[Federal Register Volume 64, Number 69 (Monday, April 12, 1999)]
[Rules and Regulations]
[Pages 17514-17522]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-8686]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-325-AD; Amendment 39-11116; AD 99-08-10]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP,
and -400F Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to all Boeing Model 747-100, -200, -300, -SP, and -400F
series airplanes.
Among other things, this amendment requires repetitive leak tests
of the lavatory drain system and repair, if necessary; installation of
a cap or flush/fill line ball valve on the flush/fill line; periodic
seal changes; and replacement of any ``donut'' type valves installed in
the waste drain system. This amendment is prompted by continuing
reports of damage to airframes 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 AD are intended to
prevent damage to 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: Effective May 17, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of May 17, 1999.
ADDRESSES: This information may be examined at the Federal Aviation
Administration (FAA), Transport Airplane Directorate, Rules Docket,
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the
Federal Register, 800 North Capitol Street, NW., suite 700, Washington,
DC.
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: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to all Boeing Model 747-100, -200, -
300, -SP, and -400F series airplanes was published in the Federal
Register on June 15, 1998 (63 FR 32624). That action proposed to
require repetitive leak tests of the lavatory drain system and repair,
if necessary; installation of a cap or flush/fill line ball valve on
the flush/fill line; periodic seal changes; and replacement of any
``donut'' type valves installed in the waste drain system.
The actions specified in that proposal are intended to prevent
damage to 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.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
1. Support for the Proposal
Two commenters support the proposed rule.
2. Request To Revise the Unsafe Condition
One commenter, the airplane manufacturer, requests that the
proposed rule be revised to remove reference to ``engine damage'' in
the description of the unsafe condition. The airplane manufacturer
bases this request on the fact that it is not aware of any in-service
reports of engine damage due to ``blue ice'' on Model 747 series
airplanes.
The FAA concurs. Since the FAA has not received any reports of
engine damage due to ``blue ice'' on Model 747 series airplanes,
reference to ``engine damage'' in the description of the unsafe
condition has been removed from the AD.
3. Request To Extend Leak Test Intervals for Model 747 Series
Airplanes
One commenter requests that the leak test intervals be specified in
flight cycles rather than flight hours as proposed in the Notice of
Proposed Rulemaking (NPRM). The commenter also requests that, if the
intervals are retained as flight hours, all of the intervals should be
extended. The commenter points out that a typical ``C'' check on Model
747 series airplanes is between 5,000 and 6,000 flight hours, as
compared to typical ``C'' checks of Models 727 and 737 series
airplanes, which are generally between 3,000 and 4,000 flight hours.
Since most of the wear and damage is caused by opening and closing the
valve, which happens during a flight cycle, and is not directly related
to the number of flight hours, flight cycles are more critical than
flight hours with regard to the potential for leakage. Because Model
747 series airplanes have a low number of flight cycles per hour, the
fleet should be allowed a greater leak test interval than the interval
specified for Models 727 and 737 series airplanes.
The FAA does not concur that the leak test intervals should be
specified in flight cycles rather than flight hours. The commenter did
not provide any specific data that correlated the number of flight
hours to the number of flight cycles for the Boeing Model 747 fleet and
the Boeing 727 and 737 fleets. Additionally, existing ``blue ice''
Airworthiness Directives for other airplanes presently specify the leak
test intervals in terms of flight hours. To change the leak test
intervals from flight hours to flight cycles could result in an
operator having some airplanes operating under flight hours intervals
and other airplanes operating under flight cycle intervals, which may
be burdensome for the operator.
However, the FAA does concur that certain leak test intervals can
be extended somewhat for Model 747 series airplanes for the reasons the
commenter suggested. Specific extensions of leak tests for certain
valves are discussed later in this disposition of comments.
4. Requests To Extend PneuDraulics Leak Test Intervals
One commenter requests that the leak test interval for the
PneuDraulics service panel drain valve be revised from 2,000 to 4,000
flight hours. The commenter advises that the PneuDraulics service panel
drain valve specified in paragraph
[[Page 17515]]
(a) of the proposal has had in excess of 800,000 flight hours of
service history documented by operators in FAA-approved maintenance
programs with only two leakage events reported.
The FAA concurs that, for the reasons provided by the commenter,
extension of the leak test interval from 2,000 flight hours to 4,000
flight hours for those PneuDraulics valves is justified. Since that
service history was obtained when the operators were using FAA-approved
maintenance programs that required reporting of any leakage, the FAA
has high confidence that this data is representative of the actual
leakage rates. Paragraph (a)(3) of the final rule has been revised to
reflect the 4,000 flight hour leak test interval.
5. Request To Extend Leak Test Interval for Certain Shaw Aero
Valves
The commenter requests that the leak test interval for certain Shaw
Aero service panel drain valves be extended from 1,000 flight hours to
2,000 flight hours. The commenter states that data submitted previously
to the FAA indicates that there are nearly 8,000 Shaw Aero service
panel drain valves on airplanes that have accumulated in excess of 50
million flight hours over the past 10 years. The commenter points out
that, on all of the airplanes on which Shaw Aero service panel drain
valves were installed during production, there were less than ten
reports of leakage during that time that could have been attributed to
a Shaw Aero Devices service panel drain valve.
In addition, the commenter states that Boeing has presented data to
the FAA showing that the Shaw Aero service panel drain valve has been
the baseline unit installed on Model 737 series airplanes since January
1991, and on Model 757 series airplanes since July 1992. All Boeing
service data available through February 1996 indicates that all
versions of the Shaw service panel drain valves can be attributed to
less than 0.60 percent of the reports of leakage on Model 737 and 757
series airplanes.
The commenter states that the data presented shows ample evidence
to support a leak test interval equal to the PneuDraulics valve, which
was granted a leak test interval extension based on only 412 valves
installed on aircraft flown over a much shorter interval than the 10
year period cited for the Shaw valves. Additionally, the commenter
points out that industry experience clearly indicates that the main
problems occur after two years of residue build-up on the sealing
surfaces of any valve, irrespective of the design features. The
commenter points out that meaningful data must be gathered over a
period of at least two years.
Additionally, the commenter advises that several airlines have
collected, or are in the process of collecting, data in order to submit
a request for extended leak test intervals for their fleets. In fact,
the commenter states that it has attached a copy of one such draft
request that indicates that there have been only two cases reported of
any evidence of leakage on a fleet of 163 Boeing Model 727 series
airplanes that have accumulated 325,678 flight hours on Shaw Aero
Devices 332 series valves.
The FAA concurs with the commenter's request to extend certain
interval times based on the general extension of intervals given to
Model 747 series airplanes explained previously. Those intervals have
been extended for certain Shaw Aero service panel drain valves from
1,000 to 1,500 flight hours. The leak test interval for certain other
Shaw Aero service panel drain valves has been increased from 600 to 800
flight hours. The FAA has revised certain sub-paragraphs of paragraph
(a) of the final rule to reflect those extensions of the leak test
intervals.
This commenter also states that in over 50 million flight hours on
8,000 valves only four instances of leakage have been reported.
However, data the FAA has received indicates that most instances of
leakage are not reported. Leakage from a service panel drain valve is
not a reportable event as required by Part 21.3 of the Federal Aviation
Regulations (14 CFR part 21.3). The service history data was not
collected as part of an FAA-approved maintenance program that requires
reporting of service panel drain valve leakage. Therefore, the FAA does
not have a high level of confidence that the reported leakage rates are
necessarily representative of the actual leakage rate in service. As an
example, a Boeing report cited by the commenter listed 157 total
reports of leakage for 662 Boeing Model 747 series airplanes for the
history of the fleet up until April of 1996, when the data was
collected. However, the FAA recently received a copy of a report
regarding ice on certain airplanes arriving at Narita Airport in Japan
during a two-week period in February 1998. For 562 arrivals of Boeing
Model 747 series airplanes that were inspected during the two-week
period, there were 14 instances of ice found at lavatory service
panels. While some of those instances were caused by leakage from the
flush/fill lines instead of the waste drain valve, the fact remains
that a two-week period of actual inspection at one airport revealed 14
instances of leakage compared to 157 cases of leakage reported by
operators to Boeing for the entire operating history of the Model 747
fleet until 1996. Clearly, the amount of actual leakage is not
reflected in the number reported by operators to Boeing.
In regard to the commenter's statement that several operators are
in the process of gathering data regarding performing leak checks, the
FAA has not received that data as of this date. Without reviewing the
actual data and information, the FAA cannot provide a decision to
extend the leak test interval. Therefore, no change is necessary to the
final rule in this regard.
6. Request To Extend the Leak Test Interval for Certain Service
Panel Ball Valves
The same commenter requests that the leak test interval (currently
1,000 flight hours) be extended for Kaiser Electroprecision service
panel ball valves, Part Number (P/N) 2651-357. The commenter contends
that the Kaiser Electroprecision service panel ball valve is designed
considerably different than the other valves that are subject to the
proposed 1,000-flight-hour intervals for valves. The commenter notes
that the Kaiser ``Expander'' valve, P/N 0218-0032, and Shaw Aero
``Posi-Lift'' valve, P/N 10101000C( ), are subject to the proposed
1,000-flight-hour intervals also. The commenter points out that Kaiser
P/N 2651-357 is considered a ball valve. The commenter questions that
if the FAA considers similarity of valves in determining an appropriate
leak test interval, Kaiser P/N 2651-357 is at least equivalent to a
PneuDraulics P/N 9527 series valve. The commenter points out that P/N
9527 series valves are essentially only a half-ball valve. Since Kaiser
makes the in-line ball valve, P/N 2651-278, which has a 4,500-flight-
hour leak test interval, Kaiser's experience in manufacturing
reliability should be considered when setting an initial leak test
interval for the panel ball valve, P/N 2651-357. The commenter
concludes that a new valve such as this should not receive a
``generic'' 1,000-flight-hour leak test, but rather should be
considered for an extension of the leak test interval based on its
design and similarity to other valves.
The FAA concurs that Kaiser Electoprecision panel ball valve, P/N
2651-357( ) series can be extended from the proposed 1,000-flight-hour
interval. In fact, the FAA has recently approved the leak test interval
for that panel ball valve to be extended from 1,000 to 2,000 flight
hours. The FAA based this extension on similarity to the Kaiser
[[Page 17516]]
Electroprecision in-line drain valve, the service history of over 20
panel ball valves with an average of over 2,000 flight hours per valve
and with no reports of leakage, and other data and analysis. The FAA
considers similarity of valves, the manufacturer's experience, and
manufacturing reliability in setting the initial leak test interval for
a particular valve. These factors are also considered in determining
the amount of in-service monitoring by operators that is required for
an extension of the leak test interval. The intent of requiring service
experience in addition to similarity analysis is to make sure that
there are no unforeseen design deficiencies in a valve for which
similarity is claimed. Similarity can be used to reduce the amount of
in-service experience needed for a particular valve to receive an
extension of the leak test interval. Therefore, paragraph (a)(4) of the
final rule specifies the 2,000-flight-hour interval for the Kaiser
Electoprecision panel ball valve, P/N 2651-357( ) series.
7. Request To Use Optional Method
One commenter requests that the proposal be revised to allow use of
Monogram P/N 4803-76 or P/N 4803-96 series vacuum breaker check valve
as an option to the installation of a lever lock cap on the flush/fill
line or a ball valve on the flush/fill line. Another commenter requests
that the proposal be revised to allow use of either a vacuum breaker
check valve or an automatic shut-off valve as an option to installing a
lever lock cap on the flush/fill line or a ball valve on the flush/fill
line. The commenters point out that such an option to installing flush/
fill line ball valves was permitted in the ``blue ice'' AD for
McDonnell Douglas Model DC-10 series airplanes [AD 96-12-18, amendment
39-9661 (61 FR 29009, June 7, 1996)].
The FAA concurs with the commenter's request. Vacuum breaker check
valves, Monogram P/N 4803-86, installed on McDonnell Douglas Model DC-
10 series airplanes, and Monogram P/N 4803-76 and -96 installed on
Boeing Model 747 series airplanes are similar to each other in design
and function. The FAA has determined that those valves are adequate to
install as an alternative to installing a lever lock cap of the flush/
fill line or a ball valve on the flush/fill line. The FAA also has
determined that installation of an automatic shut-off valve is an
adequate method to prevent leakage from the flush/fill line. Certain
paragraphs of this AD [(a), (b)(3), and (a)(9)(ii)] have been revised
to add provisions to install vacuum breaker valves as an option to
installing a lever lock cap or ball valve on the flush/fill line.
Additionally, the final rule has been revised to add provisions in
paragraphs (b)(3) and (a)(9)(iv) of this AD to install and test a shut-
off valve per Boeing specification number 60B50341 as an option to
installing a lever lock cap or flush/fill line ball valve on the flush/
fill line.
In addition to listing optional valves for the flush/fill line, the
FAA also added vacuum leak test procedures as discussed in comment 10
below, and reorganized the seal change and leak test requirements
previously contained in paragraph (a)(8) of the NPRM, and moved them
into paragraphs (a)(9) and (a)(10) of the final rule.
8. Request To Revise Specifications of the Leak Test of the Toilet
Tank Dump Valve
The commenter, the airplane manufacturer, points out that the
proposal specifies that the toilet tank be filled with a ``minimum of
10 gallons of water/rinsing fluid'' prior to performing the leak test
of the toilet tank dump valve. The commenter requests that the
specifications for the leak test be changed to require ``a minimum of
10 gallons of water/rinsing fluid for tanks with less than 30 gallons
capacity, and a minimum of 20 gallons of water/rinsing fluid for tanks
with more than 30 gallons capacity.'' The commenter states that due to
the wide variation in toilet tank sizes on the Model 747 fleet, 10
gallons may not be adequate in some cases to properly conduct a leak
test.
The FAA concurs that the amount of fluid in the tank should be
sufficient to test for leakage of the toilet tank dump valve, and that
the specifications for conducting the leak test should be revised. The
intent of specifying that the leak test be performed with ``a minimum
of 10 gallons'' was to indicate that sufficient fluid be used to
perform a valid leak test, without having to completely fill the tank
and risk a spill of fluid inside the airplane. Since some Model 747
series airplanes are equipped with toilet tanks that are considerably
larger than tanks in other airplanes, an increase in the minimum amount
of fluid used to perform the test is considered necessary for airplanes
with the larger tanks. The FAA has revised the final rule to specify
the requested revision.
9. Request To Revise Table 1 of the Proposal
The commenter requests that Table 1 of the proposal be revised to
correct the serial numbers of 10101000B-A-1 valves and to add
10101000C-R and 10101000C-G valves to Table 1.
The FAA concurs with the request to correct the serial numbers for
10101000B-A-1 valves and has revised Table 1 accordingly. However, the
FAA does not concur with the commenter's request to add the two
additional valves to Table 1. The FAA has determined that those valves
are not used on the airplanes affected by this AD. Further, the FAA has
removed certain other part numbers of valves (10101000B-A and
10101000C-A) listed in Table 1 of the proposal since they are not
eligible for the 1,000-flight-hour leak test interval. Additionally,
Note 2 of the AD has been revised to specify that Table 1 of the AD
contains only valves that are eligible for a leak check interval of
1,500 hours.
10. Request To Use Vacuum Tool
One commenter requests that the proposal be revised to allow
testing of the inner seal of the service panel valve with a vacuum tool
for a period of one minute without any fluid upstream of the valve.
This same commenter states that testing with air (vacuum tool) is more
stringent than testing with water. The commenter points out that when
testing with air, a leak path is detected readily within one minute
because the pressure gauge will move indicating a loss of vacuum. The
commenter also points out that previous AD's have permitted leak
testing with a vacuum tool. A second commenter states that by allowing
a leak test without requiring that the inner door of the service panel
be covered with fluid, the likelihood of ``blue showers'' (i.e.,
uncontrolled leakage of waste tank drain line inside the airplane)
would be reduced.
The FAA concurs with the request to allow a vacuum leak test
procedure for the reasons the commenter provided. The FAA has revised
paragraphs (a), (a)(10)(ii), and Note 3 of the final rule to add
provisions and instructions for the use of vacuum leak test procedures.
However, the FAA does not concur with the request to establish a period
of one minute for the vacuum leak test. The commenter did not provide
sufficient evidence to support reducing the leak test period from five
minutes to one minute. Therefore, no change is necessary to the final
rule regarding the time period required for the leak test.
11. Request To Revise ``Dump Valve'' Terminology
One commenter requests that paragraph (a)(5)(i) of the proposal be
revised to change the current wording of ``dump valve'' to the correct
terminology of ``toilet tank dump valve.'' The commenter points out
that changing the terminology in that particular paragraph would make
the
[[Page 17517]]
use of the term ``toilet tank dump valve'' consistent throughout the
proposal. The FAA concurs and has revised the final rule accordingly.
12. Request To Clarify Seal Replacement Interval
One commenter requests that the compliance time for replacement of
seals be revised to clarify that the seal replacement interval would
begin when the new valve is installed or a new airplane is delivered.
The FAA concurs. Installation of a new valve or delivery of a new
airplane would also mean that a new seal is in place. Therefore, the
FAA considers that a new valve installation or delivery of a new
airplane constitutes the ``last documented seal change.'' The FAA has
revised paragraphs (a)(1) and (a)(9) of the final rule to reflect this
change. The FAA points out that, for the purposes of this AD, a ``new''
airplane is one that has accumulated less than 100 total flight hours
or 30 calendar days, whichever occurs later, since the issuance of the
original airworthiness certificate.
13. Request To Correct a Part Number
One commenter requests that paragraphs (a)(8)(ii) and (b)(2) of the
proposal be revised to reflect the correct part number for the flush/
fill ball valve. The commenter advises that the correct part number is
Kaiser Electroprecision part number series 0062-0010, not ``0062-
0009,'' as specified in the proposal. The FAA concurs with the
commenter's request, and has revised paragraphs (a)(9)(iii) and (b)(2)
of the final rule to reflect the correct part numbers.
14. Request To Extend the Seal Change Interval
One commenter requests that paragraph (a)(1)(ii) of the proposal be
revised to reduce the seal change interval from 6,000 to 5,000 flight
hours for the PneuDraulics valve. The commenter states that the seal in
a ball-valve or half-ball valve located at the service panel is
subjected to a significantly greater dynamic action than that of a seal
in a flapper-type valve. The distance that the ball or half-ball drags
across the seal subjects the seal to considerably more wear that the
wear experienced by an O-ring seal in a flapper-type valve as it moves
from a sealed to an unsealed position. The plastic seals used in the
ball or half-ball valves are much less forgiving and less compressible
than elastomer type seals used in flapper-type valves. Therefore, the
ball or half-ball valves are more susceptible to being damaged by
foreign objects and consequent leakage. The potential for ice, hardened
debris, and ``black tar'' to build up on the ball at the service panel
makes the seals more susceptible to damage by service and maintenance
personnel than the seals of an in-line ball valve. Additionally, the
commenter contends that the performance of the seals in the in-line
ball valve cannot be replicated in-service on ball or half-ball valves
used at the service panel. Service panel components also experience
greater temperature fluctuations (-65 degrees Fahrenheit to +130
degrees Fahrenheit) than those experienced by components upstream.
The FAA does not concur with the commenter's request to reduce the
seal change interval for the PneuDraulics valve. The commenter did not
provide any specific data to demonstrate that ball valve seals or half-
ball valve seals actually do have greater failure rates than flapper
type valves. The FAA established the seal change interval for the
PneuDraulics valve based on data submitted by an operator and the valve
manufacturer. No change is necessary to the final rule.
15. Request To Standardize the Requirements for Extension of the
Leak Test
One commenter, a valve manufacturer, requests that the proposal be
revised to require ``equivalent'' criteria for extending the leak tests
of all valves. The manufacturer states that certain criteria were
required to obtain leak test extensions for its product, but that other
valves were not subjected to the same stringent criteria. The commenter
notes that valves with components prone to multiple failure and easily
damaged seals will leak if exposed to the hourly usage schedules (as
proposed in the NPRM). The commenter contends that a valve with exposed
soft seals can leak immediately after successfully passing a test if
damaged by ice, tools, or loss of the donut plug. The commenter further
contends that the valves should have a primary seal and a secondary
seal as required by the specifications of the airplane manufacturer for
panel valves.
The FAA does not concur that the final rule should be revised in
regard to establishing ``equivalent'' criteria for extending the leak
test intervals. The FAA has required all operators requesting an
extension to provide service history and data to support any extensions
of leak test intervals. Previous service experience, similarity to
existing valves, and the quality of the data are considered in
determining an appropriate extension of the leak check interval for
each valve. No change is necessary to the final rule.
16. Request To Establish Consistent Testing Intervals for
Components
One commenter, the airplane manufacturer, states that it is
concerned that test and maintenance intervals for a particular part
number component may not be consistent across all models. The commenter
requests that any increased intervals for a specific component be
applied to all models using that component.
The FAA does not concur. As explained in a previous disposition of
comment (number 3), the flight cycles per flight hours are different on
various airplane models. Therefore, the cyclic wear on various
components differs according to the airplane model on which the
component is installed. Consequently, the FAA cannot approve consistent
flight hour intervals for leak checks on specific components that apply
to all airplane models.
Operators who wish to take advantage of the increase in leak test
intervals may request information concerning the existence of approved
alternative methods of compliance, in accordance with Note 5 of this
AD. Additionally, paragraph (d) of this AD provides for any operator to
request approval of an alternative method of compliance that provides
an acceptable level of safety.
17. Request To Provide a Maintenance Option
One commenter, the airplane manufacturer, requests that the FAA add
a maintenance option to the AD that would permit operators to revise
their FAA-approved maintenance program to include the requirements
specified in the proposal. The commenter points out that such a
revision would permit operators to justify extending leak test
intervals to intervals that are consistent with their regularly
scheduled maintenance.
The FAA does not concur. The FAA did not provide the maintenance
option in this AD based on information it received that few operators
were inclined to revise their maintenance program to incorporate the
requirements of this AD. Additionally, comments submitted regarding
previous ``blue ice'' AD's that did contain the maintenance option
stated that the proposed AD's were ``too long, and hard to
understand.'' The FAA's intent by not specifying the maintenance option
in this AD is to simplify and clarify the requirements of this AD. No
change to the final rule is necessary in that regard. However, if an
operator wishes to request approval for revision of its
[[Page 17518]]
maintenance program, a request should be submitted to the FAA in
accordance with the provisions of paragraph (d) of this AD.
18. Request To Include Terminating Action in the AD
One commenter, the airplane manufacturer, requests that a provision
for terminating action be included in the AD. The commenter agrees that
incorporation of the proposed AD requirements such as ``donut'' lug
removal, seal replacement, rinse system upgrade, and installation of
improved drain valves will result in reduced incidences of ``blue
ice.'' However, if an operator incorporates the requirements of the
proposed AD, and revises its maintenance program to include seal
replacement and/or seal visual inspections, the commenter considers
those actions to be sufficient to provide terminating action.
The FAA does not concur. The FAA finds that previous requests for
terminating action based on the installation of certain valves have
been unsuccessful. Accomplishment of the requirements of this AD will
ensure that an effective and uniform program to prevent incidents of
``blue ice'' is in effect for the entire fleet. Therefore, no change to
the final rule is necessary in that regard.
19. Request To Remove the Requirement to Replace ``Donut'' Valves
One commenter, an airline operator, requests that the proposal be
revised to remove the requirement ``to replace `donut' valves with
another FAA-approved valves within 5,000 flight hours.'' The commenter
points out that other AD's concerning ``blue ice'' have not required
replacement of ``donut'' valves. Further, the commenter contends that
the repetitive leak test intervals specified in the proposal will
address the safety considerations. The commenter states that, based on
financial considerations, the replacement of ``donut'' valves should be
an option for operators.
The FAA does not concur with the request to remove the requirement
to replace ``donut valves.'' The FAA finds that several incidents of
``blue ice'' were caused by ``donut'' valve leakage on airplanes,
despite a required leak test at intervals of 200 hours. Additionally,
the largest and most potentially dangerous pieces of ``blue ice'' have
been associated with ``donut'' valves. Based on the continued problems
associated with the use of ``donut'' valves, the FAA has determined
that those valves must be replaced. No change to the final rule is
necessary in that regard. Regarding current AD's addressing ``blue
ice,'' continuing to require the leak test intervals for the ``donut''
valves may motivate operators to replace the ``donut'' valves. However,
if the FAA finds that ``donut'' valves continue to be a source of
``blue ice,'' additional rulemaking may be considered.
20. Request To Call Out Part Numbers by Name
One commenter requests that lever/lock caps manufactured in
accordance with an FAA-Parts Manufacturer Approval granted to Shaw Aero
Devices be called out by part number the same way the Kaiser flush/fill
ball valve part number is called out in the proposal. The commenter did
not provide an explicit reason for this request.
The FAA does not concur. Reference to lever lock caps as ``FAA-
approved lever lock caps'' rather than specific part numbers that are
called out has been the standard practice in the development of the
``blue ice'' AD's. Therefore, the Shaw Aero Devices lever lock cap,
part number 580-116, is encompassed in the final rule as an ``FAA-
approved lever lock cap.'' However, the Kaiser flush/fill line ball is
not a lever lock cap and would not be encompassed by the phrase ``FAA-
approved lever lock caps.'' Consequently, the Kaiser valve part number
is specifically called out in the final rule. No change is necessary to
the final rule in that regard.
21. Requests To Revise the Cost Impact Information
One commenter, a parts manufacturer, requests that the cost impact
information, below, be revised to reflect an optional use of a hand
held vacuum pump as the most cost effective method to perform the leak
tests. The commenter points out that a hand held vacuum pump takes less
time and does not require fuel to power-up the airplane.
The FAA does not concur with the commenter's request. The cost
impact figures provided in an AD are intended to provide an approximate
cost of performing required tasks. The FAA has no way of determining
the specific cost figures of each possible method of accomplishing a
required task. The cost estimates, as provided, are simply estimates
based on the best information the FAA has available at the time the
rule is developed. No change is necessary to the final rule in that
regard.
Another commenter states that the work hours necessary to install
the flush/fill line cap is estimated in the proposal to be 1 work hour
per cap. The commenter requests that the work hour estimate be revised
to include heating the flush/fill line to prevent ice build-up within
the line behind the cap. The commenter provided no work hour figures
that would include heating of the flush/fill line.
The FAA does not concur. Heating for the line behind the flush/fill
cap may be considered a good practice and possibly the most practical
solution where flush/fill lines take a long time to drain. The FAA
typically provides cost estimates only for those actions that are
required to be accomplished. In this case, heating of the line behind
the flush/fill cap is not necessary when operators allow the flush/fill
line to drain before closing the cap. The FAA considers it to be the
operator's choice to allow the flush/fill line to drain after
servicing, or to install heating for the flush/fill line. Therefore, no
change is necessary to the final rule.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes previously
described. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
There are approximately 711 Model 747 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 201
airplanes of U.S. registry and 89 U.S. operators will be affected by
this AD.
The waste drain system leak test and outer cap inspection will 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 the waste drain system leak test and outer
cap inspection is estimated to be $72,360, 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
will be required to be leak tested as few as 1 time 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 $360
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
[[Page 17519]]
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 would be incurred.
The FAA estimates that it will take approximately 1 work hour per
airplane lavatory drain to accomplish a visual inspection of the
service panel drain valve cap/door seal and seal mating surfaces, at an
average labor rate of $60 per work hour. As with leak tests, certain
airplanes will be required to be visually inspected as many as 15 times
or as few as 3 times each year. Based on these figures, the 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 installation of the flush/fill line cap will take approximately
1 work hour per cap to accomplish, at an average labor rate of $60 per
work hour. The cost of required parts will be $275 per cap. There are
an average of 4 caps per airplane. Based on these figures, the cost
impact on U.S. operators of these requirements of this AD is estimated
to be $269,340, or $1,340 per airplane, per replacement cycle.
The seal replacements of the drain valves required by paragraph (a)
of this AD will require approximately 2 work hours to accomplish, at an
average labor cost of $60 per hour. The cost of required parts will be
$200 per each seal change. Based on these figures, the cost impact on
U.S. operators of these requirements of this AD is estimated to be
$64,320, or approximately $320 per airplane, per replacement.
The number of required work hours, as indicated above, is presented
as if the accomplishment of the actions of this AD will 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.
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 AD, makes a
finding of an unsafe condition, this means that the original cost-
beneficial level of safety is no longer being achieved and that the
required actions are necessary to restore that level of safety. Because
this level of safety has already been determined to be cost-beneficial,
a full cost-benefit analysis for this AD would be redundant and
unnecessary.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Compliance: Required as indicated, unless accomplished previously.
99-08-10 Boeing: Amendment 39-11116. Docket 97-NM-325-AD.
Applicability: All Model 747-100, -200, -300, -SP, and -400F
series 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 request approval for an
alternative method of compliance in accordance with paragraph (d) 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 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) Accomplish the applicable requirements of paragraphs (a)(1)
through (a)(11) 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: The toilet tank dump
valve leak test must be performed by filling the toilet tank with
water/rinsing fluid to fill the toilet tank to a level that
submerges the toilet
[[Page 17520]]
tank dump valve seals with sufficient fluid to perform a valid test,
and testing for leakage after a period of five minutes. For
guidance, a minimum of 10 gallons is considered sufficient for a
tank of 30 gallons or less capacity, and 20 gallons of fluid is
considered sufficient for a tank with more than 30 gallons capacity.
For tests of service panel drain valves, unless otherwise specified
by this AD: 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. As an alternative to the
above test procedure for the service panel drain valves and in-line
drain valves, a vacuum test may be done in accordance with Shaw Aero
Devices Document ILS-193, Operation Instructions for the Waste Drain
Valve Inner Flapper and Lavatory Rinse/Fill Valve Leak Test Tool,
dated November 17, 1998, using a minimum of 3 PSID across the in-
line drain valve or waste drains system service panel valve inner
door for a period of 5 minutes. Any movement of the needle of the
pressure gauge during the test period constitutes failure of the
test. Other leak test tools may by used for this test if approved
per paragraph (d) of this AD. Any revision of the seal change
intervals or leak test intervals must be approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(1) Replace the valve seals with new valve seals in accordance
with the applicable schedule specified in paragraphs (a)(1)(i),
(a)(1)(ii), and (a)(1)(iii) of this AD. For purposes of determining
seal replacement times specified in this AD: If a new valve is
installed or a ``new airplane'' is delivered, it is considered that
the new valve installation or airplane delivery constitutes the
``last documented seal change.'' A ``new airplane'' for the purposes
of this AD is an airplane that has accumulated less than 100 total
flight hours or 30 calendar days, whichever occurs later, since the
issuance of the original airworthiness certificate.
(i) For each lavatory drain system that has an in-line drain
valve installed, Kaiser Electroprecision part number series 2651-278
or a Kaiser Electroprecision service panel ball valve, part number
series 2651-357: 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 6,000 flight hours after the effective date of this AD,
and thereafter at intervals not to exceed 6,000 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. Take precautions to
avoid 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
4,000 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 4,000
flight hours.
(i) Conduct leak tests of the toilet tank dump valve and service
panel drain valve. 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
2651-357-(2) or higher -() (dash number): Within 2,000 flight hours
after the effective date of this AD, and thereafter at intervals not
to exceed 2,000 flight hours, conduct a leak test of the toilet tank
dump valve and service panel drain valve. 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.
(5) 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 1,500 flight hours after the effective date of
this AD, and thereafter at intervals not to exceed 1,500 flight
hours, accomplish the requirements of paragraphs (a)(5)(i) and
(a)(5)(ii) of this AD:
Table 1.--Shaw Aero Valves Approved for 1,500 Flight Hour Leak Test
Interval
------------------------------------------------------------------------
Serial numbers of part number
Shaw waste drain valve part number valve approved for 1,500 hour
leak test interval
------------------------------------------------------------------------
331 Series, 332 Series................. All.
10101000B-A-1.......................... 0201 and higher.
10101000BA2............................ 0130 and higher.
10101000C-A-1.......................... 0277 and higher.
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 list of approved Shaw valves that are
eligible for a 1,500 hour leak test, including those valves approved
by Parts Manufacturer Approval (PMA) or Supplemental Type
Certificate (STC) for installation on Boeing Model 747 series
airplanes that are subject to this AD.
(i) Conduct a leak test of the toilet tank dump valve and
service panel drain valve. 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) For each valve, perform a visual inspection of the outer
cap/door and seal mating surface for any wear or damage that may
cause leakage.
[[Page 17521]]
(6) 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 800 flight hours after the effective date of this AD, and
thereafter at intervals not to exceed 800 flight hours, accomplish
the requirements of paragraphs (a)(6)(i) and (a)(6)(ii) of this AD:
(i) Conduct a leak test of the toilet tank dump valve and the
service panel drain valve. 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.
(7) 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; Shaw Aero Devices assembly
part number 0008-100; or other FAA-approved equivalent parts;
accomplish the requirements of paragraphs (a)(7)(i), (a)(7)(ii), and
(a)(7)(iii) of this AD at the times specified in those paragraphs.
For the purposes of this paragraph [(a)(7)], ``FAA-approved
equivalent part'' means either a ``donut'' plug which mates with the
cap/flange part numbers listed above, or a cap/flange which mates
with the ``donut'' plug part numbers listed above, such that the
cap/flange and ``donut'' plug are used together as an assembled
valve.
(i) Within 250 flight hours after the effective date of this AD,
and thereafter at intervals not to exceed 250 flight hours, conduct
leak tests of the toilet tank dump valve and the service panel drain
valve. 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)(7)(i).
(iii) Within 5,000 flight hours after the effective date of this
AD, replace the donut valve [part numbers per paragraph (a)(7) 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.
(8) For each lavatory drain system not addressed in paragraphs
(a)(2), (a)(3), (a)(4), (a)(5), (a)(6), or (a)(7) of this AD: Within
250 flight hours after the effective date of this AD, and thereafter
at intervals not to exceed 250 flight hours, accomplish the
requirements of paragraphs (a)(8)(i) and (a)(8)(ii) of this AD:
(i) Conduct a leak test of the toilet tank dump valve and the
service panel drain valve. 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.
(9) For flush/fill lines: Within 5,000 flight hours after the
effective date of this AD, perform the requirements of paragraph
(a)(9)(i), (a)(9)(ii), (a)(9)(iii), or (a)(9)(iv) 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. For the purpose of determining
seal replacement times required by this AD: If a new valve has been
installed or a new airplane has been delivered, the new valve
installation or airplane delivery may be considered to constitute
the ``last documented seal change.'' For the purposes of this AD, a
``new airplane'' is defined as an airplane that has accumulated less
than 100 total flight hours or 30 calendar days, whichever occurs
later, since the issuance of the original airworthiness certificate.
(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)(10)(i) or
(a)(10(ii), or (a)(10)(iii) of this AD, as applicable.
(ii) If a vacuum breaker check valve having Monogram part number
series 4803-76 or 4803-96 is installed on the subject lavatory,
prior to further flight, replace the seals/o-rings in the vacuum
breaker check valve. Perform a leak test of the vacuum breaker check
valve in accordance with paragraph (a)(10)(i) or (a)(10)(ii) of this
AD, as applicable. Verify proper operation of the vent line vacuum
breaker in accordance with paragraph (a)(10)(iii) of this AD.
(iii) If a flush/fill ball valve having Kaiser Electroprecision
part number series 0062-0010 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)(10)(i) or (a)(10)(ii) of
this AD, as applicable.
(iv) If a shut-off valve having Boeing Specification #SCD
60B50341 is installed on the flush/fill line of the subject
lavatory, replace the seals in the shut-off valve. Perform a leak
test of the shut-off valve with a minimum of 3 PSID across the
valve, in accordance with paragraph (a)(10)(ii) of this AD. At the
time the test is performed, ground handling bus power must be
removed from the shutoff valve and level sensor. This can be
accomplished by de-energizing the ground handling bus completely
(refer to Boeing Maintenance Manual 38-32-00/1 and 24-22-00/201 as
an additional source of service information) or by removing ground
handling bus supplied power to only the shutoff valve and waste
level sensor. To remove ground handling bus supplied power to the
shutoff valve and waste level sensor, open the ground service
lavatory lights circuit breaker supplying 115V AC to the shutoff
valve and the lavatory tank fill control circuit breaker supplying
28 V DC to the level sensor. These circuit breakers are located on
panel P14 of Model 747-100, -200, -300 and SP airplanes, and on
panel P414 of Model 747-400F series airplanes.
(10) Perform the tests specified in paragraph (a)(9) of this AD
in accordance with the instructions of paragraph (a)(10)(i),
(a)(10)(ii), or (a)(10)(iii) of this AD, as applicable.
(i) Leak test the toilet tank anti-siphon valve or the vacuum
breaker check valve by filling the bowl above the toilet tank
approximately half-full with water/rinsing fluid (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 or opened during the test. Test for
leakage at the flush/fill line port for a period of 5 minutes.
Note 3: The leak test may be accomplished by pressurizing the
airplane or by performing the leak test using Boeing vacuum test rig
described in Boeing Maintenance Manual, 38-32-00/501, which is
considered to be an additional source of service information for
this test, if the toilet tank is filled to the level specified in
paragraph (a)(10)(i) of this AD.
(ii) As an alternative to the leak tests of the flush/fill line
valve specified in paragraph (a)(10)(i) of this AD, a vacuum test
may be done using a minimum of 3 PSID across the anti-siphon valve,
vacuum breaker valve, or shut-off valve in the flush/fill line for a
period of 5 minutes, in accordance with Shaw Aero Devices Document
ILS-193 (Operation Instructions for the waste Drain Valve Inner
Flapper and Lavatory Rinse/Fill Valve Leak Test Tool) dated November
17, 1998. 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. Any movement of the needle of the
pressure gauge during the test period constitutes failure of the
test and shall be considered evidence of leakage. Other leak test
tools may by used for this test if approved in accordance with
paragraph (d) of this AD.
(iii) 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.
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. If back
drainage does not occur, prior to further flight, replace the vent
line vacuum breaker or repair the vacuum breaker check valve in
accordance with the appropriate component maintenance manual to
obtain proper back drainage.
[[Page 17522]]
(11) If evidence of leakage or valve damage that may cause
leakage is found during the leak tests and inspections required by
paragraph (a) of this AD or at any other time: Accomplish the
requirements of paragraph (a)(11)(i), (a)(11)(ii), or (a)(11)(iii)
of this AD, as applicable.
(i) If any leakage is discovered, prior to further flight,
perform the requirements of paragraphs (a)(11)(i)(A) and
(a)(11)(i)(B) of this AD.
(A) Repair the leakage in accordance with the applicable
component repair or maintenance manual.
(B) Perform the appropriate leak test, as specified in paragraph
(a) of this AD; thoroughly clean the surfaces adjacent to any
leakage to remove any horizontal fluid residue streaking. Cleaning
must be to the extent that any future appearance of a horizontal
fluid residue streak would indicate that the system is leaking.
Note 4: For purposes of this AD, ``leakage'' is defined as any
visible leakage, if observed during a leak test. At any time other
than during a leak test, ``leakage'' is defined as the presence of
ice in the service panel, horizontal fluid residue streaks, or 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 and that wear or damage could result in
a leak, 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)(11)(i) or (a)(11)(ii) of this AD: Prior to further flight, drain
the affected lavatory system and placard the lavatory inoperative
until repairs are accomplished.
(b) For all airplanes: Unless accomplished previously, within
5,000 flight hours after the effective date of this AD, install one
of the caps/valves specified in paragraph (b)(1), (b)(2), (b)(3), or
(b)(4) of this AD on each flush/fill line of all lavatories.
(1) Install an FAA-approved lever/lock cap on the flush/fill
line. Or
(2) Install a flush/fill ball valve Kaiser Electroprecision part
number series 0062-0010 on the flush/fill line. Or
(3) Install a vacuum breaker valve, Monogram part number series
4803-76 or 4803-96 on the flush/fill line. Or
(4) Install a shut-off valve, Boeing specification number
60B50341, on the flush/fill line.
(c) 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 (c)(1) or (c)(2) of
this AD, as applicable. After each leak test has been performed
once, each subsequent leak test must be performed according to the
new operator's schedule, in accordance with paragraph (a) of this
AD.
(1) For airplanes that have been maintained previously 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
results in the earlier accomplishment date for that leak test.
(2) For airplanes that have not been maintained previously 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 Principal Maintenance
Inspector (PMI), but within a period not to exceed 250 flight hours.
(d) 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 Aircraft Certification
Office, Transport Airplane Directorate, Operators shall submit their
requests through an appropriate FAA PMI, who may add comments and
then send it to the Manager, Seattle ACO.
Note 5: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) 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.
(f) Except as provided in paragraph (a) of this AD, the vacuum
leak tests of the service panel drain valves and in-line drain
valves, and vacuum leak tests of the service panel drain valves and
flush/fill line valves, if accomplished, shall be done in accordance
with Shaw Aero Devices, Doc. ILS-193, Operation Instructions for the
Waste Drain Valve Inner Flapper and Lavatory Rinse/Fill Valve Leak
Test Tool, dated November 1998. This incorporation by reference was
approved by the Director of the Federal Register in accordance with
5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Shaw
Aero Devices, Inc., 12291 Towne Lake Drive, Ft. Myers, Florida
33913. Copies may be inspected at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
(g) This amendment becomes effective on May 17, 1999.
Issued in Renton, Washington, on April 1, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-8686 Filed 4-9-99; 8:45 am]
BILLING CODE 4910-13-P