Tdata AD

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2011-06-05	THE BOEING COMPANY: Amendment 39-16629. Docket No. FAA-2009-1253; Directorate Identifier 2009-NM-080-AD.

EFFECTIVE DATE

(a) This AD becomes effective April 26, 2011.

AFFECTED ADS

(b) This AD supersedes AD 2007-18-52, Amendment 39-15197.

APPLICABILITY

(c) This  AD  applies  to  The Boeing Company Model  737-600, -700, -700C,
    -800, -900, and -900ER series airplanes, certificated in any category,
    as  identified  in  Boeing Service  Bulletin 737-57A1302,  Revision 1,
    dated October 18, 2010.

SUBJECT

(d) Air Transport Association (ATA) of America Code 57: Wings.

UNSAFE CONDITION

(e) This AD results from reports of  parts coming off  the main slat track
    downstop assemblies.  The Federal  Aviation Administration  is issuing
    this AD to  prevent loose or  missing parts from  the main slat  track
    downstop  assemblies  from  falling into  the slat  can and  causing a
    puncture, which could result in a fuel leak and consequent fire.

COMPLIANCE

(f) You are responsible  for  having  the  actions  required  by  this  AD
    performed within  the compliance  times specified,  unless the actions
    have already been done.

RESTATEMENT OF AD 2007-18-52, WITH NO CHANGES

NOTE 1: Paragraph  (g) of  this AD  merely restates  the  requirements  of
paragraph (f)(1) of  emergency AD 2007-18-51  (which was superseded  by AD
2007-18-52). As allowed  by the phrase,  "unless the actions  have already
been done," if  the applicable initial  inspections required by  paragraph
(f)(1) of emergency AD 2007-18-51 have already been done, this AD does not
require that those inspections  be repeated until the  repetitive interval
of 3,000 flight cycles.

REPETITIVE DETAILED INSPECTIONS

(g) Within 10 days after  September 26, 2007 (the  effective  date  of  AD
    2007-18-52): Do  a detailed  inspection or  a borescope  inspection of
    each main slat track  downstop assembly to verify  proper installation
    of the slat track hardware  (i.e., the bolt, washers, downstops,  stop
    location, and nut  shown in Figure  1 of Boeing  Service Letter 737-SL
    -57-084-B, dated July 10, 2007,  and in this AD). Proper  installation
    of the sleeve need not be confirmed, and the stop location part may be
    installed  on either  the inboard  or the  outboard side  of the  slat
    track.  If any  part is  missing or  is installed  improperly,  before
    further  flight, install  a new  or  serviceable  part using  a method
    approved in accordance with the procedures specified in paragraph  (j)
    of this AD; and do a detailed inspection of the inside of the slat can
    for foreign  object debris  (FOD) and  damage. Before  further flight,
    remove  any FOD  found and  repair any  damage found  using  a  method
    approved in accordance with the procedures specified in paragraph  (j)
    of this AD. Verify proper  installation; install a new or  serviceable
    part;  and inspect  for damage  and FOD,  and remove  FOD  and  repair
    damage;  in  accordance with  a  method by  approved  by the  Manager,
    Seattle  Aircraft Certification  Office, FAA;  or  in  accordance with
    Boeing Multi Operator Message Number 1-523812011-1, issued August  25,
    2007, or  1-527463441-1, issued  August 28,  2007. Repeat  the actions
    required by paragraph  (g) of this  AD thereafter at  intervals not to
    exceed 3,000 flight cycles.

NOTE 2: Paragraph  (h) of  this AD  merely restates  the  requirements  of
paragraph (f)(2)  of emergency  AD 2007-18-51.  As allowed  by the phrase,
"unless the  actions have  already been  done," if  the torque application
required by paragraph (f)(2) of  AD emergency 2007-18-51 has already  been
done, this AD does not require that the torque application be repeated.

ONE-TIME TORQUING

(h) Within 24 days after receipt  of  emergency  AD  2007-18-51:  Apply  a
    torque between 50 to 80 inch-pounds to the nut.  The bolt head must be
    held with the torque applied to the nut.

NOTE 3: For the  purposes  of this  AD,  a  detailed  inspection  is:  "An
intensive examination  of a  specific item,  installation, or  assembly to
detect damage,  failure, or  irregularity. Available  lighting is normally
supplemented with a direct source of good lighting at an intensity  deemed
appropriate. Inspection aids such as mirror, magnifying lenses, etc.,  may
be necessary. Surface cleaning and elaborate procedures may be required."

                          ILLUSTRATION (Figure 1)

NEW REQUIREMENTS OF THIS AD

MODIFICATION AND INSPECTION

(i) Within 36 months after the effective date  of  this  AD:  Replace  the
    hardware of the  down stop assembly  with new hardware,  do a detailed
    inspection or a borescope inspection of the slat cans on each wing and
    the lower rail  of the slat  main tracks for  debris, and replace  the
    bolts of the aft side guide with new bolts, in accordance with Part  2
    of the  Accomplishment Instructions  of Boeing  Alert Service Bulletin
    737-57A1302, dated December 15,  2008; or Boeing Service  Bulletin 737
    -57A1302, Revision  1, dated  October 18,  2010; except,  where Boeing
    Alert  Service  Bulletin  737-57A1302, dated  December  15,  2008, and
    Boeing Service  Bulletin 737-57A1302,  Revision 1,  dated October  18,
    2010, specify to replace the slat main track or to contact Boeing  for
    further  repair  instructions if  the  hole diameter  is  greater than
    0.5005 inch,  before further  flight, replace  the slat  main track in
    accordance  with  Boeing  Alert  Service  Bulletin  737-57A1302, dated
    December 15, 2008, Boeing  Service Bulletin 737- 57A1302,  Revision 1,
    dated  October  18,  2010,  or  repair  using  a  method  approved  in
    accordance with the procedures specified in paragraph (j) of this  AD.
    If debris is found during  any inspection required by this  AD, before
    further   flight,   remove   the  debris   in   accordance   with  the
    Accomplishment  Instructions  of  Boeing  Alert  Service  Bulletin 737
    -57A1302,  dated December  15, 2008;  or Boeing  Service Bulletin  737
    -57A1302,  Revision  1,  dated October  18,  2010.  Doing the  actions
    required by paragraph (i) of  this AD terminates the actions  required
    by paragraphs (g) and (h) of this AD. Installation of stainless  steel
    lockwire  having  part  number  (P/N)  MS20995C32  is  acceptable  for
    compliance  in lieu  of lockwire  P/ N  MS20995NC32,  as  specified in
    Boeing Alert Service Bulletin  737-57A1302,  dated December  15, 2008,
    for this AD.

ALTERNATIVE METHODS OF COMPLIANCE

(j)(1) The Manager, Seattle Aircraft Certification Office (ACO),  FAA, has
       the authority to approve AMOCs for this AD, if requested using  the
       procedures found in 14 CFR 39.19. In accordance with 14 CFR  39.19,
       send  your  request to  your  principal inspector  or  local Flight
       Standards District Office,  as appropriate. If  sending information
       directly to the manager of the ACO, send it to the attention of the
       person identified in  the Related Information  section of this  AD.
       Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.

(2) Before using any  approved AMOC,  notify  your  appropriate  principal
    inspector, or lacking a principal inspector, the manager of the  local
    flight standards district office/certificate holding district office.

(3) An AMOC that provides  an  acceptable  level of safety may be used for
    any  repair required  by this  AD, if  it is  approved  by  the Boeing
    Commercial Airplanes Organization Designation Authorization (ODA) that
    has  been  authorized  by  the Manager,  Seattle  ACO,  to  make those
    findings. For a repair method to be approved, the repair must meet the
    certification  basis   of  the   airplane,  and   the  approval   must
    specifically refer to this AD.

(4) AMOCs  approved  previously  in  accordance  with  AD  2007-18-52  are
    approved as AMOCs for the corresponding provisions of this AD.

RELATED INFORMATION

(k) For more information about  this  AD,  contact Nancy Marsh,  Aerospace
    Engineer,  Airframe  Branch,  ANM-120S, FAA,  Seattle  ACO,  1601 Lind
    Avenue, SW., Renton,  Washington 98057-3356; telephone:  425-917-6440;
    fax: 425-917-6590; e-mail: nancy.marsh@faa.gov.

MATERIAL INCORPORATED BY REFERENCE

(l) You must use Boeing Alert Service Bulletin 737-57A1302, dated December
    15, 2008; or  Boeing Service Bulletin  737-57A1302, Revision 1,  dated
    October 18, 2010; to do the actions required by this AD, unless the AD
    specifies otherwise.

(1) The  Director  of  the  Federal Register approved the incorporation by
    reference of this service information under 5 U.S.C. 552(a) and 1  CFR
    part 51.

(2) For  service  information  identified  in  this  AD,   contact  Boeing
    Commercial Airplanes, Attention: Data & Services Management, P.O.  Box
    3707,  MC  2H-65, Seattle,  Washington  98124-2207; telephone  206-544
    -5000,  extension  1; fax  206-766-5680;  e-mail me.boecom@boeing.com;
    Internet https://www.myboeingfleet.com.

(3) You may review copies of the service information at the FAA, Transport
    Airplane Directorate, 1601 Lind  Avenue, SW., Renton, Washington.  For
    information on the availability of this material at the FAA, call  425
    -227-1221.

(4) You may  also  review  copies  of  the  service  information  that  is
    incorporated  by  reference  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.

Issued in Renton,  Washington, on February  23, 2011. Kalene  C. Yanamura,
Acting  Manager,  Transport Airplane  Directorate,  Aircraft Certification
Service.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, Airframe
Branch, ANM-120S,  FAA, Seattle  Aircraft Certification  Office, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440;  fax
(425) 917-6590.

PREAMBLE

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

SUMMARY: The FAA is superseding an existing airworthiness directive
(AD), which applies to all Model 737-600, -700, -700C, -800, -900, and
-900ER series airplanes. That AD currently requires repetitive detailed
inspections of the slat track downstop assemblies to verify that proper
hardware is installed, one-time torquing of the nut and bolt, and
corrective actions if necessary. This new AD also requires replacing
the hardware of the downstop assembly with new hardware of the downstop
assembly, doing a detailed inspection or a borescope inspection of the
slat cans on each wing and the lower rail of the slat main tracks for
debris, replacing the bolts of the aft side guide with new bolts, and
removing any debris found in the slat can. This AD also removes
airplanes from the applicability. This AD results from reports of parts
coming off the main slat track downstop assemblies. We are issuing this
AD to prevent loose or missing parts from the main slat track downstop
assemblies from falling into the slat can and causing a puncture, which
could result in a fuel leak and consequent fire.

DATES: This AD becomes effective April 26, 2011.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in the AD as of April 26,
2011.

ADDRESSES: For service information identified in this AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com;
Internet https://www.myboeingfleet.com. You may review copies of the
referenced service information at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information
on the availability of this material at the FAA, call 425-227-1221.

Examining the AD Docket

You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, the regulatory evaluation,
any comments received, and other information. The address for the
Docket Office (telephone 800-647-5527) is the Document Management
Facility, U.S. Department of Transportation, Docket Operations, M-30,
West Building Ground Floor, Room W12-140,
1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425)
917-6440; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to include an AD that supersedes AD 2007-18-52, Amendment
39-15197 (72 FR 53928, September 21, 2007). The existing AD applies to
all Model 737-600, -700, -700C, -800, -900, and -900ER series
airplanes. That NPRM was published in the Federal Register on January
11, 2010 (75 FR 1297). That NPRM proposed to require repetitive
detailed inspections of the slat track downstop assemblies to verify
that proper hardware is installed, one-time torquing of the nut and
bolt, and corrective actions if necessary. That NPRM also proposed to
require replacing the hardware of the downstop assembly with new
hardware of the downstop assembly, doing a detailed inspection or a
borescope inspection of the slat cans on each wing and the lower rail
of the slat main tracks for debris, replacing the bolts of the aft side
guide with new bolts, and removing any debris found in the slat can.
That NPRM proposed to remove airplanes from the applicability of the
existing AD.

Comments

We provided the public the opportunity to participate in the
development of this AD. We have considered the comments that have been
received on the NPRM.

Request To Use Revised Service Information

Boeing requested that the NPRM refer to Boeing Service Bulletin
737-57A1302, Revision 1. Boeing stated that Revision 1 of this service
bulletin will be forwarded to the FAA for approval.
We agree with Boeing's request to refer to Boeing Service Bulletin
737-57A1302, Revision 1, dated October 18, 2010. Revision 1 of this
service bulletin has been published and made available to operators.
There are no new actions in Boeing Service Bulletin 737-57A1302,
Revision 1, dated October 18, 2010. We have revised paragraph (i) of
this AD to add a reference to this service bulletin.

Request To Allow Optional Parts for Installation

Air Transport Association (ATA), on behalf of its member airline
American Airlines (AAL), expressed concern about the lack of optional
manufacturer part numbers, and/or optional specifications concerning
the parts specified in the NPRM. AAL stated that part
interchangeability is allowed for airplanes with the same design that
are not affected by the NPRM. AAL gave four examples:
The NPRM allows only bolt part number (P/N) BACB30NR7DK12,
but bolt P/N BACB30NR7DK12 has an optional part P/N 114A4102-19, that
can be used on airplanes unaffected by the NPRM.
The NPRM specifies retaining pin P/N BACP18BC03A06P only,
but per Boeing part data, P/N MS24665-300 is fully interchangeable with
P/N BACP18BC03A06P.
The NPRM specifies to use lockwire P/N MS20995NC32 only,
but for airplanes unaffected by the AD, the use of cable assembly P/N
BACC13AT4K6 is allowed.
Boeing Drawing 65-88700 allows the use of P/N MS20995C32
and P/N MS20995N32 in lieu of P/N MS20995NC32.
AAL stated that the intent of the NPRM is not to restrict parts to
specific manufacturer part numbers when optional parts are readily
available. AAL stated that similar airplanes unaffected by the AD with
the same design allow for greater part equivalent/substitution options.
AAL requested that the FAA, in an effort to assist the operator for
compliance, include optional parts in the NPRM, or provide a global
AMOC for acceptable substitutes per Boeing Drawing 65-88700, which is
an acceptable specification interchangeability, or part substitution
per Boeing Drawing D-590.
We partially agree with AAL's request that optional parts be
allowed for installation. The alternative lockwire part proposed by AAL
has already been approved as an AMOC for those operators who have made
the request to the FAA. Boeing has not requested approval of a global
AMOC for all operators. We have revised paragraph (i) of this AD to
specify that installation of stainless steel lockwire, P/N MS20995C32,
is acceptable for compliance with this AD.
We disagree with AAL regarding use of the alternative bolt and
cotter pin. The alternative bolt was never produced and could be
removed from the Boeing drawing system in the future. The alternative
cotter pin proposed by AAL may require the use of special tooling for
installation on in-service airplanes. The cotter pin specified in
Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008; and
Boeing Service Bulletin 737-57A1302, Revision 1, dated October 18,
2010; requires the use of a special tool designed to facilitate the
installation by the operators. Until an alternative cotter pin and
tooling are validated for use in maintenance facilities (as opposed to
the manufacturing environment), the proposed AMOC by AAL cannot be
approved. If AAL obtains additional data to support such a request, it
may apply for approval of an AMOC in accordance with the provisions
specified in paragraph (j) of this AD.
We disagree with AAL's request to approve the use of substitutions
provided in Boeing Drawing 65-88700 or Drawing D-590. Boeing did not
provide us with information to ensure that these parts adequately
address the unsafe condition. In addition, Boeing has not requested
approval of a global AMOC for all operators. However, operators may
apply for approval of an AMOC in accordance with the provisions
specified in paragraph (j) of this AD.

Request for AMOC Clarification for the Track Repair Requirements

ATA, on behalf of its member airline AAL, expressed concern with
requiring an AMOC for repair of a hole larger than 0.5005 inch in the
slat main track as stated in the NPRM. AAL requested that the FAA
clarify the boundaries of the AMOC track repair requirements and the
method to identify the AMOC repaired tracks. AAL stated that the flap
tracks are fully removable from the slat and are fully interchangeable
with airplanes unaffected by the AD. AAL stated that the tracks do not
have unique identifiers (i.e., no serial numbers) marked on the track.
AAL stated that the requirement may also be interpreted as, for Boeing
Alert Service Bulletin 737-57A1302, dated December 15, 2008, listed
aircraft, repairs to the downstop hole (when greater than 0.5005 inch)
of a slat main track performed at any time during the life of the part
would require an AMOC.
We provide the following clarifications.
For clarification of the AMOC track repair requirements, the AD
requires that any time the fastener hole in an affected slat can is
oversized to greater than 0.5005 inch, the track must be replaced in
accordance with Boeing Alert Service Bulletin 737-57A1302, dated
December 15, 2008; Boeing Service Bulletin 737-57A1302, Revision
1, dated October 18, 2010; or repaired in accordance with paragraph (j)
of this AD. AMOCs can be approved for airplanes included in the AD
applicability. AMOCs are not applicable to airplanes outside the AD
even if AD-related parts are rotated onto them. We have not changed the
AD in this regard.
For clarification, the method to identify the AMOC-repaired tracks,
including the tracking of affected parts, is a requirement under Parts
39, 121, and 43 of the Federal Aviation Regulations (14 CFR 39, 121,
and 43). Under these parts, each airline may develop its own unique
methodology to accomplish this activity per the procedures approved in
its operation specification. We have not changed the AD in this regard.

Request for Re-Evaluation of Out-of-Spec Hole Issue

ATA, on behalf of its member airline AAL, recommended re-evaluating
the impact of an out-of-spec hole (hole larger than 0.5005 inch in the
slat main track), and recommended the FAA gather additional information
from operators concerning the out-of-spec hole issue.
We disagree with AAL's recommendation. The proposal to provide and
gather operator data should be proposed to the manufacturer. Once
additional data are evaluated by technical specialists, operators may
request approval of an AMOC in accordance with the provisions specified
in paragraph (j) of this AD based on the new recommendation.

Request To Provide Reference in the Component Maintenance Manual (CMM)

ATA, on behalf of its member airline AAL, expressed concern with
the bushing repair of the slat main track in accordance with Boeing
Alert Service Bulletin 737-57A1302, dated December 15, 2008. AAL stated
that in an effort to ensure compliance with the NPRM, this repair may
need to be referenced in the appropriate CMM section to provide the
reference to the source of the repair data.
From these statements, we infer that AAL is requesting that the
bushing repair provided in Boeing Alert Service Bulletin 737-57A1302,
dated December 15, 2008; and Boeing Service Bulletin 737-57A1302,
Revision 1, dated October 18, 2010; be referenced in the appropriate
CMM. We do not agree with this request. CMMs are not regulated by the
FAA, and Boeing does not provide us with information to ensure that
these documents remain unchanged and thus adequately address the unsafe
condition. We have not changed the AD in this regard.

Request That the AD Clarify and Highlight Only Specific Sections of the
Service Bulletin Affected by the AD

ATA, on behalf of its member airline AAL, expressed concern
regarding the requirements in Boeing Alert Service Bulletin 737-
57A1302, dated December 15, 2008, as proposed in the NPRM. AAL stated
that the NPRM may be misinterpreted in that ``all steps'' of that
service bulletin must be complied with. AAL requested that the AD be
clarified and highlighted to explain only those specific sections of
that service bulletin that are affected by the NPRM.
AAL stated that panel open/close procedures and access procedures
(slat extension/retraction) should not affect the compliance with the
NPRM. AAL also stated that the actuator disconnection/reconnection and
slat removal/installation also should not affect compliance with the
NPRM. AAL stated that clarification may be made with the following
statement: ``Only the service bulletin procedures specified by the AD
are affected by the AD. Other procedures described by the service
bulletin not specified by the AD are not affected by FAA AD compliance
requirements.''
We partially agree with AAL's request to clarify and highlight only
specific sections of Boeing Alert Service Bulletin 737-57A1302, dated
December 15, 2008; and Boeing Service Bulletin 737-57A1302, Revision 1,
dated October 18, 2010; that are affected by the AD. For clarification,
the manufacturer revises service bulletins, not the FAA. When the words
``refer to'' are used in Boeing Alert Service Bulletin 737-57A1302,
dated December 15, 2008; or Boeing Service Bulletin 737-57A1302,
Revision 1, dated October 18, 2010; and the operator has an accepted
alternative procedure, the accepted alternative procedure may be used.
However, we have changed paragraph (i) of this AD to delete reference
to the access and close sections of the Accomplishment Instructions of
Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008;
this AD now requires that the actions be accomplished in accordance
with Part 2 of the Accomplishment Instructions of Boeing Alert Service
Bulletin 737-57A1302, dated December 15, 2008; or Boeing Service
Bulletin 737-57A1302, Revision 1, dated October 18, 2010.

Request To Provide a Global AMOC

ATA, on behalf of its member airline AAL, stated that Boeing issued
Service Bulletin Information Notice (IN) 737-57A1302 IN 01, dated
February 25, 2009, to Boeing Alert Service Bulletin 737-57A1302, dated
December 15, 2008. AAL stated that Boeing Service Bulletin IN 737-
57A1302 IN 01 provides additional instructions to install the guide
bolts and reassemble the track downstop hole. AAL stated that Boeing
Service Bulletin IN 737-57A1302 IN 01 also provides additional
instructions for access and panel reinstallation. AAL requested that
Boeing Service Bulletin IN 737-57A1302 IN 01 be approved as a global
AMOC, or be incorporated as an option into the AD requirements to allow
the operator to use the best practices to accomplish the job.
We do not agree with this request. We note that a global AMOC
already has been approved under FAA Letter 120S-09-528, dated September
16, 2009, for Boeing Service Bulletin IN 737-57A1302 IN 01, dated
February 25, 2009, and paragraph (i) of this AD has been revised to
include reference to Boeing Service Bulletin 737-57A1302, Revision 1,
dated October 18, 2010, which includes the information provided in that
information notice. AAL may request a copy of this global AMOC from
Boeing.

Request for Validation of the Service Bulletin Instructions To Be
Accomplished

ATA, on behalf of its member airline AAL, expressed concern that a
validation program was not performed on Boeing Alert Service Bulletin
737-57A1302, dated December 15, 2008, to ensure that data,
instructions, and processes specified in that service bulletin are
correct, clear, appropriate, and understood by maintenance personnel
performing the work.
From this statement we infer that AAL is requesting that validation
of the instructions in Boeing Alert Service Bulletin 737-57A1302, dated
December 15, 2008, be accomplished. We partially agree with AAL's
request. We have confirmed that validation of Boeing Alert Service
Bulletin 737-57A1302, dated December 15, 2008, was completed in
December 2009. Operators may obtain further details of the validation
from Boeing. We have not changed the AD in this regard.

Request To Revise Service Information To Include Steps To Re-Install
Slat Can Assembly and Access Panels (If Removed)

ATA, on behalf of its member airline AAL, stated that there are no
steps in Boeing Alert Service Bulletin 737-57A1302, dated December 15,
2008, to install the slat can, if removed, in
accordance with Part 2 of the Accomplishment Instructions of Boeing
Alert Service Bulletin 737-57A1302, dated December 15, 2008. AAL
requested that to ensure compliance with the AD, a step, ``If removed,
install slat, refer to AMM 27-81-21,'' be included in Boeing Alert
Service Bulletin 737-57A1302, dated December 15, 2008, in the
appropriate location.
AAL also stated that there is no procedure referenced in Boeing
Alert Service Bulletin 737-57A1302, dated December 15, 2008, to
reinstall the access panels removed from the lower leading edge of the
wing. AAL stated that to ensure compliance with the AD, a step,
``reinstall the panels that were removed from the lower leading edge of
the wing, refer to AMM 27-81-21,'' be included in Boeing Alert Service
Bulletin 737-57A1302, dated December 15, 2008, in the appropriate
location.
We disagree with AAL's request. For clarification, the
manufacturer, not the FAA, revises service bulletins. Part 3.B.3.b. of
the Accomplishment Instructions of Boeing Alert Service Bulletin 737-
57A1302, dated December 15, 2008; and Boeing Service Bulletin 737-
57A1302, Revision 1, dated October 18, 2010; specify that the airplane
be returned ``to a serviceable condition,'' and accomplishment of this
step would require reinstallation of any components that were removed
from the airplane. When the words ``refer to'' are used in Boeing Alert
Service Bulletin 737-57A1302, dated December 15, 2008; and Boeing
Service Bulletin 737-57A1302, Revision 1, dated October 18, 2010; and
the operator has an accepted alternative procedure, the accepted
alternative procedure can be used to accomplish reinstalling the slat
can assembly and access panels. Boeing Service Bulletin 737-57A1302,
Revision 1, dated October 18, 2010, does include new phrasing similar
to that requested by AAL. We have not changed this AD in this regard.

Request for an Optional Requirement to the AD

ATA, on behalf of its member airline AAL, expressed concern with
the measurement requirements of the slat track hole diameter. AAL
requested that Boeing and/or the FAA provide an optional requirement to
this AD, or a global AMOC, to allow use of a ``no-go'' type gauge or
similar device and the associated procedure to establish hole size. AAL
also requested providing an additional (initial) procedure consistent
with using common maintenance measurement tools to better allow the
operator to comply with these requirements. AAL stated that Boeing
Alert Service Bulletin 737-57A1302, dated December 15, 2008, states
that if the bolt has side-to-side play in the hole, then measure the
hole. AAL stated that the allowable measurement is four decimal places
of accuracy (0.XXXX). AAL stated that this dimension is in Boeing
Assembly Drawing 114A7511 specification for the purpose of
manufacturing the part in a machine shop setting. AAL also stated that
since this task is intended to be accomplished on wing, or slat removed
(on bench) in a dock maintenance setting, it is not practical and may
not be feasible to require measurement within four decimal places. AAL
stated that the methods to machine to four decimal place accuracy are
different from the requirement to measure to four decimal place
accuracy. AAL stated that typical tools used in a maintenance setting
would be a ball/T gauge, micrometer, and a vernier caliper in certain
situations (hole not near minimum/maximum limits). AAL also stated that
using these tools on the wing could result in inaccuracy due to the
difficulty of the measuring location and the access to the location.
We disagree with AAL's requests to provide an optional requirement
to this AD or a global AMOC to allow the use of a ``no-go'' type gauge
or similar device and the associated procedure to establish hole size.
We also disagree with AAL to add a procedure using common maintenance
measurement tools.
Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008;
Boeing Service Bulletin 737-57A1302, Revision 1, dated October 18,
2010; nor this AD; specify which tools are to be used to measure the
hole size. In the absence of specific instructions on how to perform a
maintenance task, operators have the discretion of developing their own
procedures to enable their maintenance personnel to meet the
requirements of this AD. In addition, it is the intent of this AD that
the operators develop their own procedures to perform a routine
maintenance task, such as drilling the close ream hole. Operators are
referred to the manufacturer's maintenance procedures, which are
published in formats such as the structural repair manual, the standard
overhaul practices manual, component maintenance manuals, and other
available resources. For further instruction, these maintenance
procedures are best obtained from these resources. We have not changed
the AD in this regard.

Explanation of Change to Applicability

We have revised the applicability of the existing AD to identify
model designations as published in the most recent type certificate
data sheet for the affected models.

Conclusion

We have carefully reviewed the available data, including the
comments that have been received, and determined that air safety and
the public interest require adopting the AD with the changes described
previously. We have determined that these changes will neither increase
the economic burden on any operator nor increase the scope of the AD.

Explanation of Change to Costs of Compliance

Since issuance of the NPRM, we have increased the labor rate used
in the Costs of Compliance from $80 per work-hour to $85 per work-hour.
The Costs of Compliance information, below, reflects this increase in
the specified hourly labor rate.

Costs of Compliance

There are about 2,699 airplanes of the affected design in the
worldwide fleet. The following table provides the estimated costs for
U.S. operators to comply with this AD.


                                                                              Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                         Average                                         Number of
                                             Work      labor                                               U.S.-
            Action                         hours     rate per    Parts      Cost per             registered        Fleet cost
                                                          hour                     airplane               airplanes
----------------------------------------------------------------------------------------------------------------
Inspection and Torquing                 8        $85         $0        $680, per                 853          $580,040, per
 (required by AD 2007-18-52).                                            inspection cycle.                     inspection
                                                                                                                                cycle.
Inspection and Modification            18         85      5,388       $6,918...........         853          $5,901,054.
 (new actions).
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, Section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

We have determined that this AD will not have federalism
implications under Executive Order 13132. This AD 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.
For the reasons discussed above, I certify that this AD:
(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.
We prepared a regulatory evaluation of the estimated costs to
comply with this AD and placed it in the AD docket. See the ADDRESSES
section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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. The Federal Aviation Administration (FAA) amends Sec. 39.13 by
removing amendment 39-15197 (72 FR 53928, September 21, 2007) and by
adding the following new airworthiness directive (AD):