no

way to determine if a valve may have begun leaking before a leak check

was conducted and was subsequently repaired; therefore, merely passing

a leak check successfully, as under the provisions of paragraph (a),

does not verify the valve's reliability. The FAA acknowledges this

commenter's observations. However, the FAA expects that some operators

will choose to comply with the provisions of paragraph (b) and will

provide the FAA with valve service history data. These data may

indicate that the current leak check intervals are acceptable for

operators operating under a maintenance program, but should be

shortened for operators without a maintenance program. If, as the

commenter suggests, leak tests alone prove to be inadequate to prevent

``blue ice'' formation, the FAA may consider revising this rule at a

later time to modify or delete paragraph (a).

Alternative Recordkeeping

Several commenters request that a revision be made to proposed

paragraph (b) that would allow for the use of an alternative method of

recordkeeping to that otherwise required by Federal Aviation

Regulations Sec. 121.380 (14 CFR 121.380), ``Maintenance recording

requirements''. The commenters' main concern is that it should be clear

to the cognizant Principal Maintenance Inspectors (PMI), and other FAA

officials in the years ahead, that once the maintenance program

revision is made and approved, the AD is ``signed off as complete.'' No

other special records should be required to track the various tasks

specified in proposed paragraph (b) (such as valve seal replacement,

training, reporting procedures, visual checks, etc.), which are in

addition to the recordkeeping requirements that now exist within each

of the affected operator's maintenance program.

The FAA does not concur with the commenters' request for many of

the same reasons it did not concur with a similar request made in

response to the previous supplemental NPRM. The FAA considers that,

even though this AD would affect the maintenance program, it is of such

importance that it warrants other than ``normal'' procedures to be

followed in certain aspects. Some method of recordkeeping must be

maintained to ensure that the required valve seal changes and periodic

leak checks continue, and to ensure that the procedures required by

this AD are not eventually dropped from any operator's maintenance

program.

Principal Maintenance Inspector Involvement

These same commenters request that a statement be added to proposed

paragraph (b) to indicate that the ``AD is no longer applicable once a

revision to the FAA-approved maintenance program is implemented.''

These commenters indicate that it would be less cumbersome to operators

to accomplish all of the AD-required tasks within the parameters of

their FAA-approved maintenance program, where the cognizant PMI would

be the FAA official permitted to approve any further changes to the

program. These commenters contend that it is much more appropriate for

the PMI, rather than the Seattle Aircraft Certification Office (ACO)

engineering staff, to approve subsequent changes to the program once

the program has been approved. The commenters consider that the PMI is

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

reporting, and adjustments to the leak check intervals based upon

reliability program recommendations. The commenters point 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 FAA does not concur with this request for the same reasons it

did not concur with a similar request made by these commenters to the

previous supplemental NPRM. While the FAA agrees that the PMI may be

permitted certain oversight of the proposed alternative maintenance

program provision of the rule (specifically with regard to

recordkeeping), the FAA does not agree that the PMI should be tasked

with approving certain adjustments of the program. As was explained in

detail in the preamble to the supplemental NPRM, 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 check 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's 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 check intervals will maintain an

acceptable level of safety.

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

required leak check intervals, seal change intervals, and data

reporting procedures should be approved in a uniform manner in order 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.

Specific Leak Check Instructions

One commenter requests that the proposed rule be revised to include

a procedure for performing the leak checks. The commenter suggests that

the instructions contained in Boeing Service Letter 737-SL-38-3-A

(which applies to Model 737 series airplanes) be referenced in order to

ensure that all affected operators perform the same leak check. The FAA

does not concur totally. The instructions contained in Boeing Service

Letter 737-SL-38-3-A address only the forward lavatory service panel

(not the aft or executive panels), and do not correlate with the

requirement to perform a leak check of the outer cap on certain valves.

The instructions do contain procedures for performing a leak test of

the toilet tank anti-siphon (check) valve, which are appropriate for

performing that leak check in accordance with the requirements of this

AD; therefore, the FAA has added a Note to paragraphs (a)(5) and (b)(3)

to indicate that operators may consider the leak check procedures

relative to the toilet tank anti-siphon (check) valve in accordance

with the service letter as an acceptable means of compliance with those

paragraphs. The FAA does agree that a standard leak check procedure

would be beneficial, and will consider revision of this final rule to

include one if an acceptable procedure becomes available in the future.

Another commenter requests that the proposed rule be revised to

include specific procedures for conducting the leak check of the dump

valve. This commenter suggests that this leak check should be performed

by filling the toilet tank with water or rinsing fluid to a level such

that the bowl is approximately half full (at least 2 inches above the

flapper in the bowl) and waiting at least 5 minutes to determine if

leakage is present. The FAA concurs and has revised the rule to include

a new Note 1, which indicates that operators may conduct this

particular leak check in accordance with the procedures suggested by

this commenter.

Service Panel Waste Drain Cap Leak Check

Several commenters request that paragraphs (a)(1)(i) and (b)(2)(i)

of the proposed rule be revised to delete the requirement to perform a

leak check of the service panel waste drain cap that does not have an

inner door with a second positive seal. These commenters state that, to

perform this leak check, approximately 20 gallons of contaminated waste

water are required to be dumped on the ramp; such dumping violates

various environmental regulations.

The FAA does not agree that conducting this leak check will

necessarily require spilling a vast amount of waste water on the ramp.

Compliance with FAA rules is not a license to violate environmental

regulations. Operators could devise a means to catch or handle the

waste water to ensure that they will be in compliance with applicable

State or Federal environmental regulations. -

However, the FAA has reconsidered this requirement for leak checks

of the service panel waste drain cap in waste drain systems

incorporating in-line drain (ball) valves. The FAA has determined that,

for these configurations, the valve reliability is sufficient to

obviate the need for additional assurance provided by performing a leak

check of the cap, as long as a leak check of the dump valve is

accomplished. A leak check of the dump valve (in-tank valve that is

spring loaded closed and operable by a T-handle at the service panel)

can be accomplished easily and does not entail spillage of waste on the

ramp. Therefore, the FAA has revised paragraph (b)(2)(i) of the final

rule to require operators to perform a leak check of the dump valve, in

lieu of performing a leak check of the cap valve. Operators would still

be required to perform a leak check of the in-line drain (ball) valve.

The leak checks must be accompanied by visual inspections of the

service panel drain valve outer cap/door seal, the inner seal (if the

valve has an inner door/closure device with a second positive seal),

and seal mating surface for wear or damage that may cause leakage.

This revision to the requirements of the final rule does not entail

any additional burden on operators. As previously proposed, operators

would have been required to perform leak checks of both the inner and

outer doors of the cap valve and of the in-line drain valve, and a

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

As now required by the final rule, operators will be required to

perform fewer leak checks of valves, and one additional visual

inspection of the (inner) door seals. Since visual inspections are less

labor-intensive and less costly than leak checks, the FAA considers

that the revised requirements will significantly reduce the economic

burden on affected operators.

Similarly, the FAA has revised the requirements of paragraphs

(b)(2)(ii) and (b)(2)(iv), which require leak checks of the dump valve

and service panel valve. The final rule now specifies that the leak

check of the service panel drain valve need only entail a leak check of

the inner door/closure device (rather than leak checks of both the

inner and outer door, as was previously proposed), provided that a

visual inspection is made of the outer cap/door seal and seal mating

surface for wear or damage.

The FAA has not revised the similar requirements of paragraph

(b)(2)(iii), which pertains to drain systems incorporating ``donut''

valves. As explained later in this preamble, the reliability of this

type of valve is such that a leak test of the downstream cap is

considered necessary; therefore, paragraph (b)(2)(iii) retains the

requirement for leak checking the cap in drain system configurations

where ``donut'' valves are installed.

Waste Drain System Leak Check Procedure

One commenter requests that proposed paragraphs (a) and (b)(2) be

clarified to specify that, for drain systems that may contain more than

one kind of valve, only one of the waste drain system leak check

procedures needs to be conducted at each service panel location. The

procedure conducted should be the one that applies to the equipment

with the longest leak check interval. The FAA concurs with the

commenter's request, since this was the intent of this requirement. The

final rule has been revised to clarify this point.

Kaiser Valve Part Numbers

One commenter requests that the part number for the Kaiser

Electroprecision in-line drain valve, specified in the proposal as

``part number 2651-329-5 (or higher dash number),'' be revised to

include the entire part number 2651-329 series. The valves in this

series are all virtually identical in design and, therefore, would have

the same reliability. The FAA concurs and has revised the final rule to

call out these valves as ``Kaiser Electroprecision part number series

2651-329.''

Additionally, this same commenter requests that the proposed rule

be revised to include Kaiser Electroprecision in-line drain valves,

having part number series 2651-334 and 2651-278, in all requirements

that apply to part number series 2651-329 valves. Although these valves

differ slightly in their inlet/outlet configurations, actuating handle

sizes and shapes, and actuating handle orientation and movement, they

are identical in their main sealing components, design standards, and

principle of operation; therefore, their reliability can be assumed to

be equivalent. The FAA concurs and has revised the final rule

accordingly. Operators should note that a review of available data

indicates that the latter valve series are not currently installed on

Boeing 727 airplanes, however.

Leak Check Interval for Kaiser Valves

Other commenters request that the proposed rule be revised to

permit the Kaiser Electroprecision part number series 0218-0026 valves

(Expander Valves) to be leak checked at the same interval as the valves

listed in the supplemental NPRM for 1,000-flight hour leak checks. This

valve series was qualified to and meets the design/performance criteria

of Boeing Specification 10-62213 (Revision A). The commenter indicates

that a large number of these valves have been installed in various

transport category aircraft, and a tracking of the service history of

the installed valves reveals that over one million flight hours have

been accumulated without any reported leakage.

The FAA partially concurs with the commenter's request to provide

an extended leak check interval for this specific valve series. The FAA

considers that the presence of a forced-opening, or ``icebreaker,''

feature in a valve reduces the likelihood that service abuse will occur

that would create a leaking valve. Unlike other valves eligible for

inspections at 1,000-flight hour intervals in this rule, the Kaiser

Electroprecision part number series 0218-0026 valves do not have such

an ``icebreaker'' feature. In light of this, as well as the service

history data provided, the FAA has revised the final rule to add a new

paragraph (a)(3) to address these Kaiser Electroprecision valves and to

provide for a repetitive 600-flight hour leak check of them for those

operators electing to comply with paragraph (a) of the final rule. The

FAA has also revised paragraph (b)(2)(ii) of the final rule to include

these Kaiser Electroprecision valves in the requirements for leak

checks at 1,000 flight hour intervals. The FAA has determined that the

difference in this leak check interval between paragraph (a) and (b) is

appropriate, since the repetitive visual inspections, seal replacement

requirements, and other comprehensive aspects of paragraph (b) will

ensure that any leakage will be detected that may be caused by service

damage inflicted on the valve (due to lack of an icebreaker feature on

the valve).

Additionally, the FAA has revised the repetitive leak check

interval for the Kaiser Electroprecision valves subject to the

requirements of paragraph (b)(2)(i). That paragraph has been revised to

provide for conducting the applicable repetitive leak checks at

intervals of ``5,000 flight hours or 24 months, whichever occurs

later.'' (The supplemental NPRM proposed a repetitive leak check

interval of 5,000 flight hours only.) This provision has been made in

acknowledgment of those operators who may have related maintenance

procedures that are conducted on a schedule based on calendar time

rather than on flight hours.

Kaiser Expander Valve

One commenter has concerns about the requirements of proposed

paragraph (b)(2)(i) of the supplemental NPRM, which is applicable to

forward lavatory drain systems modified in accordance with Boeing

Service Bulletin 727-38-0021. This commenter indicates that the

proposed paragraph does not require that a Kaiser Electroprecision

Expander Valve or a lever-lock cap be installed in accordance with that

Boeing service bulletin, even though the service bulletin does refer to

such installations in certain of its modification procedures. This

commenter questions whether those installations are required to be

installed and, if so, suggests that the FAA re-issue this AD action as

a proposal to clearly indicate the intent of that paragraph.

The FAA acknowledges this commenter's concerns and agrees that

different interpretations are possible from the wording of paragraph

(b)(2)(i) as it appeared in the supplemental NPRM. The FAA has revised

the final rule to delete reference to Boeing Service Bulletin 727-38-

0021, and to merely call out the applicable Kaiser Electroprecision

part number series valves. This revision should make clear that there

is no requirement for installation of a Kaiser Electroprecision

Expander Valve to qualify for the repetitive 5,000 flight hour leak

checks. The requirement for installing a lever lock cap is contained in

paragraph (d) of the supplemental NPRM and this final rule.

Kaiser Expander Valve/In-Line Drain Valve Combination

One commenter requests that the proposed rule be revised to

establish a 6,000-flight hour leak check interval for installations of

an in-line drain valve in combination with a Kaiser Electroprecision

Expander Valve. As proposed, the leak check interval for this

combination of valves is 5,000 flight hours. The commenter provided no

justification for this request, however.

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

data have demonstrated that the seal life and reliability of the

Expander Valve are significantly less than that of the in-line drain

valve. In light of this, an extension of the 5,000-flight hour interval

to a 6,000-flight hour interval is not justified for the in-line drain

valve in combination with the Expander Valve. However, under the

provisions of paragraph (b)(5)(i)(B) of the final rule, if an in-line

drain valve is found to have abnormal operation of the handle, the

system may continue in operation, provided a service panel drain valve

that is in the 1,000-flight hour leak check interval category is

installed in the system and has passed a leak check within the

preceding 1,000 flight hours.

Shaw Aero Valves Part Numbers

Several commenters request that the proposed rule be revised to

include Shaw Aero Devices valves in the part number 1010100B and

1010100C series in the requirements for 1,000-flight hour leak check

intervals. One of these commenters indicates that these part-numbered

valves are merely later generations of the Shaw Aero Devices part

number 1010100C-N (or higher dash number) valve, which was called out

in the supplemental NPRM and for which a 1,000-flight hour leak check

interval was proposed.

The FAA agrees that these Shaw Aero Devices valves should be

addressed in the AD, and that some increase in the leak check interval,

above the basic 200-flight hour interval, is justified for these

valves. However, the FAA does not concur with the commenters' request

to provide for a 1,000-flight hour leak check interval for them in all

circumstances. The FAA has obtained data on certain design

improvements, such as an ``ice breaker'' feature, that have been made

to certain Shaw Aero Devices valves to correct previously identified

deficiencies. Evidence indicates that Shaw Aero Devices valves having

part number 1010100B-A-1, and having serial numbers 0115 through 0121

(inclusive), 0146 through 0164 (inclusive), and 0180 and higher,

incorporate these design improvements. Therefore, the FAA has revised

paragraph (a)(2) of the final rule to include these specific valves in

the requirements for the 1,000-flight hour leak check interval.

These data also indicate that, while some Shaw Aero Devices valves

in the part number series 1010100C incorporate the ``ice breaker''

feature and have a configuration that corrects known design

deficiencies, other valves in this same series do not incorporate these

features. Therefore, not all Shaw Aero Devices part number series

1010100 are included in the 1,000-flight hour interval leak check

category. Accordingly, the FAA has revised the final rule to include a

new paragraph (a)(3), applicable to certain part number series 1010100C

valves (those without the ice breaker feature and other improvements),

which provides for a 600-flight hour leak check interval for them.

Paragraph (b)(2)(ii) of the final rule has been revised to address

these valves and provides for a 1,000-flight hour leak check interval

for them. [As explained previously, justification for the extended

interval under paragraph (b) is that the maintenance program provisions

of paragraph (b) should detect any leakage caused by service damage

inflicted due to lack of an icebreaker feature or other improvement on

the valve.] This is considered interim action, however. The FAA plans

further review of the valves in this part number series to determine if

these leak check intervals are appropriate, or whether they should be

extended or shortened.

For these same reasons, the FAA also is reviewing the valves

included in the part number 1010100C-N (and higher dash number) group,

which was called out in paragraphs (a)(2) and (b)(2)(ii) of the

supplemental NPRM. Currently, this final rule provides for a 1,000-

fight hour leak check interval for these valves. However, as more data

become available, the FAA may consider further rulemaking to address

the leak check interval for this particular valve group.

``Donut'' Valves

One commenter contends that ``donut'' valves, which are addressed

in proposed paragraph (b)(2)(iii), are unsafe and should be banned

immediately. This commenter states that these valves are of design that

has resulted in significant leakage and ``blue ice'' incidents. In

discussions with airline personnel, this commenter has found that it is

commonplace to find these valves leaking, or to find that the

``donuts'' are missing when an aircraft reaches its destination. It is

common to have the ``donut'' installed at the start of the day and find

it to be missing only one to two flights into the day. This is clearly

a dangerous situation.

The FAA acknowledges this commenter's remarks. During the past year

the FAA has received two additional reports of engine damage caused by

``blue ice'' formation from lavatory drain systems using ``donut''

valves. The FAA is continuing to review this service history of these

valves and may consider further rulemaking to require their removal

from service.

Additionally, the FAA has revised paragraph (b)(2)(iii) of the

final rule to specify certain Kaiser Roylyn part-numbered valves as

ones that incorporate the ``donut'' configuration and are, therefore,

subject to the requirements of that paragraph.

``Taco'' Valves

One commenter requests that the Kaiser Electroprecision ``taco''

valve be deleted from proposed paragraph (b)(2)(iii), which would

require that it be leak checked at intervals of 200 flight hours. The

commenter suggests that it be included in paragraph (b)(2)(iv),

instead, since that paragraph addresses similar double-door types of

valves and requires their inspection at intervals of 400 flight hours.

The FAA concurs with this request and has revised the final rule

accordingly. This change leaves only the ``donut'' valve in the

category of valves [addressed by paragraph (b)(2)(iii)] requiring leak

checks at the 200-flight hour interval. The FAA considers this

appropriate, since the ``donut'' valve clearly has been the valve

associated with the greatest number of problems relative to ``blue

ice.''

Visual Inspections To Detect Leakage

Several commenters request that paragraph (b)(4) be revised to

allow flight crew to perform the visual inspections to detect leakage.

These commenters state that, since this inspection involves only a

visual examination, trained maintenance personnel should not be made to

accomplish it.

The FAA does not concur with the commenters' request. While flight

crews are authorized to perform walk-around inspections of the

airplane, in accordance with FAR 91.7(b) [14 CFR 91.7(b)], ``Civil

aircraft airworthiness,'' there is no requirement for the flight crew

to record the results of that inspection. The FAA considers that

certified maintenance personnel are best suited to perform this

inspection due to their specific skills, training, and experience with

reporting procedures.

Flush/Fill Line Cap Installation

Several commenters request that the proposed rule be revised to

delete paragraph (d), which would require the installation of a cap on

the flush/fill lines for forward, aft, and executive lavatories. One

commenter states that the caps on the service panel are a secondary

sealing system, and that the toilet check valve is the primary seal

preventing fluid from flowing back down this line. Other commenters

also request that the requirements for periodic leak testing of the cap

be deleted. Additionally, one commenter believes that installation of a

cap on the flush/fill line will cause problems because, in their

experience, if the caps are installed, the residual flush/fill fluid

trapped inside the line will freeze by the time it reaches the next

destination; the frozen line and installed cap must be thawed out prior

to servicing of the lavatory, which can create a delay in normal

operations. This commenter and others suggest that, as an alternative

to the installation of a cap and a leak test, the proposed rule should

be revised to require periodic replacement of the seal in the toilet

tank anti-siphon (check) valve. The commenters point out that this

valve, when maintained, effectively prevents the toilet fluid from

being siphoned out through the flush/fill line, thereby making the cap

unnecessary.

The FAA does not concur with the requests to delete the requirement

for installation of a cap on the flush/fill line, but does concur that

certain alternative procedures may be provided. The FAA has received a

report of a Boeing Model 727 series airplane that experienced an in-

flight shutdown of the number 3 engine due to the ingestion of ``blue

ice'' caused by leakage from the flush/fill line. Investigation

revealed that approximately one in four of the toilet tank anti-siphon

(check) valves in the affected operator's fleet was found to leak

within a three-month period. The FAA has concluded that the anti-siphon

(check) valve alone does not appear to have sufficient integrity and

reliability to prevent leakage from the flush/fill line. However, the

FAA does acknowledge that, because the flush/fill line does not

normally have water in it and a leak test of the flush/fill line cap is

impractical in many circumstances, it is sufficient to replace the

seals in the toilet tank anti-siphon valve and the cap, and perform a

leak check of the toilet tank anti-siphon (check) valve. Paragraphs

(a)(5) and (b)(3) of the final rule have been revised to provide for

this alternative procedure.

Several commenters request that proposed paragraph (d) be revised

to delete the requirement that installation of the cap must be

accomplished only in accordance with Boeing Service Bulletin 727-38-

0021, dated July 30, 1992. That service bulletin specifies the

installation of a particular lever-lock cap; however, the commenters

request that other FAA-approved lever-lock caps also be permitted to be

used. (In their comments, certain commenters provided design and

service history data on another such lever-lock cap.) The FAA agrees

that other FAA-approved lever-lock caps are acceptable in this

installation, and has revised the final rule to specify this.

One commenter requests that any FAA approved cap, as opposed to

only lever/lock caps, be considered sufficient for the installation

required by proposed paragraph (d). The FAA does not concur, since the

commenter provided no design or service history data for any other

particular cap. However, under the provisions of paragraph (f) of the

final rule, this commenter may elect to provide such data in a request

for an alternative method of compliance with the rule.

One commenter considers that installation of a cap without a

provision for a heating element will cause ice to form in the line at

the cap. This commenter has experienced this problem on airplanes in

its fleet that are equipped with a lever-lock cap. This freezing

problem has been further exacerbated when service personnel have

damaged the caps or flush/fill line by trying to remove the ice with a

tool (such as a screw driver). The commenter suggests that the rule

should require installation of a heating element to prevent freezing in

or on the flush/fill line, and points out that Boeing Service Bulletin

727-38-0021, which is referenced in proposed paragraph (d) for the cap

installation procedures, does not call for installation of any heating

element.

The FAA agrees that one way to prevent freezing in the subject area

may be to install an FAA-approved heating element. It is also possible

to avoid the freezing problem by allowing the fluid to drain out of the

flush/fill line after servicing the tank. Since frozen flush/fill lines

are avoidable without a heating element, provided proper servicing is

done, the FAA does not consider a specific requirement to install a

heating element to be warranted.

Terminating Action

One commenter requests that installation of an in-line drain valve

per Boeing Specification S417T105 be considered terminating action for

the required leak checks. As justification for this request, the

commenter provided data indicating that, out of several million flight

hours of airplanes equipped with this particular valve, there have been

very few incidents of leakage.

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

available data to date relative to all valves, the FAA has determined

that periodic leak testing of valves, as well as the replacement of

valve seals, is warranted in order to ensure that the valves do not

start to leak. Because of this, the FAA does not consider that there is

currently a ``terminating action'' for these necessary requirements.

Terminology Changes

One commenter requests that the wording of the proposed rule be

revised by changing the term ``operating torque'' to ``operation'' in

all procedures relative to inspections of the valve handle for the in-

line drain valves. This commenter points out that the actuation of

neither the in-line drain valve nor the service panel drain valve is a

rotational movement at the service panel. The FAA concurs and has

revised the terminology of the final rule accordingly.

This same commenter requests that proposed paragraph (b)(5) be

revised by changing the phrase ``blue streak findings'' to ``horizontal

blue streak findings'' when specifying which findings must be reported

to maintenance. The commenter states that this change is necessary in

order to differentiate between indications of leakage that has resulted

from spills that occurred during servicing and indications of leakage

that occurred during flight. Leakage that has occurred during flight

would be indicated by horizontal blue streaks. The FAA concurs and has

revised the terminology in the final rule accordingly.

This commenter also requests that the proposed rule be revised by

deleting the terms ``forward and aft'' when referring to ``each

lavatory * * * having an in-line drain valve installed.'' This

commenter states that some Model 727 aircraft have been built with an

executive mid-cabin lavatory with an in-line drain valve. The FAA

concurs and has revised the rule accordingly. The intent of the rule is

clear that the related procedures are to be performed on ``each''

lavatory having the subject drain valve, regardless of where the

lavatory is located on the airplane.

This commenter further points out that the terms ``service panel

drain valve,'' ``cap valve,'' and ``drain valve at the service panel''

are used in various places throughout the proposed rule to describe the

same valve. The commenter suggests that, in order to be consistent, the

rule be revised to call this valve ``the service panel drain valve'' in

all pertinent references. The FAA concurs and has revised the final

rule accordingly. For similar reasons, the final rule has been revised

by changing the term ``ball valve'' to ``in-line drain valve'' in

several places.

Estimated Cost Figures

Several operators state that the estimated cost impact of the rule,

as presented in the preamble to the supplemental NPRM, is too low and

should be revised to reflect estimates of the costs as submitted by

these individual operators. The FAA does not concur that the estimated

cost impact figure need to be revised. While it is reasonable to assume

that the costs to some operators may be higher than those presented in

this preamble, it is also reasonable to assume that the costs to other

operators may be considerably lower. Therefore, the estimated cost

impact represents an average for the U.S. fleet, based on the best data

available to date. The FAA considers the cost impact estimate, as

presented, to be sufficiently accurate for the purposes of this

rulemaking action.

Cost Impact

There are approximately 1,752 Boeing Model 727 series airplanes of

the affected design in the worldwide fleet, operated by 153 operators.

It is estimated that 1,277 airplanes of U.S. registry and 54 U.S.

operators will be affected by this AD.

The FAA estimates that it will take approximately 4 work hours per

airplane lavatory drain (normally, there are 2 drains per airplane) to

accomplish a leak check, at an average labor cost of $55 per work hour.

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

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

each year. Certain other airplanes having other valve configurations

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

airplanes that have various combinations drain valves installed will

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

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

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

checks on U.S. operators is estimated to be between $6,600 and $1,320

per airplane per year.

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

airplane lavatory drain to accomplish a visual inspection of the

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

average labor cost of $55 per work hour.

As with leak checks, certain airplanes will be required to be

visually inspected as many as 15 times or as few as 3 times each year.

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

required repetitive visual inspections on U.S. operators is estimated

to be between $825 and $165 per airplane per year.

The 1,277 affected airplanes of U.S. registry have, on an average,

3 flush/fill lines per airplane. The FAA estimates that the

installation of a level lock cap assembly will require approximately 2

work hours to accomplish, at an average labor cost of $55 per work

hour. Required parts are estimated to be $275 per drain installation.

Based on these figures, the total cost impact of the requirement to

install a cap on the flush/fill lines is estimated to be $1,474,935, or

an average of $1,155 per airplane.

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

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

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

these actions could be accomplished coincidentally or in combination

with normally scheduled airplane inspections and other maintenance

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

work hours will 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 AD action, the FAA

estimates that it will take approximately 40 work hours per operator to

incorporate the lavatory drain system leak check procedures into the

maintenance programs, at an average labor cost of $55 per work hour.

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

maintenance revision requirement of this AD action on the 54 U.S.

operators is estimated to be $118,800, or $2,200 per operator.

The ``total cost impact'' figures described above are based on

assumptions that no operator has yet accomplished any of the

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

actions in the future if this AD were not adopted.

The FAA recognizes that the obligation to maintain aircraft in an

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

require specific actions to address specific unsafe conditions, they

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

However, because of the general obligation of operators to maintain

aircraft in an airworthy condition, this appearance is deceptive.

Attributing those costs solely to the issuance of this AD is

unrealistic because, in the interest of maintaining safe aircraft,

prudent operators would accomplish the required actions even if they

were not required to do so by the AD.

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

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

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

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

complies with all applicable airworthiness requirements. In adopting

and maintaining those requirements, the FAA has already made the

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

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

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

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

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

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

analysis for this AD would be redundant and unnecessary.

Regulatory Impact

The regulations adopted herein will not have substantial direct

effects on the States, on the relationship between the national

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

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) will not have a

significant economic impact, positive or negative, on a substantial

number of small entities under the criteria of the Regulatory

Flexibility Act. A final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends part 39 of

the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-5250 (51 FR

7767, March 6, 1986), and by adding a new airworthiness directive (AD),

amendment 39-9073, to read as follows:

94-23-10 Boeing: Amendment 39-9073, Docket No. 90-NM-265-AD.

Supersedes AD 86-05-07, Amendment 39-5250.

Applicability: All Model 727 series airplanes, certificated in

any category.

Compliance: Required as indicated, unless previously

accomplished.

To prevent engine damage or separation, 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 and

dislodged from the airplane, accomplish the following:

Note 1: The dump valve leak checks required by this AD may be

performed by filling the toilet tank with water/rinsing fluid to a

level such that the bowl is approximately half full (at least 2

inches above the flapper in the bowl) and checking for leakage after

a period of 5 minutes.

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

the applicable procedures specified in paragraphs (a)(1), (a)(2),

(a)(3), (a)(4), (a)(5) and (a)(6) of this AD. If the waste drain

system incorporates more than one type of valve, only one of the

waste drain system leak check procedures (the one that applies to

the equipment with the longest leak check interval) must be

conducted at each service panel location.

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

valve installed, Kaiser Electroprecision part number series 2651-

329, 2651-334, or 2651-278: Within 1,500 flight hours after the

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

1,500 flight hours, accomplish the following:

(i) Conduct a leak check of the dump valve (in-tank valve that

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

panel) and the in-line drain valve. The in-line drain valve leak

check must be performed with a minimum of 3 pounds per square inch

differential pressure (PSID) applied across the valve. -

(ii) Visually inspect the service panel drain valve outer cap

seal and the inner seal (if the valve has an inner door/closure

device with a second positive seal), and the seal mating surfaces,

for wear or damage that may allow leakage. Prior to further flight,

replace any worn or damaged seal, and repair or replace any damaged

seal mating surfaces, in accordance with the valve manufacturer's

maintenance manual.

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

drain valve installed, Kaiser Electroprecision part number series

0218-0032; or Shaw Aero Devices part number 1010100C-N (or higher

dash number); or Shaw Aero Devices part number 1010100B-A-1, serial

numbers 0115 through 0121, 0146 through 0164, and -0180 and higher;

or Pneudraulics part number series 9527: Within 1,000 flight hours

after the effective date of this AD, and thereafter at intervals not

to exceed 1,000 flight hours, conduct a leak check of the dump valve

and drain valve. The service panel drain valve leak check must be

performed with a minimum of 3 PSID applied across the valve. Both

the inner door/closure device and the outer cap/door must be leak

checked.

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

drain valve installed, Kaiser Electroprecision part number series

0218-0026, or Shaw Aero Devices part number series 1010100C (except

as called out in paragraph (a)(2) above), or Shaw Aero Devices part

number 1010100B (except as called out in paragraph (a)(2) above):

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

thereafter at intervals not to exceed 600 flight hours, conduct a

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

service panel drain valve leak check must be performed with a

minimum 3 PSID applied across the valve. Both the inner door/closure

device and the outer cap/door must be leak checked.

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

(a)(1), (a)(2), or (a)(3) of this AD: Within 200 flight hours after

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

exceed 200 flight hours, conduct a leak check of the dump valve and

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

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

valve. If the service panel drain valve has an inner door with a

second positive seal, both the inner door and the outer cap/door

must be leak checked.

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

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

5,000 flight hours, accomplish either of the following procedures

specified in paragraphs (a)(5)(i) or (a)(5)(ii) of this AD:

(i) Conduct a leak check of the flush/fill line cap. This leak

check must be made with a minimum of 3 PSID applied across the cap.

Or

(ii) Replace the seals on the toilet tank anti-siphon (check)

valve and the flush/fill line cap. Additionally, perform a leak

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

3 PSID across the valve.

-Note 2: The leak test procedure specified in Boeing Service

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

guidance for the procedures required by this paragraph.

(6) If a leak is discovered during any leak check required by

paragraph (a) of this AD, prior to further flight, accomplish one of

the following procedures:

(i) Repair the leak; or

(ii) 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: Within 180 days after the effective date of this AD, revise

the FAA-approved maintenance program to include the requirements

specified in paragraphs (b)(1), (b)(2), (b)(3), (b)(4), (b)(5), and

(b)(6) of this AD.

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

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

AD. Any revision to this replacement schedule must be approved by

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

Transport Airplane Directorate.

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

valve installed, Kaiser Electroprecision part number series 2651-

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

hours after revision of the maintenance program in accordance with

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

52 months.

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

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

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

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

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

in accordance with the applicable schedule specified in paragraphs

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

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

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

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

must be conducted at each service panel location. Any revision to

the leak check schedule must be approved by the Manager, Seattle

ACO, FAA, Transport Airplane Directorate.

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

valve, Kaiser Electroprecision part number series 2651-278, 2651-

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

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

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

hours, whichever occurs later, accomplish the procedures specified

in paragraphs (b)(2)(i)(A) and (b)(2)(i)(B) of this AD: -

(A) Conduct a leak check of the dump valve (in-tank valve that

is spring loaded, closed and operable by a T-handle at the service

panel), and in-line drain valve. The in-line drain valve leak check

must be performed with a minimum of 3 pounds per square inch

differential pressure (PSID) applied across the valve.

(B) Visually inspect the service panel drain valve outer cap/

door seal and the inner seal (if the valve has an inner door/closure

device with a second positive seal) and seal mating surface for wear

or damage that may cause leakage. Any worn or damaged seal must be

replaced and any damaged seal mating surface must be repaired or

replaced, prior to further flight, in accordance with the valve

manufacturer's maintenance manual.

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

drain valve installed, Kaiser Electroprecision part number series

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

or Shaw Aero Devices part number series 1010100C, or Shaw Aero

Devises part number series 1010100B, or Pneudraulics part number

series 9527: Within 1,000 flight hours after revising the

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

thereafter at intervals not to exceed 1,000 flight hours, accomplish

the procedures specified in paragraphs (b)(2)(ii)(A) and

(b)(2)(ii)(B) of this AD:

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

drain valve. The service panel drain valve leak check must be

performed with a minimum of 3 PSID applied across the valve. Only

the inner door/closure device of the service panel drain valve must

be leak checked.

(B) Visually inspect the service panel drain valve outer cap/

door seal and seal mating surface for wear or damage that may cause

leakage. Any worn or damaged seal must be replaced, and any damaged

seal mating surface must be repaired or replaced, prior to further

flight, in accordance with the valve manufacturer's maintenance

manual.

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

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

substitute assemblies from another manufacturer) Kaiser

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

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

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

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

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

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

checks of the dump valve and the service panel drain valve. The

service panel drain valve leak check must be performed with a

minimum 3 PSID applied across the valve. Both the donut and the

outer cap/door must be leak checked.

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

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

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

thereafter at intervals not to exceed 400 flight hours accomplish

the procedures specified in paragraphs (b)(2)(iv)(A) and

(b)(2)(iv)(B) of this AD:

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

drain valve. The service panel drain valve leak check must be

performed with a minimum 3 PSID applied across the valve. If the

service panel drain valve has an inner door/closure device with a

second positive seal, only the inner door must be leak checked.

(B) If the valve has an inner door/closure device with a second

positive seal: Visually inspect the service panel drain valve outer

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

cause leakage. Any worn or damaged seal must be replaced and any

damaged seal mating surface must be repaired or replaced, prior to

further flight, in accordance with the valve manufacturer's

maintenance manual.

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

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

5,000 flight hours, accomplish either of the procedures specified in

paragraphs (b)(3)(i) or (b)(3)(ii) of this AD:

(i) Conduct a leak check of the flush/fill line cap. This leak

check must be made with a minimum of 3 PSID applied across the cap.

Or

(ii) Replace the seals on the toilet tank anti-siphon (check)

valve and the flush/fill line cap. Additionally, perform a leak

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

3 PSID across the valve.

Note 3: The leak test procedure specified in Boeing Service

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

guidance for the procedures required by this paragraph.

(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,

whichever occurs later.

(5) Provide procedures for reporting leakage. These procedures

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

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

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

inoperative.

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

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

The reporting procedures must include provisions for reporting to

maintenance any instances of abnormal operation of the valve handle

for the in-line drain valve, as observed by service personnel during

normal servicing.

(A) Additionally, these provisions must include procedures for

either: prior to further flight, following the in-line drain valve

manufacturer's recommended troubleshooting procedures and correction

of the discrepancy; or prior to further flight, draining the

lavatory system and placarding it inoperative until the correction

of the discrepancy can be accomplished.

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

panel drain valve, Kaiser Electroprecision part number series 0218-

0026 or 0218-0032, or Shaw Aero Devices part number series 1010100C

or 1010100B, or Pneudraulics part number series 9527, indications of

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

need not be addressed immediately if a leak check of the service

panel drain valve indicates no leakage or other discrepancy. In

these cases, repair of the in-line drain valve must be accomplished

within 1,000 flight hours after the leak check of the additional

service panel drain valve.

(6) Provide training programs for maintenance and servicing

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

hazards of ``blue ice.''

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

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

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

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

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

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

include the following information:

(1) The operator's name;

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

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

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

number, and serial number);

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

(5) The current FAA leak check interval;

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

replacement intervals required by this AD; -

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

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

worn seals, foreign materials on sealing surface, scratched or

damaged sealing surface or valve, etc.); -

(8) Whether or not any leak check was conducted without first

inspecting or cleaning the sealing surfaces, changing the seals, or

repairing the valve. [If such activities have been accomplished

prior to conducting the periodic leak check, that leak check shall

be recorded as a ``failure'' for purposes of the data required for

this request submission. The exception to this is the normally

scheduled seal change in accordance with paragraph (b)(1) of this

AD. Performing this scheduled seal change prior to a leak check will

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

-Note 4: Requests for approval of revised leak check intervals

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

level of assurance specified in paragraph (c) of this AD.

-Note 5: For the purposes of expediting resolution of requests

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

requester summarize the raw data; group the data gathered from

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

same kind of valve; and provide a recommendation from pertinent

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

revised leak check interval.

-(d) For all airplanes: Within 5,000 flight hours after the

effective date of this AD, install a lever/lock cap on the flush/

fill lines for forward, aft, and executive lavatories. The cap must

be either an FAA-approved lever/lock cap, or a cap installed in

accordance with Boeing Service Bulletin 727-38-0021, dated July 30,

1992. -

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

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

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

accomplishment of the leak checks required by this AD shall be

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

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

once, each subsequent leak check must be performed in accordance

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

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

(1) For airplanes previously maintained in accordance with this

AD, the first leak check to be performed by the new operator must be

accomplished in accordance with the previous operator's schedule or

with the new operator's schedule, whichever would result in the

earlier accomplishment date for that leak check. -

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

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

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

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

period not to exceed 200 flight hours. -

(f) 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.

-Note 6: Information concerning the existence of approved

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

obtained from the Seattle ACO.

-Note 7: For any valve that is not eligible for the extended

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

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

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

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

with a request for an alternative method of compliance with this AD.

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. Additionally, the request should include 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,

including a winter season, collected in accordance with the

requirements of paragraph (c) of this AD or a similar program. One

of the factors that the FAA will consider in approving alternative

valve designs is whether the valve meets Boeing Specification

S417T105 or 10-62213; however, meeting the Boeing specification is

not a prerequisite for approval of alternative valve designs.

-(g) Special flight permits may be issued in accordance with

sections 21.197 and 21.199 of the Federal Aviation Regulations (14

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

the requirements of this AD can be accomplished. -

(h) This amendment becomes effective on December 16, 1994.

Issued in Renton, Washington, on November 9, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-28243 Filed 11-15-94; 8:45 am]

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