[Federal Register Volume 62, Number 227 (Tuesday, November 25, 1997)]
[Proposed Rules]
[Pages 62708-62721]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-30855]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-111-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,
and -500 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This document revises an earlier proposed airworthiness
directive (AD), applicable to all Boeing Model 737-100, -200, -300, -
400, and -500 series airplanes, which would have superseded an existing
AD that currently requires either leak tests of the forward lavatory
service system, and repair, as necessary; or draining the system and
placarding the lavatory inoperative. That proposed AD would have
provided an option for accomplishing terminating action for certain
leak tests. It would have required leak tests of other lavatory drain
systems; installation of a cap or vacuum break on the flush/fill line;
and either periodic replacement of the seal for the cap and tank anti-
siphon valve or periodic maintenance of the vacuum break in the flush/
fill line. This action revises the proposed AD by removing the
terminating action; requiring periodic changing of the seals of certain
lavatory drain systems; replacing ``donut valves'' with other FAA-
approved valves; revising certain leak test intervals; and revising the
pressurization and fluid level requirements for testing. The actions
specified by this proposed AD are intended to prevent damage to
engines, airframes, and property on the ground that is associated with
the problems of ``blue ice'' that forms from leaking lavatory drain
systems on transport category airplanes and subsequently dislodges from
the airplane fuselage.
DATES: Comments must be received by January 5, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-111-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except
Federal holidays.
The service information referenced in the proposed rule may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington;
telephone (425) 227-2788; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 95-NM-111-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this supplemental NPRM by
submitting a request to the FAA, Transport Airplane Directorate, ANM-
103, Attention: Rules Docket No. 95-NM-111-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an airworthiness directive (AD), applicable to all
Boeing Model 737-100, -200, -300, -400, and -500 series airplanes, was
published as a notice of proposed rulemaking (NPRM) in the Federal
Register on November 2, 1995 (60 FR 55673). That NPRM proposed to
supersede AD 89-11-03, amendment 39-6223 (54 FR 21933, May 22, 1989),
applicable to certain Boeing Model 737-300 and -400 series airplanes.
That proposal would have continued to require either repetitive leak
tests on the forward lavatory service system, and repair, as necessary;
or draining of the system and placarding the lavatory inoperative. It
would have also added a requirement to
[[Page 62709]]
perform leak tests of other lavatory drain systems; provided for the
option of revising the FAA-approved maintenance program to include a
schedule of leak tests; required the installation of a cap or vacuum
break on the flush/fill line; and required either a periodic
replacement of the seal for the cap and tank anti-siphon valve or
periodic maintenance of the vacuum break in the flush/fill line. That
proposal also would have expanded the applicability of the rule to
include all Model 737 series airplanes.
That NPRM was prompted by continuing reports of damage to engines
and airframes, separation of engines from airplanes, and damage to
property on the ground, caused by ``blue ice'' that forms from leaking
lavatory drain systems on transport category airplanes and subsequently
dislodges from the airplane fuselage. Such formation and dislodging of
``blue ice,'' if not corrected, could result in damage to the engine
and potential separation of the engine from the airplane.
Actions Since the Issuance of Previous NPRM
Since the issuance of that previous NPRM, the FAA has received
reports indicating that leakage of certain in-line valves of the
lavatory waste drain systems has been detected. In consideration of
this and other factors (a more detailed discussion of the other factors
is presented later in this supplemental NPRM), the FAA has determined
that the terminating action provided by the previous NPRM must be
removed from this supplemental NPRM. In addition, the FAA has
determined that certain additional changes to the previous NPRM are
necessary.
Related AD's
On November 9, 1994, the FAA issued AD 94-23-10, amendment 39-9073
(59 FR 59124, November 16, 1994), which is applicable to Boeing Model
727 series airplanes. That AD contains numerous requirements that are
similar to those proposed in this action, which is applicable to Model
737 series airplanes. In fact, several of the proposed requirements of
this action are based on alternative methods of compliance that the FAA
had approved previously for compliance with AD 94-23-10.
The FAA is currently considering additional rulemaking to address
the problems associated with ``blue ice'' on other transport category
airplanes.
General Changes to the Proposal: Revision of Optional Maintenance
Program
As discussed previously, the FAA has received recent reports of
leakage in certain in-line drain (ball) valves. In order to ensure that
leak check results are uniformly reviewed before any extension of leak
check intervals, the FAA has determined that the previously proposed
optional terminating action provided for in paragraph (b) of the
previous NPRM must be removed from this supplemental NPRM in order to
maintain an adequate level of safety. The 5,000-hour leak test interval
remains unchanged.
General Changes to the Proposal: Revised Leak Test Intervals for
Certain Valves
Based on recently received new data submitted by various operators,
the supplemental NPRM would revise the previously proposed leak test
intervals for certain valves. These changes have been added to
paragraphs (a) and (b) of this supplemental NPRM. (A more detailed
discussion of those proposed changes in the leak test intervals is
presented later in the preamble.)
General Changes to the Proposal: Requirement To Change Seals
One comment submitted to the Rules Docket in response to the
previously issued NPRM, requests that a requirement to change the valve
seals be added to paragraph (a) of the proposal. The commenter points
out that if the seals are not changed periodically, they could fail and
leak in between leak testing. The FAA concurs with the request, and has
added a requirement to paragraph (a) of this supplemental NPRM to
change the seals of valves at intervals similar to the proposed
requirements of the valve seal changes in paragraph (b) of this
supplemental NPRM.
General Changes to the Proposal: Requirement To Remove ``Donut''
Valves
Another comment submitted to the Rules Docket in response to the
previously issued NPRM, requests that the FAA mandate the removal of
``donut'' style valves from the airplane and require replacement with
one of the three service panel valves, as specified in the proposed
rule. The commenter states that the ``donut'' valves have a long
history of poor performance.
The FAA concurs that the ``donut'' style valves should be removed.
``Donut'' style valves have been involved in more cases of leakage and
consequent formation of ``blue ice'' than any other valve design. In
addition, cases of leakage of ``donut'' style valves that have been
leak tested (as required by previous AD's) are still being reported.
Therefore, the FAA has determined that the ``donut'' style valves
should be removed.
However, the FAA finds that, rather than require replacement of the
``donut'' style valves with one of the three service panel valves
listed in the previous NPRM, a requirement to replace the ``donut''
valves with ``an FAA-approved valve'' is more appropriate. This leaves
an opportunity for operators to choose valves that may be ``FAA-
approved,'' but that may not be specified in the rule. Paragraphs
(a)(6)(iii) and (b)(2)(iv)(C) of this supplemental NPRM have been
revised to reflect this change.
General Changes to the Proposal: Revised Pressurization
Requirements
Several comments submitted to the Rules Docket in response to the
previously issued NPRM included requests to revise the requirement to
pressurize the airplane while performing leak tests to verify the
integrity of in-line drain valves or service panel drain valves. The
commenters state that applying a minimum pressure of 3 pounds per
square inch differential pressure (PSID) across the line by using a
leak test tool, such as a hand-held vacuum pump, would be just as
effective as pressurizing the airplane, yet would provide a more
economical method of accomplishing the leak test. Additionally, the
commenters point out that using a 3 PSID differential pressure is
consistent with the ``blue ice'' AD requirements for Boeing Model 727
series airplanes.
The FAA concurs. Paragraphs (a) and (b) of this supplemental NPRM
have been revised to require the tests while applying a minimum 3 PSID
differential pressure in the same direction as would occur during
flight.
General Changes to the Proposal: Revised Requirement of Fluid Level
Several comments submitted to the Rules Docket in response to the
previously issued NPRM included requests that the FAA revise the
proposed leak test procedure to empty and refill the lavatory to within
two inches of overflowing. The commenters state that the difference
between that specified level of fluid and actual overflowing of the
fluid is approximately only one gallon. Since overflow of the lavatory
could cause damage to the airplane, the commenters consider that any
fluid above normal level (10 gallons) is unnecessary.
[[Page 62710]]
Therefore, the commenters request that the required fluid level be
reduced.
The FAA concurs that a lower fluid level is acceptable, except in
the case of testing the anti-siphon valve. The FAA finds that fluid at
the 10-gallon level is too low to result in fluid contacting the seals
during the test of the anti-siphon valve; the lack of contact of the
fluid with the seals would invalidate the test. Therefore, this
supplemental NPRM has been revised to require that the lavatory be
filled with a minimum of 10 gallons of fluid, except when testing the
anti-siphon valve. However, operators should take precautions to ensure
that the tank is not overfilled; a statement to this effect has been
added to this supplemental NPRM.
Conclusion
Since the changes described above expand the scope of the
previously issued proposed rule, the FAA has determined that it is
necessary to reopen the comment period to provide additional
opportunity for public comment.
Comments Received
Due consideration has been given to the comments received in
response to the NPRM issued previously.
Support for the Proposal
One commenter supports the proposed rule.
Request To Withdraw the Proposal: Risk of Injury From ``Blue Ice''
Is Extremely Remote
The Air Transport Association (ATA) of America, on behalf of its
members, requests that the proposed rule be withdrawn. The commenter
considers that, from a statistical standpoint, the risk of injury to
persons on the ground from falling ``blue ice'' is extremely remote.
The FAA does not concur that the proposed rule should be withdrawn.
The FAA has responded to the commenter on this issue during previous
rulemaking concerning ``blue ice'' on Boeing Model 727 series
airplanes. As stated in the preamble of that final rule, the FAA
pointed out that demographic studies have shown that population density
has increased around airports, and probably will continue to increase.
These are populations that are at greatest risk of damage and injury
due to ``blue ice'' dislodging from an airplane during descent. Without
actions to ensure that leaks from the aft lavatory drain systems are
detected and corrected in a timely manner, ``blue ice'' incidents would
go untested and eventually someone would be struck, perhaps fatally, by
falling ``blue ice.'' To discount the unsafe condition to persons on
the ground presented by falling ``blue ice'' would be a gross breach of
the FAA's safety obligations and commitment to the public.
Request To Withdraw the Proposal: Issue an Advisory Circular in
Lieu of an AD
This same commenter suggests that, if some type of action must be
taken, a more manageable alternative to issuing an AD should be
considered. The commenter suggests that such an alternative could be
the development of an Advisory Circular (AC).
The FAA does not concur that issuance of an AC would provide a
``more manageable'' method of addressing the ``blue ice'' safety issue.
In certain cases, the issuance of an AC is an appropriate first step to
address a concern at a more informal level than an AD. In line with
this approach, Advisory Circular 120-39, ``Hazards of Waste Water Ice
Accumulation Separating from Aircraft in Flight,'' was issued on
October 31, 1980. Paragraph 3. of that AC states, ``Each operator
should initiate and accomplish inspections and maintenance of waste
drain valves, caps, and heater systems to the extent necessary to
ensure that these systems remain airworthy and function as designed, to
prevent ice build-up from leaking waste water, and the resultant
separation from the aircraft.'' The FAA concludes that the time elapsed
since the issuance of that AC has given industry sufficient opportunity
to make this approach work. The continuing problems with ``blue ice,''
however, demonstrate the need for a more definitive solution; this
proposed rule is an appropriate approach.
Request To Revise Rulemaking Criteria To Ensure Level of Safety Is
Cost Beneficial
The ATA requests that the FAA redefine the criteria used to
determine an ``unsafe condition'' so that the cost of rulemaking
(airworthiness directives) is commensurate with the risks associated
with not correcting the identified safety concern. Additionally, the
commenter states that in meetings between the ATA and FAA management,
participants agreed to a definition of ``airworthiness.'' The ATA would
like to see that definition adopted for use in determining the need for
an airworthiness directive. ATA states that without specific criteria
and definitions of these terms, the FAA's determination of an unsafe
condition and compliance period for adoption of the proposed rule must
be viewed as subjective and, therefore, deficient as rulemaking.
The FAA does not concur with the commenter's assertion that
``without further guidance, the FAA's determination of an unsafe
condition must be viewed as subjective and, therefore, deficient as
rulemaking.'' The legal question is whether the FAA has identified an
unsafe condition that may exist or develop in other products of the
same type design. The FAA's determination on this issue is legally
appropriate (and the rulemaking is not ``deficient'') as long as the
FAA has a reasonable basis for that determination. In this supplemental
proposed rule, the FAA finds that there is an unsafe condition based on
reports of damage to engines, airframes, and property on the ground
that is associated with the problems of ``blue ice'' that forms from
leaking lavatory drain systems on transport category airplanes and
subsequently dislodges from the airplane fuselage. Although these
reasons may be characterized as ``subjective'' because they are
qualitative rather than quantitative, the FAA considers them to be
appropriate and sufficient to establish the reasonableness of this
proposed action.
Request To Consider the Cost Impact to Airline Operators
One commenter states that in order to standardize leak testing
intervals at 1,000 and 4,500 flight hours, it will have to install a
part in the aft drain system on its entire fleet, and in the forward
drain system on airplanes that do not have Kaiser in-line ball valves
installed in the forward drain system. The commenter requests that,
since the annual cost for this will be $8,064, the FAA should
reconsider that requirement.
Another commenter asserts that compliance with the proposed rule
will force airlines with good maintenance programs and high levels of
``blue ice'' awareness to spend money accomplishing repetitive leak
tests that will not add any additional levels of safety to the aircraft
or to people on the ground. The commenter further states that the
additional ground time required to perform these tests will also
complicate scheduling and hamper efforts to increase aircraft
utilization. The FAA infers that the commenter is requesting that the
FAA reconsider the cost impact of the proposed action.
The FAA acknowledges that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. ``Blue ice''
[[Page 62711]]
frequently is not traceable to the particular airplane, operator, and
waste system that produced it. Incidents of leakage usually are not
reported; only the relatively serious leakage incidents become known to
the FAA. Previous attempts to rely solely upon increased maintenance
while using lower reliability hardware have not proven to be
successful. Therefore, a system to prevent incidents of ``blue ice'' in
the fleet must be based upon reduction of the number of incidents of
leakage by encouraging the use of more reliable equipment, and
requiring that, if an incident of leakage does occur, it is detected
and corrected in a timely manner.
In addition, because AD's require specific actions to address
specific unsafe conditions, they appear to impose costs that would not
otherwise be borne by operators. However, because of the general
obligation of operators to maintain aircraft in an airworthy condition,
this appearance is deceptive. Attributing those costs solely to the
issuance of this proposal is unrealistic because, in the interest of
maintaining safe aircraft, prudent operators would accomplish the
proposed actions even if they were not required to do so.
Request To Distinguish Risks Associated With Forward and Aft
Lavatories Drain Systems
Two commenters note that the compliance times of the NPRM do not
reflect a difference between risks associated with leakage from the
forward lavatory drain system and the risks associated with leakage
from the aft drain. One of the commenters asserts that operators who
upgraded their forward lavatory systems to address the more significant
safety concern over ice ingestion in engines would still be subject to
the more stringent leak test intervals of the aft lavatory drain
systems because of difficulties in redesigning and implementing
retrofit of the aft lavatory drain systems. The commenters assert that
the differences between the risks of leakage from the forward lavatory
should be reflected by an adjustment to the proposed compliance times.
The FAA does not concur that the risks associated with either the
forward or aft lavatories should be distinguished by an adjustment to
the proposed compliance times of the NPRM. As discussed previously,
``blue ice'' detaching from the forward lavatory could cause damage to
the engine and airframe, as well as present a hazard to persons on the
ground; ``blue ice'' detaching from the aft lavatory presents a hazard
to persons on the ground. Regardless of whether the formation of ``blue
ice'' occurs on the forward or aft lavatory drain system, the resultant
unsafe condition would exist. Even if the formation of ``blue ice'' on
the aft lavatory drain systems may appear to be a less ``significant''
safety concern than the forward systems, a safety concern for those
persons on the ground, nevertheless, still exists.
Request To Involve Principal Maintenance Inspectors (PMI)
This same commenter, in reference to paragraph (b) of the previous
NPRM, contends that it is more appropriate for the PMI, rather than the
Seattle Aircraft Certification Office (ACO) engineering staff, to
approve subsequent changes to the maintenance program once the program
has been approved. The commenter considers that the PMI is more
qualified than the ACO staff to approve tasks on training, reporting,
and adjustment to the leak test intervals based upon reliability
program recommendations. The commenter points out that the subject
matter of the rule is clearly maintenance-related, and the ACO staff is
not equipped to effectively respond to requests for maintenance
interval changes that may occur. The commenter states that paragraph
(b) of the proposal should be revised to include a statement that the
AD is no longer applicable once a revision to the FAA-approved
maintenance program is implemented.
The FAA does not concur. Although the FAA agrees that the PMI
should have oversight of most of the requirements of the proposed
alternative maintenance program provision of the rule, the FAA does not
agree that the PMI should be tasked with approving certain adjustments
of the program. Failure threshold criteria and definitive leak/failure
rate data do not exist for the majority of the subject valves;
therefore, a PMI would have no data on which to base the approval of an
extension of a leak test interval for many valves with the assurance
that the valve would not fail within the adjusted interval. In light of
this, it is essential that the FAA, at the ACO level, have feedback as
to the leak and failure rates experienced in the field. Although the
PMI's serve as the FAA's critical link with the operators (and the PMI
oversight responsibilities will not be minimized by this AD action), it
is the staff of the ACO that provides the engineering support necessary
to evaluate whether increases in leak test intervals will maintain an
acceptable level of safety.
Further, the FAA considers it essential that any adjustment of the
required leak test intervals, seal change intervals, and data reporting
procedures should be approved in a uniform manner to ensure that the
program is administered uniformly (and appropriately) fleetwide. The
staff of the Seattle ACO is in the best position to ensure that this is
accomplished. Additionally, given that possible new relevant issues
might be revealed during the approval process, it is imperative that
the engineering staff at the ACO have such feedback. In any case, the
ACO staff will work closely with the cognizant PMI to ensure that any
approved revisions to this aspect of the maintenance program are
appropriate and workable for the applicable airline.
Request To Increase Leak Test Intervals for Pneudraulics Drain
Valves
Several commenters request that the leak test interval for
Pneudraulics drain valve having part number (P/N) 9527-1 be increased
from the proposed 1,000 flight hours. Two of the commenters requested
the interval be increased to 2,000 flight hours; and one of the
commenters, the valve manufacturer, requests that the interval be
increased to 4,500 flight hours.
The FAA concurs partially. Since the issuance of the NPRM, the FAA
has received new data regarding the in-service performance of the
Pneudraulics 9527 series drain valve. The data was obtained in
accordance with procedures similar to those of paragraphs (b) and (c)
of this supplemental NPRM. This data revealed that, only two leak tests
failures were detected during a total time of 847,927 hours on 412
Pneudraulics valves. In consideration of this data, the FAA finds that,
for those operators who choose to comply with the requirements of
paragraph (a) of the AD, this information justifies an increase of the
leak test interval of Pneudraulics valves having P/N 9527 series from
1,000 hours to 2,000 hours. Additionally, the FAA finds that, for
operators who choose to comply with the maintenance option of paragraph
(b) of the AD, this information justifies an increase of the leak test
interval of the Pneudraulics valves P/N 9527 series from 1,000 hours to
4,000 hours. Paragraphs (a) and (b) of this supplemental NPRM have been
revised accordingly. However, if following the requirements of
paragraphs (b) and (c) of this supplemental NPRM, similar data is
gathered by a number of operators and are submitted to the FAA in
support of an extension of the leak check interval for another type of
valve, the FAA will consider extension of the leak check intervals for
that valve for all operators using the valve.
[[Page 62712]]
Request To Increase Leak Test Intervals of Certain Other Shaw
Valves
One commenter states that its fleet has a mixture of valves that
have been modified in accordance with Shaw Service Bulletin SB
10101000B-38-1, and valves that have not been modified in accordance
with that service bulletin. The operator requests that the currently
proposed leak test interval of 600 flight hours (for the valves that
have not been modified in accordance with the service bulletin) be
increased to equal the 1,000 flight hour leak test interval of the
valves modified in accordance with that service bulletin. Because of
the operator's high level of awareness, it sees no safety compromise in
requiring the unmodified valves to be leak tested at 1,000 flight
hours.
The FAA does not concur. The modifications described by the subject
service bulletin were designed to make the valves less likely to leak.
Therefore, the leak test interval is permitted to be increased only for
those valves that have been modified in accordance with Shaw Service
Bulletin SB 1010000B-38-1.
Request To Increase Leak Test Interval for Other Shaw Valves
One commenter, a valve manufacturer, requests that the leak test
interval for certain Shaw valves be extended from 1,000 flight hours to
2,000 flight hours when the maintenance procedures have been revised
and data have been submitted to substantiate the increased interval.
The FAA concurs that when maintenance procedures have been revised
and data have been submitted to substantiate the increased interval,
approval may be granted to increase the leak test intervals. Under the
provisions of this supplemental NPRM, an operator has the option of
proposing a change to its maintenance program, gathering data, and
making a request for extension of the leak test interval. Operators
interested in this option should contact the Seattle Aircraft
Certification Office to discuss implementation of this option before
submitting the request to extend the leak test intervals. If a number
of operators successfully follow this procedure and provide data
similar to that provided for the Pneudraulics P/N 9527 series valve,
the FAA will consider an ``across the board'' increase for extension of
the leak check interval for the valve that they are using. This
procedure is applicable to valve manufacturers as well.
Request To Increase Interval of Replacement of Pneudraulics Valve
Seals
One commenter, an operator, requests that the replacements of the
seals of the Pneudraulics valves be extended from the proposed ``prior
to 5,000 flight hours after the effective date of the AD, and
thereafter at intervals not to exceed 18 months,'' to replacement of
the seal ``every third leak test of the drain system, or every 6,000
flight hours.'' The commenter states that implementation of the revised
compliance times would provide a scheduling convenience, and would
still maintain an acceptable level of safety.
The FAA concurs that the intervals for the repetitive replacements
can be extended somewhat. Since the Pneudraulics valve seals are
similar to those used in the in-line drain valves and replacement of
those seals are approved for longer replacement intervals, the FAA has
revised paragraphs (a)(1)(ii) and (b)(1)(ii) of this supplemental NPRM
to require accomplishment of repetitive seal replacements at intervals
not to exceed 18 months or 6,000 flight hours, whichever occurs later.
Request To Revise Compliance Times for Certain Seal Changes
One commenter, the airplane manufacturer, requests that the
proposed rule be revised to provide for an alternative repetitive
interval for accomplishment of the seal changes. Specifically, the
commenter requests that, ``or within 48 months after the last
documented seal change'' be added after the proposed repetitive
interval of ``5,000 flight hours'' in paragraph (b)(1)(i) of the
proposed rule. The commenter states that this alternative repetitive
interval would prevent unnecessary seal changes for operators that have
recently performed the seal change.
The FAA concurs that the requested alternative repetitive interval
would prevent unnecessary seal changes for operators that have recently
performed the seal change. The FAA considers that those alternative
repetitive intervals provide an equivalent level of safety. Therefore,
the FAA has revised paragraph (b)(3) of this supplemental NPRM (which
appeared as paragraph (b)(1) of the previous proposal). The FAA also
has made a corresponding change to paragraph (a)(8) of this
supplemental NPRM since it is similar to the requirements of paragraph
(b)(3) of the supplemental NPRM.
Request To Delete Certain Seal Part Numbers
One commenter, the airplane manufacturer, requests that valve seal
part numbers 2651-329, 2651-334, 10101000C-G, 10101000C-M, and
1010000C-R be deleted from the proposal. The commenter considers that
part numbers that have not been installed, either in production or
retrofit, on Boeing Model 737 series airplanes should not be cited in
the NPRM. The FAA concurs with the commenter's remarks, and has removed
all references to those parts numbers from this supplemental NPRM.
Request To Mandate Leak Testing of All Seals in the Lavatory System
One commenter notes that, while the previous NPRM proposes leak
testing of the dump valve seal and the inner seal of the drain valve of
the service panel, no testing of the outer cap/door seal is required.
The commenter states that since the outer cap/door seal is the ``last
resort'' in preventing leakage of ``blue ice,'' leak testing should be
required of the outer cap/door.
The FAA does not concur. Some valve designs are such that the valve
must be partially disassembled (removing the inner seal, interlocking
inner plugs, etc.) to allow the outer door to be tested, which would
invalidate the test of the inner seal. Additionally, different valve
designs may require valve disassembly and reassembly as part of the
test procedure with different test procedures for different valve
designs. These factors complicate the specification of a usable test of
both inner and outer doors for all existing valve designs. Therefore,
the FAA finds that the requirement to apply 3 PSID across the valve
inner door and to visually inspect the outer door seal for damage that
could cause leakage on all service panel valves to be adequate and
appropriate. However, if an operator prefers to test the outer door and
inspect the inner door, the FAA will consider requests for an
alternative method of compliance as provided in paragraph (f) of this
proposed AD.
Request To Require a Lever Lock Cap and a Vacuum Breaker Check
Valve
One commenter states that, instead of permitting a vacuum breaker
check valve to be used as an alternative to the installation of a lever
lock cap, the FAA should require both of them. The commenter states
that a long history of poor performance of check valves and lever lock
caps indicates that a redundant system requiring both the valve and cap
would have greater reliability.
[[Page 62713]]
The FAA does not concur in this case. The FAA acknowledges that
redundant systems generally provide a higher level of safety; however,
in this case, redundancy to the check valve function is provided by the
vacuum breaker. In the case of a check valve alone, the lever lock cap
provides redundancy to the check valve. There are insufficient data to
show which combination is more reliable.
However, service history information indicates that vacuum breaker
check valves with poppet check valves (rather than mushroom check
valves) have a greater reliability record. Therefore, the FAA has
removed reference to Monogram Part Number 3765-175 (mushroom type) from
paragraphs (a) and (b) of this supplemental NPRM. By requiring repair
of leaking components when ``blue streaks'' are observed, the FAA
intends that operators, through their own experience, will determine
which combination of valves works the best to avoid leakage. However,
if the FAA receives data indicating service problems or unreliability
with vacuum breaker check valves using poppet checks, the FAA may
consider further rulemaking action.
Request To Revise Approvals of Certain Vacuum Breakers
Two commenters request that the approval of vacuum breakers, as
referenced in the proposed rule, be revised. One commenter requests
that reference to all Monogram part number series 3765-175 or 3765-190
series be deleted, and replaced with ``* * * an FAA-approved check
valve with a vacuum breaker * * *,'' or replaced with a specific
reference to valves having Shaw part number 301-0009-01. This commenter
states that the vacuum breaker check valves leaked, and should not be
provided as an alternative to installation of a lever lock cap on the
flush/fill line. The other commenter requests that instead of
specifying particular part numbers, the approval reference should be to
``* * * an FAA-approved vacuum break in the * * *.'' This commenter
considers that this would cover all vacuum breaker manufacturers.
The FAA concurs partially. The FAA has reviewed available service
history data and concluded that vacuum breaker check valves of the
poppet type (such as Monogram part number series 3765-190) have fewer
reports of leakage than the vacuum breaker test valves of the mushroom
type (such as Monogram part number 3765-175). Therefore, as stated
previously, the FAA has removed reference to Monogram part number 3765-
175 as an approved valve from this supplemental NPRM.
The FAA also has reviewed the design of Shaw part number 301-0009-
01, which is a vacuum breaker check valve of the poppet type, and has
added it as an acceptable part number in paragraphs (a)(8)(ii) and
(b)(3)(ii) of this supplemental NPRM.
Additionally, since the issuance of the previous NPRM, another
acceptable valve for the flush/fill line has been certified. The
installation of Kaiser Electroprecision flush/fill ball valve part
number series 0062-0009 has been added to paragraphs (a)(8)(iii),
(b)(3)(iii), and (d)(3) of this supplemental NPRM as an alternative
method of preventing leakage from the flush/fill line.
Request To Shorten Leak Test Intervals of Flush/Fill Caps
The commenter states that there is no discussion in the proposal of
what would prompt an airline to ensure flush/fill caps are installed in
all positions prior to each flight. The commenter contends that it is
common practice for caps to be removed from airplanes due to their
nuisance value. The commenter also states that the flush/fill caps, as
well as the lever lock caps, are difficult to operate and commonly have
the seals removed, which render them inoperable on the airplane. The
commenter considers the ease with which the seal is removed is a design
flaw of the valve itself. Therefore, the commenter requests that
another device be considered instead of the flush/fill caps that is not
on the exterior of the aircraft and cannot be tampered with by ground
maintenance personnel. The commenter notes that a device incorporated
further upstream with positive shut-off and anti-siphon features would
eliminate the ``blue ice'' that occurs at the flush/fill port.
Therefore, the commenter requests that, until such a device can be
developed and FAA-approved, the leak tests and inspections of this area
should be performed more frequently.
The FAA does not concur with the commenter's request. The FAA does
not consider it necessary to require an additional inspection to ensure
installation of the flush/fill caps when they are installed in
accordance with an AD. If, as the commenter asserts, cases of
uninstalled flush/fill caps commonly occur, the FAA does not find that
reason to assume that operators would continue that practice in the
future if operation without the flush/fill caps would be a violation of
an AD. Further, lever lock caps are specified by this supplemental NPRM
precisely because they must be in the closed position to allow the
service panel door to be closed. In addition, this supplemental NPRM
specifies that if there is evidence of leakage, the leaking device must
be corrected, or the lavatory drained and placarded inoperative.
Therefore, if seals or caps are removed and result in leakage, this
provision will ensure that the system is repaired before the lavatory
is returned to service.
Additionally, the FAA notes that the vacuum break poppet type check
valves specified in the previous NPRM can be used as an alternative to
using lever lock caps. The FAA is not aware of any data, presently,
that supports an increase or decrease in the leak test intervals of the
devices on the flush/fill line. Consequently, this supplemental NPRM
contains neither an increase nor a decrease in the leak test intervals
of these devices. However, if such data becomes available that supports
a decrease in the leak test intervals, the FAA may consider additional
rulemaking.
Request To Revise the Leak Test of the Inner Door of the Service
Panel Drain Valve
Several commenters request that the leak test of the inner door of
the service panel drain be revised to require the test to be run with
the outer door open when using a vacuum box so that the 3 PSID
differential is applied across the inner door. One of these commenters,
the airplane manufacturer, points out that if the outer door seal is
good, the inner door seal will not reflect a pressure differential. For
this reason, the FAA concurs. The FAA has revised the supplemental NPRM
to specify that the test be run with the outer door open when using a
vacuum box.
Request To Revise Testing of Drain Panel Valves
One commenter requests that testing of the drain valves cover both
the inner door of the valve and the outer door/cap of the valve. The
commenter also notes that some valves have their primary seals on the
outer doors, not the inner doors, so that omitting the test of the
outer door, as proposed in the NPRM, results in the primary seal of the
valve being untested.
The FAA does not concur. As discussed previously in the request to
mandate leak testing of all seals in the lavatory system, the FAA has
revised the requirements of the leak testing of the drain valves of
service panels to require applying 3 PSID across the valve inner door
and visually inspecting the outer door seal for damage. This approach
should adequately test valves with inner and outer doors. However, if
[[Page 62714]]
an operator elects to test the outer door and visually inspect the
inner door, that operator should apply for approval of an alternative
method of compliance under the provisions of paragraph (f) of this
supplemental NPRM.
Request To Require Visual Inspection of the Outer Cap/Door
Two commenters request that paragraphs (a)(4) and (b)(2)(iii) of
the proposal be revised to delete the requirement to perform a leak
test of the outer door of ``donut'' type valves, and add a visual
inspection of the outer doors instead. The commenters state that the
``donut'' valves are similar to other valves in that they provide two
sealing surfaces. The commenters note that for those other valves, the
proposal would require only a test of the inner door or the sealing
surface.
The FAA concurs and has revised paragraphs (a)(4) and (b)(2)(iii)
of this supplemental NPRM accordingly. In light of the fact that this
supplemental NPRM would require eventually removing all ``donut''
valves and replacing them with FAA-approved valves, the FAA finds that,
in the interim, a visual inspection of the outer doors, rather than a
leak test, will ensure an acceptable level of safety.
Request To Require a Leak Test of the Outer Door of the Service
Panel Drain
Another commenter states that since the FAA required it to perform
the leak test of the outer door, the rules for testing the service
panel drain should not be changed at this time. The commenter states
that by requiring leak tests only of the inner door, the proposal
provides an unfair competitive advantage in favor of its competitors
because some valves have their primary seals on the outer doors instead
of the inner doors. In addition, by not requiring a leak test of the
outer door, the actual primary seal of the valve would not be tested.
The FAA does not concur with the request to require leak tests of
the outer door seal. The FAA finds that performing a leak test of the
inner door and visual inspections of the outer door provide an
acceptable level of safety. However, if an operator chooses to test the
outer door and visually inspect the inner door, under the provisions of
paragraph (f) of this supplemental NPRM, that operator may request
approval of an adjustment of this requirement if data are submitted to
substantiate that such an adjustment would provide an acceptable level
of safety.
Request To Extend Leak Test Intervals in Paragraph (b) of the
Proposal
Several commenters state that the leak test intervals specified in
paragraph (b) of the proposal should be relaxed so that operators would
be encouraged to select it as an alternative to the accomplishment of
the requirements of paragraph (a) of the proposal. One of the
commenters states that this same request was made in response to the
proposed rule concerning ``blue ice'' for Boeing Model 727 series
airplanes, and that the FAA did not respond to that request. Several
commenters assert that paragraph (b) of the proposal should
additionally provide terminating action once an operator's FAA-approved
maintenance plan has been incorporated.
The FAA does not concur with the commenters' request to increase
the leak test intervals specified in paragraph (b) simply in order to
encourage operators to choose that option. For the reasons specified
previously under the ``General Changes to the Proposal: Revision of
Optional Maintenance Program'' section of this supplemental NPRM, the
FAA finds that the previously proposed terminating action must be
deleted. Further, the expansion of leak test intervals that are
included in paragraph (b) of this supplemental NPRM is primarily
related to the reliability of the waste drain valves involved. The
additional requirements of paragraph (b) provide assurance that
expansion of the intervals will not result in significant leakage
events in the time between the leak tests. The FAA included paragraph
(b) of this supplemental NPRM not only because it does contain certain
``attractive'' features, but also to provide a format for verifiable
empirical data to serve as a reliability indicator for the waste drain
valves. To date, three operators have opted to follow requirements
similar to those provided in paragraph (b) of this supplemental NPRM.
The FAA concludes, therefore, that compliance with the optional
provisions of paragraph (b) of this supplemental NPRM is of value to
some operators.
Additionally, in reviewing the preamble of AD 94-23-10 (applicable
to Boeing Model 727 series airplanes), the FAA finds that the
commenter's request regarding the leak test intervals of paragraph (b)
of that AD was specifically addressed in the final rule. The FAA's
response noted the revision of several requirements of paragraph (b) of
that final rule to make it more ``attractive'' to operators; certain of
those revised requirements included extended leak test intervals for
some valves.
Request To Revise Leak Test Intervals for Service Panel Drain
Valves
The airplane manufacturer requests that paragraph (b)(2)(ii) of the
proposal be revised to increase the replacement interval of the service
panel drain valves from 1,000 flight hours to 2,000 flight hours. The
commenter states that increasing this interval would not decrease the
level of safety because of other requirements of paragraph (b) of the
proposal. Further, the commenter notes that two alternative methods of
compliance have been granted to increase the interval to 2,000 flight
hours.
The FAA does not concur with the commenter's request to increase
the leak test interval ``across the board'' for service panel drain
valves at this time. However, if data are submitted for specific
service panel drain valves in accordance with the data gathering
requirements of paragraph (b) of this supplemental NPRM, the FAA will
review the data and may consider extending the leak test intervals
accordingly. If a number of operators have successfully accomplished
such programs, the FAA will evaluate all the data submitted for a
particular valve and consider an ``across the board'' extension of the
leak test interval.
Request for Clarification of Compliance Times
The airplane manufacturer requests that compliance times in
paragraph (b)(4) of the proposal be revised. That proposed compliance
time is currently specified as ``* * * at intervals not to exceed 4
calendar days or 45 flight hours, whichever occurs later.'' The
commenter requests that the phrase ``not to exceed'' be deleted and
replaced with the word ``of.'' The manufacturer states that the phrase
``not to exceed'' appears to be in conflict with the phrase ``* * *
whichever occurs later.'' Therefore, the manufacturer suggests revising
the compliance time to read ``at intervals of 4 calendar days or 45
flight hours, whichever occurs later.''
The FAA does not concur that the phrases are in conflict with each
other. The phrases ``at intervals not to exceed 4 calendar days or 45
flight hours, whichever occurs later'' are standard phrasing the FAA
uses routinely in providing certain compliance times. The phrase, ``not
to exceed,'' allows accomplishment of the required action at
frequencies less than the specified intervals. The phrase, ``whichever
occurs later,'' allows an operator to select the means of measuring the
[[Page 62715]]
interval that results in less frequent accomplishment of the required
actions, depending upon the operator's individual utilization rates.
Therefore, no change of compliance time is required to paragraph (b)(4)
of the supplemental NPRM.
Request To Incorporate Paragraph (b) Into Paragraph (f) of the
Proposal
One commenter considers that the provisions in paragraph (b) of the
NPRM are merely guidelines for submitting alternative methods of
compliance. Therefore, the commenter requests that paragraph (b) of the
proposal be incorporated into the paragraph that specifically addresses
alternative methods of compliance [paragraph (f) of the proposal].
The FAA does not concur. The maintenance option provided by
paragraph (b) of this supplemental NPRM provides for the acquisition of
data that are required to justify extending leak test intervals.
Compliance with paragraph (b) of the supplemental NPRM is an approved
method of establishing empirical data on valve reliability. The FAA
sees no added value in changing the paragraph numbering of the
proposal. Moreover, the FAA considers that a change in the numbering of
the paragraphs would have the potential for added confusion since an
existing AD for the Boeing Model 727 series airplanes concerning ``blue
ice'' also has paragraph (b) designated as the maintenance option.
Request To Revise Test Requirements for Flush/Fill Line Anti-Siphon
Valves
The airplane manufacturer requests that paragraph (b)(3) of the
proposal be revised from ``Thereafter, repeat the requirements at
intervals not to exceed 5,000 flight hours'' to ``Thereafter, repeat
the requirements at intervals not to exceed 5,000 flight hours or 24
months.'' The commenter notes that the paragraph would then be
consistent with the test requirements of the in-line drain valve in
paragraph (b)(2)(i) of the proposal.
The FAA does not concur. The compliance times for testing the in-
line drain valves specified in paragraph (b)(2)(i) of the supplemental
NPRM were based on supportive data to justify those times. The FAA has
not received data justifying a similar compliance time for the flush/
fill line anti-siphon valve.
Request To Clarify Table 1 of the Proposal
One commenter, a valve manufacturer, requests that specific Shaw
Aero valves approved for a leak test interval of 1,000 flight hours be
clarified. The FAA has revised Table 1 of this supplemental NPRM to
clarify specifically which Shaw valves have been approved for use on
Boeing Model 737 series airplanes.
Request To Base Leak Test Intervals for Valves on Valve Quality
One commenter states that it is more important to use a quality
valve than a ``maintenance program'' to ensure reliability. The
commenter asserts that maintenance programs should be required of all
airlines, so that leak test intervals would be based on the quality and
performance of the hardware.
The FAA does not concur that claims of valve quality should be the
only basis for determining leak test intervals, or that all operators
should be required to follow the requirements of the optional
maintenance program [paragraph (b) of the supplemental NPRM]. Extension
of the leak test interval is based primarily upon hardware reliability,
as stated elsewhere in this supplemental NPRM. However, verification of
the actual reliability of the hardware is difficult to determine.
Review of maintenance data that is obtained through the maintenance
program and verified by FAA Flight Standards plays a major role in
determining the extension of leak test intervals. Although valve
manufacturers and some operators claim that the hardware and systems
currently in service are providing adequate levels of safety, incidents
of ``blue ice'' continue to occur.
Since leakage from the waste system is not a reportable event
according to part 21 of the Federal Aviation Regulations (14 CFR part
21), the FAA included the provisions of paragraph (b) of the proposal
to make leakage from the waste system a reportable event. Those
operators who choose to compile that data will have documented
information to submit to the FAA as a basis for increasing leak test
intervals. As stated earlier, the FAA has already used this program to
extend the leak test interval for a certain valve.
With regard to the commenter's statement that all operators should
be required to follow a maintenance program, the FAA has incorporated
requirements to periodically change valve seals and correct any leakage
found in accordance with paragraph (a) of this supplemental NPRM. The
more extensive requirements of the maintenance program specified in
paragraph (b) of the supplemental NPRM provide assurance that
significant leakage will not occur during the expanded leak test
intervals.
Request To Increase Certain Leak Test Intervals
The ATA asserts that leak test intervals of every 200 flight hours
for certain drain system valves cannot be justified based on safety
concerns with ``blue ice.'' The ATA requests that those leak test
intervals be extended.
The FAA does not concur. The current leak test interval for certain
drain system valves is every 200 flight hours, as required by AD 89-11-
03. Nevertheless, the FAA has continued to receive reports of damage to
airplanes. The FAA intends to increase the leak test interval only for
those valves documented to be reliable, in accordance with the proposed
requirements of this supplemental NPRM.
Request for Definition of ``Vent Line''
Another operator requests that the term ``vent line'' be defined
specifically. The commenter questions if ``vent line'' as cited in the
proposed AD refers only to the portion of the line shown on the
Monogram check valve.
The FAA acknowledges that clarification is necessary. The vent line
vacuum breaker is that portion of the valve and vent line that
functions as a vacuum breaker, as opposed to the part of the valve
performing a ``check valve'' function. The intent of the previous NPRM
was to perform maintenance on the vacuum breaker check valve and ensure
that the vacuum break feature operates correctly. For clarification
purposes, reference to the term ``vent line'' has been removed from
this supplemental NPRM, and the applicable paragraphs have been revised
to reference a ``vent line vacuum breaker.''
Request To Revise Reference to Service Information
The airplane manufacturer advised that the correct service
bulletins that should be cited in paragraph (f)(2) of the proposal are
Boeing Service Bulletins 737-38-1026 (lavatory A), and 737-38-1031
(lavatory F). Those service bulletins describe alternative methods of
compliance with the requirements of only paragraph (a)(2) of the
supplemental NPRM. The FAA inadvertently cited an incorrect service
bulletin in the previous NPRM; the supplemental NPRM has been revised
to cite the correct service bulletins.
Request To Change Reference to Certain Drain System Valves
One commenter requests that the description of the ``donut'' valves
in paragraphs (a)(4) and (b)(2)(iii) of the NPRM be expanded to read,
``For each lavatory drain system that incorporates
[[Page 62716]]
``donut'' plugs (Kaiser Electroprecision, part number 4259-20 or 4259-
31), or FAA-approved equivalent, or incorporates Kaiser
Electroprecision cap/flange, part numbers * * *.'' The FAA concurs, and
has revised paragraphs (a)(6) and (b)(2)(iv) of this supplemental NPRM
[which appeared as paragraphs (a)(4) and (b)(2)(iii), respectively, of
the previous NPRM] to provide clarification concerning the specific
``donut'' valves, as suggested by the commenter.
Request To Revise Notes 3 and 5 of the Proposal
The airplane manufacturer requests that Notes 3 and 5 of the NPRM
be corrected to reference Boeing Maintenance Manual Section 38-32-00/
501 instead of the currently referenced Boeing service letter.
The FAA acknowledges that Boeing Maintenance Manual Section 38-32-
00/501 is the appropriate guidance for the testing, and has revised
Note 3 of this supplemental NPRM accordingly. However, since reference
to guidance for performing leak tests specifically addressed in Note 5
of the previous NPRM is no longer necessary or applicable, it has been
removed from this supplemental NPRM. (Note 5 of this supplemental NPRM
now contains information unrelated to NOTE 5 of the previous NPRM.)
Request To Delete Reference to Development of Future In-Line Drain
Valves
One commenter, a valve manufacturer, requests that reference to the
development of future in-line drain valves that would provide for
possible terminating action be deleted from the proposal since that
statement may mislead airlines and other interested parties to think
that development and approval of those valves is currently in progress.
The commenter states that the NPRM is a place for facts, not
supposition of what might be. The commenter further states that it
believes it has been ``damaged'' by mention of a future valve,
specifically when the FAA has not considered existing in-service data
concerning the reliability of this manufacturer's valves.
The FAA acknowledges the commenter's request. The FAA has removed
reference to current in-line drain valves, as well as possible future
development of those valves, from consideration as terminating action
for certain requirements of this supplemental NPRM. As discussed
previously in the preamble of this supplemental NPRM, the FAA has
determined that terminating action for the leak testing of the in-line
valves under an approved maintenance program is no longer appropriate,
based on recent reports of leakage of drain systems with in-line drain
valves installed.
In addition, it is common practice for the FAA to provide
information in NPRM's concerning possible development and approval of
various corrective actions. For example, in certain cases, compliance
times for corrective actions are based on a time frame that is
determined to be adequate in order to develop, approve, and install
such corrective actions, e.g., repair, parts, or modifications.
Establishment of a reasonable compliance time enables the manufacturer
to plan its schedules and resources so that the corrective action is
made available to the airlines well within the compliance time
established by an AD. For these reasons, the FAA finds that the
development and approval of future parts, repair, or modifications are
not only relevant to discussions in proposed rules, they are, in
certain cases, inherent to the discussion itself.
Economic Impact
There are approximately 2,410 Model 737 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 1,031
airplanes of U.S. registry and 110 U.S. operators would be affected by
this proposed AD.
The proposed waste drain system leak test and outer cap inspection
would take approximately 6 work hours per airplane to accomplish, at an
average labor rate of $60 per work hour. Based on these figures, the
cost impact on U.S. operators of these proposed requirements of this AD
is estimated to be $371,160, or $360 per airplane, per test/inspection.
Certain airplanes (i.e., those that have ``donut'' type drain
valves installed) may be required to be leak tested as many as 15 times
each year. Certain other airplanes having other valve configurations
would be required to be leak tested as few as 3 times each year. Some
airplanes that have various combinations drain valves installed would
require approximately 2 leak tests of one drain valve and 3 leak tests
of the other drain valve each year. Based on these figures, the annual
(recurring) cost impact of the required repetitive leak tests on U.S.
operators is estimated to be between $1,080 and $5,400 per airplane per
year.
With regard to replacement of ``donut'' type drain valves, the cost
of a new valve is approximately $1,200. However, the number of leak
tests for an airplane that is flown an average of 3,000 flight hours a
year is thereby reduced from 15 tests to 3 tests. The cost reduction
because of the number of tests required is approximately equal to the
cost of the replacement valve. Therefore, no additional cost is
incurred because of this change.
The FAA estimates that it would take approximately 1 work hour per
airplane lavatory drain to accomplish a visual inspection of the
service panel drain valve cap/door seal and seal mating surfaces, at an
average labor cost of $60 per work hour. As with leak tests, certain
airplanes would be required to be visually inspected as many as 15
times or as few as 3 times each year. Based on these figures, the
annual (recurring) cost impact of the required repetitive visual
inspections on U.S. operators is estimated to be between $180 and $900
per airplane per year.
The proposed installation of the flush/fill line cap would take
approximately 1 work hour per cap to accomplish, at an average labor
rate of $60 per work hour. The cost of required parts would be $275 per
cap. There are an average of 2.5 caps per airplane. Based on these
figures, the cost impact on U.S. operators of these proposed
requirements of this AD is estimated to be $863,463, or $838 per
airplane.
The addition of the seal change requirement to paragraph (a) will
require approximately 2 work hours to accomplish, at an average labor
cost of $60 per hour. The cost of required parts would be $200 per each
seal change. Based on these figures, the cost impact on U.S. operators
of these proposed requirements of this AD is estimated to be $329,920,
or approximately $320 per airplane per year.
The number of required work hours, as indicated above, is presented
as if the accomplishment of the actions proposed in this AD were to be
conducted as ``stand alone'' actions. However, in actual practice,
these actions could be accomplished coincidentally or in combination
with normally scheduled airplane inspections and other maintenance
program tasks. Therefore, the actual number of necessary ``additional''
work hours would be minimal in many instances. Additionally, any costs
associated with special airplane scheduling should be minimal.
In addition to the costs discussed above, for those operators who
elect to comply with proposed paragraph (b) of this proposed AD action,
the FAA estimates that it would take approximately 40 work hours per
operator to incorporate the lavatory drain system leak test procedures
into the maintenance programs, at an average
[[Page 62717]]
labor cost of $60 per work hour. Based on these figures, the cost
impact of the proposed maintenance revision requirement of this AD
action on the 110 U.S. operators is estimated to be $264,000, or $2,400
per operator.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the current or proposed
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address specific unsafe conditions, they
appear to impose costs that would not otherwise be borne by operators.
However, because of the general obligation of operators to maintain
aircraft in an airworthy condition, this appearance is deceptive.
Attributing those costs solely to the issuance of this AD is
unrealistic because, in the interest of maintaining safe aircraft,
prudent operators would accomplish the required actions even if they
were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this
proposed AD. As a matter of law, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that it complies with all applicable airworthiness
requirements. In adopting and maintaining those requirements, the FAA
has already made the determination that they establish a level of
safety that is cost-beneficial. When the FAA, as in this proposed AD,
makes a finding of an unsafe condition, this means that the original
cost-beneficial level of safety is no longer being achieved and that
the required actions are necessary to restore that level of safety.
Because this level of safety has already been determined to be cost-
beneficial, a full cost-benefit analysis for this proposed AD would be
redundant and unnecessary.
Regulatory Impact
The regulations proposed herein would not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part 39 of the Federal Aviation Regulations (14 CFR part 39) as
follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-6223 (54 FR
21933, May 22, 1989), and by adding a new airworthiness directive (AD),
to read as follows:
Boeing: Docket 95-NM-111-AD. Supersedes AD 89-11-03, Amendment 39-
6223.
Applicability: All Boeing Model 737 series 100, 200, 300, 400
and 500 airplanes, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (f) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent engine damage, airframe damage, and/or hazard to
persons or property on the ground as a result of ``blue ice'' that
has formed from leakage of the lavatory drain system or flush/fill
systems and dislodged from the airplane, accomplish the following:
(a) Except as provided by paragraph (b) of this AD, accomplish
the applicable requirements of paragraphs (a)(1) through (a)(9) of
this AD at the time specified in each paragraph. If the waste drain
system incorporates more than one type of valve, only one of the
waste drain system leak test procedures (the one that applies to the
equipment with the longest leak test interval) must be conducted at
each service panel location. The waste drain system valve leak tests
specified in this AD shall be performed in accordance with the
following requirements: fluid shall completely cover the upstream
end of the valve being tested; the direction of the 3 pounds per
square inch differential pressure (PSID) shall be applied across the
valve in the same direction as occurs in flight; the other waste
drain system valves shall be open; and the minimum time to maintain
the differential pressure shall be 5 minutes. Any revision of the
seal change intervals or leak test intervals must be approved by the
Manager, Seattle Aircraft Certification Office (SACO), FAA,
Transport Airplane Directorate.
(1) Replace the valve seals in accordance with the applicable
schedule specified in paragraphs (a)(1)(i), (a)(1)(ii), and
(a)(1)(iii) of this AD.
(i) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
278: Replace the seals within 5,000 flight hours after the effective
date of this AD, or within 48 months after the last documented seal
change, whichever occurs later. Thereafter, repeat the replacement
of the seals at intervals not to exceed 48 months.
(ii) For each lavatory drain system that has a Pneudraulics part
number series 9527 valve: Replace the seals within 5,000 flight
hours after the effective date of this AD, or within 18 months of
the last documented seal change, whichever occurs later. Thereafter,
repeat the replacement of the seals at intervals not to exceed 18
months or 6,000 flight hours, whichever occurs later.
(iii) For each lavatory drain system that has any other type of
drain valve: Replace the seals within 5,000 flight hours after the
effective date of this AD, or within 18 months after the last
documented seal change, whichever occurs later. Thereafter, repeat
the replacement of the seals at intervals not to exceed 18 months.
(2) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
278: Within 4,500 flight hours after the effective date of this AD,
and thereafter at intervals not to exceed 4,500 flight hours,
accomplish the procedures specified in paragraphs (a)(2)(i) and
(a)(2)(ii) of this AD:
(i) Conduct a leak test of the toilet tank dump valve (in-tank
valve that is spring loaded closed and operable by a T-handle at the
service panel) and the in-line drain valve. The toilet tank dump
valve leak test must be performed by filling the toilet tank with a
minimum of 10 gallons of water/rinsing fluid and testing for leakage
after a period of 5 minutes. Take precautions to avoid
[[Page 62718]]
overfilling the tank and spilling fluid into the airplane. The in-
line drain valve leak test must be performed with a minimum of 3
PSID applied across the valve.
(ii) If a service panel valve or cap is installed, perform a
visual inspection of the service panel drain valve outer cap/door
seal and the inner seal (if the valve has an inner door with a
second positive seal), and the seal mating surfaces for wear or
damage that may allow leakage.
(3) For each lavatory drain system that has a service panel
drain valve installed, Pneudraulics part number series 9527: Within
2,000 flight hours after the effective date of this AD, accomplish
the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD.
Thereafter, repeat the leak tests at intervals not to exceed 2,000
flight hours.
(i) Conduct leak tests of the toilet tank dump valve and service
panel drain valve. The toilet tank dump valve leak test must be
performed by filling the toilet tank with a minimum of 10 gallons of
water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid into the airplane. The leak test of the service panel drain
valve must be performed with a minimum of 3 PSID applied across the
valve inner door/closure device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(4) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0032 or Shaw Aero part number/serial number as listed in Table
1 of this AD: Within 1,000 flight hours after the effective date of
this AD, and thereafter at intervals not to exceed 1,000 flight
hours, accomplish the requirements of paragraphs (a)(4)(i) and
(a)(4)(ii) of this AD:
Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Test
Interval
------------------------------------------------------------------------
Serial Nos. of part number
Shaw waste drain valve part no. valve approved for 1,000-hour
leak test interval
------------------------------------------------------------------------
331 Series, 332 Series................. All.
10101000B-A............................ None.
10101000B-A-1.......................... 0207-0212, 0219, 0226 and
higher.
10101000BA2............................ 0130 and higher.
10101000C-A-1.......................... 0277 and higher.
10101000C-J............................ None.
10101000C-J-2.......................... None.
10101000CN OR C-N...................... 3649 and higher.
Certain 10101000B valves............... Any of these ``B'' series
valves that incorporate the
improvements of Shaw Service
Bulletin 10101000B-38-1, dated
October 7, 1994, and are
marked ``SBB38-1-58''.
Certain 10101000C valves............... Any of these ``C'' series
valves that incorporate the
improvements of Shaw Service
Bulletin 10101000C-38-2 dated
October 7, 1994, and are
marked ``SBC38-2-58''.
------------------------------------------------------------------------
Note 2: Table 1 is a comprehensive list of all approved Shaw
Valves, including those valves approved by Parts Manufacturer
Approval (PMA) or Supplemental Type Certificate (STC) for
installation on Boeing Model 737 series airplanes.
(i) Conduct a leak test of the toilet tank dump valve and
service panel drain valve. The toilet tank dump valve leak test must
be performed by filling the toilet tank with a minimum of 10 gallons
of water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid into the airplane. The service panel drain valve leak test
must be performed with a minimum of 3 PSID applied across the valve
inner door/closure device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(5) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0026; or Shaw Aero Devices part number series 10101000B or
10101000C [except as specified in paragraph (a)(4) of this AD]:
Within 600 flight hours after the effective date of this AD, and
thereafter at intervals not to exceed 600 flight hours, accomplish
the requirements of paragraphs (a)(5)(i) and (a)(5)(ii) of this AD:
(i) Conduct a leak test of the dump valve and the service panel
drain valve. The leak test of the dump valve must be performed by
filling the toilet tank with a minimum of 10 gallons of water/
rinsing fluid and testing for leakage after a period of 5 minutes.
Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum 3 PSID applied across the valve inner
door/closure device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(6) For each lavatory drain system with a lavatory drain system
valve that incorporates either ``donut'' plug, Kaiser
Electroprecision part number 4259-20 or 4259-31; Kaiser Roylyn/
Kaiser Electroprecision cap/flange part numbers 2651-194C, 2651-
197C, 2651-216, 2651-219, 2651-235, 2651-256, 2651-258, 2651-259,
2651-260, 2651-275, 2651-282, 2651-286; or other FAA-approved
equivalent parts; accomplish the requirements at the specified times
of paragraphs (a)(6)(i), (a)(6)(ii), and (a)(6)(iii) of this AD. For
the purposes of this paragraph [(a)(6)], ``equivalent part'' means
either a ``donut'' plug that mates with the cap/flange having part
numbers listed in this paragraph, or a cap/flange that mates with
the ``donut'' plug having part numbers listed in this paragraph,
such that the cap/flange and ``donut'' plug are used together as an
assembled valve.
(i) Within 200 flight hours after the effective date of this AD,
and thereafter at intervals not to exceed 200 flight hours, conduct
leak tests of the toilet tank dump valve and the service panel drain
valve. The leak test of the toilet tank dump valve must be performed
by filling the toilet tank with a minimum of 10 gallons of water/
rinsing fluid and testing for leakage after a period of 5 minutes.
Take precautions to avoid overfilling the tank and spilling fluid on
the airplane. The service panel drain valve leak test must be
performed with a minimum 3 PSID applied across the valve.
(ii) Perform a visual inspection of the outer door/cap and seal
mating surface for wear or damage that may cause leakage. This
inspection shall be accomplished in conjunction with the leak tests
of paragraph (a)(6)(i).
(iii) Within 5,000 flight hours after the effective date of this
AD, replace the donut valve (part numbers per paragraph (a)(6) of
this AD) with another type of FAA-approved valve. Following
installation of the replacement valve, perform the appropriate leak
tests and seal replacements at the intervals specified for that
replacement valve, as applicable.
(7) For each lavatory drain system not addressed in paragraph
(a)(2), (a)(3), (a)(4), (a)(5), and (a)(6) of this AD: Within 200
flight hours after the effective date of this AD, and thereafter at
intervals not to exceed 200 flight hours, accomplish the
requirements of paragraphs (a)(7)(i) and (a)(7)(ii) of this AD:
(i) Conduct a leak test of the toilet tank dump valve and the
service panel drain valve. The toilet tank dump valve leak test must
be performed by filling the toilet tank with a minimum of 10 gallons
of water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum 3 PSID applied across the valve inner
door/closure device.
[[Page 62719]]
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(8) For flush/fill lines: Within 5,000 flight hours after the
effective date of this AD, perform the requirements of paragraph
(a)(8)(i), (a)(8)(ii), or (a)(8)(iii) of this AD, as applicable.
Thereafter, repeat the requirements at intervals not to exceed 5,000
flight hours, or 48 months after the last documented seal change,
whichever occurs later.
(i) If a lever lock cap is installed on the flush/fill line of
the subject lavatory, replace the seals on the toilet tank anti-
siphon (check) valve and the flush/fill line cap. Perform a leak
test of the toilet tank anti-siphon (check) valve with a minimum of
3 PSID across the valve, in accordance with paragraph (a)(8)(ii)(A)
of this AD, as applicable.
Note 3: The leak test procedure described in Boeing Maintenance
Manual, 38-32-00/501, may be referred to as guidance for this test
if the toilet tank is filled to the level specified in paragraph
(a)(8)(ii)(A) of this AD.
(ii) If a vacuum breaker check valve, Monogram part number
series 3765-190, or Shaw Aero Devises part number series 301-0009-01
is installed on the subject lavatory, replace the seals/o-rings in
the valve. Perform a leak test of the vacuum breaker check valve and
verify proper operation of the vent line vacuum breaker in
accordance with paragraphs (a)(8)(ii)(A) and (a)(8)(ii)(B) of this
AD.
(A) Leak test the toilet tank anti-siphon valve or the vacuum
breaker check valve by filling the toilet tank with water/rinsing
fluid to a level such that the bowl is approximately half full (at
least 2 inches above the flapper in the bowl.) Apply 3 PSID across
the valve in the same direction as occurs in flight. The vent line
vacuum breaker on vacuum breaker check valves must be pinched closed
or plugged for this leak test. If there is a cap/valve at the flush/
fill line port, the cap/valve must be removed/open during the test.
Check for leakage at the flush/fill line port for a period of 5
minutes.
(B) Verify proper operation of the vent line vacuum breaker by
filling the tank and testing at the fill line port for back drainage
after disconnecting the fluid source from the flush/fill line port.
If back drainage does not occur, replace the vent line vacuum
breaker or repair the vacuum breaker check valve in accordance with
the component maintenance manual to obtain proper back drainage. As
an alternative to the above test technique, verify proper operation
of the vent line vacuum breaker in accordance with the procedures of
the applicable component maintenance manual.
(iii) If a flush/fill ball valve, Kaiser Electroprecision part
number series 0062-0009 is installed on the flush/fill line of the
subject lavatory, replace the seals in the flush/fill ball valve and
the toilet tank anti-siphon valve. Perform a leak test of the toilet
tank anti-siphon valve with a minimum of 3 PSID across the valve, in
accordance with paragraph (a)(8)(ii)(A) of this AD.
(9) As a result of the leak tests and inspections required by
paragraph (a) of this AD, or if evidence of leakage is found at any
other time, accomplish the requirements of paragraph (a)(9)(i),
(a)(9)(ii), or (a)(9)(iii), as applicable.
(i) If a leak is discovered, prior to further flight, repair the
leak. Prior to further flight after repair, perform the appropriate
leak test, as applicable. Additionally, prior to returning the
airplane to service, clean the surfaces adjacent to where the
leakage occurred to clear them of any horizontal fluid residue
streaks; such cleaning must be to the extent that any future
appearance of a horizontal fluid residue streak will be taken to
mean that the system is leaking again.
Note 4: For purposes of this AD, ``leakage'' is defined as any
visible leakage, if observed during a leak test. At any other time
(than during a leak test), ``leakage'' is defined as the presence of
ice in the service panel, or horizontal fluid residue streaks/ice
trails originating at the service panel. The fluid residue is
usually, but not necessarily, blue in color.
(ii) If any worn or damaged seal is found, or if any damaged
seal mating surface is found, prior to further flight, repair or
replace it in accordance with the valve manufacturer's maintenance
manual.
(iii) In lieu of performing the requirements of paragraph
(a)(9)(i) or (a)(9)(ii): Prior to further flight, drain the affected
lavatory system and placard the lavatory inoperative until repairs
can be accomplished.
(b) As an alternative to the requirements of paragraph (a) of
this AD, operators may revise the FAA-approved maintenance program
to include the requirements specified in paragraphs (b)(1) through
(b)(7) of this AD. However, until the FAA-approved maintenance
program is so revised, operators must accomplish the requirements of
paragraph (a) of this AD. The waste drain system valve leak tests
specified in this AD shall be performed in accordance with the
following requirements: fluid shall completely cover the upstream
end of the valve being tested; the direction of the 3 pounds per
square inch differential pressure (PSID) shall be applied across the
valve in the same direction as occurs in flight; the other waste
drain system valves shall be open; and the minimum time to maintain
the differential pressure shall be 5 minutes. Any revision of the
seal change intervals or leak test intervals must be approved by the
Manager, Seattle ACO.
(1) Replace the valve seals in accordance with the applicable
schedule specified in paragraphs (b)(1)(i), (b)(1)(ii), or
(b)(1)(iii) of this AD.
(i) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
278: Replace the seals within 5,000 flight hours after the effective
date of this AD, or within 48 months of the last documented seal
change, whichever occurs later. Thereafter, repeat the replacement
of the seals at intervals not to exceed 48 months.
(ii) For each lavatory drain system that has a Pneudraulics part
number series 9527 valve: Replace the seals within 5,000 flight
hours after the effective date of this AD, or within 18 months of
the last documented seal change, whichever occurs later. Thereafter,
repeat the replacement of the seals at intervals not to exceed 18
months or 6,000 flight hours, whichever occurs later.
(iii) For each lavatory drain system that has any other type of
drain valve: Replace the seals within 5,000 flight hours after the
effective date of this AD, or within 18 months of the last
documented seal change, whichever occurs later. Thereafter, repeat
the replacement of the seals at intervals not to exceed 18 months.
(2) Conduct periodic leak tests of the lavatory drain systems in
accordance with the applicable schedule specified in paragraphs
(b)(2)(i), (b)(2)(ii), (b)(2)(iii), (b)(2)(iv), and (b)(2)(v) of
this AD. Only one of the waste drain system leak test procedures
(the one that applies to the equipment with the longest leak test
interval) must be conducted at each service panel location.
(i) For each lavatory drain system, that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
278: Within 5,000 flight hours after the effective date of this AD,
or within 5,000 hours of the last documented leak test, whichever
occurs later, accomplish the procedures specified in paragraphs
(b)(2)(i)(A) and (b)(2)(i)(B) of this AD. Thereafter repeat the
procedures at intervals not to exceed 24 months or 5,000 flight
hours, whichever occurs later.
(A) Conduct a leak test of the dump valve (in-tank valve that is
spring loaded closed and operable by a T-handle at the service
panel) and the in-line drain valve. The leak test of the toilet tank
dump valve must be performed by filling the toilet tank with a
minimum of 10 gallons of water/rinsing fluid and testing for leakage
after a period of 5 minutes. Take precautions to avoid overfilling
the tank and spilling fluid on the airplane. The in-line drain valve
leak test must be performed with a minimum of 3 PSID applied across
the valve.
(B) If a service panel valve or cap is installed, perform a
visual inspection of the service panel drain valve outer cap/door
seal and the inner seal (if the valve has an inner door with a
second positive seal), and the seal mating surfaces, for wear or
damage that may allow leakage.
(ii) For each lavatory drain system that has a service panel
drain valve installed, Pneudraulics part number series 9527: Within
4,000 flight hours after the effective date of this AD, or within
4,000 flight hours of the last documented leak test, whichever
occurs later, accomplish the requirements of paragraph (b)(2)(ii)(A)
and (b)(2)(ii)(B) of this AD. Thereafter, repeat the requirements at
intervals not to exceed 4,000 flight hours.
(A) Conduct leak tests of the toilet tank dump valve and service
panel drain valve. The toilet tank dump valve leak test must be
performed by filling the toilet tank with a minimum of 10 gallons of
water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum of 3 PSID applied across the valve inner
door/closure device.
(B) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
[[Page 62720]]
(iii) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0032, or Kaiser Electroprecision part number series 0218-0026,
or Shaw Aero Devices part number series 10101000B, 10101000C, 331-
series, 332-series: Within 1,000 flight hours after the effective
date of this AD, or within 1,000 flight hours of the last documented
leak test, whichever occurs later, accomplish the requirements of
paragraphs (b)(2)(iii)(A) and (b)(2)(iii)(B) of this AD. Thereafter,
repeat the requirements at intervals not to exceed 1,000 flight
hours.
(A) Conduct leak tests of the toilet tank dump valve and service
panel drain valve. The toilet tank dump valve leak test must be
performed by filling the toilet tank with a minimum of 10 gallons of
water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum of 3 PSID applied across the valve inner
door/closure device.
(B) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(iv) For each lavatory drain system with a lavatory drain system
valve that incorporates either ``donut'' plugs Kaiser
Electroprecision part number 4259-20 or 4259-31; Kaiser Roylyn/
Kaiser Electroprecision cap/flange part number 2651-194C, 2651-197C,
2651-216, 2651-219, 2651-235, 2651-256, 2651-258, 2651-259, 2651-
260, 2651-275, 2651-282, 2651-286; or other FAA-approved equivalent
part; accomplish the requirements at the times specified in
paragraphs (b)(2)(iv)(A), (b)(2)(iv)(B), and (b)(2)(iv)(C) of this
AD. For the purposes of this paragraph [(b)(2)(iv)], ``FAA-approved
equivalent part'' means either a ``donut'' plug that mates with the
cap/flange having part numbers listed in this paragraph, or a cap/
flange that mates with the ``donut'' plug having part numbers listed
in this paragraph, such that the cap/flange and ``donut'' plug are
used together as an assembled valve.
(A) Within 200 flight hours after the effective date of this AD,
or within 200 flight hours after the last documented leak test,
whichever occurs later, conduct leak tests of the dump valve and the
service panel drain valve. Thereafter, repeat the tests at intervals
not to exceed 200 flight hours. The dump valve leak test must be
performed by filling the toilet tank with a minimum of 10 gallons of
water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum 3 PSID applied across the valve.
(B) Perform a visual inspection of the outer door/cap and seal
mating surface for wear or damage that may cause leakage. Perform
this inspection in conjunction with the leak tests specified in
paragraph (b)(2)(iv)(A).
(C) Within 5,000 flight hours after the effective date of this
AD, replace the donut valve with another type of FAA-approved valve.
Following replacement of the valve, perform the subsequent leak
tests and seal replacements at the intervals specified for the new
valve.
(v) For each lavatory drain system that incorporates any other
type of approved valves: Within 400 flight hours after the effective
date of this AD, or within 400 flight hours of the last documented
leak test, whichever occurs later, accomplish the requirements of
paragraph (b)(2)(v)(A) and (b)(2)(v)(B) of this AD. Thereafter,
repeat the requirements at intervals not to exceed 400 flight hours.
(A) Conduct leak tests of the toilet tank dump valve and the
service panel drain valve. The toilet tank dump valve leak test must
be performed by filling the toilet tank with a minimum of 10 gallons
of water/rinsing fluid and testing for leakage after a period of 5
minutes. Take precautions to avoid overfilling the tank and spilling
fluid on the airplane. The service panel drain valve leak test must
be performed with a minimum 3 PSID applied across the valve. If the
service panel drain valve has an inner door with a second positive
seal, only the inner door must be tested.
(B) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(3) For flush/fill lines: Within 5,000 flight hours after the
effective date of this AD, perform the requirements of paragraph
(b)(3)(i), (b)(3)(ii), or (b)(3)(iii), as applicable. Thereafter,
repeat the requirements at intervals not to exceed 5,000 flight
hours, or 48 months after the last documented seal change, whichever
occurs later.
(i) If a lever lock cap is installed on the flush/fill line of
the subject lavatory, replace the seals on the toilet tank anti-
siphon (check) valve and the flush/fill line cap. Perform a leak
test of the toilet tank anti-siphon (check) valve with a minimum of
3 PSID across the valve as specified in paragraph (b)(3)(ii)(A) of
this AD.
(ii) If a vacuum breaker check valve, Monogram part number
series 3765-190 or Shaw Aero Devises part number series 301-0009-01,
is installed on the subject lavatory; replace the seals/o-rings in
the valve. Prior to further flight, leak test the vacuum breaker
check valve, and test for proper operation of the vent line vacuum
breaker as specified in paragraphs (b)(3)(ii)(A) and (b)(3)(ii)(B)
of this AD.
(A) Leak test the toilet tank anti-siphon valve or the vacuum
breaker check valve by filling the toilet tank with water/rinsing
fluid to a level such that the bowl is approximately half full (at
least 2 inches above the flapper in the bowl). Pressurize the
airplane to 3 PSID. The vent line vacuum breaker on vacuum breaker
check valves must be pinched closed or plugged for this leak test.
If there is a cap/valve at the flush/fill line port, the cap/valve
must be removed/opened during the test. Test for leakage at the
flush/fill line port for a period of 5 minutes.
Note 5: The leak test procedure in the appropriate section of
Boeing Maintenance Manual 38-32-00 may be used as guidance for this
test if the toilet tank is filled approximately half full (at least
2 inches above the flapper in the bowl).
(B) Verify proper operation of the vent line vacuum breaker by
filling the tank and testing at the fill line port for back drainage
after disconnecting the fluid source from the flush/fill line port.
If back drainage does not occur, replace the vent line vacuum
breaker or repair the vacuum breaker check valve in accordance with
the component maintenance manual as required to obtain proper back
drainage.
(iii) If a flush/fill ball valve, Kaiser Electroprecision part
number series 0062-009 installed on the flush/fill line of the
subject lavatory, replace the seals in the flush/fill ball valve and
the toilet tank anti-siphon valve. Perform a leak test of the toilet
tank anti-siphon valve in accordance with paragraph (b)(3)(ii))(A)
of this AD.
(4) Provide procedures for accomplishing visual inspections to
detect leakage, to be conducted by maintenance personnel at
intervals not to exceed 4 calendar days or 45 flight hours, which
ever occurs later.
(5) Provide procedures for reporting leakage. These procedures
shall provide that any ``horizontal blue streak'' findings must be
reported to maintenance and that, prior to further flight, the
leaking system shall either be repaired, or be drained and placard
inoperative.
(6) Provide training programs for maintenance and servicing
personnel that include information on ``Blue Ice Awareness'' and the
hazards of ``blue ice''.
(7) If a leak is discovered during a leak test required by
paragraph (b) of this AD; or if evidence of leakage is found at any
other time; or if repair/replacement of a valve (or valve parts) is
required as a result of a visual inspection required in accordance
with this AD; prior to further flight, accomplish the requirements
of paragraph (b)(7)(i), (b)(7)(ii), or (b)(7)(iii), as applicable.
Note 6: For purposes of this AD, ``leakage'' is defined as any
visible leakage, if observed during a leak test. At any other time
(than during a leak test), ``leakage'' is defined as the presence of
ice in the service panel, or horizontal fluid residue streaks/ice
trails originating at the service panel. The fluid residue is
usually, but not necessarily, blue in color.
(i) Repair the leak and, prior to further flight after repair,
perform a leak test. Additionally, prior to returning the airplane
to service, clean the surfaces adjacent to where the leakage
occurred to clear them of any horizontal fluid residue streaks; such
cleaning must be to the extent that any future appearance of a
horizontal fluid residue streak will be taken to mean that the
system is leaking again.
(ii) Repair or replace the valve or valve parts.
(iii) In lieu of either paragraph (b)(7)(i) or (b)(7)(ii), drain
the affected lavatory system and placard the lavatory inoperative
until repairs can be accomplished.
(c) For operators who elect to comply with paragraph (b) of this
AD: Any revision to (i.e., extension of) the leak test intervals
required by paragraph (b) of this AD must be approved by the
Manager, Seattle ACO, FAA, Transport Airplane Directorate. Requests
for such revisions must be submitted to the Manager of the Seattle
ACO through the FAA Principal Maintenance Inspector (PMI), and must
include the following information:
(1) The operator's name;
[[Page 62721]]
(2) A statement verifying that all known cases/indications of
leakage or failed leak tests are included in the submitted material;
(3) The type of valve (make, model, manufacturer, vendor part
number, and serial number);
(4) The period of time covered by the data;
(5) The current FAA leak test interval;
(6) Whether or not seals have been replaced between the seal
replacement intervals required by this AD;
(7) Whether or not a service panel drain valve is installed
downstream of an in-line drain valve, Kaiser Electroprecision part
number series 2651-278: Data on a service panel valve installed
downstream of an in-line drain valve will not be considered as an
indicator of the reliability of the service panel drain valve
because the in-line valve prevents potential leakage from reaching
the service panel drain valve.
(8) Whether or not leakage has been detected between leak test
intervals required by this AD, and the reason for leakage (i.e.,
worn seals, foreign materials on sealing surface, scratched or
damaged sealing surface on valve, etc.);
(9) Whether or not any cleaning, repairs, or seal changes were
performed on the valve prior to conducting the leak test. [If such
activities have been accomplished prior to conducting the periodic
leak test, that leak test shall be recorded as a ``failure'' for
purposes of the data required for this request submission. The
exception to this is the normally-scheduled seal change in
accordance with paragraph (b)(1) of this AD. Performing this
scheduled seal change prior to a leak test will not cause that leak
test to be recorded as a failure. Debris removal of major blockages
done as part of normal maintenance for previous flights is also
allowable and will not cause a leak test to be recorded as a
failure. Minor debris removal that is not commonly removed during
the normal ground maintenance test should not be removed prior to
the leak test.]
Note 7: Requests for approval of revised leak test intervals may
be submitted in any format, provided the data give the same level of
assurance specified in paragraph (c) above. Results of an
Environmental Quality Analysis (EQA) examination and leak test on a
randomly selected high-flight-hour valve, with seals that have not
been replaced during a period of use at least as long as the desired
interval, may be considered a valuable supplement to the service
history data, reducing the amount of service data that would
otherwise be required.
Note 8: For the purposes of expediting resolution of requests
for revisions to the leak test intervals, the FAA suggests that the
requester summarize the raw data; group the data gathered from
different airplanes (of the same model) and drain systems with the
same kind of valve; and provide a recommendation from pertinent
industry group(s) and/or the manufacturer specifying an appropriate
revised leak test interval.
Note 9: In cases where changes are made to a valve design
approved for an extended leak test interval such that a new valve
dash number or part number is established for the valve, the FAA may
not require extensive service history data to approve the new valve
to the same leak test interval as the previous valve design.
Similarity of design, the nature of the design changes, the nature
and amount of testing, and like factors will be considered by the
FAA to determine the appropriate data requirements and leak test
interval for a new or revised valve based upon an existing design.
(d) For all airplanes: Unless already accomplished, within 5,000
flight hours after the effective date of this AD, perform the
actions specified in paragraph (d)(1), (d)(2), or (d)(3) of this AD:
(1) Install an FAA-approved lever/lock cap on the flush/fill
lines for all lavatories. Or
(2) Install a vacuum break, Monogram part number series 3765-
190, or Shaw Aero Devises part number series 301-0009-01, in the
flush/fill lines for all lavatories. Or
(3) Install a flush/fill ball valve Kaiser Electroprecision part
number series 0062-0009 on the flush/fill lines for all lavatories.
(e) For any affected airplane acquired after the effective date
of this AD: Before any operator places into service any airplane
subject to the requirements of this AD, a schedule for the
accomplishment of the leak tests required by this AD shall be
established in accordance with either paragraph (e)(1) or (e)(2) of
this AD, as applicable. After each leak test has been performed
once, each subsequent leak test must be performed in accordance with
the new operator's schedule, in accordance with either paragraph (a)
or (b) of this AD as applicable.
(1) For airplanes previously maintained in accordance with this
AD, the first leak test to be performed by the new operator must be
accomplished in accordance with the previous operator's schedule or
with the new operator's schedule, whichever would result in the
earlier accomplishment date for that leak test.
(2) For airplanes that have not been previously maintained in
accordance with this AD, the first leak test to be performed by the
new operator must be accomplished prior to further flight, or in
accordance with a schedule approved by the FAA PMI, but within a
period not to exceed 200 flight hours.
(f) Alternative method(s) of compliance with this AD:
(1) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle ACO, FAA, Transport
Airplane Directorate. Operators shall submit their requests through
an appropriate FAA PMI, who may add comments and then send it to the
Manager, Seattle ACO.
(2) Alternative methods of compliance previously approved for AD
89-11-03, which permit a 4,500-flight hour interval between leak
tests of the forward waste drain system for those operators
installing the modifications specified in Boeing Service Bulletin
737-38-1026, Revision 2, dated May 4, 1995, or Boeing Service
Bulletin 737-38-1031, Revision 1, dated April 20, 1995, and later
FAA-approved revisions, are considered acceptable alternative
methods of compliance with the requirements of only paragraph (a)(2)
of this AD. For those operators, the other requirements of this AD
are still required to be accomplished. All other alternative methods
of compliance approved for AD 89-11-03 are terminated and are no
longer in effect.
Note 10: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
Note 11: For any valve that is not eligible for the extended
leak test intervals of this AD: To be eligible for the extended leak
test intervals specified in paragraph (b) of this AD, the service
history data of the valve must be submitted to the Manager, Seattle
ACO, FAA, Transport Airplane Directorate, with a request for an
alternative method of compliance. The request should include an
analysis of known failure modes for the valve, if it is an existing
design, and known failure modes of similar valves, with an
explanation of how design features will preclude these failure
modes, results of qualification tests, and approximately 25,000
flight hours or 25,000 flight cycles of service history data which
include a winter season, collected in accordance with the
requirements of paragraph (c) above, or a similar program. One of
the factors that the FAA will consider in approving alternative
valve designs is whether the valve meets Boeing Specification
S417T105 or 10-62213. However, meeting the Boeing specification is
not a prerequisite for approval of alternative valve designs.
(g) Special flight permits may be issued in accordance with
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR
21.197 and 21.199) to operate the airplane to a location where the
requirements of this AD can be accomplished.
Issued in Renton, Washington, on November 18, 1997.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-30855 Filed 11-24-97; 8:45 am]
BILLING CODE 4910-13-U
