DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0399; Product Identifier 2018-NM-149-AD; Amendment
39-19823; AD 2020-03-10]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for The
Boeing Company Model 737 series airplanes, except for Model 737-100, -
200, -200C, -300, -400, and -500 series airplanes. This AD was prompted
by reports of separation of the lower aft wing-to-body fairing panel
194E (``fairing panel 194E'') during flight, due to worn or damaged
nutplates on the support structure. This AD requires repetitive inspections for
discrepancies of fairing panel 194E, wheel well panel 193D, and support
structure, and related investigative and corrective actions if
necessary. This AD also requires rework of the panels and support
structure, which terminates the repetitive inspections. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective March 27, 2020.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of March 27,
2020.

ADDRESSES: For service information identified in this final rule,
contact Boeing Commercial Airplanes, Attention: Contractual & Data
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA
90740-5600; telephone 562-797-1717; internet https://www.myboeingfleet.com.
You may view this service information at the
FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA.
For information on the availability of this material at the FAA, call
206-231-3195. It is also available on the internet at https://www.regulations.gov
by searching for and locating Docket No. FAA-2019-0399.

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.gov
by searching for and locating Docket No. FAA-2019-
0399; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations is 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: Michael Bumbaugh, Aerospace Engineer,
Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206-231-3522; email:
michael.bumbaugh@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to The Boeing Company
Model 737 series airplanes, except for Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes. The NPRM published in the Federal
Register on June 19, 2019 (84 FR 28429). The NPRM was prompted by
reports of separation of the lower aft wing-to-body fairing panel 194E
(``fairing panel 194E'') during flight, due to worn or damaged
nutplates on the support structure. In the NPRM, the FAA proposed to
require repetitive inspections of fairing panel 194E, wheel well panel
193D, and support structure for discrepancies, and required related
investigative and corrective actions if necessary. The NPRM also
proposed to require rework of the panels and support structure, which
would terminate the repetitive inspections.
The FAA is issuing this AD to address separation of fairing panel
194E.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.

Support for the NPRM

One individual and United Airlines (United) stated support for the
NPRM. United, commenting that they had no records of the unsafe
condition, also concurred with the intent of the NPRM. In a subsequent
comment submission, United also requested several changes, which are
addressed later in this comment disposition.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that accomplishing the Supplemental
Type Certificate (STC) ST00830SE, the installation of blended or split
scimitar winglets, does not affect the ability to accomplish the
actions specified in the NPRM, which affect the lower aft wing-to-body
area.
The FAA agrees with the commenter. The FAA has added paragraph
(c)(2) to this AD to state that installation of STC ST00830SE does not
affect the ability to accomplish the actions required by this final
rule. Therefore, for airplanes on which STC ST00830SE is installed, a
``change in product'' alternative method of compliance (AMOC) approval
request, per 14 CFR 39.17, is not necessary to comply with the
requirements of this AD.

Request To Delay Issuance of Final Rule Until Service Information Is
Revised

Southwest Airlines (SWA) and Delta Airlines (DAL) asked that the
final rule not be issued until a revision of the Boeing Special
Attention Service Bulletin 737-53-1307, dated January 12, 2012, has
been issued.
SWA stated that the referenced service information should be
revised and released to include clarification on the fastener and
hardware installation requirements to prevent the potential of
overtorquing the fasteners and causing additional damage to the panels
and the support structure. SWA noted that the referenced service
information provides minimum and maximum torque values, but added that
an Aircraft Maintenance Manual (AMM) referenced in the service
information provides different torque values, including a higher
maximum torque value. SWA added that the referenced service information
does not provide an installation torque for the fasteners and nutplate,
but stated that Boeing told it to use 29 to 31 in-lb.
The FAA notes that the torque values specified in Boeing Special
Attention Service Bulletin 737-53-1307, dated January 12, 2012, must,
as a result of this AD, be complied with. When those values contradict
the values specified in the AMM referenced in the service information,
the torque minimum and maximum specified in Boeing Special Attention
Service Bulletin 737-53-1307, dated January 12, 2012, must be used,
since it is now mandatory.
SWA also stated that the guidance currently provided in the
referenced service information does not include provisions to address
the open rivet holes after the removal of the existing nutplates. SWA
added that the referenced service information provides guidance for
repair of the fairing panel support structure in accordance with
structural repair manual (SRM) 53-60-71, but that SRM 53-60-71, Repair
2, specifies installing a repair strap at the damaged nutplate
location, which SWA states would interfere with the ability to install
the support/plate assemblies at the nutplate locations specified in the
referenced service information. SWA concluded that the referenced
service information cannot be accomplished without multiple deviations,
and requested clarification whether these deviations would require an
AMOC.
DAL also stated that paragraph (g)(1) of the proposed AD would
require doing a general visual inspection for discrepancies of fairing
panel 194E, wheel well panel 193D, and support structure, in accordance
with Part 1 and Part 2 of the Accomplishment Instructions of Boeing
Special Attention Service Bulletin 737-53-1307, dated January 12, 2012;
however, Part 1 of the referenced service information does not provide
any instructions to inspect or
repair the 193D panel, so it would be necessary to request an AMOC.
Regarding DAL's suggestion that the referenced service information
does not provide any instructions to inspect or repair the 193D panel,
the FAA notes that the torque check specified in figure 1, step 1 of
the referenced service information is an inspection of the 193D panel.
If any repairs are needed that are not addressed in the referenced
service information, operators will need to request an AMOC.
DAL also stated that it has already performed the actions specified
in Boeing Special Attention Service Bulletin 737-53-1307, dated January
12, 2012, on three Model C-40A (737-700C military variant) airplanes
and found that previous installation of repair parts per SRM 53-60-71
for damage at the nutplates will interfere with parts installed using
the instructions provided in the referenced service information. DAL
also stated that the referenced service information does not currently
take into account that existing repairs on the fairing support
structure may inhibit compliance with the service information as
written, which will drive the need for AMOCs.
Regarding DAL's comment that the referenced service information
does not take into account existing repairs, the FAA notes that an AD
cannot predict every change in product that is different than type
design; therefore DAL would need to request an AMOC if an existing
repair prevented it from accomplishing the actions required by this AD.
The FAA acknowledges the commenters' concerns regarding the need to
clarify the service information for the specific scenarios raised and
is working with Boeing to address these concerns as soon as possible.
If this effort culminates in a global AMOC that is approved by the FAA
before the 24-month compliance time for the inspection has passed, and
that AMOC addresses all the necessary deviations, commenters and other
affected operators would not need to seek a separate AMOC. Therefore,
the FAA has added paragraph (j)(1) to this AD to provide operators with
information regarding how to address any actions in the service
information that cannot be accomplished.
In light of the critical nature of the identified unsafe condition
(i.e., the possible separation of the lower aft wing-to-body fairing
panel during flight) and the scope of affected airplanes, the FAA does
not consider it warranted to delay the issuance of this final rule. If
Boeing provides a revision to Boeing Special Attention Service Bulletin
737-53-1307, dated January 12, 2012, the FAA will review it in
consideration of an AMOC to this AD or may consider future rulemaking
action.

Request To Specify Applicability of a Note in the Service Information

DAL noted that figure 5, sheet 5, of the referenced service
information includes note (b), which specifies procedures for
installing a panel but is not referenced in the instructions for figure
5, and DAL does not know where that note should be applied.
The FAA clarifies that note (b) in figure 5, sheet 5 applies to
steps 8 and 10 of figure 5 in Boeing Special Attention Service Bulletin
737-53-1307, dated January 12, 2012. The FAA has added paragraph (j)(2)
of this AD to include this information.

Request To Clarify Cleaning Procedures

SWA and DAL requested that the cleaning procedures in Boeing
Special Attention Service Bulletin 737-53-1307, dated January 12, 2012,
be clarified. The commenters stated that although the referenced
service information refers to cleaning procedures ``CM3'' and ``CM5''
in standard wiring practices manual (SWPM) 20-20-00, those procedures
do not exist. SWA added that SWPM 20-20-00, as revised on June 1, 2015,
lists what SWA considers to be corresponding cleaning procedures in
paragraphs 2.E and 2.C. DAL suggested allowing operators to use
standard cleaning procedures.
The FAA does not agree that any standard cleaning procedure would
be acceptable, however the FAA agrees to clarify the acceptable
cleaning procedures. The FAA has added paragraph (j)(3) to this AD to
clarify that where note (a) to figure 5 of Boeing Special Attention
Service Bulletin 737-53-1307, dated January 12, 2012 specifies to clean
``per abrasive cleaning method CM5'' and refers to ``SWPM 20-20-00,''
for this AD operators must use ``cleaning procedure 3'' and refer to
``SWPM 20-20-00.'' The FAA has also added paragraph (j)(4) to this AD
to clarify that where note (a) to figure 5 of Boeing Special Attention
Service Bulletin 737-53-1307, dated January 12, 2012, specifies to
clean ``per solvent cleaning method CM3,'' and refers to ``SWPM 20-20-
00,'' for this AD operators must use ``cleaning procedure 5'' and refer
to ``SWPM 20-20-00.''

Request To Limit Inspection Area for Certain Airplanes

SWA requested that the FAA revise paragraph (g)(2) of the proposed
AD such that for line numbers 3533 and subsequent that have not altered
the type design since the original airworthiness certificate, the
inspection should be limited to an external visual inspection of the
panels only. SWA noted that, for those airplanes, the rework to the
support structure can be verified based upon the number of attachments
on the panels.
The FAA agrees with the commenter's request because, for those
airplanes, an equivalent change to the support structure and panels was
made in production, and this change can be verified by an external
visual inspection. The FAA has revised paragraphs (g)(1) and (2) of the
proposed AD and added paragraph (g)(3) to specify that, for airplanes
having line numbers 3533 and subsequent that have not altered the type
design since the issuance of an original airworthiness certificate or
an original export certificate of airworthiness, an external visual
inspection of fairing panel 194E and wheel well panel 193D may be used
to verify the correct panel configuration, provided it can be
determined that fairing panel 194E, wheel well panel 193D, and the
support structure have the number and type of attachments specified in
the post-reworked configuration of Boeing Special Attention Service
Bulletin 737-53-1307, dated January 12, 2012.

Request To Clarify Repairs That Require an AMOC

SWA and DAL commented on the need for an AMOC for repairs to the
panel and substructure interface, which are classified as secondary
structure.
SWA stated that the subject structure is classified as secondary,
non-FCBS (fatigue critical baseline structure) in 737NG SRM 51-00-04,
and repairs to the panel and substructure that do not adversely alter
the panel to the substructure interface should not require an AMOC to
the AD (i.e., as long as the required number and type of fasteners
attaching the panel to the substructure remain the same). SWA added
that requiring an AMOC would necessitate the original equipment
manufacturer (OEM) to generate an FAA Form 8100-9 for a minor repair,
which is in conflict with FAA Order 8100-17B and Boeing Service Letter
737-SL-51-041-E.
DAL stated that repairs to AD-related secondary structure per SRM
51-70 are minor repairs (SRM 51-00-04) and should not require an AMOC
or additional approvals for any deviations to the SRM repairs. DAL
added that repairs to the panel or substructure that do not adversely
affect or inhibit the intended function of the modification of the
panel-to-substructure interface
should continue to be done in accordance with approved data or data
that is acceptable to the Administrator with no additional approval or
AMOC required.
The FAA acknowledges the commenters' concerns and infers that the
commenters are requesting that the agency clarify the requirements of
paragraph (g) of this AD regarding the need for AMOCs. The FAA agrees
to clarify this paragraph. Repairs or alterations to the panel that do
not interfere with the requirements of this AD will not require an
AMOC. The FAA has added paragraph (g)(4) of this AD to specify that
repairs that do not affect the number or type of fasteners necessary
for the post-reworked configuration may be deviated from using accepted
methods in accordance with the operator's maintenance or inspection
program without obtaining an AMOC.

Request To Clarify Certain Procedures in the Referenced Service
Information

SWA and DAL asked that Boeing Special Attention Service Bulletin
737-53-1307, dated January 12, 2012, be clarified to define the
procedures for panels 194E and 193D that have not been reworked.
SWA stated that the proposed AD does not allow fairing panel 194E
or wheel well panel 193D to be installed on any airplane after the
effective date of the AD, if the panels have not been reworked. SWA
noted that this would prohibit normal maintenance of the panels prior
to implementing the terminating action. SWA requested that the proposed
AD be revised to add a grace period for normal maintenance of
unmodified panels prior to accomplishment of the terminating action.
SWA added that the referenced service information does not provide part
numbers for the reworked panels, and should be revised in order to
control the part number of the modified panels.
DAL stated that the referenced service information should be
revised because it does not identify a post-service bulletin part
number in order to track and maintain the fairing panel configuration.
DAL recommended that it be revised before issuance of the final rule to
ensure a separate part number is created for tracking of the attachment
configuration. DAL noted that as the proposed AD is currently written,
any panel installed after the effective date of the AD will drive
immediate full incorporation of the referenced service information. DAL
believes that paragraph (i) of the proposed AD would force immediate
compliance in the event of non-routine maintenance action or just
accomplishment of paragraph (g)(1) of the proposed AD, either of which
may not be associated with the identified unsafe condition, although
the proposed compliance time for the terminating action is 72 months.
The proposed AD would have, at paragraph (i), prohibited installation
of fairing panel 194E ``unless fairing panel 194E, wheel well panel
193D, and the support structure have the number and type of attachments
specified in the post-reworked configuration of Boeing Special
Attention Service Bulletin 737-53-1307, dated January 12, 2012.'' DAL
suggested that paragraph (i) be changed to prohibit installation of
fairing panel 194E ``unless a general visual inspection for
discrepancies has been accomplished on fairing panel 194E, wheel well
panel 193D, and the support structure, within the compliance times
specified in SB 737-53-1307 Paragraph 1.E.''
The FAA agrees that some clarification is necessary. Boeing Special
Attention Service Bulletin 737-53-1307, dated January 12, 2012, already
provides a method of identifying modified panels in figure 5, step 9.
The FAA has revised paragraph (i) of this AD to include separate
requirements for airplanes with an original airworthiness certificate
or an original export certificate of airworthiness dated after the
effective date of this AD, for airplanes with an original airworthiness
certificate or an original export certificate of airworthiness dated
before the effective date of this AD, and for airplanes on which the
terminating action has been done.

Request To Define Final Configuration of the Panel-to-Substructure

SWA asked that the final configuration of the panel-to-substructure
interface be defined in the subject of the proposed AD, rather than
referenced in Boeing Special Attention Service Bulletin 737-53-1307,
dated January 12, 2012, in its entirety, by the individual
configuration of the discrepant panels, or the associated substructure.
SWA noted that the subject structure is classified as secondary, non-
FCBS in 737NG SRM 51-00-04; therefore, typical repairs given in 737NG
SRM 51-70 apply to the panel and the associated substructure. SWA
stated that as there is no specific section in the published SRM for
the discrepant structure, these typical SRM repairs can be accomplished
with no additional approval from the operator or the applicable
regulatory body. SWA and DAL both noted that there are no provisions to
alert the mechanic that the structure is subject to an AD.
The FAA acknowledges the commenter's concern; however, the agency
relies on the referenced service information to define the
modification, and operators must ensure that they are meeting all the
requirements of any applicable AD. As noted in prior comments, there
are a significant number of other SRM repairs or modifications that can
be present and alter the final configuration of the support structure
or panel. It would be difficult if not impossible to address all
possible individual configurations in this AD. Under the provisions of
paragraph (k) of this AD, the FAA will consider requests for approval
of other SRM repairs or modifications if sufficient data are submitted
to substantiate that the change would provide an acceptable level of
safety. The AD has not been changed in this regard.

Request To Revise Compliance Time for the Inspections

SWA, DAL, and United asked that the compliance time for the
inspections be extended.
United stated that the proposed compliance time of 24 months for
the initial general visual inspection, with a repetitive interval of
1,000 flight cycles thereafter, would require operators performing both
the inspection and the terminating action in a line environment. United
asked that the FAA and Boeing to consider revising the AD and service
information to allow an initial detailed visual inspection within 36
months and the repeat inspections every 4,000 flight cycles thereafter,
in lieu of the proposed inspection method and compliance times. United
noted that this would allow more time to properly schedule the
airplanes in a heavy check environment where both the inspection and
rework per the referenced service information can be easily
accomplished.
DAL stated that a 36-month compliance time for the initial
inspection would provide a better opportunity to catch the initial
inspection at a C-check (a type of heavy check) and not drive special
visits. DAL noted that waiting on approvals if damage is found would
cause significant delays.
The FAA does not agree with the commenters' requests to extend the
compliance time for the initial and repetitive inspections. In
developing an appropriate compliance time for this action, the FAA
considered not only the safety implications of the identified unsafe
condition, but also the average
utilization rate of the affected fleet, the availability of required
parts, and the practical aspect of accomplishing the required
inspections within a period of time that corresponds to the normal
scheduled maintenance for most affected operators. Further, United did
not provide substantiation in support of its request to increase
inspection intervals with a detailed visual inspection. The FAA has not
changed this AD in this regard.
SWA stated that the inspection specified in paragraph (g) and the
terminating action specified in paragraph (h) of the proposed AD
require compliance within a calendar time of 24 months and 72 months of
the AD effective date, respectively; however, due to the unknown
return-to-service (RTS) dates of the Boeing Model 737-8 and -9 (MAX)
airplanes, SWA is awaiting delivery of several airplanes. SWA
recommended the compliance thresholds be defined based upon total
flight cycles, in order to alleviate the concerns regarding the MAX
airplanes' RTS.
The FAA does not agree to define the compliance thresholds based on
total flight cycles. Consistent with 14 CFR 39.7, no person will be in
violation of this AD because the MAX airplanes are not currently
operated. The actions required by this AD can be accomplished before
the airplanes' RTS. In addition, the actions required by this AD will
be accomplished on all new MAX airplanes before delivery. Therefore,
this AD has not been changed in this regard.

Request To Change Applicability

Boeing and United asked that the applicability in the proposed AD
be changed.
Boeing noted that there is a difference between Boeing Special
Attention Service Bulletin 737-53-1307, dated January 12, 2012, and the
proposed AD in capturing airplane effectivity. Boeing stated that there
may be some instances where operators are rotating parts outside of
type design, beyond effectivity limits, or having ``pre-mod'' panels
installed on airplane configurations where service bulletins and design
changes have already been incorporated. Boeing noted that it
understands the FAA's concerns with the possibility of parts being
rotated outside the effectivity contained in the referenced service
information, and would like to seek an alternative solution to address
these FAA concerns. Boeing recommended that it and the FAA collaborate
with the company's airline partners, other OEMs, and other Civil
Aviation Authorities (CAAs) to develop an action to implement safe,
fair, and consistent policy to address the company's concerns on
rotable parts for the industry. Boeing concluded that the applicability
of the proposed AD extends beyond that specified in the referenced
service information, and suggested that rotable parts be addressed
separately.
United stated that the proposed airplane effectivity range in the
proposed AD falls outside of the effectivity specified in Boeing
Special Attention Service Bulletin 737-53-1307, dated January 12, 2012.
United added that the specified action is to add airplanes with the new
panels already incorporated at the OEM to the current effectivity range
given in the referenced service information, for a one-time inspection
verification. (The range is for line numbers (L/Ns) 3533 and subsequent
with an original airworthiness certificate or an original export
certificate of airworthiness dated on or before the effective date of
this AD.) United noted that the reason for the inspection verification
is that the FAA believes that since these parts are rotable, there is a
possibility the older parts could be installed on future airplanes.
United respectfully disagreed on this action and requested that the FAA
revisit this matter and keep the effectivity range limited to those
airplanes identified in the referenced service information. United
disagreed with the FAA because even though the subject parts are
rotable, United controls and maintains all its interchangeability and
installation of these panels through production drawings and aircraft
manuals, such as the illustrated parts catalog (IPC), which have always
shown the latest up-to-date panels affected for L/Ns 3533 and
subsequent. United concluded that to this day, it has never had a
parts-departing-airplane (PDA) incident with the subject panels 193D
and 194E on any of its Model 737-NG airplanes.
The FAA does not agree to change the applicability. The affected
parts are rotable parts, and the FAA has determined that, regardless of
operator diligence, these parts could later be installed on airplanes
that were initially delivered with acceptable parts, thereby subjecting
those airplanes to the unsafe condition. The FAA has not changed this
AD in this regard.

Request To Allow the Use of Later Revisions of the Service Information

An individual asked the FAA to modify the AD to allow later
revisions of the referenced service information. He said this would
ensure that operators are promptly in compliance with obligations and
all maintenance is certified to the latest approved version of the
maintenance data. The commenter also stated that this would remove the
requirement for the proposed AD to be revised to reflect changes in
revised service information, and to eliminate the need to request an
AMOC to approve the use of the revised service information, again
reducing the delay in implementing a revision and reducing the
maintenance costs associated with the issuance of an AMOC. The
commenter added that the European Union Aviation Safety Agency (EASA)
already incorporates the ``or later revision'' statement in any EASA
AD. The commenter noted that this would demonstrate a further
harmonization of regulatory control.
The FAA does not agree to change the AD to allow the use of later
revisions of the service information. The FAA may not require
compliance with a document that does not yet exist. In general terms,
the FAA is required by Office of the Federal Register (OFR) regulations
for approval of materials incorporated by reference, as specified in 1
CFR 51.1(f), to either publish the service document contents as part of
the actual AD language; or submit the service documents to the OFR for
approval as referenced material, in which case the FAA may only refer
to such material in the text of an AD. The AD may refer to the service
document only if the OFR approved it for incorporation by reference.
See 1 CFR part 51. To allow operators to use later revisions of the
referenced document (issued after publication of the final rule),
either the FAA must revise the AD to reference specific later
revisions, or operators must request approval to use later revisions as
an AMOC with this AD under the provisions of paragraph (k) of this AD.
The AD has not been changed regarding this issue.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. The FAA has determined that these minor
changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Boeing Special Attention Service Bulletin 737-53-
1307, dated January 12, 2012. This service information describes
procedures for repetitive inspections of fairing panel 194E, wheel well
panel 193D, and support structure for discrepancies (including
incorrect torque at the fasteners and worn and damaged nutplates and
fastener holes) and corrective actions (including repair and
replacement of nutplates and fasteners). This service information also
describes procedures for rework of the panels and support structure,
including related investigative actions (general visual inspection of
the panel and support structure for damage) and repair, which together
would eliminate the need for the repetitive inspections. This service
information is reasonably available because the interested parties have
access to it through their normal course of business or by the means
identified in the ADDRESSES section.

Costs of Compliance

The FAA estimates that this AD affects 983 airplanes of U.S.
registry. The agency estimates the following costs to comply with this
AD:

Estimated Costs

The FAA has received no definitive data that would enable the
agency to provide cost estimates for the on-condition repairs specified
in this AD.

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.
The FAA is 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

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) Will not affect intrastate aviation in Alaska, 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.

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 FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):