[Federal Register: July 27, 2004 (Volume 69, Number 143)]
[Rules and Regulations]
[Page 44580-44586]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr27jy04-3]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-78-AD; Amendment 39-13738; AD 2004-15-04]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-200, -200C, -300, -
400, and -500 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to certain Boeing airplane models, that currently
requires either inspections for discrepancies of the fueling float
switch wiring in the center fuel tank and follow-on actions, or
deactivation of the float switch. This amendment requires replacing the
float switches in the center and wing fuel tanks with new, improved
parts; installing a conduit liner system in the center fuel tank; and
replacing conduit assemblies in the wing fuel tanks with new parts,
which terminates the existing requirements. For certain airplanes, this
amendment also requires replacing certain existing sections of the
electrical conduit in the center fuel tank with new conduit. This
amendment also adds one additional airplane model to the applicability
and removes another. The actions specified by this AD are intended to
prevent contamination of the fueling float switch by moisture or fuel,
and chafing of the float switch wiring against the fuel tank conduit,
which could present an ignition source inside the fuel tank that could
cause a fire or explosion. This action is intended to address the
identified unsafe condition.
DATES: Effective August 31, 2004.
The incorporation by reference of certain publications, as listed
in the regulations, is approved by the Director of the Federal Register
as of August 31, 2004.
The incorporation by reference of certain other publications, as
listed in the regulations, was approved previously by the Director of
the Federal Register as of March 18, 1999 (64 FR 10213, March 3, 1999).
ADDRESSES: The service information referenced in this AD may be
obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle,
Washington 98124-2207. 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 National
Archives and Records Administration (NARA). For information on the
availability of this material at NARA, call (202) 741-6030, or go to:
http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html
.
FOR FURTHER INFORMATION CONTACT: Sherry Vevea, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone
(425) 917-6514; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by superseding AD 99-05-12,
amendment 39-11060 (64 FR 10213, March 3, 1999); which is applicable to
certain Boeing Model 737-100, -200, -300, -400, and -500 series
airplanes; was published as a supplemental notice of proposed
rulemaking (NPRM) in the Federal Register on June 11, 2003 (68 FR
34843). (A correction of AD 99-05-12 was published in the Federal
Register on March 9, 1999 (64 FR 11533)). The action proposed to
continue to require inspection of the fueling float switch wiring in
the center fuel tank to detect discrepancies, accomplishment of
corrective actions, and installation of double Teflon sleeving over the
wiring of the float switch. The action also proposed to add new
requirements for replacement of the float switches with new, improved
float switches and installation of a conduit liner system in the center
fuel tank, and replacement of the float switches and conduit assemblies
with new, improved float switches and conduit assemblies in the wing
fuel tanks. (The action proposed that this replacement would terminate
the requirements of the existing AD.) For certain airplanes, the action
also proposed to require replacement of certain sections of conduit in
the center fuel tank with new conduit. The action also proposed to add
one additional airplane model to the applicability and remove another.
Comments
Interested persons have been afforded an opportunity to participate
in the making of this amendment. The FAA has given due consideration to
the comments received.
Request To Refer to Revised Service Information
Several commenters request that we revise the supplemental NPRM to
refer
[[Page 44581]]
to the latest service information issued by the airplane manufacturer.
The commenters note that the work instructions in Boeing Alert Service
Bulletin 737-28A1141, Revision 1, dated December 19, 2002, have been
revised to correct errors in the installation instructions.
We concur. Since the issuance of the supplemental NPRM, we have
reviewed and approved Boeing Alert Service Bulletin 737-28A1141,
Revision 2, dated August 21, 2003. Revision 2 of the service bulletin,
among other things, modifies work instructions for installing the
bonding strap to the float switch mounting bracket in the center fuel
tank, modifies torque values for the B-nuts on the float switch cable
conduit, and specifies that lock wire be installed on the boltheads on
the front spar. Due to the nature of these changes, we have revised
paragraphs (b)(1)(i)(A), (b)(1)(ii), and (h)(1) of this final rule to
refer to Boeing Alert Service Bulletin 737-28A1141, Revision 2, as the
appropriate source of service information for the replacement of float
switches required by those paragraphs. Also, we have revised paragraph
(i) of this final rule to give credit for actions accomplished before
the effective date of this AD per the original issue or Revision 1 of
that service bulletin, provided that the B-nuts on the float switch
cable conduit are torqued to the correct values, the float switch
bonding strap is installed and securely fastened to the float switch
bracket or main structure, and lock wire is installed in the boltheads
on the front spar, as stated in Revision 2 of the service bulletin. We
find that this change does not expand the scope of the proposed AD but
merely provides necessary clarification of the work instructions.
Request To Extend Compliance Time for Replacement
Three commenters request that we extend the compliance time for the
proposed replacement. One commenter requests that we extend the
compliance time from 2 years to 36 months due to concerns about parts
availability. The commenter notes that the replacement of the fuel tank
float switch that would be required by the proposed AD is also required
on Model 737-600, -700, -700C, -800, and -900 series airplanes by AD
2002-26-18, amendment 39-13006 (68 FR 481, January 6, 2003). Also,
another Boeing service bulletin specifies installing the same float
switches on auxiliary tanks of Boeing Model 737 series airplanes. The
other commenters request that we extend the compliance time from 2
years to 4 years. One of these commenters states that this would enable
operators to accomplish the replacements and installations during a
scheduled heavy maintenance visit. We infer that the other commenter's
request is intended to minimize the number of fuel tank entries by
allowing the proposed actions to be accomplished at the same time as
other ADs that require fuel tank entry.
We do not concur with the commenters' request. We have confirmed
with Boeing that the necessary parts will be available for the affected
airplanes within the 2-year compliance time stated in this final rule.
In developing an appropriate compliance time for this final rule, we
considered the manufacturer's recommendation, the degree of urgency
associated with the subject unsafe condition, and the maintenance
schedules of affected operators. In light of all of these factors, we
find that 2 years represents an appropriate interval of time for
affected airplanes to continue to operate without compromising safety.
We have made no change to this final rule in this regard.
Request To Allow Repetitive Inspections in Lieu of Replacement
One commenter requests that we revise the supplemental NPRM to
allow operators to perform repetitive inspections of the fueling float
switches and wiring, at intervals not to exceed 30,000 flight hours, in
lieu of accomplishing the replacement of the float switches and conduit
assemblies with new, improved parts. The commenter explains that it has
accomplished the actions currently required by AD 99-05-12 and has
found no discrepancy and has installed double Teflon sleeving on the
wiring for the float switch in the center fuel tank. The commenter also
states that it has installed grease in the interior of the float switch
electrical conduits per AD 93-17-02, amendment 39-8672 (58 FR 54945,
October 25, 1993).
We do not concur with the commenter's request. The repetitive
inspections only address issues with the wiring. The repetitive
inspections do not correct the unsafe condition in the float switch. We
can better ensure long-term continued operational safety by
modifications or design changes to remove the source of the problem,
rather than by repetitive inspections. Long-term inspections may not
provide the degree of safety necessary for the transport airplane
fleet. This, coupled with a better understanding of the human factors
associated with numerous repetitive inspections, has led us to consider
placing less emphasis on special procedures and more emphasis on design
improvements. The proposed replacement and installation requirements
are consistent with these considerations. We have made no change to
this final rule in this regard.
Request To Require Installation of Transient Suppression Devices (TSDs)
Two commenters request that we require the installation of TSDs for
the fuel tank float switches to limit the transfer of electrical energy
and power through the float switch wires in lieu of requiring the
installation of new, improved float switches and a conduit liner system
or conduit assemblies. Both commenters note that a modification for
installing TSDs on the float switches has been developed for use on
other airplanes, including on Boeing Model 737-600, -700, -800, and -
900 series airplanes. One of the commenters considers that the proposed
requirements to install improved float switches and associated
modifications are not consistent with the requirements of Special
Federal Aviation Regulation (SFAR) No. 88, ``Transport Airplane Fuel
Tank System Design Review, Flammability Reduction, and Maintenance and
Inspection Requirements'' (66 FR 23086, May 7, 2001). The commenter
notes that the new, improved float switch is powered by 28 volts direct
current (DC), which exceeds the intrinsically safe level for equipment
located in fuel tanks, as defined by SFAR No. 88. The commenter states
that installation of TSDs would be a more attractive solution for
operators because installation of TSDs would not involve entry into and
replacement of complex parts in the fuel tank.
We agree in principle with the commenters' statements that
installation of TSDs on the fuel tank float switches may be an
acceptable alternative to the requirement to replace the float switches
with new, improved float switches and install a conduit liner system or
conduit assemblies. We have previously approved installation of TSDs on
the float switches on Model 737-600, -700, -700C, -800, and -900 series
airplanes. However, at this time, a float switch TSD has not been
approved for installation on the airplane models affected by this final
rule. Should a float switch TSD for these airplanes be developed and
approved in the future, operators may request approval of an
alternative method of compliance (AMOC) for the requirements of this
final rule, as provided by paragraph (k)(1) of this final rule.
With regard to the one commenter's concerns about potential non-
[[Page 44582]]
compliance with SFAR No. 88, we do not agree. We note that the design
standards are contained within Part 25 (``Airworthiness Standards:
Transport Category Airplanes'') of the Federal Aviation Regulations (14
CFR part 25), not in SFAR 88. We agree that a finding of direct
compliance with the requirements of part 25 could not be made for the
new, improved float switch and conduit liner or conduit assemblies
because the design is not fail-safe. However, we have approved the
fueling float switch, conduit liner system, and conduit assemblies
having a conduit liner, as providing a level of safety equivalent to
the requirements of Sections 25.901 (``Powerplant installation'') and
25.981(a) and (b) (``Fuel tank ignition prevention'') of the Federal
Aviation Regulations (14 CFR 25.901 and 25.981), relative to the fuel
tank float switch installation and maintenance instructions for the
subject airplane models. We find that the new, improved design of the
float switch provides an equivalent level of safety because of special
compensating design features and maintenance that is required. The new,
improved float switch is hermetically sealed and is more resistant than
the old design to contamination by fuel or water. A new flexible
ethylene tetrafluorethylene (ETFE) conduit liner installed in the float
switch wiring conduit protects the wiring from chafing inside the
conduit. Maintenance documents specify that this conduit liner be
replaced with a new liner whenever the wiring is removed from the
conduit for any reason. Also, the design of the new, improved float
switch, conduit, liner, and wiring system will be listed as a Critical
Design Configuration Control Limitation for the Model 737 fuel system,
to ensure that operators do not modify the system without appropriate
design review.
We have made no change to this final rule in this regard.
Request To Revise Cost Impact Information
One commenter states that the cost impact for replacing the float
switches and installing a conduit liner or conduit assemblies is higher
than stated in the supplemental NPRM. The commenter states that 87 work
hours are required, and the cost of required parts is $7,500. A second
commenter also states that the estimated cost of parts is conservative
and that the actual cost is higher.
We agree with the commenter's statement that the total number of
work hours for accomplishing the required actions is somewhat higher
than stated in the supplemental NPRM. Accordingly, we have revised the
estimated work hours stated in the Cost Impact section of this final
rule to 94.
We do not concur with the commenters' request to revise the
estimated cost of required parts. We note that the estimated cost of
required parts, between $3,633 and $5,061, is consistent with figures
provided in the referenced service bulletin. We have made no change to
this final rule in this regard.
Request To Require Similar Actions on Auxiliary Fuel Tanks
One commenter, the airplane manufacturer, requests that we revise
the supplemental NPRM to refer to Boeing Alert Service Bulletin 737-
28A1192, Revision 1, dated August 21, 2003. This service bulletin
describes procedures for replacing the fuel tank float switch and
installing a conduit liner system on Model 737 series airplanes with
auxiliary fuel tanks.
We do not concur with the commenter's request. We may consider
additional rulemaking to require replacing the fuel tank float switch
with a new, improved float switch and installing a conduit liner system
on Model 737 series airplanes with auxiliary fuel tanks. However, we
have determined that it is not appropriate to add such a requirement to
this AD. We have made no change to this final rule in this regard.
Request To Allow Installation of Existing Float Switch
One commenter requests that we revise the proposed AD to remove
paragraph (j). The commenter notes that this paragraph prohibits the
installation of the existing float switch, part number F8300-146, as of
the effective date of this AD. The commenter is concerned about the
need to replace an inoperative main or center tank fuel float switch on
an in-service airplane that has not been modified per Boeing Alert
Service Bulletin 737-28A1141.
We do not concur with the commenter's request. The new, improved
float switch is more resistant to fuel and water contamination than the
existing float switch. Fluid contamination in the existing float switch
design could provide an electrical path between the float switch and
the airplane structure, which could result in a potential ignition
source in the fuel tank. Considering the criticality of the unsafe
condition, we find that it would be inappropriate to allow installation
of the existing float switch after the effective date of this final
rule. However, in the case of a need to replace an inoperative main or
center fuel tank float switch, paragraphs (c) and (d) of this final
rule provide for deactivation of the float switch until the necessary
replacement can be accomplished. No change to this final rule is
necessary in this regard.
Request To Remove Inaccurate Statements
One commenter requests that we revise the ``Actions Since Issuance
of Previous Proposal'' section of the supplemental NPRM to remove the
statement that ``the new conduit assemblies for the float switch
eliminate sharp bends within the conduit. * * *'' The commenter notes
that this statement is not true for the affected airplane models.
We acknowledge that this statement is incorrect for the airplane
models subject to this AD. This statement pertains to the new conduit
assemblies that are installed in the center and wing fuel tanks on
Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes.
However, the ``Actions Since Issuance of Previous Proposal'' section is
not restated in this final rule, so no change is possible in this
regard.
The same commenter requests that we revise the ``Other Relevant
Rulemaking'' section of the supplemental NPRM to clarify that this AD
would not require the replacement of float switch conduit assemblies in
the center fuel tank.
We concur that this AD does not require replacement of all conduit
assemblies in the center fuel tank. However, for airplanes subject to
the inspections required by paragraph (b)(3)(ii)(A) of this final rule,
this final rule does require replacement of any section of conduit
where arcing or a fuel leak has occurred. Since the ``Other Relevant
Rulemaking'' is not restated in this final rule, no change is possible
in this regard.
The same commenter requests that we delete the last sentence of
paragraph (b) of the supplemental NPRM, which states, ``Pay particular
attention to the wire bundle where it passes through the wing pylon
vapor seals and under the wire bundle clamps.'' The commenter notes
that the wing pylon vapor seal is not in the area of rework.
We concur with the commenter's request, and have deleted this
sentence from paragraph (b) of this final rule.
Request To Clarify Requirement To Replace Electrical Conduit
One commenter requests that we revise the ``Summary'' and
``Explanation of Proposed Requirements of Supplemental NPRM'' sections
of the supplemental NPRM to clarify what sections of the conduit in the
center fuel
[[Page 44583]]
tank need to be replaced with new conduit. Specifically, the commenter
requests that we revise these sections to specify that sections of the
conduit found to have damage due to arcing must be replaced.
We acknowledge the commenter's concern, but we do not agree that
any change to this final rule is necessary. The summary of an AD is
intended to provide only a general description of the requirements of
the AD. The reference in the ``Summary'' section to replacing ``certain
existing sections of the electrical conduit'' is an accurate, although
general, description of the required action. Further, we acknowledge
that the wording of the ``Explanation of Proposed Requirements of the
Supplemental NPRM'' section could have been more precise as to which
sections of the conduit may need to be replaced. However, this section
is not restated in this final rule, so no change is possible in this
regard. We find that the requirement stated in paragraph (h)(2) of the
supplemental NPRM and this final rule clearly states that any section
of the electrical conduit in the center fuel tank where arcing or a
leak occurred must be replaced with new conduit. We have made no change
to this final rule in this regard.
Explanation of Additional Changes to Final Rule
For clarification, we have revised paragraph (b)(4) of this final
rule to refer specifically to Boeing Alert Service Bulletin 737-
28A1132, dated December 2, 1998; Revision 1, dated January 15, 1999; or
Revision 2, dated June 17, 1999; instead of to ``the alert service
bulletin.''
Also, paragraph (e) of the supplemental NPRM states that dispatch
with the float switch deactivated ``is allowed until replacement float
switches and wiring are available for installation or until the
compliance time for the replacement required by paragraph (h) of this
AD.'' For clarification, we have revised that paragraph to state that
dispatch with the float switch deactivated ``is allowed until
replacement float switches and wiring are available for installation,
but not later than the compliance time for the replacement required by
paragraph (h) of this AD.''
Also, paragraph (f) of the supplemental NPRM states that, ``If the
actions required by paragraph (h) of this AD are accomplished within
the compliance time specified in this paragraph, operators are not
required to do paragraph (b) or (c) of this AD.'' Our intent was that
accomplishment of paragraph (h) of this final rule also entails
accomplishment of paragraph (h)(2) of this final rule (as applicable).
Thus, for clarification, we have revised paragraph (f) of this final
rule to explicitly state that operators must accomplish the
requirements of paragraph (h)(2) for the provision in paragraph (f) of
this final rule to apply.
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
significantly increase the economic burden on any operator nor increase
the scope of the AD.
Changes to 14 CFR Part 39/Effect on the AD
On July 10, 2002, the FAA issued a new version of 14 CFR part 39
(67 FR 47997, July 22, 2002), which governs the FAA's airworthiness
directives system. The regulation now includes material that relates to
altered products, special flight permits, and alternative methods of
compliance (AMOCs). Because we have now included this material in part
39, only the office authorized to approve AMOCs is identified in each
individual AD. However, for clarity and consistency in this final rule,
we have retained the language of the supplemental NPRM regarding that
material.
Change to Labor Rate Estimate
Since the issuance of the supplemental NPRM, we have reviewed the
figures we have used over the past several years to calculate AD costs
to operators. To account for various inflationary costs in the airline
industry, we find it necessary to increase the labor rate used in these
calculations from $60 per work hour to $65 per work hour. The cost
impact information, below, reflects this increase in the specified
hourly labor rate.
Cost Impact
There are approximately 2,886 Model 737-200, -200C, -300, -400, and
-500 series airplanes of the affected design in the worldwide fleet.
The FAA estimates that 1,111 airplanes of U.S. registry will be
affected by this AD.
The removal and inspection of the fueling float switch in the
center fuel tank and installation of double Teflon sleeving, which are
provided as one alternative for compliance with AD 99-05-12, takes
approximately 18 work hours per airplane to accomplish, at an average
labor rate of $65 per work hour. Required parts cost approximately $30
per airplane. Based on these figures, the cost impact of the removal
and inspection of the float switch and installation of double Teflon
sleeving, if accomplished, is estimated to be $1,200 per airplane.
The deactivation of the float switch and installation of
``Caution'' signs that are provided as the other alternative for
compliance with AD 99-05-12, takes approximately 3 work hours per
airplane to accomplish, at an average labor rate of $65 per work hour.
Based on these figures, the cost impact of the deactivation and
installation, if accomplished, is estimated to be $195 per airplane.
The new replacement of float switches and installation of a conduit
liner in the center fuel tank, and the replacement of float switches
and conduit assemblies in the wing fuel tanks, that are required by
this AD will take approximately 94 work hours per airplane to
accomplish, at an average labor rate of $65 per work hour. Required
parts will cost between $3,633 and $5,061 per airplane. Based on these
figures, the cost impact of this replacement is estimated to be between
$9,743 and $11,171 per airplane.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the requirements of this
AD action, and that no operator would accomplish those actions in the
future if this AD were not adopted. The cost impact figures discussed
in AD rulemaking actions represent only the time necessary to perform
the specific actions actually required by the AD. These figures
typically do not include incidental costs, such as the time required to
gain access and close up, planning time, or time necessitated by other
administrative actions.
Regulatory Impact
The regulations adopted herein will not have a substantial direct
effect 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, it
is determined that this final rule does not have federalism
implications under Executive Order 13132.
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
[[Page 44584]]
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
0
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
0
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]
0
2. Section 39.13 is amended by removing amendment 39-11060 (64 FR
10213, March 3, 1999), corrected at 64 FR 11533, March 9, 1999, and by
adding a new airworthiness directive (AD), amendment 39-13738, to read
as follows:
2004-15-04 Boeing: Amendment 39-13738. Docket 99-NM-78-AD.
Supersedes AD 99-05-12, Amendment 39-11060.
Applicability: Model 737-200, -200C, -300, -400, and -500 series
airplanes; on which the center wing tanks are activated; excluding
those airplanes equipped with center wing tank volumetric top-off
systems, or alternating current (AC) powered center tank float
switches; 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 (k)(1)
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 contamination of the fueling float switch by moisture
or fuel, and chafing of the float switch wiring against the fuel
tank conduit, which could present an ignition source inside the fuel
tank that could cause a fire or explosion, accomplish the following:
Requirements of AD 99-05-12
Compliance Time for Initial Action
(a) For Model 737-200, -300, -400, and -500 series airplanes
having line numbers (L/N) 1 through 3108 inclusive: Prior to the
accumulation of 30,000 total flight hours, or within 30 days after
March 18, 1999 (the effective date of AD 99-05-12, amendment 39-
11060), whichever occurs later, accomplish the requirements of
paragraph (b) or (c) of this AD.
Initial Inspection: Procedures
(b) Remove the fueling float switch and wiring from the center
fuel tank and perform a detailed inspection of the float switch
wiring to detect discrepancies (i.e., evidence of electrical arcing,
exposure of the copper conductor, presence or scent of fuel on the
electrical wires, or worn insulation), in accordance with Part 1 of
the Accomplishment Instructions of Boeing Alert Service Bulletin
737-28A1132, dated December 2, 1998; Revision 1, dated January 15,
1999; or Revision 2, dated June 17, 1999. After the effective date
of this AD, only Revision 2 may be used.
Note 2: For the purposes of this AD, a detailed inspection is
defined as: ``An intensive visual examination of a specific
structural area, system, installation, or assembly to detect damage,
failure, or irregularity. Available lighting is normally
supplemented with a direct source of good lighting at intensity
deemed appropriate by the inspector. Inspection aids such as mirror,
magnifying lenses, etc., may be used. Surface cleaning and elaborate
access procedures may be required.''
Initial Inspection: Follow-On Actions
(1) If no discrepancy is detected, prior to further flight,
accomplish either paragraph (b)(1)(i) or (b)(1)(ii) of this AD.
(i) Measure the resistance between the wires and the float
switch housing, in accordance with Boeing Alert Service Bulletin
737-28A1132, dated December 2, 1998; Revision 1, dated January 15,
1999; or Revision 2, dated June 17, 1999.
(A) If the resistance is less than 200 megohms, prior to further
flight, replace the float switch and wiring with a new float switch
and wiring, and install double Teflon sleeving over the wiring of
the float switch, in accordance with Boeing Alert Service Bulletin
737-28A1132, dated December 2, 1998; Revision 1, dated January 15,
1999; or Revision 2, dated June 17, 1999; or replace the float
switch and wiring with a new, improved float switch and wiring in
accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 737-28A1141, Revision 2, dated August 21, 2003.
After the effective date of this AD, only a new, improved float
switch and wiring may be installed. If a replacement float switch
and wiring are not available, prior to further flight, accomplish
the requirements specified in paragraphs (c) and (d) of this AD.
(B) If the resistance is greater than or equal to 200 megohms,
prior to further flight, blow dirt out of the conduit, install
double Teflon sleeving over the wiring of the float switch, and
reinstall the existing float switch, in accordance with Boeing Alert
Service Bulletin 737-28A1132, dated December 2, 1998; Revision 1,
dated January 15, 1999; or Revision 2, dated June 17, 1999.
(ii) Replace the float switch and wiring with a new float switch
and wiring, and install double Teflon sleeving over the wiring of
the float switch, in accordance with Boeing Alert Service Bulletin
737-28A1132, dated December 2, 1998; Revision 1, dated January 15,
1999; or Revision 2, dated June 17, 1999; or replace the float
switch and wiring with a new, improved float switch and wiring in
accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 737-28A1141, Revision 2, dated August 21, 2003.
After the effective date of this AD, only a new, improved float
switch and wiring may be installed. If a replacement float switch
and wiring are not available, prior to further flight, accomplish
the requirements specified in paragraphs (c) and (d) of this AD.
(2) If any worn insulation is detected, and if no copper
conductor is exposed, and if no evidence of arcing is detected;
accomplish the requirements specified in either paragraph (b)(1)(i)
or (b)(1)(ii) of this AD.
(3) If any electrical arcing or exposed copper conductor is
detected, prior to further flight, accomplish either paragraph
(b)(3)(i) or (b)(3)(ii) of this AD.
(i) Replace any section of the electrical conduit where the
arcing occurred with a new section, in accordance with Boeing Alert
Service Bulletin 737-28A1132, dated December 2, 1998; Revision 1,
dated January 15, 1999; or Revision 2, dated June 17, 1999; and
accomplish the requirements specified in paragraph (b)(1)(ii) of
this AD.
(ii) Perform a detailed inspection to detect fuel leaks of the
electrical conduit, in accordance with Boeing Alert Service Bulletin
737-28A1132, dated December 2, 1998; Revision 1, dated January 15,
1999; or Revision 2, dated June 17, 1999.
(A) If no fuel leak is detected, prior to further flight,
accomplish the requirements specified in paragraph (b)(1)(ii) of
this AD. Repeat the inspection required by paragraph (b)(3)(ii) of
this AD thereafter at intervals not to exceed 1,500 flight hours,
until the replacement required by paragraph (b)(3)(ii)(B) of this AD
is accomplished.
(B) If any fuel leak is detected, prior to further flight,
replace, with new conduit, any section of the electrical conduit
where a leak is found, in accordance with Boeing Alert Service
Bulletin 737-28A1132, dated December 2, 1998; Revision 1, dated
January 15, 1999; or Revision 2, dated June 17, 1999. Prior to
further flight after accomplishment of the replacement, accomplish
the requirements specified in paragraph (b)(1)(ii) of this AD.
Accomplishment of electrical conduit replacement constitutes
terminating action for the repetitive inspection requirements of
paragraph (b)(3)(ii)(A) of this AD.
(4) If any presence or scent of fuel on the electrical wires is
detected, prior to further flight, locate the source of the leak and
replace the damaged conduit with a new conduit, in accordance with
Boeing Alert
[[Page 44585]]
Service Bulletin 737-28A1132, dated December 2, 1998; Revision 1,
dated January 15, 1999; or Revision 2, dated June 17, 1999; and
accomplish the requirements specified in either paragraph (b)(1)(i)
or (b)(1)(ii) of this AD, unless accomplished previously in
accordance with paragraph (b)(1), (b)(2), or (b)(3) of this AD.
Deactivation of Float Switch
(c) Accomplish the requirements specified in either paragraph
(c)(1) or (c)(2) of this AD, in accordance with Part 2 of the
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
28A1132, dated December 2, 1998; Revision 1, dated January 15, 1999;
or Revision 2, dated June 17, 1999.
(1) Deactivate the center tank float switch (i.e., cut the two
wires for the float switch at the splices on the front spar and cap
and stow the four wire ends), paint a ``Caution'' sign that shows a
conservative maximum fuel capacity for the center tank on the
underside of the right-hand wing near the fueling station door, and
install an INOP placard on the fueling panel.
(2) Deactivate the center tank float switch (i.e., cut, stow,
and splice the two wires for the float switch at the splices on the
front spar), and paint a ``Caution'' sign that shows a conservative
maximum fuel capacity for the center tank on the underside of the
right-hand wing near the fueling station door.
Deactivation of Float Switch: Additional Requirements
(d) For airplanes on which the requirements specified in
paragraph (c) of this AD have been accomplished: Accomplish the
requirements specified in paragraphs (d)(1), (d)(2), and (d)(3) of
this AD.
(1) Operators must ensure that airplane fueling crews are
properly trained in accordance with the procedures specified in
Boeing Telex M-7200-98-04486, dated December 1, 1998, or procedures
approved by the FAA. This one-time training must be accomplished
prior to utilizing the procedures specified in paragraph (d)(3) of
this AD.
(2) Prior to fueling the airplane, perform a check to verify
that the fueling panel center tank quantity indicator is operative.
Repeat this check thereafter prior to fueling the airplane. If the
fueling panel center tank quantity indicator is not operative, prior
to further flight, replace the fueling panel center tank quantity
indicator with a serviceable part.
(3) One of the two manual fueling procedures for the center fuel
tank must be used for each fueling occurrence, in accordance with
Boeing Telex M-7200-98-04486, dated December 1, 1998, or a method
approved by the FAA.
Note 3: For the purposes of this AD, the term ``the FAA,'' is
defined in paragraph (d) of this AD as ``the cognizant Principal
Maintenance Inspector (PMI).''
Note 4: Where there are differences between Boeing Alert Service
Bulletin 737-28A1132 and this AD, the AD prevails.
Deactivation of Float Switch: Dispatch
(e) Dispatch with the center fuel tank float switch deactivated,
in accordance with Boeing Alert Service Bulletin 737-28A1132, dated
December 2, 1998; Revision 1, dated January 15, 1999; or Revision 2,
dated June 17, 1999; is allowed until replacement float switches and
wiring are available for installation, but not later than the
compliance time for the replacement required by paragraph (h) of
this AD. Where there are differences between the Master Minimum
Equipment List (MMEL) and the AD, the AD prevails.
New Requirements of This AD
Compliance Time for Initial Action for Model 737-200C Series
Airplanes
(f) For Model 737-200C series airplanes having L/Ns 1 through
3108 inclusive: Prior to the accumulation of 30,000 total flight
hours, or within 30 days after the effective date of this AD,
whichever occurs later, accomplish the requirements of paragraph (b)
or (c) of this AD. (If the actions specified in paragraph (b) or (c)
of this AD have been accomplished before the effective date of this
AD, no further action is required by this paragraph.) If the actions
required by paragraph (h) of this AD, including the replacement
required by paragraph (h)(2) of this AD, are accomplished within the
compliance time specified in this paragraph, operators are not
required to do paragraph (b) or (c) of this AD.
Replacement of Conduit
(g) For airplanes having L/Ns 1 through 3108 inclusive, on which
the inspection required by paragraph (b)(3)(ii) of this AD has been
accomplished prior to the effective date of this AD, and on which
replacement of conduit specified in paragraph (b)(3)(ii)(B) has not
been accomplished: Within 1,500 flight hours or 6 months after the
effective date of this AD, whichever occurs first, replace, with new
conduit, any section of the electrical conduit where arcing or a
leak occurred, in accordance with the Accomplishment Instructions of
Boeing Alert Service Bulletin 737-28A1132, Revision 2, dated June
17, 1999. Such replacement of the conduit constitutes terminating
action for the repetitive inspection requirements of paragraph
(b)(3)(ii)(A) of this AD.
Replacement of Center and Wing Tank Float Switches
(h) Within 2 years after the effective date of this AD,
accomplish paragraphs (h)(1) and (h)(2) of this AD, as applicable.
Except as provided by paragraph (j) of this AD, accomplishment of
the actions in paragraphs (h)(1) and (h)(2) of this AD, as
applicable, terminates the requirements of this AD.
(1) For all airplanes: In the center fuel tank, replace the
existing float switches with new, improved float switches, and
install a conduit liner system; and in the wing fuel tanks, replace
the existing float switches and conduit assemblies with new,
improved float switches and conduit assemblies that include a liner
system inside the conduit. Do these replacements in accordance with
the Accomplishment Instructions of Boeing Alert Service Bulletin
737-28A1141, Revision 2, dated August 21, 2003.
(2) For airplanes subject to the repetitive inspections required
by paragraph (b)(3)(ii)(A) of this AD, on which the electrical
conduit in the center fuel tank has not been replaced as specified
in paragraph (b)(3)(ii)(B) or (g) of this AD: Prior to or
concurrently with the replacement of the float switch in the center
fuel tank required by paragraph (h)(1) of this AD, replace, with new
conduit, any section of the center fuel tank electrical conduit
where arcing or a leak occurred, in accordance with the
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
28A1132, Revision 2, dated June 17, 1999. Such replacement
constitutes terminating action for the repetitive inspection
requirements of paragraph (b)(3)(ii)(A) of this AD.
Credit for Previously Accomplished Actions
(i) Replacement of float switches and conduit assemblies, and
installations of conduit liner systems, as applicable, accomplished
before the effective date of this AD in accordance with Boeing Alert
Service Bulletin 737-28A1141, dated September 5, 2002; or Revision
1, dated December 19, 2002; are considered acceptable for compliance
with the corresponding action specified in this AD, provided that
the requirements of paragraphs (i)(1), (i)(2), and (i)(3) of this AD
are met.
(1) The B-nuts on the float switch cable conduit must be torqued
to the values specified in the Accomplishment Instructions of Boeing
Alert Service Bulletin 737-28A1141, Revision 2, dated August 21,
2003.
(2) The float switch bonding strap must be installed and
securely fastened to the float switch bracket or main structure, as
specified in the Accomplishment Instructions of Boeing Alert Service
Bulletin 737-28A1141, Revision 2, dated August 21, 2003.
(3) Lock wire must be installed in the boltheads on the front
spar, as specified in the Accomplishment Instructions of Boeing
Alert Service Bulletin 737-28A1141, Revision 2, dated August 21,
2003.
Parts Installation
(j) As of the effective date of this AD, no person may install a
float switch having part number F8300-146 on any airplane.
Alternative Method of Compliance
(k)(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 Aircraft Certification
Office (ACO), FAA. Operators shall submit their requests through an
appropriate FAA Principal Maintenance Inspector, who may add
comments and then send it to the Manager, Seattle ACO.
(2) Alternative methods of compliance, approved previously in
accordance with AD 99-05-12, amendment 39-11060, are approved as
alternative methods of compliance with the corresponding
requirements of this AD.
Note 5: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
[[Page 44586]]
Special Flight Permits
(l) 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.
Incorporation by Reference
(m) Unless otherwise specified in this AD, the actions shall be
done in accordance with Boeing Alert Service Bulletin 737-28A1132,
dated December 2, 1998; Boeing Alert Service Bulletin 737-28A1132,
Revision 1, dated January 15, 1999; Boeing Alert Service Bulletin
737-28A1132, Revision 2, dated June 17, 1999; Boeing Alert Service
Bulletin 737-28A1141, Revision 2, dated August 21, 2003; and Boeing
Telex M-7200-98-04486, dated December 1, 1998; as applicable.
(1) The incorporation by reference of Boeing Alert Service
Bulletin 737-28A1132, Revision 2, dated June 17, 1999; and Boeing
Alert Service Bulletin 737-28A1141, Revision 2, dated August 21,
2003; is approved by the Director of the Federal Register in
accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
(2) The incorporation by reference of Boeing Alert Service
Bulletin 737-28A1132, dated December 2, 1998; Boeing Alert Service
Bulletin 737-28A1132, Revision 1, dated January 15, 1999; and Boeing
Telex M-7200-98-04486, dated December 1, 1998; was approved
previously by the Director of the Federal Register as of March 18,
1999 (64 FR 10213, March 3, 1999).
(3) Copies may be obtained from Boeing Commercial Airplanes,
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be
inspected at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington; or at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA, call (202) 741-6030, or go to: http://
http://www. archives. gov/ federal-- register/ code-- of-- federal--
regulations/ ibr-- locations. html.
Effective Date
(n) This amendment becomes effective on August 31, 2004.
Issued in Renton, Washington, on July 1, 2004.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-16676 Filed 7-26-04; 8:45 am]
BILLING CODE 4910-13-P