2016-22699. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (SNPRM); reopening of comment period.

SUMMARY:

We are revising an earlier proposal to supersede Airworthiness Directive (AD) 2008-13-12 R1, for certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 2008-13-12 R1 requires various repetitive inspections for cracking of the upper-frame-to-side-frame splice of the fuselage, and other specified and corrective actions if necessary; and also provides for an optional preventive modification, which would terminate the repetitive inspections. This action revises the notice of proposed rulemaking (NPRM) by adding post-repair/post-modification inspections. We are proposing this SNPRM to detect and correct fatigue cracking of the upper-frame-to-side-frame splice of the fuselage, which could result in reduced structural integrity of the frame and adjacent lap joint, causing increased loading in the fuselage skin, which will accelerate skin crack growth and result in decompression of the airplane. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.

DATES:

We must receive comments on this SNPRM by December 29, 2016.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this SNPRM, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone [phone], extension 1; fax [phone]; Internet https://www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221. It is also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-3984.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-3984; 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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2015-3984; Directorate Identifier 2015-NM-033-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

We issued an NPRM to amend 14 CFR part 39 to supersede AD 2008-13-12 R1, Amendment 39-15719 (73 FR 67383, November 14, 2008) (“AD 2008-13-12 R1”). AD 2008-13-12 R1 applied to certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 2008-13-12 R1 requires various repetitive inspections for cracking of the upper-frame-to-side-frame splice of the fuselage, and other specified and corrective actions if necessary. AD 2008-13-12 R1 also provides for an optional preventive modification, which terminates the repetitive inspections. AD 2008-13-12 R1 resulted from a report that the upper frame of the fuselage was severed between stringers (S) S-13L and S-14L at station (STA) 747, and the adjacent frame at STA 767 had a 1.3-inch-long crack at the same stringer location. The NPRM published in the Federal Register on October 9, 2015 (80 FR 61133) (“The NPRM”). The NPRM was prompted by reports of additional fatigue cracking of the upper-frame-to-side-frame splice of the fuselage, and one report of a severed frame. The NPRM proposed to add, for certain airplanes, an inspection to determine if the existing frame repair meets all specified requirements, and for certain other airplanes, a new modification of the upper-frame-to-side-frame splice, which would terminate the repetitive inspections. The NPRM also proposed to reduce certain inspection thresholds and repetitive intervals.

Actions Since Previous NPRM Was Issued

Since we issued the NPRM, we have determined that it is necessary to require post-repair/post-modification inspections that were not included in the NPRM.

Related Service Information Under 1 CFR Part 51

We reviewed Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015. The service information describes procedures for various repetitive inspections for cracking of the upper-frame-to-side-frame splice of the fuselage, a preventive modification to prevent WFD, an inspection to determine if the existing frame repair meets all specified requirements, and corrective actions. 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.

Comments

We gave the public the opportunity to comment on the NPRM. The following presents the comments received on the NPRM and the FAA's response to each comment. One commenter supported the actions specified in the NPRM.

Request To Require Post-Repair/Post-Modification Inspections

Boeing asked that we change paragraph (j) of the proposed AD (in the NPRM) to require the post-repair/post-modification inspections that are not required in that paragraph. Boeing stated that the WFD evaluation of the frame repair/modification specified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, indicated the need for reduced repetitive inspection intervals from those provided in Boeing Damage Tolerance Inspection Data Service Bulletin 737-00-1006, dated March 12, 2010. Boeing added that since the inspections specified in Boeing Service Bulletin 737-00-1006, dated March 12, 2010, are not to be used for the post-repair/post-modification inspections required by 14 CFR 121.1109(c)(2) or 129.109(c)(2), they should be required by paragraph (j) of the proposed AD.

We agree with the commenter for the reasons provided. We have changed paragraph (j) of this SNPRM to require that post-repair/post-modification inspections be done in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that accomplishing the Supplemental Type Certificate (STC) ST01219SE does not affect the actions specified in the NPRM.

We agree with the commenter. We have changed paragraph (c) of this proposed AD to state that installation of STC ST01219SE does not affect the ability to accomplish the actions required by this final rule. Therefore, for airplanes on which STC ST01219SE is installed, a “change in product” alternative methods of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.

Request To Clarify That the NPRM Addresses WFD

Boeing asked that we update the language in “Actions Since AD 2008-13-12 R1, Amendment 39-15719 (73 FR 67383, November 14, 2008) Was Issued” section of the NPRM to clarify that this action is intended to address WFD by supporting the airplane's limit of validity (LOV). Boeing noted that a recently issued WFD-related AD action used different language regarding WFD. Boeing stated that Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, was released in support of the requirements of 14 CFR 26.21(b) and (c) and provides additional service action required to support LOV.

We agree to provide clarification. The NPRM addressed WFD in several locations in the preamble. To clarify, this action is intended to address WFD by supporting the airplane's LOV, as stated by Boeing. However, we have not updated the language in that section of the NPRM because that section of the NPRM is not carried over to this SNPRM. Therefore, no change to this SNPRM is necessary in this regard.

Request To Clarify Certain Procedures in the Related Service Information Section

Boeing asked that we change the “Related Service Information under 1 CFR part 51” section in the NPRM to clarify the description of the modification procedures in the service information. Boeing asked that the proposed language “. . . a new preventive modification, which would eliminate the need for the repetitive inspections” be changed to “. . . a preventive modification to prevent the WFD.” Boeing stated that Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, retains all inspections specified in Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006, and mandates the previously optional preventive modification to mitigate the WFD concern.

We agree with the commenter for the reasons provided. We have clarified the “Related Service Information under 1 CFR part 51” section of this SNPRM accordingly.

Request To Clarify Reason for Supersedure

Boeing asked that we clarify in the SUMMARY section of the NPRM the events that prompted the proposed supersedure of AD 2008-13-12 R1. Boeing stated that instead of two reports of severed frames, as specified in the NPRM, there was just one report of a severed frame.

We agree to provide clarification. We agree that the commenter's statement is accurate. However, we have removed details relating to the NPRM from the SUMMARY section of this SNPRM; therefore, no change is necessary to this SNPRM in this regard.

Request To Clarify Provisions Related to Repetitive Actions

Boeing asked that we clarify paragraph (g)(1)(ii) of the proposed AD (in the NPRM) to state that the actions are to be repeated until the preventive modification in paragraph (k) or the terminating action in paragraph (l) of the proposed AD has been accomplished. Boeing added that this change is consistent with the provisions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, and the requirements of AD 2008-13-12 R1.

We agree with the commenter for the reasons provided. We have clarified paragraph (g)(1)(ii) of this proposed AD accordingly.

Request To Clarify Inspection Locations

Boeing asked that we change paragraph (g)(2)(i) of the proposed AD (in the NPRM) to clarify that the inspections are for “existing frame repairs,” instead of “frames.” Boeing requested that we change “frame” to “frame repairs,” and “tied frames” to “existing frame repairs.”

We agree with the commenter. We have revised paragraph (g)(2)(i) of this proposed AD accordingly.

Request To Revise Inspection Type

Boeing asked that we revise paragraphs (k) and (l) of the proposed AD (in the NPRM) by changing “detailed and HFEC inspections” to just “HFEC inspections.” Boeing stated that detailed inspections are not specified during accomplishment of the preventive modification in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015.

We agree with the commenter for the reason provided. We have removed “detailed” inspections from paragraphs (k) and (l) of this proposed AD.

Request To Change Certain Language in Paragraph (l)(2) of the Proposed AD

Boeing asked that we change paragraph (l)(2) of the proposed AD (in the NPRM), which stated that the repair would terminate the repetitive inspections required by paragraph (g)(1) of this AD. Boeing requested that the proposed AD instead state that the repair would terminate not only the repetitive inspections, but also the preventive modification required by paragraph (k) of the proposed AD. Boeing added that Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, provides a terminating action provision for the repetitive inspections and the preventive modification under the repair. Boeing stated that accomplishment of the repair removes the WFD, and therefore the preventive modification is not required for repaired frames.

We agree with the commenter for the reasons provided. We have clarified the language in paragraph (l)(2) of this proposed AD accordingly.

Request To Move Terminating Action in Paragraph (l)(3) of the Proposed AD to the Credit Paragraph

Boeing asked that we move the terminating action specified in paragraph (l)(3) of the proposed AD (in the NPRM) into the credit for previous actions specified in paragraph (m) of the proposed AD (in the NPRM) for clarification. Boeing stated that accomplishment of the repair or preventive modification, as specified in Boeing Message M-7200-02-1294, dated August 20, 2002, is a “previous action” similar to accomplishment of the repair or preventive modification specified in Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006. Boeing added that paragraph (l)(3) of the proposed AD (in the NPRM) stated that the repair or preventive modification done before the effective date of the AD terminates the repetitive inspection requirements of paragraph (g)(1) of the proposed AD (in the NPRM). Boeing also asked that we revise the proposed AD (in the NPRM) to state that accomplishment of the repair or preventive modification in accordance with Boeing Message M-7200-02-1294, dated August 20, 2002, if performed before the effective date of the AD, would also terminate the preventive modification required by paragraph (k) of the proposed AD (in the NPRM).

We agree to revise paragraph (l)(3) of this proposed AD to state that a repair or preventive modification done in accordance with Boeing Message M-7200-02-1294, dated August 20, 2002, is acceptable for terminating both the inspections and the preventive modification requirements in paragraphs (g)(1) and (k) of this proposed AD respectively. We have changed paragraph (l)(3) of this proposed AD accordingly.

We do not agree to move paragraph (l)(3) of the proposed AD (in the NPRM) into the credit for previous actions specified in paragraph (m) of this proposed AD. Paragraph (m) of this proposed AD is intended to give credit for actions accomplished using previous revisions of service information for accomplishing corresponding actions prior to the effective date of the AD; it does not terminate any actions and does not address future actions.

Request To Provide Credit for Certain Repairs

Boeing asked that we change paragraph (m) of the proposed AD (in the NPRM) to provide credit for repairs that were accomplished before the effective date of the AD, in accordance with Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006. Boeing stated that the repair procedures are the same as those in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015 (as specified in paragraph (l)(2) of the proposed AD (in the NPRM)).

We agree with the commenter for the reason provided. We have added a new paragraph (m)(3) to this proposed AD to give credit for repairs specified in paragraph (l)(2) of the this proposed AD that are accomplished before the effective date of this proposed AD.

Request To Remove Repairs as Terminating Action Under Certain Conditions

Boeing asked that we change paragraph (l)(4) of the proposed AD (in the NPRM) to remove repairs as acceptable terminating action. Boeing stated that paragraph (l)(4) of the proposed AD (in the NPRM) would provide a terminating action provision for the repetitive inspections required by paragraph (g)(2) of the proposed AD (in the NPRM) if a repair or preventive modification is accomplished that is different from the one provided in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, provided it has been approved by the Manager, Los Angeles Aircraft Certification Office. Boeing added that there have been repairs performed in the past that involve trimming the production upper frame web near S-11 and replacing it with an identical replacement frame web without additional reinforcement similar to the preventive modification or repair. Boeing noted that the repair is structurally acceptable; however, it does not sufficiently reinforce the frame to provide terminating action for the inspections, and would require further service actions, including inspections and a preventive modification. Boeing added that the additional inspection requirements should be specified in the AMOC approval, and noted that a preventive modification would not necessarily be required since prior approvals would not have taken the WFD requirements into account.

We agree with the commenter for the reasons provided. All previously installed repairs or modifications installed in accordance with Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006, must be reevaluated or replaced to ensure that all WFD requirements are met. Therefore, we have removed paragraph (l)(4) of the proposed AD (in the NPRM) from this proposed AD.

FAA's Determination

We are proposing this SNPRM because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. Certain changes described above expand the scope of the NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this SNPRM.

Proposed Requirements of This SNPRM

This SNPRM would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between this AD and the Service Information.” Refer to this service information for information on the procedures and compliance times.

Difference Between This SNPRM and the Service Information

Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, specifies to contact the manufacturer for certain repair instructions, but this proposed AD would require repair methods, modification deviations, and alteration deviations in one of the following ways:

• In accordance with a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.

Costs of Compliance

We estimate that this proposed AD affects 391 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Retained inspections from AD 2008-13-12 R1	Between 18 and 38 work-hours × $85 per hour, depending on airplane configuration = between $1,530 and $3,230 per inspection cycle	$0	Between $1,530 and $3,230 per inspection cycle	Between $598,230 and $1,262,930, per inspection cycle.
New proposed inspections	213 work-hours × $85 per hour, $18,105 per inspection cycle	$0	$18,105 per inspection cycle	$7,079,055, per inspection cycle.
New proposed modification	256 work-hours × $85 per hour = $21,760	(¹)	$21,760	$8,508,160
1 We currently have no specific cost estimates associated with the parts necessary for the proposed modification.

We have received no definitive data that would enable us to provide a cost estimate for the on-condition actions specified in this proposed 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.

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 determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by removing Airworthiness Directive (AD) 2008-13-12 R1, Amendment 39-15719 ( 73 FR 67383, November 14, 2008), and adding the following new AD.

The Boeing Company: Docket No. FAA-2015-3984; Directorate Identifier 2015-NM-033-AD.

(a) Comments Due Date

We must receive comments by December 29, 2016.

(b) Affected ADs

This AD replaces AD 2008-13-12 R1, Amendment 39-15719 (73 FR 67383, November 14, 2008) (“AD 2008-13-12 R1”).

(c) Applicability

(1) This AD applies to The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015.

(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgstc.nsf/​0/​BE866B732F6CF31086257B9700692796?​OpenDocument&​Highlight=​st01219se) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a ”change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.

(d) Subject

Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

This AD was prompted by reports of additional fatigue cracking of the upper-frame-to-side-frame splice of the fuselage, and one report of a severed frame due to susceptibility to widespread fatigue damage (WFD). We are issuing this AD to detect and correct fatigue cracking of the upper-frame-to-side-frame splice of the fuselage, which could result in reduced structural integrity of the frame and adjacent lap joint, causing increased loading in the fuselage skin, which will accelerate skin crack growth and result in decompression of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Repetitive Inspections and Corrective Actions for Certain Airplanes

(1) For Groups 1 through 3, Configurations 1, 3, 4, and 5 airplanes; Group 7, Configurations 1, 3, 4, and 5 airplanes; Groups 4 through 6, Configurations 1, 3, 4, and 6 airplanes; and Groups 8 through 11, Configurations 1, 3, 4, and 6 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Do the actions specified in paragraphs (g)(1)(i) and (g)(1)(ii) of this AD, and all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD. Do all applicable corrective actions before further flight.

(i) At the applicable time specified in Tables 1, 2, 3, 5, 6, and 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraphs (i)(1) and (i)(2) of this AD: Do medium frequency eddy current inspections for cracking of the upper-frame-to-side-frame splice of the fuselage.

(ii) Repeat the inspections specified in paragraph (g)(1)(i) of this AD at the applicable time specified in Tables 1, 2, 3, 5, 6, and 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, until the preventive modification required by paragraph (k) of this AD, or a terminating action specified in paragraph (l) of this AD, has been accomplished. The inspections are terminated for the repaired or modified areas only.

(2) For Groups 4 through 6, Configurations 2 and 5 airplanes; and Groups 8 through 11, Configurations 2 and 5 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Do the actions specified in paragraphs (g)(2)(i) and (g)(2)(ii) of this AD, and all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD. Do all applicable corrective actions before further flight.

(i) At the applicable time specified in Tables 4 and 7 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraphs (i)(1) and (i)(2) of this AD: Do a detailed inspection to determine if the existing frame repair meets all requirements specified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, and for any frame repair that does meet all requirements, do detailed and high frequency eddy current (HFEC) inspections for cracking of the existing frame repairs.

(ii) Repeat the inspections for cracking specified in paragraph (g)(2)(i) of this AD at the applicable time specified in Tables 4 and 7 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015.

(h) Post-Repair and Post-Modification Actions for Certain Airplanes

For Group 1, Configurations 2 and 6 airplanes; Group 2, Configurations 2 and 6 airplanes; Group 3, Configurations 2 and 6 airplanes; and Group 7, Configurations 2 and 6 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Within 120 days after the effective date of this AD, do post-repair and post-modification actions using a method approved in accordance with the procedures specified in paragraph (n) of this AD.

(i) Exceptions to Service Bulletin Specifications

(1) Where Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, specifies a compliance time “after the Revision 1 date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.

(2) Where the “Condition” column of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, specifies a condition based on whether an airplane has or has not been inspected, this AD bases the condition on whether an airplane has or has not been inspected as of the effective date of this AD.

(3) Where Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, specifies to contact Boeing for repair instructions: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (n) of this AD.

(j) Post-Repair/Post-Modification Inspections

For Groups 4 through 6, Configurations 1, 3, 4, 6, 7, 8, 9, and 10 airplanes; and Groups 8 through 11, Configurations 1, 3, 4, 6, 7, 8, 9, and 10 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Except as provided by paragraphs (i)(1) and (i)(2) of this AD, at the applicable time specified in Tables 12 through 17 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015; do the post-repair/post-modification inspections, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD. Do all applicable corrective actions before further flight.

(k) Preventive Modification for Certain Airplanes

For Groups 4 through 6, Configurations 1, 3, 4, and 6 airplanes; and Groups 8 through 11, Configurations 1, 3, 4, and 6 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Except as provided by paragraphs (i)(1) and (i)(2) of this AD, at the applicable time specified in Tables 3, 5, 6, and 8 in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, do the preventive modification, including HFEC inspections for cracking and applicable corrective actions, in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD. Do all applicable corrective actions before further flight. Accomplishing the modification required by this paragraph terminates the inspections required by paragraph (g)(1) of this AD for the modified area only.

(l) Terminating Action

(1) For Groups 4 through 6, Configurations 1, 3, 4, and 6 airplanes; and Groups 8 through 11, Configurations 1, 3, 4, and 6 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Accomplishing the preventive modification, including HFEC inspections for cracking and applicable corrective actions, in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD, terminates the inspections required by paragraph (g)(1) of this AD for the modified area only.

(2) For Groups 4 through 6, Configurations 3 and 6 airplanes; and Groups 8 through 11, Configurations 3 and 6 airplanes; as identified in Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015: Accomplishing the repair, including HFEC inspections for cracking and applicable corrective actions, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1261, Revision 1, dated January 30, 2015, except as required by paragraph (i)(3) of this AD, terminates the repetitive inspections required by paragraph (g)(1) of this AD, and the preventive modification required by paragraph (k) of this AD, for the repaired area only.

(3) Accomplishment of the repair or the preventive modification specified in Boeing Message M-7200-02-1294, dated August 20, 2002, before the effective date of this AD terminates the repetitive inspections required by paragraph (g)(1) of this AD and the preventive modification required by paragraph (k) of this AD for the repaired or modified area only.

(m) Credit for Previous Actions

(1) This paragraph provides credit for the inspections required by paragraph (g) of this AD, if those inspections were performed before the effective date of this AD using Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006, which was incorporated by reference in AD 2008-13-12, Amendment 39-15575 (73 FR 38905, July 8, 2008) (“AD 2008-13-12”).

(2) This paragraph provides credit for the modification specified in paragraphs (k) and (l)(1) of this AD, if performed before the effective date of this AD using Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006.

(3) This paragraph provides credit for repairs specified in paragraphs (l)(2) of this AD, if performed before the effective date of this AD using Boeing Alert Service Bulletin 737-53A1261, dated January 19, 2006.

(n) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Los Angeles 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 paragraph (o)(1) of this AD. Information may be emailed to: [e-mail].

(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, Los Angeles 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 for AD 2008-13-12, and AD 2008-13-12 R1; are approved as AMOCs for the corresponding provisions of paragraph (g) of this AD.

(o) Related Information

(1) For more information about this AD, contact Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone [phone], extension 1; fax [phone]; Internet https://www.myboeingfleet.com. You may view this 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.

Issued in Renton, Washington, on September 12, 2016.

Michael Kaszycki,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.