2013-00186. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to revise an existing airworthiness directive (AD) that applies to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The existing AD requires repetitive inspections to detect cracking in the web of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord, various inspections for discrepancies at the aft pressure bulkhead, and related investigative and corrective actions if necessary. Since we issued that AD, we have determined that certain inspection and repair conditions must be clarified, as well as certain paragraph references related to the terminating action. This proposed AD would clarify certain actions specified in the existing AD. We are proposing this AD to detect and correct fatigue cracking, which could result in rapid decompression of the fuselage.

DATES:

We must receive comments on this proposed AD by February 25, 2013.

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: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; 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 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:

Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 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-2012-1316; Directorate Identifier 2012-NM-186-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

On August 31, 2012, we issued AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. (AD 2012-18-13 superseded AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999).) That AD requires repetitive inspections to detect cracking in the web of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord, various inspections for discrepancies at the aft pressure bulkhead, and related investigative and corrective actions if necessary. That AD resulted from several reports of fatigue cracking at that location. We issued that AD to detect and correct such fatigue cracking, which could result in rapid decompression of the fuselage.

Actions Since Existing AD (77 FR 57990, September 19, 2012) Was Issued

Since we issued AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), we have determined that a certain inspection and repair required by paragraph (l) of AD 2012-18-13 must be clarified. Paragraph (l) of the existing AD specifies to inspect for “incorrectly drilled fasteners and elongated fasteners” (as well as for cracking and corrosion), and also that “if any crack, incorrectly drilled fastener, elongated fastener, or corrosion is found, before further flight, repair the web * * * .” However, the intent of paragraph (l) of AD 2012-18-13 with regard to this inspection is to inspect the fastener holes, not the fasteners. This also reflects the corresponding instructions specified in Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011 (which is the appropriate source of service information for accomplishing the actions required by paragraph (l) of AD 2012-18-13). It is not possible to inspect “fasteners” using the procedures specified in Part III of the Accomplishment Instructions of that service bulletin. That is, the inspection procedures in that service bulletin apply to “fastener holes” and cannot be used to inspect “fasteners.” Therefore, we have revised paragraph (l) of this proposed AD to specify to inspect, in part, for “incorrectly drilled fastener holes” and “elongated fastener holes,” as well as to specify that “if any crack, incorrectly drilled fastener hole, elongated fastener hole, or corrosion is found, before further flight, repair * * *.”

In addition, we also find it necessary to revise certain paragraph references related to the terminating action, as specified in paragraph (s) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Paragraph (s) of AD 2012-18-13 states that accomplishing the requirements of paragraphs (k) through (q) of that AD terminates the requirements of paragraphs (g) through (j) of that AD. However, we have determined that it is only necessary to accomplish the requirements of paragraph (k) of that AD in order to terminate the requirements of paragraphs (g) through (j) of that AD. We have revised paragraph (s) of this AD accordingly.

FAA's Determination

We are proposing this AD 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.

Proposed AD Requirements

This proposed AD would retain all requirements of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). This proposed AD would clarify certain actions in paragraph (l) of this proposed AD, would revise certain paragraph references related to the terminating action in paragraph (s) of this proposed AD, and would add new paragraph (u)(5) to this proposed AD as a new provision of the alternative method of compliance (AMOC) paragraph to allow the continued use of AMOCs approved previously in accordance with AD 2012-18-13.

Costs of Compliance

We estimate that this proposed AD affects 566 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
Low frequency eddy current (LFEC) inspection [retained action from AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999)]	8 work-hours × $85 per hour = $680	$0	$680	$384,880
Detailed visual inspection [retained action from AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999)]	2 work-hours × $85 per hour = $170	$0	$170	$96,220
Detailed, high frequency eddy current inspection (HFEC), and LFEC inspections of the web at the “Y” chord of the bulkhead, the web located under the outer circumferential tear strap, the “Z” stiffeners at the dome cap, and existing repairs [retained actions from AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012)]	Up to 60 work-hours × $85 per hour = $5,100 per inspection cycle	$0	Up to $5,100 per inspection cycle	Up to $2,886,600 per inspection cycle.

We estimate the following costs to do any necessary on-condition inspections that would be required based on the results of the initial inspection. We have no way of determining the number of aircraft that might need these inspections:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Detailed and HFEC inspections for oil-canning	1 work-hour × $85 per hour = $85	$0	$85
LFEC or HFEC inspection for cracking	2 work-hours × $85 per hour = $170	$0	$170

We have received no definitive data that would enable us to provide cost estimates for the crack repairs 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 have 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 that the 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 adding the following new AD:

The Boeing Company: Docket No. FAA-2012-1316; Directorate Identifier 2012-NM-186-AD.

(a) Comments Due Date

The FAA must receive comments on this AD action by February 25, 2013.

(b) Affected ADs

This AD revises AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012).

(c) Applicability

This AD applies to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.

(d) Subject

Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

This AD was prompted by several reports of fatigue cracks in the aft pressure bulkhead. We are issuing this AD to detect and correct such fatigue cracking, which could result in rapid decompression of the fuselage.

(f) Compliance

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

(g) Retained Initial Inspection

This paragraph restates the initial inspection required by paragraph (g) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Perform either inspection specified by paragraph (g)(1) or (g)(2) of this AD at the time specified in paragraph (h) of this AD.

(1) Perform a low frequency eddy current (LFEC) inspection from the aft side of the aft pressure bulkhead to detect discrepancies (including cracking, misdrilled fastener holes, and corrosion) of the web of the upper section of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord, from stringer 15 left (S-15L) to stringer 15 right (S-15R), in accordance with Boeing 737 Nondestructive Test Manual D6-37239, Part 6, Section 53-10-54, dated December 5, 1998.

(2) Perform a detailed visual inspection of the aft fastener row attachment to the “Y” chord from the forward side of the aft pressure bulkhead to detect discrepancies (including cracking, misdrilled fastener holes, and corrosion) of the entire web of the aft pressure bulkhead at body station 1016.

(h) Retained Compliance Times

This paragraph restates the compliance times specified in paragraph (h) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Perform the inspection required by paragraph (g) of this AD at the time specified in paragraph (h)(1), (h)(2), or (h)(3) of this AD, as applicable.

(1) For airplanes that have accumulated 40,000 or more total flight cycles as of May 10, 1999 (the effective date of AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999)): Inspect within 375 flight cycles or 60 days after May 10, 1999 (the effective date of AD 99-08-23), whichever occurs later.

(2) For airplanes that have accumulated 25,000 or more total flight cycles and fewer than 40,000 total flight cycles as of May 10, 1999 (the effective date of AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999)): Inspect within 750 flight cycles or 90 days after May 10, 1999 (the effective date of AD 99-08-23), whichever occurs later.

(3) For airplanes that have accumulated fewer than 25,000 total flight cycles as of May 10, 1999 (the effective date of AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999)): Inspect prior to the accumulation of 25,750 total flight cycles.

(i) Retained Repetitive Inspections

This paragraph restates the repetitive inspections required by paragraph (i) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Within 1,200 flight cycles after performing the initial inspection required by paragraph (g) of this AD, and thereafter at intervals not to exceed 1,200 flight cycles: Perform either inspection specified by paragraph (g)(1) or (g)(2) of this AD.

(j) Retained Corrective Actions

This paragraph restates the corrective actions required by paragraph (j) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). If any discrepancy is detected during any inspection required by paragraph (g), (h), or (i) of this AD: Prior to further flight, accomplish the actions specified by paragraphs (j)(1) and (j)(3) of this AD, and paragraph (j)(2) of this AD, if applicable.

(1) Perform a high frequency eddy current inspection from the forward side of the bulkhead to detect cracking of the web at the “Y” chord attachment, around the entire periphery of the “Y” chord, in accordance with Boeing 737 Nondestructive Test Manual D6-37239, Part 6, Section 51-00-00, Figure 23, dated November 5, 1995.

(2) If the most recent inspection performed in accordance with paragraph (g) of this AD was not a detailed visual inspection: Accomplish the actions specified by paragraph (g)(2) of this AD. If the inspection was a detailed visual inspection, it is not necessary to repeat that inspection prior to further flight.

(3) Repair any discrepancy such as cracking or corrosion or misdrilled fastener holes using a method approved in accordance with the procedures specified in paragraph (u) of this AD.

(k) Retained Inspections of the Web at the “Y” Chord Upper Bulkhead From S-15L to S-15R

This paragraph restates the inspections of the web at the “Y” chord upper bulkhead from S-15L to S-15R required by paragraph (k) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). At the later of the times specified in paragraphs (k)(1) and (k)(2) of this AD: Do detailed and LFEC inspections of the aft side of the bulkhead web, or do detailed and high frequency eddy current (HFEC) inspections from the forward side of the bulkhead, and do all applicable related investigative and corrective actions; in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraphs (r)(1) and (r)(3) of this AD. Inspect for cracks, incorrectly drilled fastener holes, and elongated fastener holes. Do all applicable related investigative and corrective actions before further flight. Repeat the inspections at the applicable times specified in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(1) Prior to the accumulation of 25,000 total flight cycles.

(2) Except as required by paragraphs (r)(2) and (r)(4) of this AD, at the later of the times specified in the “Compliance Time” column in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(l) Retained Inspections of the Web at the “Y” Chord in the Lower Bulkhead From S-15L to S-15R With Revised Inspection and Repair Conditions

This paragraph restates the inspections of the web at the “Y” chord in the lower bulkhead from S-15L to S-15R required by paragraph (l) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), with revised inspection and repair conditions. Except as required by paragraphs (r)(2) and (r)(5) of this AD, at the applicable time specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do detailed and eddy current inspections of the web from the forward or aft side of the bulkhead for cracks, incorrectly drilled fastener holes, and elongated fastener holes, in accordance with Part III of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraphs (r)(1) and (r)(3) of this AD. If any crack, incorrectly drilled fastener hole, elongated fastener hole, or corrosion is found, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD. Repeat the inspections at the applicable times specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(m) Retained One-Time Inspection Under the Tear Strap

This paragraph restates the one-time inspection under the tear strap required by paragraph (m) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as required by paragraphs (r)(2) and (r)(5) of this AD, at the applicable time specified in table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do a one-time LFEC inspection for cracks on the aft side of the bulkhead of the web located under the outer circumferential tear strap, or do a one-time HFEC inspection for cracks from the forward side of the bulkhead of the web located under the outer circumferential tear strap, in accordance with Part II of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(1) of this AD. If any cracking is found, before further flight, repair the bulkhead using a method approved in accordance with the procedures specified in paragraph (u) of this AD.

(n) Retained Inspection for Oil-Canning

This paragraph restates the inspection for oil-canning required by paragraph (n) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as required by paragraph (r)(2) of this AD, at the applicable time specified in table 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do a detailed inspection from the aft side of the bulkhead for oil-canning and do all applicable related investigative and corrective actions, in accordance with Part II of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(1) of this AD. Do all related investigative and corrective actions before further flight. Thereafter, repeat the inspection at the applicable times specified in table 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. For oil-cans found within the limits specified in Part II of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: In lieu of installing the repair before further flight, at the applicable times specified in table 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, do initial and repetitive detailed and HFEC inspections for cracks of the oil-canning and install the repair, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. If any crack is found, before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (u) of this AD. Installing the repair terminates the repetitive inspections for cracks.

(o) Retained Inspection of the Dome Cap at the Center of the Bulkhead

This paragraph restates the inspection of the dome cap at the center of the bulkhead required by paragraph (o) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as required by paragraphs (r)(2) and (r)(5) of this AD, at the applicable time specified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do an eddy current inspection to detect any cracking of the dome cap at the center of the bulkhead, and do all applicable corrective actions, in accordance with Part IV of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. Do all corrective actions before further flight. Repeat the inspection at the times specified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(p) Retained Inspection of the Forward Flange of the “Z” Stiffeners at the Dome Cap

This paragraph restates the inspection of the forward flange of the “Z” stiffeners at the dome cap required by paragraph (p) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as required by paragraphs (r)(2) and (r)(5) of this AD, at the applicable time specified in table 6 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do an HFEC inspection to detect any cracking of the “Z” stiffener flanges at the dome cap in the center of the bulkhead, in accordance with Part V of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(1) of this AD. If any crack is found, before further flight, repair the flanges using a method approved in accordance with the procedures specified in paragraph (u) of this AD. Repeat the inspection at the applicable times specified in table 6 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(q) Retained Inspection for Existing Repairs on the Bulkhead

This paragraph restates the inspection for existing repairs on the bulkhead required by paragraph (q) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as required by paragraph (r)(2) of this AD, at the applicable time specified in table 7 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do a detailed inspection of the bulkhead web and stiffeners for existing repairs, in accordance with Part VI of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(1) of this AD.

(1) If any repair identified in the “Condition” column of table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, is found and the “Reference” column refers to Appendix A, B, C, or D of that service bulletin: At the applicable times specified in table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(2) of this AD, do an HFEC inspection or an LFEC inspection of the web for cracking, in accordance with Appendix A, B, C, or D, as applicable, of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. If any cracking is found, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD. Repeat the inspections thereafter at the applicable intervals specified in table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(2) If any repair identified in the “Condition” column of table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, is found and the “Reference” column refers to Appendix E of that service bulletin: At the applicable times specified in table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as required by paragraph (r)(2) of this AD, remove the repair and replace with a new repair, in accordance with Appendix E of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(3) If any non-SRM (structural repair manual) repair is found and the repair does not have FAA-approved damage tolerance inspections, except as required by paragraph (r)(2) of this AD, at the applicable time specified in table 7 of Paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Contact the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle Aircraft Certification Office, for damage tolerance inspections. Do those damage tolerance inspections at the times given using a method approved in accordance with the procedures specified in paragraph (u) of this AD.

(r) Retained Exceptions to the Service Information

This paragraph restates the exceptions to the service information required by paragraph (r) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012).

(1) Where Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, specifies to contact Boeing for repair instructions: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD.

(2) Where Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, specifies a compliance time “after the date of Revision 1 to this service bulletin,” “from the date of Revision 3 of this service bulletin,” “after the date of Revision 3 to this service bulletin,” or “of the effective date of AD 99-08-23,” this AD requires compliance within the specified compliance time after October 24, 2012 (the effective date of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012)).

(3) Access and restoration procedures specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, are not required by this AD. Operators may do those procedures following their maintenance practices.

(4) Where table 1 of paragraph 1.E., “Compliance” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, specifies a compliance time relative to actions done “in accordance with paragraph (a)(2) of AD 99-08-23,” this AD requires compliance within the specified compliance time relative to actions specified in paragraph (g)(2) of this AD.

(5) Where the Condition columns in tables 2, 3, 5, and 6 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, refer to total flight cycles, this AD applies to the airplanes with the specified total flight cycles as of October 24, 2012 (the effective date of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012)).

(s) Retained Terminating Action With Revised Paragraph Reference

This paragraph restates the terminating action specified in paragraph (s) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), with a revised paragraph reference. Accomplishment of the requirements in paragraph (k) of this AD terminates the requirements of paragraphs (g) through (j) of this AD.

(t) Credit for Previous Actions

This paragraph restates the credit for previous actions specified by paragraph (t) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). This paragraph provides credit for the actions required by paragraphs (k) through (s) of this AD, if the actions were performed before the effective date of this AD using the service bulletins specified in paragraphs (t)(1) through (t)(4) of this AD.

(1) Boeing Alert Service Bulletin 737-53A1214, dated June 17, 1999.

(2) Boeing Alert Service Bulletin 737-53A1214, Revision 1, dated June 22, 2000.

(3) Boeing Alert Service Bulletin 737-53A1214, Revision 2, dated May 24, 2001.

(4) Boeing Alert Service Bulletin 737-53A1214, Revision 3, dated January 19, 2011.

(u) Alternative Methods of Compliance (AMOCs)

(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. 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 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 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 1999), are approved as AMOCs for the corresponding provisions of this AD.

(5) AMOCs approved previously in accordance with AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), are approved as AMOCs for the corresponding provisions of this AD.

(v) Related Information

(1) For more information about this AD, contact Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 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, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; 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.

Issued in Renton, Washington, on January 2, 2013.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.