[Federal Register Volume 60, Number 212 (Thursday, November 2, 1995)]
[Proposed Rules]
[Pages 55673-55680]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-27074]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-111-AD]
Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,
and -500 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Boeing Model 737-
300 and -400 series airplanes, that currently requires either
repetitive leak checks on the forward lavatory service system and
repair as necessary, or draining of the system and placarding the
lavatory inoperative. This action would expand the applicability of the
rule to include all Model 737 series airplanes. It would also add a
requirement to perform leak checks of other lavatory drain systems;
provide for the option of revising the FAA-approved maintenance program
to include a schedule of leak checks; require the installation of a cap
or vacuum break on the flush/fill line; and require either a periodic
replacement of the seal for the cap and tank anti-siphon valve or
periodic maintenance of the
[[Page 55674]]
vacuum break in the flush/fill line. This proposal is prompted by
continuing reports of damage to engines and airframes, separation of
engines from airplanes, and damage to property on the ground, caused by
``blue ice'' that forms from leaking lavatory drain systems on
transport category airplanes and subsequently dislodges from the
airplane fuselage. The actions specified by this proposed AD are
intended to prevent such damage associated with the problems of ``blue
ice.''
DATES: Comments must be received by January 30, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-111-AD, 1601 Lind Avenue SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT:
Don Eiford, Aerospace Engineer, Systems and Equipment Branch, ANM-130S,
FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW.,
Renton, Washington; telephone (206) 227-2778; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 95-NM-111-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 95-NM-111-AD, 1601 Lind Avenue SW., Renton, Washington
98055-4056.
Discussion of the Existing AD
On May 9, 1989, the FAA issued AD 89-11-03, amendment 39-6223 (54
FR 21933, May 22, 1989), applicable to certain Boeing Model 737-300 and
-400 airplanes, to require repetitive leak checks of the forward
lavatory service system at intervals of 200 hours time-in-service, and
repair, if necessary. That AD also provides operators with an optional
action in lieu of performing these periodic checks, which entails
draining the system, locking the lavatory, and placarding the lavatory
inoperative. That action was prompted by several reports of leakage
from the forward lavatory service system on in-service transport
category airplanes that resulted in the formation of ``blue ice'' on
the fuselage. In some instances, the ``blue ice'' subsequently
dislodged from the fuselage and was ingested into an engine. In one
incident, ``blue ice'' was ingested into the right engine and resulted
in the loss of an engine fan blade, severe engine damage, and an in-
flight shutdown of the engine. The requirements of that AD are intended
to prevent such ingestion of ``blue ice'' into the engine, which could
consequently result in damage to the engine and potential separation of
the engine from the airplane.
New Incidents Prompting This Proposed Action
Since the issuance of that AD, the FAA has continued to receive
reports of engine damage on transport category airplanes caused by
``blue ice'' that has formed from leaking lavatory waste systems or
flush/fill lines and is ingested in to the engine(s) of the airplane.
The FAA also has received reports of at least three incidents of
damage caused by foreign objects from the forward toilet drain valve
and flush/fill line on certain airplanes. One report was of a dent on
the right horizontal stabilizer leading edge on a Model 737 series
airplane that was caused by ``blue ice'' that had formed from leakage
through a flush/fill line; in this case, the flush/fill cap was missing
from the line at the forward service panel. Numerous operators of Model
737 series airplanes have stated that leakage from the flush/fill line
is a significant source of the type of ``blue ice'' problems addressed
by the current AD action.
Additionally, there have been numerous reports of ``blue ice''
dislodging from airplanes and striking houses, cars, buildings, and
other occupied areas on the ground. Although there have been no reports
of any person being struck by ``blue ice,'' the FAA considers that the
large number of reported cases of ``blue ice'' falling from lavatory
drain system is sufficient to support the conclusion that ``blue ice''
presents an unsafe condition to people on the ground. Demographic
studies have shown that population density has increased around
airports, and probably will continue to increase. These are populations
that are at greatest risk of damage and injury due to ``blue ice''
dislodging from an airplane during descent. Without actions to ensure
that leaks from the lavatory drain systems are detected and corrected
in a timely manner, ``blue ice'' incidents could go unchecked and
eventually someone may be struck, perhaps fatally, by falling ``blue
ice.''
In light of these continuing incidents and the data received
concerning them, the FAA has determined that the inspections currently
required by AD 89-11-03 are not adequate to positively address the
unsafe condition(s) associated with ``blue ice.'' -
Additionally, since the lavatory systems on Model 737-100, -200,
and -500 series airplanes are similar to those installed on Model 737-
300 and -400 series airplanes (the models currently subject to AD 89-
11-03), the FAA has determined that the potential unsafe condition
exists with regard to all of these models.
Description of the Proposed Rule -
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the FAA
proposes to issue a new AD to supersede AD 89-11-03. -
Paragraph (a) of the proposed AD would require various repetitive
leak checks of the dump valve and drain valve (either service panel or
in-line drain valve). The intervals for performing these leak checks
would vary from the currently required 200 flight hours to 4,500 flight
hours,
[[Page 55675]]
depending upon the type of valve installed at each location. If any
leak is discovered during a leak check, operators would be required
either to repair the leak, or drain the lavatory system and placard the
lavatory inoperative. -
Proposed paragraph (a) also would require replacement of certain
seals on the toilet tank anti-siphon (check) valve and flush/fill line
cap; and replacement or cleaning of the vacuum break vent line. -
Paragraph (b) of this proposed AD would provide an optional
procedure for complying with the rule, which would entail revising the
FAA-approved maintenance program to incorporate a schedule and
procedure to conduct leak checks of the lavatory drain systems.
However, operators electing to comply with this option would be
required to accomplish the actions required by paragraph (a) of the
proposal until their maintenance program is revised. -
Additionally, operators electing to comply with this option would
be required to obtain approval from the Manager of the FAA's Seattle
Aircraft Certification Office (ACO) for any revision to the leak check
intervals. Requests for such revisions must be accompanied by certain
data when submitted to the ACO [through the appropriate FAA Principal
Maintenance Inspector (PMI)] for approval. In paragraph (c) of the
proposed rule, the FAA proposes a ``data collection format'' for these
requests. Data submitted in accordance with the proposed format, if
favorable to an increase in the leak check interval, will allow the FAA
to justify increasing the leak check interval with assurance that the
valves involved have the required reliability. The data provided also
will be important in assisting the FAA in making future determinations
of appropriate leak check intervals for new valves that have shown
promising, but not conclusive, service data. -
This proposal also includes a process for terminating the leak
checks of waste drain systems for those operators who have installed
in-line drain (ball) valves and elect to comply with the proposed AD
via the ``maintenance program option.'' The FAA has determined that
these types of valves are currently the best solution to the addressed
problems, and provide very reliable operation. In combination with a
normal maintenance program, these valves provide a system that is
superior in reliability to the combination of less reliable valves and
the proposed leak checks. Further, the FAA has been advised that
additional versions of the in-line drain valve may become available for
aft lavatory and flush/fill line applications. This could make it
possible to install in-line drain type valves in all drain systems and
flush/fill line locations. Assuming the new versions are designed,
certified, and found acceptable, based upon the guidelines of NOTE 9 of
the proposed AD, it eventually could be possible to obtain terminating
action for all systems addressed by the AD. -
Paragraph (d) of the proposed AD would require that a lever/lock
cap or a vacuum break be installed for the forward, aft, and executive
lavatories. -
Paragraph (e) of the proposed AD would require that, before an
operator places an airplane subject to the AD into service, the
operator must establish a schedule for accomplishment of the leak
checks. This provision is intended to ensure that transferred airplanes
are inspected in accordance with the AD on the same basis as if there
were continuity in ownership, and that scheduling of the leak checks
for each airplane is not delayed or postponed due to a transfer of
ownership. Airplanes that have previously been subject to the AD would
have to be checked in accordance with either the previous operator's or
the new operator's schedule, whichever would result in the earlier
accomplishment date for that leak check. Other airplanes would have to
be inspected before an operator could begin operating them or in
accordance with a schedule approved by the FAA PMI, but within a period
not exceeding 200 flight hours.
Related AD's -
On November 9, 1994, the FAA issued AD 94-23-10, amendment 39-9073
(59 FR 59124, November 16, 1994), which is applicable to Boeing Model
727 series airplanes. That AD contains numerous requirements that are
similar to those proposed in this action applicable to Model 737 series
airplanes. In fact, several of the proposed requirements of this action
are based on alternative methods of compliance that the FAA had
previously approved for compliance with AD 94-23-10. -
The FAA is currently considering additional rulemaking to address
the problems associated with ``blue ice'' on other transport category
airplanes.
Economic Impact -
There are approximately 2,410 Model 737 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 1,031
airplanes of U.S. registry and 110 U.S. operators would be affected by
this proposed AD. -
The proposed waste drain system leak check and outer cap inspection
would take approximately 6 work hours per airplane to accomplish, at an
average labor rate of $60 per work hour. Based on these figures, the
total cost impact on U.S. operators of these proposed requirements of
this AD is estimated to be $371,160, or $360 per airplane, per check/
inspection. -
Certain airplanes (i.e., those that have ``donut'' type of drain
valve installed) may be required to be leak checked as many as 15 times
each year. Certain other airplanes having other valve configurations
would be required to be leak checked as few as 3 times each year. Some
airplanes that have various combinations drain valves installed would
require approximately 2 leak checks of one drain valve and 3 leak
checks of the other drain valve each year. Based on these figures, the
total annual (recurring) cost impact of the required repetitive leak
checks on U.S. operators is estimated to be between $1,080 and $5,400
per airplane per year. -
The FAA estimates that it would take approximately 1 work hour per
airplane lavatory drain to accomplish a visual inspection of the
service panel drain valve cap/door seal and seal mating surfaces, at an
average labor cost of $60 per work hour. As with leak checks, certain
airplanes would be required to be visually inspected as many as 15
times or as few as 3 times each year. Based on these figures, the total
annual (recurring) cost impact of the required repetitive visual
inspections on U.S. operators is estimated to be between $180 and $900
per airplane per year. -
The proposed installation of the flush/fill line cap would take
approximately 1 hour per cap to accomplish, at an average labor rate of
$60 per work hour. The cost of required parts would be $275 per cap.
There are an average of 2.5 caps per airplane. Based on these figures,
the total cost impact on U.S. operators of these proposed requirements
of this AD is estimated to be $863,463, or $838 per airplane. -
The number of required work hours, as indicated above, is presented
as if the accomplishment of the actions proposed in this AD were to be
conducted as ``stand alone'' actions. However, in actual practice,
these actions could be accomplished coincidentally or in combination
with normally scheduled airplane inspections and other maintenance
program tasks. Therefore, the actual number of necessary ``additional''
work hours would be minimal in many instances. Additionally, any costs
associated with special airplane scheduling should be minimal. -
In addition to the costs discussed above, for those operators who
elect to
[[Page 55676]]
comply with proposed paragraph (b) of this proposed AD action, the FAA
estimates that it would take approximately 40 work hours per operator
to incorporate the lavatory drain system leak check procedures into the
maintenance programs, at an average labor cost of $60 per work hour.
Based on these figures, the total cost impact of the proposed
maintenance revision requirement of this AD action on the 110 U.S.
operators is estimated to be $264,000, or $2,400 per operator.
The total cost impact figures discussed above are based on
assumptions that no operator has yet accomplished any of the current or
proposed requirements of this AD action, and that no operator would
accomplish those actions in the future if this AD were not adopted.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address specific unsafe conditions, they
appear to impose costs that would not otherwise be borne by operators.
However, because of the general obligation of operators to maintain
aircraft in an airworthy condition, this appearance is deceptive.
Attributing those costs solely to the issuance of this AD is
unrealistic because, in the interest of maintaining safe aircraft,
prudent operators would accomplish the required actions even if they
were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this AD.
As a matter of law, in order to be airworthy, an aircraft must conform
to its type design and be in a condition for safe operation. The type
design is approved only after the FAA makes a determination that it
complies with all applicable airworthiness requirements. In adopting
and maintaining those requirements, the FAA has already made the
determination that they establish a level of safety that is cost-
beneficial. When the FAA, as in this AD, makes a finding of an unsafe
condition, this means that the original cost-beneficial level of safety
is no longer being achieved and that the required actions are necessary
to restore that level of safety. Because this level of safety has
already been determined to be cost-beneficial, a full cost-benefit
analysis for this AD would be redundant and unnecessary.
Regulatory Impact
The regulations proposed herein would not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part 39 of the Federal Aviation Regulations (14 CFR part 39) as
follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-6223 (54 FR
21933, May 22, 1989), and by adding a new airworthiness directive (AD),
to read as follows:
Boeing. Docket 95-NM-111-AD. Supersedes AD 89-11-03, Amendment 39-
6223.
Applicability: Boeing Model 737 series 100, 200, 300, 400 and
500 airplanes, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (f) of this AD to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition; or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless previously
accomplished.
To prevent engine damage, airframe damage, and/or hazard to
persons or property on the ground as a result of ``blue ice'' that
has formed from leakage of the lavatory drain system or flush/fill
systems and dislodged from the airplane, accomplish the following:
(a) Except as provided by paragraph (b) of this AD, accomplish
the applicable requirements of paragraphs (a)(1) through (a)(7) of
this AD at the time specified in each paragraph. If the waste drain
system incorporates more than one type of valve, only one of the
waste drain system leak check procedures (the one that applies to
the equipment with the longest leak check interval) must be
conducted at each service panel location. The leak check of the in-
line drain valve or service panel drain valve must be performed
while the airplane is pressurized, unless another leak check method
is approved under the provisions of paragraph (f) of this AD.
(1) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
329, 2651-334, or 2651-278: Within 4,500 flight hours after the
effective date of this AD, and thereafter at intervals not to exceed
4,500 flight hours, accomplish the procedures specified in
paragraphs (a)(1)(i) and (a)(1)(ii) of this AD:
(i) Conduct a leak check of the dump valve (in-tank valve that
is spring loaded closed and operable by a T-handle at the service
panel) and the in-line drain valve. The dump valve leak check must
be performed by filling the toilet tank with water/rinsing fluid to
a level such that the bowl is approximately half full (at least 2
inches above the flapper in the bowl) and checking for leakage after
a period of 5 minutes. The in-line drain valve leak check must be
performed with a minimum of 3 pounds per square inch differential
pressure (PSID) applied across the valve.
(ii) If a service panel valve or cap is installed, perform a
visual inspection of the service panel drain valve outer cap/door
seal and the inner seal (if the valve has an inner door with a
second positive seal), and the seal mating surfaces, for wear or
damage that may allow leakage.
(2) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0032; or Pneudraulics part number series 9527; or Shaw Aero
part number/serial number as listed in Table 1 of this AD: Within
1,000 flight hours after the effective date of this AD, and
thereafter at intervals not to exceed 1,000 flight hours, accomplish
the requirements of paragraphs (a)(2)(i) and (a)(2)(ii) of this AD:
[[Page 55677]]
Table 1.--Shaw Aero Valves Approved for 1,000 Flight Hour Leak Check
Interval
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Serial numbers of part
number valve approved for
Shaw Waste Drain Valve Part No. 1,000-hour leak check
interval
------------------------------------------------------------------------
331 Series, 332 Series.................... All.
10101000B-A-.............................. None.
10101000B-A-1............................. 0207-0212, 0219, 0226 and
higher.
10101000BA2-.............................. 0130 and higher.
10101000B-B-.............................. None.
10101000BB2-.............................. 0011 and higher.
10101000B-C-.............................. None.
10101000B-K-.............................. 0007 and higher.
10101000BJ-............................... 0023 and higher.
10101B-577-............................... 0254 and higher.
10101B-577-1.............................. None.
10101B587-................................ 0009 and higher.
10101000C-A-.............................. None.
10101000C-A-1............................. 0277 and higher.
10101000CB-............................... 0061 and higher.
10101000C-G-.............................. None.
10101000C-J-.............................. None.
10101000C-J-2............................. None.
10101000CJ3-.............................. 0014 and higher.
10101000CK-............................... 0317 and higher.
10101000C-M-.............................. 0044 and higher.
10101000CN OR C-N-........................ 3649 and higher.
10101000C-R-.............................. 0191 and higher.
10101C739-................................ 0022 and higher.
Certain 10101000B valves-................. Any of these ``B'' series
valves that incorporate the
improvements of Shaw
Service Bulletin 10101000B-
38-1, dated October 7,
1994, and are marked
``SBB38-1-58''.
Certain 10101000C valves.................. Any of these ``C'' series
valves that -incorporate
the improvements of Shaw
Service Bulletin 10101000C-
38-2 dated October 7, 1994,
and are marked ``SBC38-2-
58''.
------------------------------------------------------------------------
Note 2: Table 1 is a comprehensive list of all approved Shaw
Valves, including those valves approved for installation on
airplanes other than the airplanes subject to this AD. (Therefore,
being listed in this table does not necessarily mean that a
particular valve is FAA-approved for installation on the Model 737
airplanes subject to this AD.)
(i) Conduct a leak check of the dump valve and drain valve. The
dump valve leak check must be performed by filling the toilet tank
with water/rinsing fluid to a level such that the bowl is
approximately half full (at least 2 inches above the flapper in the
bowl) and checking for leakage after a period of 5 minutes. The
service panel drain valve leak check must be performed with a
minimum of 3 PSID applied across the valve inner door/closure
device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(3) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0026; or Shaw Aero Devices part number series 10101000B or
10101000C [except as specified in paragraph (a)(2) of this AD]:
Within 600 flight hours after the effective date of this AD, and
thereafter at intervals not to exceed 600 flight hours, accomplish
the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD:
(i) Conduct a leak check of the dump valve and the service panel
drain valve. The dump valve leak check must be performed by filling
the toilet tank with water/rinsing fluid to a level such that the
bowl is approximately half full (at least 2 inches above the flapper
in the bowl) and checking for leakage after a period of 5 minutes.
The service panel drain valve leak check must be performed with a
minimum 3 PSID applied across the valve inner door/closure device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(4) For each lavatory drain system with a lavatory drain system
valve that incorporates either ``donut'' assemblies (or substitute
assemblies from another manufacturer) Kaiser Electroprecision part
number 4259-20 or 4259-31, or incorporates Kaiser Roylyn part number
2651-194C, 2651-197C, 2651-216, 2651-219, 2651-235, 2651-256, 2651-
258, 2651-259, 2651-260, 2651-275, 2651-282, 2651-286: Within 200
flight hours after the effective date of this AD, and thereafter at
intervals not to exceed 200 flight hours, conduct leak checks of the
dump valve and the service panel drain valve. The dump valve leak
check must be performed by filling the toilet tank with water/
rinsing fluid to a level such that the bowl is approximately half
full (at least 2 inches above the flapper in the bowl) and checking
for leakage after a period of 5 minutes. The service panel drain
valve leak check must be performed with a minimum 3 PSID applied
across the valve. Both the donut and the outer cap/door must be leak
checked.
(5) For each lavatory drain system not addressed in paragraph
(a)(1), (a)(2), (a)(3) or (a)(4) of this AD: Within 200 flight hours
after the effective date of this AD, and thereafter at intervals not
to exceed 200 flight hours, accomplish the requirements of
paragraphs (a)(5)(i) and (a)(5)(ii) of this AD:
(i) Conduct a leak check of the dump valve and the service panel
drain valve. The dump valve leak check must be performed by filling
the toilet tank with water/rinsing fluid to a level such that the
bowl is approximately half full (at least 2 inches above the flapper
in the bowl) and checking for leakage after a period of 5 minutes.
The service panel drain valve leak check must be performed with a
minimum 3 PSID applied across the valve inner door/closure device.
(ii) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage.
(6) For flush/fill lines: Within 5,000 flight hours after the
effective date of this AD, and thereafter at intervals not to exceed
5,000 flight hours, perform the requirements of either paragraph
(a)(6)(i) or (a)(6)(ii), as applicable.
(i) If a lever lock cap is installed on the flush/fill line of
the subject lavatory, replace the seals on the toilet tank anti-
siphon (check) valve and the flush/fill line cap. Prior to further
flight after replacement, perform a leak check of the toilet tank
anti-siphon (check) valve with a minimum of 3 PSID across the valve.
Note 3: The leak test procedure described in Boeing Service
Letter 737-SL-38-3-A dated March 19, 1990, may be referred to as
guidance for this test.
(ii) If a vacuum break, Monogram part number 3765-175 series or
3765-190 series, is installed on the subject lavatory, replace or
clean the vent line in accordance with the manufacturer's
maintenance manual.
(7) As a result of the leak checks and inspections required by
this paragraph, or if evidence of leakage is found at any other
time, accomplish the requirements of paragraph (a)(7)(i),
(a)(7)(ii), or (a)(7)(iii), as applicable.
(i) If a leak is discovered, prior to further flight, repair the
leak. Prior to further flight after repair, perform the leak test.
Additionally, prior to returning the airplane to service, clean the
surfaces adjacent to where the leakage occurred to clear them of any
horizontal fluid residue streaks; such cleaning must be to the
extent that any future appearance of a horizontal fluid residue
streak will be taken to mean that the system is leaking again.
Note 4: For purposes of this AD, ``leakage'' is defined as any
visible leakage, if observed during a leak test. At any other time
(than during a leak test), ``leakage'' is defined as the presence of
ice in the service panel, or horizontal fluid residue streaks/ice
trails originating at the service panel. The fluid residue is
usually, but not necessarily, blue in color.
(ii) If any worn or damaged seal is found, or if any damaged
seal mating surface is found, prior to further flight, repair or
replace it in accordance with the valve manufacturer's maintenance
manual.
(iii) In lieu of performing the requirements of paragraph
(a)(7)(i) or (a)(7)(ii): Prior to further fight, drain the affected
lavatory system and placard the lavatory inoperative until repairs
can be accomplished.
(b) As an alternative to the requirements of paragraph (a) of
this AD, operators may revise the FAA-approved maintenance program
to include the requirements specified in paragraphs (b)(1) through
(b)(7) of this AD. However, until the FAA-approved maintenance
program is so revised, operators must accomplish the leak test
requirements of paragraph (a) of this AD. Incorporation of the
requirements specified in paragraphs (b)(1)(i), (b)(2)(i), (b)(4),
(b)(5), (b)(6) and (b)(7) of this AD into the operator's FAA-
approved maintenance program constitutes terminating action for
waste drain systems that incorporate the ball valves specified in
paragraph (b)(1)(i) of this AD. However, the requirements of this AD
that affect flush/fill lines and waste drain systems with valves
different from those listed in paragraph (b)(1)(i) remain in effect.
[[Page 55678]]
(1) Replace the valve seals in accordance with the applicable
schedule specified in paragraphs (b)(1)(i) and (b)(1)(ii) of this
AD.
(i) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
329, 2651-334, or 2651-278: Replace the seals within 5,000 flight
hours after revision of the maintenance program in accordance with
paragraph (b) of this AD, and thereafter at intervals not to exceed
48 months.
(ii) For each lavatory drain system that has any other type of
drain valve: Replace the seals within 5,000 flight hours after
revision of the maintenance program in accordance with paragraph (b)
of this AD, and thereafter at intervals not to exceed 18 months. Any
revision to this replacement schedule must be approved by the
Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport
Airplane Directorate.
(2) Conduct periodic leak checks of the lavatory drain systems
in accordance with the applicable schedule specified in paragraphs
(b)(2)(i), (b)(2)(ii), (b)(2)(iii), and (b)(2)(iv) of this AD. Only
one of the waste drain system leak check procedures (the one that
applies to the equipment with the longest leak check interval) must
be conducted at each service panel location. The leak check of the
in-line drain valve or service panel drain valve shall be performed
while the airplane is pressurized, unless another leak check method
is approved under the provisions of paragraph (g) of this AD.
(i) For each lavatory drain system, that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-
329, 2651-334, or 2651-278: Within 5,000 flight hours after the
effective date of this AD, and thereafter at intervals not to exceed
24 months or 5,000 flight hours, whichever occurs later, accomplish
the procedures specified in paragraphs (b)(2)(i)(A) and (b)(2)(i)(B)
of this AD:
(A) Conduct a leak check of the dump valve (in-tank valve that
is spring loaded closed and operable by a T-handle at the service
panel) and the in-line drain valve. The dump valve leak check must
be performed by filling the toilet tank with water/rinsing fluid to
a level such that the bowl is approximately half full (at least 2
inches above the flapper in the bowl) and checking for leakage after
a period of 5 minutes. The in-line drain valve leak check must be
performed with a minimum of 3 pounds per square inch differential
pressure (PSID) applied across the valve.
(B) If a service panel valve or cap is installed, perform a
visual inspection of the service panel drain valve outer cap/door
seal and the inner seal (if the valve has an inner door with a
second positive seal), and the seal mating surfaces, for wear or
damage that may allow leakage. Any worn or damaged seal must be
replaced, and any damaged seal mating surfaces repaired or replaced,
prior to further flight, in accordance with the valve manufacturer's
maintenance manual.
(ii) For each lavatory drain system that has a service panel
drain valve installed, Kaiser Electroprecision part number series
0218-0032, or Kaiser Electroprecision part number series 0218-0026,
or Shaw Aero Devices part number series 10101000B, 10101000C, 331-
series, 332-series, or Pneudraulics part number series 9527: Within
1,000 flight hours after revising the maintenance program in
accordance with paragraph (b) of this AD, and thereafter at
intervals not to exceed 1,000 flight hours, accomplish the
following:
(A) Conduct leak checks of the dump valve and service panel
drain valve . The dump valve leak check must be performed by filling
the toilet tank with water/rinsing fluid to a level such that the
bowl is approximately half full (at least 2 inches above the flapper
in the bowl) and checking for leakage after a period of 5 minutes.
The service panel drain valve leak check must be performed with a
minimum of 3 PSID applied across the valve inner door/closure
device. Any revision to this leak check schedule must be approved by
the Manager, Seattle ACO, FAA, Transport Airplane Directorate.
(B) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage. Any worn
or damaged seal must be replaced and any damaged seal mating surface
must be repaired or replaced, prior to further flight, in accordance
with the valve manufacturer's maintenance manual.
(iii) For each lavatory drain system with a lavatory drain
system valve that incorporates either ``donut'' assemblies (or
substitute assemblies from another manufacturer) Kaiser
Electroprecision part number 4259-20 or 4259-31, or incorporates
Kaiser Roylyn part number 2651-194C, 2651-197C, 2651-216, 2651-219,
2651-235, 2651-256, 2651-258, 2651-259, 2651-260, 2651-275, 2651-
282, 2651-286: Within 200 flight hours after revising the
maintenance program in accordance with paragraph (b), and thereafter
at intervals not to exceed 200 flight hours, conduct leak checks of
the dump valve and the service panel drain valve. Both the donut and
the outer cap/door must be leak checked. The dump valve leak check
must be performed by filling the toilet tank with water/rinsing
fluid to a level such that the bowl is approximately half full (at
least 2 inches above the flapper in the bowl) and checking for
leakage after a period of 5 minutes. The service panel drain valve
leak check must be performed with a minimum 3 PSID applied across
the valve.
(iv) For each lavatory drain system that incorporates any other
type of approved valves: Within 400 flight hours after revising the
maintenance program in accordance with paragraph (b) of this AD, and
thereafter at intervals not to exceed 400 flight hours, accomplish
the following:
(A) Conduct leak checks of the dump valve and the service panel
drain valve. The dump valve leak check must be performed by filling
the toilet tank with water/rinsing fluid to a level such that the
bowl is approximately half full (at least 2 inches above the flapper
in the bowl) and checking for leakage after a period of 5 minutes.
The service panel drain valve leak check must be performed with a
minimum 3 PSID applied across the valve. If the service panel drain
valve has an inner door with a second positive seal, only the inner
door must be tested.
(B) Perform a visual inspection of the outer cap/door and seal
mating surface for wear or damage that may cause leakage. Any worn
or damaged seal must be replaced and any damaged seal mating surface
must be repaired or replaced, prior to further flight, in accordance
with the valve manufacturer's maintenance manual.
(3) For flush/fill lines: Within 5,000 flight hours after the
effective date of this AD, and thereafter at intervals not to exceed
5,000 flight hours, perform the requirements of either paragraph
(b)(3)(i) or (b)(3)(ii), as applicable.
(i) If a lever lock cap is installed on the flush/fill line of
the subject lavatory, replace the seals on the toilet tank anti-
siphon (check) valve and the flush/fill line cap. Perform a leak
check of the toilet tank anti-siphon (check) valve with a minimum of
3 PSID across the valve.
Note 5: The leak test procedure of Boeing Service Letter 737-SL-
38-3-A, dated March 19, 1990, May be referred to as guidance for
this test.
(ii) If a vacuum break, Monogram part number 3765-175 series, or
3765-190 series, is installed on the subject lavatory, replace or
clean the vent line in accordance with the manufacturer's
maintenance manual.
(4) Provide procedures for accomplishing visual inspections to
detect leakage, to be conducted by maintenance personnel at
intervals not to exceed 4 calendar days or 45 flight hours, which
ever occurs later.
(5) Provide procedures for reporting leakage. These procedures
shall provide that any ``horizontal blue streak'' findings must be
reported to maintenance and that, prior to further flight, the
leaking system shall either be repaired, or be drained and placarded
inoperative.
(i) For systems incorporating an in-line drain valve, Kaiser
Electroprecision part number series 2651-329, 2651-334 or 2651-278:
The reporting procedures also must include the following:
(A) Provisions for reporting to maintenance any instances of
abnormal operation of the valve handle for the in-line drain valve,
as observed by service personnel during normal servicing.
(B) For instances where abnormal operation of the valve handle
is identified, instructions to accomplish, prior to further flight,
either the in-line drain valve manufacturer's recommended
troubleshooting procedures and correction of the discrepancy; or
drainage of the lavatory system and placarding it inoperative until
the correction of the discrepancy can be accomplished.
(ii) If the drain system also includes an additional service
panel drain valve, Kaiser Electroprecision part number series 0218-
0026 or 0218-0032 or Shaw Aero Devices series 10101000B, series
10101000C, series 331, or series 332, or Pneudraulics part number
series 9527: Indications of abnormal operation of the valve handle
for the in-line drain valve need not be addressed immediately if a
leak check of the service panel drain valve indicates no leakage or
other discrepancy. In these cases, repair of the in-line drain valve
must be accomplished within 1,000 flight hours after the leak check
of the additional service panel drain valve.
(6) Provide training programs for maintenance and servicing
personnel that
[[Page 55679]]
include information on ``Blue Ice Awareness'' and the hazards of blue
ice.
(7) If a leak is discovered during a leak check required by this
paragraph; or if evidence of leakage is found at any other time; or
if repair/replacement of a valve (or valve parts) is required as a
result of a visual inspection required in accordance with this AD;
prior to further flight, accomplish the requirements of paragraph
(b)(7)(i), (b)(7)(ii), or (b)(7)(iii), as applicable.
Note 6: For purposes of this AD, ``leakage'' is defined as any
visible leakage, if observed during a leak test. At any other time
(than during a leak test), ``leakage'' is defined as the presence of
ice in the service panel, or horizontal fluid residue streaks/ice
trails originating at the service panel. The fluid residue is
usually, but not necessarily, blue in color.
(i) Repair the leak and, prior to further flight after repair,
perform a leak test. Additionally, prior to returning the airplane
to service, clean the surfaces adjacent to where the leakage
occurred to clear them of any horizontal fluid residue streaks; such
cleaning must be to the extent that any future appearance of a
horizontal fluid residue streak will be taken to mean that the
system is leaking again.
(ii) Repair or replace the valve or valve parts.
(iii) In lieu of either paragraph (b)(7)(i) or (b)(7)(ii), drain
the affected lavatory system and placard the lavatory inoperative
until repairs can be accomplished.
(c) For operators who elect to comply with paragraph (b) of this
AD: Any revision to (i.e., extension of) the leak check intervals
required by paragraph (b) of this AD must be approved by the
Manager, Seattle ACO, FAA, Transport Airplane Directorate. Requests
for such revisions must be submitted to the Manager of the Seattle
ACO through the FAA Principal Maintenance Inspector (PMI), and must
include the following information:
(1) The operator's name;
(2) A statement verifying that all known cases/indications of
leakage or failed leak tests are included in the submitted material;
(3) The type of valve (make, model, manufacturer, vendor part
number, and serial number);
(4) The period of time covered by the data;
(5) The current FAA leak check interval;
(6) Whether or not seals have been replaced between the seal
replacement intervals required by this AD;
(7) Whether or not leakage has been detected between leak check
intervals required by this AD, and the reason for leakage (i.e.,
worn seals, foreign materials on sealing surface, scratched or
damaged sealing surface or valve, etc.);
(8) Whether or not any cleaning, repairs, or seal changes were
performed on the valve prior to conducting the leak check. [If such
activities have been accomplished prior to conducting the periodic
leak check, that leak check shall be recorded as a ``failure'' for
purposes of the data required for this request submission. The
exception to this is the normally-scheduled seal change in
accordance with paragraph (b)(1) of this AD. Performing this
scheduled seal change prior to a leak check will not cause that leak
check to be recorded as a failure. Debris removal done as part of
normal maintenance for previous flights is also allowable and will
not cause a leak check to be recorded as a failure].
Note 7: Requests for approval of revised leak check intervals
may be submitted in any format, provided the data give the same
level of assurance specified in paragraph (c) above. Results of an
Environmental Quality Analysis (EQA) examination and leak test on a
randomly selected high-flight-hour valve, with seals that have not
been replaced during a period of use at least as long as the desired
interval, may be considered a valuable supplement to the service
history data, reducing the amount of service data that would
otherwise be required.
Note 8: For the purposes of expediting resolution of requests
for revisions to the leak check intervals, the FAA suggests that the
requester summarize the raw data; group the data gathered from
different airplanes (of the same model) and drain systems with the
same kind of valve; and provide a recommendation from pertinent
industry group(s) and/or the manufacturer specifying an appropriate
revised leak check interval.
Note 9: In cases where changes are made to a valve design
approved for an extended leak test interval such that a new valve
dash number or part number is established for the valve, the FAA may
not require extensive service history data to approve the new valve
to the same leak check interval as the previous valve design.
Similarity of design, the nature of the design changes, the nature
and amount of testing, and like factors will be considered by the
FAA to determine the appropriate data requirements and leak check
interval for a new or revised valve based upon an existing design.
Note 10: If other valve designs achieve the reliability (as
demonstrated by equivalent service history and data) of the valves
cited in paragraph (b)(2)(i) of this AD, the FAA may consider
granting terminating action using the same guidelines.
(d) For all airplanes: Unless already accomplished, within 5,000
flight hours after the effective date of this AD, perform the
actions specified in either paragraph (d)(1) or (d)(2) of this AD:
(1) Install a FAA approved lever/lock cap on the flush/fill
lines for the forward, aft, and executive lavatories. Or -
(2) Install a vacuum break, Monogram part number 3765-175 series
or 3765-190 series, in the flush/fill lines for the forward, aft,
and executive lavatories. -
(e) For any affected airplane acquired after the effective date
of this AD: Before any operator places into service any airplane
subject to the requirements of this AD, a schedule for the
accomplishment of the leak checks required by this AD shall be
established in accordance with either paragraph (e)(1) or (e)(2) of
this AD, as applicable. After each leak check has been performed
once, each subsequent leak check must be performed in accordance
with the new operator's schedule, in accordance with either
paragraph (a) or (b) of this AD as applicable.
(1) For airplanes previously maintained in accordance with this
AD, the first leak check to be performed by the new operator must be
accomplished in accordance with the previous operator's schedule or
with the new operator's schedule, whichever would result in the
earlier accomplishment date for that leak check.
(2) For airplanes that have not been previously maintained in
accordance with this AD, the first leak check to be performed by the
new operator must be accomplished prior to further flight, or in
accordance with a schedule approved by the FAA PMI, but within a
period not to exceed 200 flight hours.
(f) Alternative method(s) of compliance with this AD:
(1) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle ACO, FAA, Transport
Airplane Directorate. Operators shall submit their requests through
an appropriate FAA PMI, who may add comments and then send it to the
Manager, Seattle ACO.
(2) Alternative methods of compliance previously approved for AD
89-11-03, which permit a 4,500-flight hour interval between leak
checks of the forward waste drain system for those operators
installing the modifications specified in Boeing Service Bulletin
737-38-1028, dated July 18, 1991, and later revisions, are
considered acceptable alternative methods of compliance with the
requirements of only paragraph (a)(1) of this AD. For those
operators, the other requirements of this AD are still required to
be accomplished. All other alternate methods of compliance approved
for AD 89-11-03 are terminated and are no longer in effect.
Note 11: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
Note 12: For any valve that is not eligible for the extended
leak check intervals of this AD: To be eligible for the leak check
interval specified in paragraphs (a)(1), (a)(2), (b)(2)(i), and
(b)(2)(ii), the service history data of the valve must be submitted
to the Manager, Seattle ACO, FAA, Transport Airplane Directorate,
with a request for an alternative method of compliance. The request
should include an analysis of known failure modes for the valve, if
it is an existing design, and known failure modes of similar valves,
with an explanation of how design features will preclude these
failure modes, results of qualification tests, and approximately
25,000 flight hours or 25,000 flight cycles of service history data
which include a winter season, collected in accordance with the
requirements of paragraph (c) above, or a similar program. One of
the factors that the FAA will consider in approving alternative
valve designs is whether the valve meets Boeing Specification
S417T105 or 10-62213. However, meeting the Boeing specification is
not a prerequisite for approval of alternative valve designs.
(g) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
[[Page 55680]]
Issued in Renton, Washington, on October 26, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-27074 Filed 11-1-95; 8:45 am]
BILLING CODE 4910-13-U
