AD 2012-18-13 R1

We are revising an existing airworthiness directive (AD) for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series \n\n((Page 27021)) \n\nairplanes. That AD currently 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. This new AD requires clarifying certain actions specified in the existing AD. 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.

Final rule.

Adoption of the Amendment \n\n\n\tAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n0 1. The authority citation for part 39 continues to read as follows: \n\n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n\n\nSec. 39.13 (Amended) \n\n0 2. The FAA amends Sec. 39.13 by removing airworthiness directive (AD) 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012), and adding the following new AD: \n\n2012-18-13 R1 The Boeing Company: Amendment 39-17429; Docket No. FAA-2012-1316; Directorate Identifier 2012-NM-186-AD. \n\n(a) Effective Date \n\n\n\tThis AD is effective June 13, 2013. \n\n(b) Affected ADs \n\n\n\tThis AD revises AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). \n\n(c) Applicability \n\n\n\t(1) This AD applies to all The Boeing Company Model 737-100, - 200, -200C, -300, -400, and -500 series airplanes, certificated in any category. \n\t(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory--and--Guidance--Library/ rgstc.nsf/0/2c6e3dbddd36f91c862576a4005d64e2/$FILE/ST01219SE.pdf) 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. \n\n(d) Subject \n\n\n\tJoint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 53, Fuselage. \n\n(e) Unsafe Condition \n\n\n\tThis AD was prompted by several reports of fatigue cracks in the aft pressure bulkhead. We are issuing this AD to detect and correct \n\n((Page 27023)) \n\nsuch fatigue cracking, which could result in rapid decompression of the fuselage. \n\n(f) Compliance \n\n\n\tComply with this AD within the compliance times specified, unless already done. \n\n(g) Retained Initial Inspection \n\n\n\tThis 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. \n\t(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. \n\t(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. \n\n(h) Retained Compliance Times \n\n\n\tThis 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. \n\t(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. \n\t(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 or90 days after May 10, 1999 (the effective date of AD 99-08-23), whichever occurs later. \n\t(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. \n\n(i) Retained Repetitive Inspections \n\n\n\tThis 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. \n\n(j) Retained Corrective Actions \n\n\n\tThis 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 detectedduring 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. \n\t(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. \n\t(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. \n\t(3) Repair any discrepancy such as cracking or corrosion or misdrilled fastener holes using a method approved in accordancewith the procedures specified in paragraph (u) of this AD. \n\n(k) Retained Inspections of the Web at the ''Y'' Chord Upper Bulkhead From S-15L to S-15R \n\n\n\tThis 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. \n\t(1) Prior to the accumulation of 25,000 total flight cycles. \n\t(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. \n\n(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 \n\n\n\tThis 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. \n\n(m) Retained One-Time Inspection Under the Tear Strap \n\n\n\tThis 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\n(n) Retained Inspection for Oil-Canning \n\n\n\tThis 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 \n\n((Page 27024)) \n\napplicable 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. \n\n(o) Retained Inspection of the Dome Cap at the Center of the Bulkhead \n\n\n\tThis 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. \n\n(p) Retained Inspection of the Forward Flange of the ''Z'' Stiffeners at the Dome Cap \n\n\n\tThis 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. \n\n(q) Retained Inspection for Existing Repairs on the Bulkhead \n\n\n\tThis 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. \n\t(1) If any repair identified inthe ''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. \n\t(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. \n\t(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 (ACO), 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. \n\n(r) Retained Exceptions to the Service Information \n\n\n\tThis 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). \n\t(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. \n\t(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)). \n\t(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. \n\t(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. \n\t(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)). \n\n(s) Retained Terminating Action With Revised Paragraph Reference \n\n\n\tThis 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. \n\n((Page 27025)) \n\n(t) Credit for Previous Actions \n\n\n\tThis 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. \n\t(1) Boeing Alert Service Bulletin 737-53A1214, dated June 17, 1999. \n\t(2) Boeing Alert Service Bulletin 737-53A1214, Revision 1, dated June 22, 2000. \n\t(3) Boeing Alert Service Bulletin 737-53A1214, Revision 2, dated May 24, 2001. \n\t(4) Boeing Alert Service Bulletin 737-53A1214, Revision 3, dated January 19, 2011. \n\n(u) Alternative Methods of Compliance (AMOCs) \n\n\n\t(1) The Manager, Seattle 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: 9-ANM-Seattle-ACO-AMOC-Requests-faa.gov. \n\t(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. \n\t(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. \n\t(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. \n\t(5) AMOCsapproved 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. \n\n(v) Related Information \n\n\n\t(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: (425) 917-6440; fax: (425) 917-6590; email: alan.pohl@faa.gov. \n\t(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P. O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; 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.(w) Material Incorporated by Reference \n\n\n\t(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. \n\t(2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. \n\t(3) The following service information was approved for IBR on October 24, 2012 (77 FR 57990, September 19, 2012). \n\t(i) Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. \n\t(ii) Reserved. \n\t(4) The following service information was approved for IBR on May 10, 1999 (64 FR 19879, April 23, 1999). \n\t(i) Boeing 737 Nondestructive Test Manual D6-37239, Part 6, Section 53-10-54, dated December 5, 1998. \n\t(ii) Boeing 737 Nondestructive Test Manual D6-37239, Part 6, Section 51-00-00, Figure 23, dated November 5, 1995. \n\t(5) For Boeing service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P. O. Box 3707, MC 2H-65, Seattle, Washington 98124- 2207; telephone 206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. \n\t(6) 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. \n\t(7) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to revise AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). That AD applies to 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)). The NPRM published in the Federal Register on January 9, 2013 (78 FR 1772). That NPRM proposed to continue to require 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 NPRM also proposed to clarify certain actions specified in the existing AD. \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal (78 FR 1772, January 9, 2013) and the FAA's response to each comment. \n\nSupportive Comment \n\n\n\tThe Boeing Company stated that it supports the NPRM (78 FR 1772, January 9, 2013). \n\nSupplemental Type Certificate (STC) Comment \n\n\n\tAviation Partners Boeing stated that the installation of winglets per STC ST01219SE (http://rgl.faa.gov/Regulatory--and--Guidance-- Library/rgstc.nsf/0/2c6e3dbddd36f91c862576a4005d64e2/$FILE/ ST01219SE.pdf) does not affect the accomplishment of the manufacturer's service instructions. \n\tWe have added paragraph (c)(2) of this AD to state that installation of STC ST01219SE (http://rgl.faa.gov/Regulatory--and-- Guidance--Library/rgstc.nsf/0/2c6e3dbddd36f91c862576a4005d64e2/$FILE/ ST01219SE.pdf) 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'' AMOC approval request is not necessary to comply with the requirements of 14 CFR 39.17. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the change described previously-and minor editorial changes. We have determined that these minor changes: \n\tAre consistent with the intent that was proposed in the NPRM (78 FR 1772, January 9, 2013) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM (78 FR 1772, January 9, 2013). \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scope of the AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 566 airplanes of U.S. registry. \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tParts Cost on U.S. \n\tActionLabor cost cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- Low frequency eddy current (LFEC) 8 work-hours x $85 per $0 $680................ $384,880. \n\tinspection (retained action from hour = $680. \n\tAD 99-08-23, Amendment 39-11132 \n\t(64 FR 19879, April 23, 1999)). Detailed visual inspection 2 work-hours x $85 per 0 $170................ $96,220. \n\t(retained action from AD hour = $170. \n\t99(dash)08-23, Amendment 39- \n\t11132 (64 FR 19879, April 23, \n\t1999)). \n\n((Page 27022)) \n\n\n\nDetailed, high frequency eddy Up to 60 work-hours x $85 0 Up to $5,100 per Up to $2,886,600 \n\tcurrent (HFEC), and LFEC per hour = $5,100 per inspection cycle. per inspection \n\tinspections of the web at the inspection cycle. cycle. \n\t''Y'' chordof the bulkhead, the \n\tweb located under the outer \n\tcircumferential tear strap, the \n\t''Z'' stiffeners at the dome \n\tcap, and existing repairs \n\t(retained actions from AD 2012- \n\t18-13, Amendment 39-17190 (77 FR \n\t57990, September 19, 2012)). ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe 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: \n\n\n\tOn-condition Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per \n\tAction Labor cost Parts cost product ---------------------------------------------------------------------------------------------------------------- Detailed and HFEC inspections for oil-canning. 1 work-hour x $85 per hour = $85...... $0 $85 LFEC or HFEC inspection for cracking.......... 2 work-hours x $85 per hour = $170.... 0 170 ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe have received no definitive data that would enable us to provide cost estimates for the crack repairs specified in this AD. \n\nAuthority for This Rulemaking \n\n\n\tTitle 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. \n\tWe 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 byprescribing 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. \n\nRegulatory Findings \n\n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a ''significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), \n\t(3) Will not affect intrastate aviation in Alaska, and \n\t(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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.