AD 2010-05-13

The FAA is superseding an existing airworthiness directive (AD) that applies to all Model 737-100, -200, -200C, -300, -400, and - 500 series airplanes. That AD currently requires a one-time inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. This new AD expands the area to be inspected and, for certain airplanes, requires earlier inspections for certain inspection zones. This AD results from additional detailed analysis of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines. The analysis resulted in different inspection zones, thresholds and repetitive intervals, and airplane groupings. We are issuing this AD to prevent rapid decompression of the airplane due to fatigue cracks resulting from scribe lines on pressurized fuselage structure.

Final rule.

2010-05-13 The Boeing Company: Amendment 39-16223. Docket No. FAA- 2009-0452; Directorate Identifier 2007-NM-326-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective April 13, 2010. \n\nAffected ADs \n\n\t(b) This AD supersedes AD 2006-07-12, Amendment 39-14539. \n\nApplicability \n\n\t(c) This AD applies to all The Boeing Company Model 737-100, - 200, -200C, -300, -400, and -500 series airplanes, certificated in any category. \n\nSubject \n\n\t(d) Air Transport Association (ATA) of America Code 53: Fuselage. \n\nUnsafe Condition \n\n\t(e) This AD results from reports of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines. Scribe line damage can also occur at many other locations, including butt joints, external doublers, door scuff plates, the wing-to-body fairing, and areas of the fuselage where decals have been applied or removed. We are issuing this AD to prevent rapid decompression of the airplane due to fatigue cracks resulting from scribe lines on pressurized fuselage structure. \n\nCompliance \n\n\t(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. \n\nRestatement of Requirements of AD 2006-07-12 \n\nInspection \n\n\t(g) Do a detailed inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, except as provided by paragraphs (h), (k), (l), (m), (n), and (o) of this AD. Except as required by paragraph (q) of this AD, do the actions at the time specified in paragraph 1.E., "Compliance," of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, except as required by paragraph (j) of this AD. Acceptable inspection exemptions are described in paragraph 1.E.1. of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. \n\n\t(1) If no scribe line is found, no further work is required by this paragraph. \n\n\t(2) If any scribe line is found: Do all applicable investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, by doing all applicable actions specified in Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, except as required by paragraph (i) of this AD. \n\n\tNote 1: A detailed inspection is defined in Note 10 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, under paragraph 3.A., "General Information." Specific magnification requirements may be specified in the steps of the Work Instructions. \n\nExceptions to and Clarification of Service Bulletin 737-53A1262 Procedures \n\n\t(h) Paragraph (g) of this AD requires accomplishment of Parts 1 through 11 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. Parts 12 and 13 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, may be accomplished, if applicable, to allow temporary return to service. This AD does not require accomplishment of Part 14 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, although the FAA-approved procedures described in Part 14 are acceptable for continued operation with scribe lines found before the applicable compliance time. \n\n\t(i) If any scribe line or crack is found during any inspection required by paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, specifies to contact Boeing for appropriate action: Before further flight, inspect or repair scribe lines and repair cracks using a method approved in accordance with the procedures specified in paragraph (y) of this AD. \n\n\t(j) Where Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, specifies a compliance time after the issuance of that service bulletin, this AD requires compliance within the specified compliance time after May 5, 2006 (the effective date of AD 2006-07-12). \n\n\t(k) Certain figures are incorrectly identified in Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. The figure cited in Part 8, step 3, should be Figure 39, not Figure 38. The figure cited in Part 9, step 4, should be Figure 38, not Figure 39. \n\n\t(l) If the operator's records show that the airplane has never been stripped and repainted under the dorsal fin fairing since delivery from The Boeing Company, then this AD does not require inspections of the butt joint, lap joint, and repair, as specified in paragraph (g) of this AD, in the areas under the dorsal fin fairing. \n\n\t(m) Figure 37 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, defines "Restricted Zones" at door cutouts as the only affected structure. Paragraph (g) of this AD considers this area to also include Zone 1B. \n\n\t(n) In Figure 1, sheets 2 and 3, of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, the first condition for the initial compliance threshold for Areas B, C, and E is for areas where the cutout modification shown in Boeing Service Bulletin 737-53A1177 was accomplished. Paragraph (g) of this AD considers this condition to also include Zone 1B. \n\n\t(o) In Figure 1, sheets 2 and 3, of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, the second condition for the initial compliance threshold for Areas B, C, and E is for areas where the cutout modification shown in Boeing Service Bulletin 737-53A1177 was not accomplished. Paragraph (g) of this AD considers this condition to apply only to Zone 1A. \n\nReporting Requirement \n\n\t(p) For airplanes on which inspections have been done in accordance with Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004: At the applicable time specified in paragraph (p)(1) or (p)(2) of this AD, submit a report of positive findings of cracks found during the inspection required by paragraph (g) of this AD to the Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Alternatively, operators may submit reports to their Boeing Company field service representatives. The report shall contain, as a minimum, the following information: Airplane serial number, flight cycles at time of discovery, location(s) and extent of positive crack findings. Under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056. \n\n\t(1) If the inspection was done before May 5, 2006: Send the report within 30 days after May 5, 2006. \n\n\t(2) If the inspection was done after May 5, 2006: Send the report within 30 days after the inspection is done. \n\nNew Requirements of This AD \n\nInspection \n\n\t(q) As of the effective date of this AD, the actions for Zones 1, 2, and 3, as specified in paragraph (g) of this AD, must be done in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, and at the applicable times specified in paragraph 1.E., "Compliance," of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, except as specified in paragraph (s) of this AD. \n\n\tNote 2: Paragraph 1.E.5. of Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008, provides a grace period for airplanes that have exceeded the revised thresholds. \n\nInspection of Zones 4 and 5 \n\n\t(r) Do a detailed inspection for scribe lines and cracks in Zones 4 and 5, as specified in Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008. Except as provided by paragraph (s) of this AD, do the actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008, and at the applicable time specified in paragraph 1.E., "Compliance," of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later. \n\n\t(1) If no scribe line or crack is found: No further work is required by this paragraph. \n\n\t(2) If any scribe line or crack is found: Do all applicable investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, by doing all applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, except as required by paragraph (s)(1) of this AD. \n\nExceptions to Specifications of Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008 \n\n\t(s) The following exceptions to Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, apply to this AD: \n\n\t(1) If any scribeline or crack is found during any inspection required by this AD, and Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, specifies to contact The Boeing Company for appropriate action: Before further flight, inspect or repair scribe lines and repair cracks using a method approved in accordance with the procedures specified in paragraph (y) of this AD. \n\n\t(2) Where Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, specifies a compliance time after the issuance of that service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD. \n\n\t(3) If the operator's records show that the airplane has never been stripped and repainted under the dorsal fin fairing since delivery from The Boeing Company, then this AD does not require inspections of the butt joint, lap joint, and repair, as specified in paragraphs (g), (q), and (r) of this AD, in the areas under the dorsal fin fairing.(4) For airplanes in Groups 3 and 29, as identified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008: At the applicable times specified in paragraphs (s)(4)(i), (s)(4)(ii), and (s)(4)(iii) of this AD, perform a detailed inspection for scribe lines and cracks on the main cargo door along the lower edge of the upper hinge, around external repairs, and around decals, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, except as provided by paragraph (s)(4)(iv) of this AD, or using a method approved in accordance with the procedures specified in paragraph (y) of this AD. If no scribe line or crack is found, no further work is required by this paragraph. If any scribe line or crack is found, do all applicable related investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008,by doing all applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008, except as required by paragraphs (s)(1), (s)(2), and (s)(3) of this AD. \n\n\t(i) For areas along the lower edge of the door hinge from body station (BS) 360 to BS 500, the initial compliance threshold is to be determined using Zone 1B. \n\n\t(ii) For external repairs, the initial compliance threshold is to be determined using Zone 1B. \n\n\t(iii) For decals, the initial compliance threshold is to be determined using Zone 2. \n\n\t(iv) When accomplishing scribe line inspections along the lower edge of the main cargo door hinge, consider the hinge-to-skin detail inspection to be equivalent to a lap joint detail inspection and use the lap joint inspection methods in accordance with Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. \n\n\t(5) For Group 11 airplanes, as specified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008: Stringer 20R between BS 727C and BS 727D+10 is in Zone 1B. \n\nActions Accomplished in Accordance With Previous Service Information \n\n\t(t)(1) Actions accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, are acceptable for compliance with the corresponding requirements of paragraphs (q) and (r) of this AD. \n\n\t(2) Actions accomplished before the effective date of this AD in accordance with Boeing Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; or Revision 2, dated September 20, 2007; are acceptable for compliance with the corresponding requirements of paragraphs (g), (q), and (r) of this AD. \n\nClarification of Procedures in the Service Bulletin \n\n\t(u) For airplanes on which inspections are done as of the effective date of this AD: This AD requires accomplishment of Parts 1 through 11, 15, and 16 of the Accomplishment Instructions ofBoeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. Parts 12 and 13 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, may be accomplished, if applicable, to allow temporary return to service. This AD does not require accomplishment of Part 14 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, although the FAA-approved procedures described in Part 14 are acceptable for continued operation with scribe lines found before the applicable compliance time. \n\nReport \n\n\t(v) For airplanes on which inspections are done in accordance with the service information identified in Table 1 of this AD: At the applicable time specified in paragraph (v)(1) or (v)(2) of this AD, submit a report of positive findings of cracks found during the inspections required by paragraphs (q), (r), and (s)(4) of this AD to the Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Alternatively, operators may submit reports to their Boeing Company field service representatives. The report must contain, as a minimum, the following information: airplane serial number, flight cycles at time of discovery, location(s) and extent of positive crack findings. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056. \n\n\t(1) For an inspection done before the effective date of this AD: Send the report within 30 days after the effective date of this AD. \n\n\t(2) For an inspection done after the effective date of this AD: Send the report within 30 days after the inspection is done. \n\n\t\t\tTable 1--Service Information\n\n\nBoeing Service Information \nRevision\nDate\nBoeing Alert Service Bulletin 737-53A1262\n3\nOctober 16, 2008\nBoeing ServiceBulletin 737-53A1262\n1\nMarch 1, 2007\nBoeing Service Bulletin 737-53A1262\n2\nSeptember 20, 2007\n\n\nRepair Plan in Lieu of Required Inspections \n\n\t(w) A repair plan approved by a Boeing Company Authorized Representative or Designated Engineering Representative before the effective date of this AD is acceptable for compliance with the requirements of paragraphs (g)(2), (i), (q), (r), (s)(1), and (s)(4) of this AD, provided the approval was documented via FAA Form 8110-3 or 8100-9, and scribe line damage identified in the title of the form. \n\nExceptions and Clarification \n\n\t(x) Paragraph 12.a.(2) of Part 12 of the Accomplishment Instructions of Boeing Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; Revision 2, dated September 20, 2007; and Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008; specifies internal inspections in accordance with Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, except for airplanes inspected internally in accordance with paragraph (b) of AD 2003-14-06, Amendment 39-13225. Inspections accomplished in accordance with AMOCs previously approved to paragraph (b) of AD 2003-14-06, are approved as an acceptable alternative method of compliance to the internal inspections specified in Part 12 of Boeing Alert Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; Revision 2, dated September 20, 2007; and Revision 3, dated October 16, 2008. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(y)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. Send information to ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6447; fax (425) 917-6590. Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov. \n\n\t(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD. \n\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 Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. \n\nMaterial Incorporated by Reference \n\n\t(z) You must use Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16,2008; to do the actions required by this AD, unless the AD specifies otherwise. \n\n\t(1) The Director of the Federal Register approved the incorporation by reference of Boeing Alert Service Bulletin 737- 53A1262, Revision 3, dated October 16, 2008, under 5 U.S.C. 552(a) and 1 CFR part 51. \n\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; e-mail me.boecom@boeing.com; Internet https://www.myboeingfleet.com. \n\n\t(3) You may review copies of the service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152. \n\n\t(4) You may also review copies of the service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http:// www.archives.gov/federal_register/code_of_federal_regulations/ ibr_locations.html.

Discussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 2006-07-12, Amendment 39-14539 (71 FR 16211, March 31, 2006). The existing AD applies to all Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That NPRM was published in the Federal Register on May 20, 2009 (74 FR 23664). That NPRM proposed to expand the area to be inspected and, for certain airplanes, require earlier inspections for certain inspection zones. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments that have been received on the NPRM. \n\nSupport for the NPRM \n\n\tAir Transport Association (ATA), on behalf of its members Alaska Airlines and United Airlines (United), agrees with the assessment and states that those two members will comply with the requirements of the NPRM. \n\nRequest To Change Reference in Paragraph (g)(2) of the NPRM \n\n\tBoeing requests that we change paragraph (g)(2) of the NPRM to refer to paragraph (i) of the NPRM instead of paragraph (h) of the NPRM. Boeing notes that this section is in the Restatement of Requirements of AD 2006-07-12, and making this change matches the original AD requirements. \n\n\tWe agree to change the reference from paragraph (h) to paragraph (i) of this AD for the reasons stated previously. \n\nRequest To Clarify Area of Inspection in Paragraph (r) of the NPRM \n\n\tBoeing requests that we remove the parenthetical phrase "(adjacent to lap joints on skin panels that do not have bonded doublers)" from paragraph (r) of the NPRM. Boeing states that this statement is not true in all cases. Boeing notes that in some cases the skins under the lap joints in Zones 4 and 5 are bonded, but they are closed pockets that are not chem-milled all the way through the thickness. \n\n\tWe agree to remove the parenthetical phrase from paragraph (r) of this AD for the reasonsstated previously. \n\nRequest To Clarify Instructions for Inspections Under the Edge of Hinges on the Main Cargo Door \n\n\tBoeing requests that we clarify the instructions for inspections under the edge of hinges on the main cargo door. Boeing notes that Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, does not give specific instructions for inspections of scribe lines found under the edge of the hinge on the main cargo door. Boeing requests that we add a statement to provide instructions for inspections in this area. Boeing states that the lap joint inspection method specified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, applies to the hinge detail. \n\n\tWe agree that additional clarification is necessary. We have added paragraph (s)(4)(iv) to the AD to provide additional instructions for inspections along the lower edge of the main cargo door for the reasons that the commenter provided. We also determined that thischange does not increase the economic burden on any operator or increase the scope of the AD. \n\nRequest To Revise Paragraph (t) of the NPRM \n\n\tLufthansa requests that we revise paragraph (t) of the NPRM. Lufthansa requests that we clarify whether Zones 4 and 5 are derived from the former Zones 1, 2, and 3 as identified in the initial release of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. Lufthansa requests that we accept inspections performed in Zones 1, 2, and 3 in accordance with Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, as acceptable for compliance with the requirements of paragraphs (q) and (r) of the NPRM. \n\n\tWe agree. The new zones were created by moving specific areas from the existing Zones 1, 2, and 3, and have been inspected as required by AD 2006-07-12. We have revised paragraph (t) of this AD to give credit for inspections accomplished before the effective date of this AD as acceptable for compliance for the requirementsof paragraphs (q) and (r) of this AD. \n\nRequest To Provide an Additional Grace Period \n\n\tLufthansa requests that we provide an additional grace period. Lufthansa notes that areas that were shifted to a more critical zone must be inspected within 4,500 flight cycles after the effective date of the AD or before reaching the applicable zonal inspection threshold, whichever occurs later. For any of the new critical zones that are inspected in accordance with the requirements of the full Limited Return to Service (LRTS) program because of previous scribe line findings in the adjacent zone on the same lap splice between two butt joints, Lufthansa requests that we extend the grace period to reach the next heavy maintenance event to do the inspection. Lufthansa states that this may be valid only for airplanes and areas where the requirements of the full LRTS are applied. \n\n\tWe disagree with the request to extend the grace period. The 4,500- flight-cycle grace period applies only to theinitial scribe line inspections and does not apply to airplanes with scribe lines that are currently being monitored in the LRTS program. Operators may request an alternative method of compliance (AMOC) in accordance with the requirements of paragraph (y) of this AD. We have not changed the AD in regard to this issue. \n\nRequest To Clarify Procedures for Scribe Lines Outside Structural Repair Manual (SRM) Limits \n\n\tLufthansa requests that we clarify procedures for areas with scribe lines that have become "no zone" (i.e., areas on the fuselage where scribe line inspections are not required) and are inspected in accordance with the LRTS program described in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. Lufthansa notes that the scribe damage in the "no zone" may be out of the SRM limits and may need to be repaired before further flight because the LRTS is no longer applicable. \n\n\tWe disagree that additional procedures are necessary. Note 5 in paragraph 3.A. in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, provides instructions on how to proceed with scribe lines in any area that is not shown in Zone 1, 2, 3, 4, or 5. We have not changed the AD in regard to this issue. \n\nRequest To Verify Inspection Threshold \n\n\tATA, on behalf of its member United, requests that we verify the inspection threshold. United notes that the inspection threshold specified in FAA Approval Letter 120S-06-141 is the accumulation of 40,000 to 50,000 flight cycles. United states that neither the AMOC nor Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, requires this terminating inspection to be accomplished after the accumulation of 40,000 flight cycles. United requests that we verify that this inspection cannot be performed before the accumulation of 40,000 flight cycles. \n\n\tWe agree that clarification may be necessary, and we agree to verify the threshold.This inspection cannot be performed for credit before the accumulation of 40,000 total flight cycles. After reviewing the scribe line damage adjacent to the lap joints, we determined that the terminating inspection performed in accordance with Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2006, mandated by AD 2003-14-06, Amendment 39-13225 (68 FR 42956, July 21, 2003), should be accomplished again in accordance with AD 2003-14-06 in the areas of known scribe lines after the accumulation of 40,000 total flight cycles. This inspection is designed to ensure that the underlying substructure is intact and would have no effect on the LRTS program. We have not changed the AD regarding this issue. \n\nRequest To Clarify Whether Inspection is Required \n\n\tATA, on behalf of its member United, asks that we clarify whether the inspection required by paragraph (g) of the NPRM is required if operators have accomplished the terminating action in accordance with AMOC 120S-06-209for AD 2003-14-06. \n\n\tWe agree that clarification is necessary. We have approved the inspection methods specified in FAA Approval Letter 120S-06-209, dated April 13, 2006, as an AMOC to the terminating action requirements of paragraph (b) of AD 2003-14-06. Paragraph 12.a.(2), of Part 12 of the Accomplishment Instructions of Boeing Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; Revision 2, dated September 20, 2007; and Revision 3, dated October 16, 2008; specify internal inspections in accordance with Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, except for airplanes inspected internally in accordance with paragraph (b) of AD 2003-14-06. Inspections accomplished in accordance with FAA Approval Letter 120S-06-209, dated April 13, 2006, are approved as an acceptable alternative method of compliance to the internal inspections specified in Paragraph 12.a.(2) of Part 12 of the Accomplishment Instructions of Boeing Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; Revision 2, dated September 20, 2007; and Revision 3, dated October 16, 2008; and required by paragraph (b) of AD 2003-14-06. We have added a reference to previously approved AMOCs in paragraph (x) of this AD. \n\nRequest To Clarify Butt-to-Butt Inspection Requirements \n\n\tATA, on behalf of its member United, requests that we clarify that the butt-to-butt inspection is only for areas where a scribe line is found within 0.063 inches of the upper skin areas in a zone. \n\n\tWe agree that clarification may be necessary. Figure 128 of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, indicates that butt-to-butt inspections are required for all scribe lines within 0.10 inch of the lap joint upper skin. We have not changed the AD regarding this issue. \n\nRequest To Issue Similar Rulemaking \n\n\tThe National Transportation Safety Board (NTSB) notes that while the NPRM addresses scribe-type damage on Model 737 airplanes, it is concerned that this type of damage is not limited to Model 737 airplanes. The NTSB urges that we conduct similar analyses and issue similar rulemaking for other makes and models of airplanes. \n\n\tWe acknowledge the NTSB's concerns. This issue is a long-term durability issue that is not limited to any particular airplane model. We are currently working to address scribe line issues on other airplanes. The effect on each airplane model varies with each model's design characteristics and the conditions under which they have been operated. We have been in contact with other governing regulatory agencies and manufacturers, and we may consider further rulemaking as a result of these efforts. We have not changed the AD in regard to this issue. \n\nExplanation of Change Made to This AD \n\n\tBoeing Commercial Airplanes has received an Organization Designation Authorization (ODA), which replaces their previous designation as a Delegation Option Authorization (DOA) holder. We have revised paragraph (y)(3) of this AD to delegate the authority to approve an alternative method of compliance for any repair required by this AD to the Boeing Commercial Airplanes ODA. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nExplanation of Change to Costs of Compliance \n\n\tSince issuance of the NPRM, we have increased the labor rate used in the Costs of Compliance from $80 per work-hour to $85 per work-hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate. \n\nCosts of Compliance \n\n\tThere are about 2,685 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, including the costsfor the new inspection areas in Zones 4 and 5, for U.S. operators to comply with this AD. \n\n\t\t\tEstimated Costs Required by AD 2006-07-12 \n\n\nZone\nAction\nWork hours\nAverage labor rate per hour\nCost per airplane\nNumber of U.S.-registered airplanes\nFleet cost\n\nSealant removal\n66\n$85\n$5,610\n787\n$4,415,070\n1\nInspection\n 4\n$85\n$ 340\n787\n$ 267,580\n\nSealant removal\n38\n$85\n$3,230\n787\n$2,542,010\n2\nInspection\n29\n$85\n$2,465\n787\n$1,939,955\n\nSealant removal\n88\n$85\n$7,480\n787\n$5,886,760\n3\nInspection\n38\n$85\n$3,230\n787\n$2,542,010\n\n\n\t\tEstimated Costs Required by New Actions of This AD\n\n\nZone\nAction\nWork hours\nAverage labor rate per hour\nCost per airplane\nNumber of U.S.-registered airplanes\nFleet cost\n\nSealant removal\n15\n$85\n$1,275\n787\n$ 1,003,425\n4\nInspection\n1\n$85\n$ 85\n787\n$ 66,895\n\nSealant removal\n31\n$85\n$2,635\n787\n$2,073,745\n5\nInspection\n2\n$85\n$ 170\n787\n$ 133,790\n\n\nAuthority for This Rulemaking \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\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 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. \n\nRegulatory Findings \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\n\tFor the reasons discussed above, I certify that this AD: \n\n\t(1) Is not a "significant regulatory action" under Executive Order 12866; \n\n\t(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \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\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 39-14539 (71 FR 16211, March 31, 2006) and by adding the following new airworthiness directive (AD):