[Federal Register Volume 59, Number 53 (Friday, March 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-6340]


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[Federal Register: March 18, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 90-NM-265-AD]

 

Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to Boeing Model 727 series airplanes, which 
would have superseded an existing AD that currently requires periodic 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. The proposed 
action would have deleted the existing provision for terminating 
action, required repetitive leak checks of both the forward and aft 
lavatory drain systems, and added an optional procedure for complying 
with the rule. That proposal was prompted by reports of engine and 
airframe damage, engine separation, 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. This action revises the proposal by changing the optional 
procedure, adding a requirement for installation of a cap on the flush/
fill line, and requiring periodic leak checks of the flush/fill system.

DATES: Comments must be received by May 2, 1994.

ADDRESSES: Submit comments in triplicate to 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 a.m. and 3 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:

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 90-NM-265-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 90-NM-265-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    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 22, 1993 (58 FR 
15305). That supplemental NPRM proposed to revise a previously issued 
NPRM that proposed the supersedure of AD 86-05-07, Amendment 39-5250 
(51 FR 7767, March 6, 1986). AD 86-05-07 currently requires periodic 
leak checks of the forward lavatory drain system and provides for the 
installation of a new drain valve as terminating action. The previously 
issued 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, and
    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.
    The proposed action was prompted by reports of engine and airframe 
damage, and one report of engine separation on a Boeing Model 727 
series airplane that occurred subsequent to the issuance of AD 86-05-
07. These incidents were caused by ``blue ice'' that had formed from 
leaking forward lavatory drain systems and subsequently had broken 
loose from the airplane and struck the fuselage or had been ingested 
into the engine. The proposed action also was prompted by reports of 
leakage from lavatory drain valves that have a configuration similar to 
that specified in AD 86-05-07 as terminating action. Such leakage can 
result in the formation of blue ice, which can dislodge from the 
airplane and result in engine damage or separation, airframe damage, 
and/or a hazard to persons or property on the ground.
    Since the issuance of that supplemental NPRM, the FAA has 
determined that certain additional changes to the proposed rule are 
necessary.

General Changes to the Proposal: ``The Comprehensive Approach''

    The FAA has reviewed its position on the option that was provided 
in the previous supplemental NPRM, which would have permitted operators 
to revise the FAA-approved maintenance program to include procedures to 
address the problems associated with blue ice. The FAA now considers 
that an even more comprehensive approach should be taken to address the 
subject unsafe condition via the FAA-approved maintenance program. This 
approach should be based upon regular maintenance, training of 
personnel, use of hardware with proven reliability, and fixed, but less 
frequent, leak checks incorporated into the FAA-approved maintenance 
program. Paragraph (b) of this supplemental NPRM has been revised to 
specify the requirements for the maintenance program revision that the 
FAA has determined are necessary in order to implement this 
``comprehensive approach.'' (A more detailed discussion of these 
proposed requirements is presented later in this preamble.)
    In lieu of the revising the maintenance program, however, this 
supplemental NPRM will continue to provide operators with the option of 
accomplishing the specific leak check procedures on the drain systems.

General Changes to the Notice: Extension of Leak Check Intervals

    The proposed AD would extend the previously-proposed leak check 
intervals for certain specific valves, provided that a suitable program 
of maintenance and training of personnel is also implemented. These 
intervals have been extended based upon data gathered to date regarding 
the service history of the valve types.
    The proposed AD would also require that any revisions to (i.e., 
extension of) the mandated leak check intervals must be approved by the 
FAA, specifically, by the Manager of the Seattle Aircraft Certification 
Office (ACO). Requests for such revisions must be accompanied by 
certain data when submitted to the ACO [through the appropriate FAA 
Principal Maintenance Inspector (PMI)] for approval. In this 
supplemental NPRM, the FAA proposes a ``data collection format'' for 
these requests. Data submitted in accordance with the proposed format, 
if favorable to an increase of leak check intervals, will allow the FAA 
to justify increasing the leak check intervals with assurance that the 
valves involved have the required reliability. The data provided will 
also be important in assisting the FAA in making future determinations 
of appropriate leak check intervals for new valves that have shown 
promising, but not conclusive, service data.

General Changes to the Notice: Flush/Fill Line Problems

    Certain comments submitted to the Rules Docket in response to the 
previously issued supplemental NPRM included reference to three 
incidents of foreign object damage from the forward toilet drain valve 
and flush/fill line on certain airplanes.
    The FAA also has received a report of a dent on the right 
horizontal stabilizer leading edge on a Boeing Model 737 series 
airplane that was caused by blue ice that had formed from leakage 
through a flush/fill line. In this case, the flush/fill cap was missing 
from the line at the forward service panel. The flush/fill line on the 
Model 737 is similar in design to that on the Model 727; therefore, the 
potential exists for the same type of incident occurring on the Model 
727.
    Further, in their comments to the Rules Docket, numerous operators 
stated that leakage from the flush/fill line is a significant source of 
the type of blue ice problems addressed by this AD action.
    While there are not many documented cases of blue ice coming from 
the flush/fill line causing damage to engines, such blue ice is still a 
hazard to persons and property on the ground and, therefore, 
constitutes an unsafe condition. In light of this, the FAA has 
reconsidered its previous statement that flush/fill line leakage would 
be ``addressed by a separate rulemaking action,'' and is proposing 
requirements in this supplemental NPRM to install a cap on the flush/
fill line and to perform periodic leak checks of the flush/fill line.
    The FAA has reviewed and approved Boeing Service Bulletin 727-38-
0021, dated July 30, 1992, that provides instructions for modifying the 
forward, aft, and executive lavatory drain systems by installing a cap 
on the flush/fill lines. This modification will prevent blue fluid 
leakage and subsequent ice accumulation in the executive and aft 
lavatory service panels, and in the forward lavatory waste system.
    This supplemental NPRM proposes to require the installation of the 
flush/fill line cap in accordance with the Boeing service bulletin 
within 5,000 flight hours.

General Changes to the Notice: New Owners' Schedules

    A new paragraph (e) has been added to this supplemental NPRM to 
require that, before an operator places an airplane subject to the AD 
into service, the operator must establish a schedule for accomplishment 
of the leak checks. This provision is intended to ensure that 
transferred airplanes are inspected in accordance with the AD on the 
same basis as if there were continuity in ownership, and that 
scheduling of the leak checks for each airplane is not delayed or 
postponed due to a transfer of ownership. Airplanes that have 
previously been subject to the AD would have to be checked in 
accordance with either the previous operator's or the new operator's 
schedule, whichever would result in the earlier accomplishment date for 
that leak check. Other airplanes would have to be inspected before an 
operator could begin operating them or in accordance with a schedule 
approved by the FAA PMI, but within a period not exceeding 200 flight 
hours.
    Since the changes described above expand the scope of the 
previously proposed rule, the FAA has determined that it is necessary 
to reopen the comment period to provide additional opportunity for 
public comment.
    Due consideration has been given to the following comments that 
were submitted in response to the previously issued supplemental NPRM:

Hardware Nomenclature

    Several commenters suggest that the proposal be revised to include 
terms that would more specifically describe the valves that are 
affected by the rule. Certain commenters suggest that generic 
references to ``ball valves'' in proposed paragraph (a) should be 
replaced with references to ``Boeing Specification S417T105,'' which 
more clearly defines the configuration of the specific ball valve that 
must be inspected. These commenters also suggest that references in 
proposed paragraph (a) to the ``Shaw Aero Devices, Inc., drain valve 
that incorporates an integral inner door with a second positive seal,'' 
be replaced with references to the ``service panel valve per Boeing 
Specification 10-62213.'' On the other hand, one commenter requests 
that the terms used in the proposal to describe the Shaw Aero valve be 
retained, so that earlier models of the Shaw Aero valve (not configured 
per Boeing Specification 10-62213) would ``benefit'' from the proposed 
extended leak check intervals. Another commenter states that the 
earlier models of those Shaw Aero valves were upgraded because they 
leaked and, therefore, those valves should not be included with the 
valves specified by ``Boeing Specification 10-62213'' for purposes of 
receiving the extended leak check periods.
    The FAA has reviewed the data submitted with these comments and 
finds that certain of the requested changes are appropriate. The FAA 
concurs with the request to specifically identify those valves approved 
for the longer leak check intervals. The FAA has reviewed the 
referenced Boeing specifications, as well as the part numbers of valves 
that have been determined to meet these specifications and that have 
service history data approved by the FAA. The FAA has determined that 
the qualifying valves are as follows:
    1. Valves meeting Boeing Specification S417T105: Kaiser 
Electroprecision valves having part number 2651-329-5 (or higher ``dash 
number'');
    2. Valves meeting Boeing Specification 10-62213: Kaiser 
Electroprecision valves having part number 0218-0032-8 (or higher 
``dash number''); and Shaw Aero Devices valves having part number 
10101000C-N (or higher ``dash numbers'').
    Therefore, this supplemental NPRM has been revised to refer to 
certain of the affected valves as those having the part numbers 
indicated above. Valves having Kaiser Electroprecision part number 
2651-329-5 (or higher ``dash number'') would be required to be leak 
checked at intervals of either 1,500 flight hours [per proposed 
paragraph (a)] or 5,000 flight hours [per proposed paragraph (b)]. 
Valves having Kaiser Electroprecision part number 0218-0032-8 (or 
higher ``dash number'') or Shaw Aero Devices part number 10101000C-N 
(or higher ``dash numbers'') would be required to be leak checked at 
intervals of 1,000 flight hours. To ensure that any valves developed at 
a later date are also reviewed first by the FAA for adequate service 
history, new paragraph (f) of the proposed rule makes a provision for 
the service history data of such additional valves to be approved by 
means of an alternative method of compliance with the rule.

Ball Valves, General

    Several commenters suggest that, because of the history of the 
general reliability of ball valves, the proposed rule should be revised 
to permit installation of a ball valve in a drain system as terminating 
action for the leak checks of that particular drain system. Other 
commenters request that, based on this history of reliability, the 
proposed 1,500-flight hour leak checks intervals for drain systems 
incorporating ball valves, as proposed in paragraph (a)(1), be extended 
to 4,000 or 6,000 flight hours.
    The FAA does not concur. While a ball valve may be reliable if 
properly maintained, it may still leak eventually due to seal wear or 
the entrapment of foreign material on the sealing surfaces. Damage to 
the sealing surfaces in a ball valve due to foreign materials, while 
uncommon, may also cause leakage at any time. If there are no 
maintenance actions aimed at detecting such leakage, the leakage could 
continue until the next leak check. An extremely long interval between 
leak checks, as suggested by the commenters, would allow leakage to go 
undetected for a long time and, thus, create conditions favorable for 
the eventual formation of blue ice. The FAA has determined that, by 
limiting the leak check interval to 1,500 flight hours, the risk of 
long term leakage is reduced.

Ball Valve Leak Checks, Plus Maintenance and Training Programs

    Several commenters request that the proposed leak check intervals 
for drain systems incorporating a ball valve be extended to 4,000 or 
6,000 flight hours, if those leak checks are coupled with a specific 
maintenance program as well as a program to train personnel to perform 
certain actions. Some of these commenters consider that incorporation 
of the 1,500-flight hour leak checks into the operators' FAA-approved 
maintenance program, as proposed in paragraph (b) of the previous NPRM, 
does not provide sufficient motivation for operators to incorporate 
ball valves into the fleet (even though the ball valves are more 
reliable than other types).
    The FAA concurs with these commenters' request. The FAA has 
determined that installation of a design package that includes a ball 
valve installed in accordance with Boeing Service Bulletin 727-38-0021, 
dated July 30, 1992, combined with certain maintenance actions and 
trained personnel (discussed in detail later) will provide adequate 
assurance that long term leakage will not occur. Therefore, the FAA has 
revised paragraph (b) of the supplemental NPRM to provide for leak 
check intervals up to 5,000 flight hours for applicable ball valve 
installations that are coupled with maintenance procedures and training 
of personnel. This change is specifically intended to encourage 
operators to use valve designs having proven reliability; the 
incorporation of sufficient maintenance practices and trained personnel 
will ensure that the inherent reliability of the design is not 
degraded.

Shaw Aero Valves

    One commenter requests that the leak check intervals for drain 
systems with Shaw Aero valves that incorporate the inner door with 
second positive seal be increased from 1,000 flight hours, as proposed 
in paragraph (a)(2), to 1,500 or 4,000 flight hours. This commenter 
considers that this request is justified based on the lack of adverse 
service history on the subject valves.
    On the other hand, another commenter objects to the proposed 1,000-
flight hour leak check interval for these valves, and suggests that it 
should be shortened. This commenter states that there are certain 
considerations that are critical in establishing leak check intervals 
based on component failure rates derived from evaluations of in-service 
history. Such considerations are:
    1. If the ball valve is installed internally so that service 
personnel cannot damage it;
    2. If the seals are composed of the correct material, and are not 
directly in the effluent path so that they cannot be damaged by items 
within the effluent that can normally cause seal damage;
    3. If, because of the location of the ball valve, it is impractical 
to perform a seal replacement;
    4. If the valve is leak checked on board the airplane without a 
seal change prior to the check;
    This commenter states that, when these items are taken into 
consideration, service data gathered on this ball valve are 
``unambiguous,'' because if the valve passes a leak check, it means 
that the valve did not leak before the check was conducted. However, 
the subject Shaw Aero valve is located in the service panel and is 
accessible to maintenance personnel; moreover, it is common practice 
for those personnel to change the seals in the panel valve prior to 
leak check intervals. Therefore, the leak check service data that have 
been presented relative to this Shaw Aero valve are ``questionable,'' 
due to the lack of reporting and the fact that seals can be changed out 
during servicing and prior to the leak checks.
    The FAA does not concur with either commenter's request. The FAA 
has reviewed the design improvements and service history data of the 
Shaw Aero valves having part number 10101000C-N (or higher dash number) 
and has determined that a leak check interval of 1,000 flight hours is 
justifiable, based upon the best available data to date. The FAA does 
agree with the latter commenter to the extent that justification for 
any further extension of this leak check interval beyond 1,000 flight 
hours must be based on unambiguous data.

Kaiser Expander Valves

    Several commenters submitted service history data on the Kaiser 
Expander valve, part number 0218-0032-8, and request that the proposed 
rule provide for a leak check interval of 4,000 or 4,500 flight hours 
for this valve. As currently written, the proposed rule would place the 
Kaiser Expander valve in the category of valves requiring leak checks 
every 200 flight hours. These commenters state that the Kaiser Expander 
valve has the same positive bore sealing inner flap as the Shaw Aero 
valve, and has a service history to prove it is as safe, rugged, and 
reliable as the Shaw Aero valve. Some of these commenters consider this 
Kaiser valve to be the ``best that is currently available,'' and note 
that it had been approved previously as terminating action for AD 86-
05-07.
    The FAA concurs that the leak check interval for the Kaiser 
Expander valve, part number 0218-0032-8 (or higher dash number), may be 
increased from the proposed 200 flight hours. The FAA has reviewed the 
service history data for the Kaiser Expander valve and finds that it is 
sufficient to justify a 1,000-flight hour leak check interval proposed 
in paragraphs (a)(2) and (b)(2)(ii) of this supplemental NPRM.

Other Brands of Valves

    Other commenters suggest that the proposal be revised to increase 
the leak test intervals to 400 flight hours for the ``other valves'' 
referred to in proposed paragraph (a)(3) of the previous supplemental 
NPRM; and to allow that interval to be increased up to 5,000 flight 
hours (an average ``C'' check). These commenters consider that a 200-
flight hour interval is too frequent and would create an undue economic 
burden on affected operators.
    For many of the same reasons previously discussed, the FAA does not 
concur. The FAA does not consider that valves without demonstrated high 
reliability should be used without frequent leak checking. Frequent 
leak checking provides assurance that the valves will be returned to a 
non-leaking condition. The FAA has recognized that some valves in the 
``other'' category (such as the earlier Shaw Aero valve models) do have 
better service history than others regarding failure and leakage; 
therefore, as described previously, the FAA has singled out these 
valves and has extended their leak check interval. However, for valves 
that are known to be more likely to leak, specifically the ``donut'' 
and ``taco'' valves, a 200-flight hour leak check interval is 
essential.
    Certain commenters request that the proposed rule be revised to 
grant other brand name valves extended leak check intervals. However, 
these commenters did not furnish sufficient service history or leak 
check data to substantiate their requests. The FAA cannot determine if 
extensions of leak check intervals are warranted without being able to 
review significant service history data.

Operators With No Record of Leakage

    One commenter suggests that the proposed rule include a provision 
for an extended leak check interval for operators that have had no 
record of waste water leakage, regardless of what hardware 
configuration is used. The commenter considers that the proposal 
penalizes operators who have had an excellent service history due to 
proper maintenance and servicing. While the installation of additional 
hardware will improve the waste system and reduce the likelihood of 
leaking, it should be used as an incentive for those operators that 
have had a history of leaking waste systems and blue ice foreign object 
damage.
    The FAA does not agree that an extended interval is warranted for 
the reasons suggested by the commenter. Blue ice 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 
assurance. The FAA considers that such assurance is provided by 
frequent leak checks to ensure that the drain systems do not leak; more 
reliable valves may be subject to less frequent leak checks, while less 
reliable valves must be subject to more frequent leak checks. As 
discussed previously, the FAA considers that maintenance and training 
are also important factors in determining appropriate leak check 
intervals, and has provided in this supplemental NPRM an option for 
either increased leak test intervals, or obtaining approval for less 
frequent intervals when hardware is demonstrated to be reliable.

Requests for No Leak Tests for Some Valves

    One commenter requests that, in cases where a ball valve is 
installed with a service panel valve that has no inner flapper, the 
proposed rule not require a leak check to be done on the service panel 
valve. The commenter also requests that the proposed rule be revised to 
require that, when a service panel valve with an inner door having a 
second positive seal is installed with a ball valve, only the inner 
seal be tested, and the outer cap seal be visually inspected and 
replaced as necessary. The commenter notes that the proposed rule would 
call for a pressure differential to be applied across both the ball 
valve and the service panel cap valve. However, on many ball valve 
installations, the service panel cap has no inner flapper. Applying a 
pressure differential across this cap would require spilling a 
substantial quantity of fluid on the ramp in order to service the 
system after completion of the leak check. The commenter recommends 
that the service panel cap valve only be leak checked if it 
incorporates a dual seal design, and that the outer cap be visually 
inspected for wear or damage, and replaced only as necessary or at 
predetermined intervals.
    The FAA does not agree with the commenter's request to delete the 
leak check requirement for service panel valves that have no inner 
flapper. This would be disadvantageous to operators who had a superior 
hardware configuration (the dual seal), since it would require that 
they perform a test that is not required of installations with only a 
single cap. However, the FAA does agree with the suggestion to require 
a leak check of only the inner flapper for service panel valves with a 
dual seal design, and the performance of visual inspections/seal 
changes of only the outer cap. This will ensure that one seal 
downstream of the ball valve is returned to a ``no-leak'' condition. 
This supplemental NPRM has been revised accordingly.

Development of New Equipment

    Several commenters request that the proposed rule provide for a 
method to encourage the development of new, more reliable equipment, 
and extend the leak check intervals for that equipment.
    The FAA agrees that the industry should be encouraged to develop 
improved hardware that will better address the unsafe condition 
presented by problems associated with blue ice. As one method to 
achieve this goal, and to provide assurance of a high degree of 
reliability of the hardware involved, the FAA has proposed in paragraph 
(c) of this supplemental NPRM, a method of data collection relative to 
the reliability of valves. This approach is not intended to supersede 
existing methods for equipment qualification and certification. 
However, this method of data collection is intended to ensure the 
collection of unambiguous data, which will provide the FAA with 
adequate resources and information to determine appropriate leak check 
intervals for new and existing designs. The FAA intends to use the data 
that are eventually collected to determine if extensions to the 
currently proposed leak check intervals are justified, specifically for 
those operators who choose to incorporate certain maintenance and 
training requirements into their FAA maintenance programs in accordance 
with paragraph (b) of this supplemental NPRM. The FAA specifically 
requests additional suggestions as to methods that will further ensure 
the validity of the data gathered.

Implementation of a New Maintenance and Training Program

    Numerous commenters request that the proposed rule be revised to 
provide for an alternative to the fixed leak check intervals by 
permitting the implementation of a program in which operators could 
incorporate a schedule of maintenance actions, training, and periodic 
leak checks into their FAA-approved maintenance program. These 
commenters state that merely performing more leak checks at greater 
frequencies will not, by itself, address the blue ice problem. Instead, 
other maintenance tasks, such as replacing seals at regular intervals 
and establishing effective communication procedures between maintenance 
personnel and the flight crew, play more significant roles in 
addressing blue ice safety concerns. The commenters request that 
compliance periods for leak checks be adjusted in accordance with 
existing FAA-approved reliability programs, or be increased to ``C'' 
check intervals, provided that certain maintenance and training 
programs were initially included in the maintenance program.
    The FAA concurs that these commenters' suggestions have merit. The 
FAA has determined that an increase in the leak check intervals could 
be justified if the equipment is demonstrated to be highly reliable, 
and a program of regular maintenance and training is implemented. The 
FAA has revised proposed paragraph (b) of the supplemental AD to 
include specific procedures considered to be essential in such a 
program. These procedures include: (1) Repetitive replacement of seals, 
(2) leak checks at various intervals depending upon the valve 
configuration, (3) leak checks of flush/fill line caps, (4) visual 
checks conducted by maintenance personnel at regular intervals to 
detect leakage, (5) procedures for reporting discrepancies, and (6) 
training programs for maintenance and service personnel that include 
information on ``Blue Ice Awareness'' and the hazards of blue ice. The 
proposal specifically would extend the leak check interval for certain 
valves to 5,000 flight hours (which is equivalent to a ``C'' check for 
the majority of affected operators), provided the specified program of 
maintenance and training is implemented.

Recordkeeping

    Some commenters request that proposed paragraph (b) of the NPRM be 
revised to specify that, once operators have acceptably revised their 
maintenance program to include the specified actions, the AD is no 
longer ``applicable'' to those operators. In effect, the maintenance 
program revision should be considered ``terminating action'' for the 
AD. These commenters would prefer to accomplish all of their AD-
required leak check tasks within the parameters of their FAA-approved 
maintenance program, since ``operators have more flexibility in 
adjusting leak check intervals in accordance with their FAA-approved 
reliability programs and recordkeeping requirements are less 
cumbersome.'' The commenters point out that paragraph (b) of the 
previous NPRM denies operators the opportunity to integrate their leak 
check tasks into their maintenance program, since ``the NPRM fails to 
indicate that AD recording procedures are not in effect, and disallows 
the opportunity to ever adjust the leak check intervals without seeking 
approval under the alternative method of compliance provision.'' The 
commenters request that, for these operators, the proposed rule provide 
for the use of an alternative method of recordkeeping to that otherwise 
required by Federal Aviation Regulations (FAR) 91.417 (``Maintenance 
records'') and 121.380 (``Maintenance recording requirements'').
    The FAA does not concur with the commenters' request to revise the 
proposal to indicate in any way that it is ``no longer applicable'' 
once the revision to the FAA-approved maintenance program is 
implemented and the appropriate logbook entry made. The FAA considers 
that, even though this proposed AD would affect the maintenance 
program, it is of such importance that it warrants other than 
``normal'' procedures to be followed in certain aspects. Specifically, 
under ``normal'' maintenance program procedures, the PMI is authorized 
to approve any revisions of the maintenance program, including 
adjustments of the leak check intervals. However, for reasons detailed 
below, the FAA has determined that the PMI is not the appropriate FAA 
official for adjusting the compliance intervals for leak checks 
specified by the terms of this AD.
    Likewise, the FAA does not concur with the commenters' request to 
revise the proposal to provide specifically for the use of an 
alternative method of recordkeeping. Although the FAA has included such 
a provision in other rulemaking actions [reference, for example, AD 92-
22-08 R1, amendment 39-8591 (58 FR 32281, June 9, 1993); and AD 92-22-
09 R1, amendment 39-8590 (58 FR 32278, June 9,1993); both of which 
require the implementation of a corrosion prevention and control 
program on certain transport category airplanes], the FAA has been 
unable to confirm that there has been any case in which an operator has 
found it necessary to use such alternative recordkeeping methods. 
Therefore, the FAA concludes that the recordkeeping methods currently 
required by FAR 91.417 and 121.380 are sufficient, and there is no need 
to include a specific provision in this proposed rule for alternatives.

Principal Maintenance Inspector (PMI) Involvement

    Some commenters recommend that the FAA recognize the merit in 
delegating complete program oversight responsibility to the cognizant 
PMI, once an operator has an approved program in accordance with the 
alternative provision of proposed paragraph (b). These commenters point 
out that justification for issuing the proposed AD is based on the 
premise that certain operators may not have a sufficiently 
comprehensive maintenance program currently in place to address the 
blue ice safety concern. However, once a proper maintenance program for 
handling the blue ice safety concerns has been approved by the FAA and 
adopted, there is no longer a safety concern to warrant oversight by 
the Seattle ACO. The administration of handling this program should be 
subject to oversight by the PMI and, as is normal for the regular 
maintenance program as a whole, the PMI should be the FAA official with 
the authority to approve any future adjustments to the leak check 
intervals.
    Although the FAA agrees that the PMI may be permitted certain 
oversight of the proposed alternative maintenance program provision of 
the rule (discussed above with regard to recordkeeping), the FAA does 
not agree that the PMI should be tasked with approving adjustments to 
the leak check intervals. In order for the PMI to have some basis for 
changing the intervals, he/she would need to know (1) when to expect 
the valve to start leaking, and (2) how to ensure that the leak check 
interval does not allow the valve to reach that point. These two 
important items are related to the concept of ``failure threshold 
criteria.'' The FAA has reviewed available service history data (as 
well as comments submitted to this and previous NPRM's) to evaluate 
which valves, if any, appear to have ``failure threshold criteria,'' 
and what those criteria are. While certain failure modes for valves 
have been identified, the failure threshold criteria are difficult to 
define in many cases. For example:
    1. ``Normal'' seal wear will eventually cause a valve to leak. Such 
seal wear should be a relatively predictable cause of failure for any 
given operator.
    2. Developmental problems related to valve or installation design 
problems (i.e., use of incorrect seal materials) may cause leakage 
after the initial installation, but after the design ``fix'' is made 
and installed, leakage from this type of problem should stop.
    3. Entrapment of waste materials on valve sealing surfaces can 
cause leakage; but this does not appear to be related to the valve's 
time-in-service, in that such entrapment is as likely to occur on the 
first cycle as on a later cycle. Entrapment of waste matter on the 
sealing surfaces has been known to cause an increase in operating 
torque of the valve handle; this would be a failure threshold criterion 
for ball valves [which the FAA has incorporated as part of the 
maintenance requirements for the in-line drain valves, as specified in 
proposed paragraph (b) of this supplemental NPRM]. For certain other 
types of valves, however, entrapment of foreign matter does not yield 
such an indicator.
    4. The valve may be damaged during service on any particular cycle, 
assuming it is in a position where it is accessible during normal 
servicing. Such damage during servicing, or even incorrect servicing 
(i.e., failure to install the plug in a donut valve), may be failure 
modes especially for service panel-mounted valves, which are 
accessible. However, they are not failure modes for in-line drain 
valves because these valves are not accessible during normal servicing.
    As one can readily recognize, different valves may or may not be 
susceptible to these modes of failure, depending upon the valve design, 
installation location, maturity of design (all fixes incorporated), and 
other factors. The data available to the FAA simply do not indicate 
which failure modes are most likely to cause leakage for any particular 
valve.
    Based on the most recent analysis and data available, however, the 
FAA has determined that only the in-line drain ball valve, as installed 
in accordance with Boeing Service Bulletin 727-38-0021, dated July 30, 
1992, may have specific failure threshold criteria. A PMI could use 
these criteria as a basis for adjusting leak check intervals with some 
degree of confidence that the valve would not be allowed to reach the 
point when it would be expected to start leaking. Given the high 
reliability of these valves (which have a very low total number of 
leaks from any cause), and the element of relative predictability of 
failure modes (change seals regularly to avoid seal wear problems, fix 
the valve if high operating torque is evident, etc.), the FAA has 
determined that it is appropriate to allow these valves to be leak 
checked at intervals of 5,000 flight hours (equivalent to a ``C'' 
check). The FAA considers it impractical, however, to allow the PMI to 
extend the leak check interval only for these in-line drain ball valve 
installations. In any case, a leak test at ``C'' check intervals 
provides assurance that operators are following correct maintenance 
procedures.
    The current data do not convince the FAA that service panel-mounted 
valves have been demonstrated (unambiguously) to be as reliable as the 
ball valve. The ratio of failures from ``unpredictable'' failure modes 
to failures from ``predictable'' failure modes is not known for these 
valves. In light of this, a PMI would have no data on which to base an 
extension of a leak check interval for panel-mounted valves with the 
assurance that the valve would not fail within the adjusted interval.
    Further, PMI's who work with smaller operators would not see 
sufficient data to give them the assurance that an expanded leak check 
interval for any valve is justified.
    Since failure threshold criteria and definitive leak/failure rate 
data do not exist for the majority of the subject valves, 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 their 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 repeat leak check intervals will maintain 
an acceptable level of safety. 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.

Relationship of Leak Checks to Certification Maintenance Requirements 
(CMR)

    Several commenters state that, because this proposal is considered 
to be a model for future AD actions applicable to other airplanes 
(presumably including newly-delivered aircraft that will be configured 
with similar in-line drain valves), the adoption of proposed paragraph 
(a) will require repetitive leak checks on all newly delivered 
aircraft. The commenters view this as ``tantamount to issuing a 
certification maintenance requirement (CMR)'' via the AD process.
    The FAA does not concur. CMR items are intended to be repetitive 
inspections or component replacements for equipment, systems, and 
installations. Accomplishment of CMR items would ensure that the 
statistical probability of certain failures that could occur during 
operation of the airplane does not exceed the limitations specified in 
Sec. 25.1309 (``Equipment, systems, and installations'') of the FAR, 
which is applicable to the design and approval of transport category 
airplanes. Further, CMR items are based on statistical safety analyses 
of airplane electrical, electronic, hydraulic, pressurization, and 
propulsion systems. These analyses must be completed by the 
manufacturer and approved by the FAA prior to the issuance of an 
airplane Type Certificate (TC). Following issuance of the TC, those 
inspections, component replacements, or overhaul interval requirements 
for airplane systems that are based on in-service experience with the 
airplane, but that do not result in re-evaluation of the basic 
statistical analysis on which approval of the system is based, do not 
qualify as CMR items.
    The leak check schedule proposed in this notice is not related to 
compliance of the airplane design with the statistical evaluation 
requirements of FAR Sec. 25.1309 for equipment, systems, and 
installations. For this reason, the proposed leak checks do not qualify 
as a CMR item. The intent of the proposed leak checks is to address the 
unsafe condition presented by the problems associated with blue ice; 
the appropriate vehicle for mandating actions to address an unsafe 
condition is the airworthiness directive.

Compliance Time for Proposed Maintenance Program Change

    Several commenters request that the proposed 30-day compliance time 
for revising the operators' FAA-approved maintenance programs be 
extended to 180 days. The commenters consider that the proposed time is 
too short, since implementing such a revision will require addition 
work hours, personnel, and material.
    The FAA concurs. In view of the increased scope of the proposed 
changes to the maintenance program, the FAA has revised paragraph (b) 
to require compliance within 180 days. This will allow operators 
adequate time to implement the required revisions to the maintenance 
program, both logistically and administratively. It will also provide 
time for the development of the necessary training programs and the 
training of personnel in the new procedures.

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 would be affected by this AD. The FAA estimates that it would 
take approximately 4 work hours per airplane lavatory drain (2 drains 
per airplane) to accomplish a leak check, and the average labor cost 
would be $55 per work hour.
    For the 1,077 airplanes that have donut/cap type or other approved 
drain valves (excluding Shaw Aero drain valves) installed in both drain 
systems, approximately 15 leak checks per airplane would be required 
each year. For the 36 airplanes that have Shaw Aero drain valves 
installed in both drain systems, approximately 3 leak checks per 
airplane would be required each year. For the 164 airplanes that have a 
ball valve installed in the forward lavatory drain and a Shaw Aero 
drain valve installed in the aft lavatory drain, approximately 2 leak 
checks of the forward drain and 3 leak checks of the aft drain would be 
required per year. Based on these figures, the total annual (recurring) 
cost impact of the repetitive leak checks on U.S. operators is 
estimated to be $7,336,120.
    The 1,277 airplanes of U.S. registry have, on an average, 3 flush/
fill lines per airplane. The FAA estimates that the installation cost 
of a level lock cap assembly would 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 would 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 would 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 would take approximately 40 work hours per operator 
to incorporate the lavatory drain system leak check procedures into the 
maintenance programs, at an average labor cost of $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 proposed 
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, most 
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 this cost-
beneficial level of safety is no longer being achieved and that the 
proposed 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 14 
CFR part 39 of the Federal Aviation Regulations 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), 
to read as follows:

    Boeing: 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:
    (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), and (a)(5) of this AD:
    (1) For each lavatory drain system, forward or aft, that has an 
in-line drain valve installed, Kaiser Electroprecision part number 
2651-329-5 (or higher dash number): 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), ball valve, and cap valve. The ball valve and cap valve leak 
checks must be performed with a minimum of 3 pounds per square inch 
differential pressure (PSID) applied across each valve. If the cap 
valve has an inner door with a second positive seal, only the inner 
door must be tested.
    (ii) Visually inspect the seal on the outer door for wear or 
damage that may cause leakage. Any worn or damaged seal must be 
replaced, prior to further flight, in accordance with the valve 
manufacturer's maintenance manual.
    (2) For each lavatory drain system, forward or aft, that has a 
service panel drain valve installed, Kaiser Electroprecision part 
number 0218-0032-8 (or higher dash number) or Shaw Aero Devices part 
number 10101000C-N (or higher dash number): 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 drain valve leak check must be 
performed with a minimum of 3 PSID applied across the valve.
    (3) For other forward or aft lavatory drain systems not 
addressed in paragraph (a)(1) or (a)(2) 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 drain valve at the service panel. The drain 
valve leak check must be performed with a minimum 3 PSID applied 
across the valve.
    (4) 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, conduct a leak check of the cap on the flush/
fill line. This leak check must be made with a minimum of 3 PSID 
applied across the cap.
    (5) 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), 
(b)(6), and (b)(7) 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, forward or aft, that has an 
in-line drain valve installed, Kaiser Electroprecision part number 
2651-329-5 (or higher dash number): 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, forward or aft, 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. Any 
revision to the leak check schedule must be approved by the Manager, 
Seattle ACO, FAA, Transport Airplane Directorate.
    (i) For forward lavatory drain systems modified in accordance 
with Boeing Service Bulletin 727-38-0021, dated July 30, 1992 
[installing an in-line drain valve, Kaiser Electroprecision part 
number 2651-329-5 (or higher dash number)]: 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 
5,000 flight hours, conduct leak checks. The ball valve and cap 
valve leak checks must be performed with a minimum of 3 pounds per 
square inch differential pressure (PSID) applied across each valve. 
If the cap valve has an inner door with a second positive seal, only 
the inner door must be tested. Additionally, visually inspect the 
seal on the outer door for wear or damage that may cause leakage; 
any worn or damaged seal must be replaced, prior to further flight, 
in accordance with the valve manufacturer's maintenance manual.
    (ii) For each lavatory drain system, forward or aft, that has a 
service panel drain valve installed, Kaiser Electroprecision part 
number 0218-0032-8 (or higher dash number) or Shaw Aero Devices part 
number 10101000C-N (or higher dash number): 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, conduct leak checks of the dump valve and drain 
valve . The drain valve leak check must be performed with a minimum 
of 3 PSID applied across the valve.
    (iii) For each lavatory drain system, forward or aft, that 
incorporates either ``donut'' valves, Kaiser Electroprecision part 
number 4259-20 or 4259-31; or that incorporates ``taco'' valves, 
Kaiser Electroprecision part number 2651-311-1, -2, -3, -4, -5, -6, 
or -7: 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 drain valve. The drain valve leak check must 
be performed with a minimum 3 PSID applied across the valve.
    (iv) For each lavatory drain system, forward or aft, 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, conduct leak checks of the dump valve and the 
drain valve. The drain valve leak check must be performed with a 
minimum 3 PSID applied across the valve.
    (3) For flush/fill lines: Within 5,000 flight hours after 
revising the maintenance program in accordance with paragraph (b) of 
this AD, and thereafter at intervals not to exceed 5,000 flight 
hours, conduct a leak check of the cap on the flush/fill line. This 
leak check must be made with a minimum of 3 PSID applied across the 
cap.
    (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 ``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 2651-329-5 (or higher dash number): The 
reporting procedures must include provisions for reporting to 
maintenance any instances of abnormal operating torque 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 0218-0032-8 
(or higher dash number) or Shaw Aero Devices part number 10101000C-N 
(or higher dash number), indications of abnormal operating torque of 
the valve handle for the in-line drain valve need not be addressed 
immediately if a leak check of the additional 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/indicates 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 1: Requests for approval of revised leak check intervals 
may be submitted in any format, provided the data give the same 
level of assurance specified in this paragraph.

    Note 2: For the purposes of expediting resolution of requests 
for revisions to the leak check intervals, the FAA suggests that the 
requestor 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 cap on the flush/fill lines for 
forward, aft, and executive lavatories 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    Note 4: 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. 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.

    (g) Special flight permits may be issued in accordance with 
Federal Aviation Regulations (FAR) 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 March 14, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-6340 Filed 3-17-94; 8:45 am]
BILLING CODE 4910-13-U