AD 2003-14-06

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-200, -200C, -300, -400, and - 500 series airplanes. This action requires repetitive inspections for cracking of certain lap splices, and corrective action if necessary. This action is necessary to detect and correct fatigue cracks in the lap joints and consequent rapid decompression of the airplane. This action is intended to address the identified unsafe condition.

Final rule; request for comments.

2003-14-06 Boeing: Amendment 39-13225. Docket 2003-NM-165-AD. \n\n\tApplicability: Model 737-200, -200C, -300, -400, and -500 series airplanes; certificated in any category; line numbers 292 through 2947 inclusive. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo detect and correct fatigue cracks in the lap joints and consequent rapid decompression of the airplane, accomplish the following: \n\nInspection \n\n\t(a) At the applicable time specified in paragraph (a)(1) or (a)(2) of this AD: Do an external detailed inspection for cracks of the fuselage skin at the upper row of fasteners on all the lap joints from body station (BS) 259 to BS 1016. Inspection of the lap joints underneath the wing-to-body fairing is not required by this paragraph. Repeat the inspection at intervals not to exceed 500 flight cycles, until the terminating action specified in paragraph (b) of this AD has been accomplished. \n\n\t(1) For line numbers 611 through 2869 inclusive: Inspect before the accumulation of 20,000 total flight cycles on the airplane, or within 20 days after the effective date of this AD, whichever occurs later. \n\n\t(2) For line numbers 292 through 610 inclusive and 2870 through 2947 inclusive: Inspect before the accumulation of 20,000 total flight cycles on the airplane, or within 90 days after the effective date of this AD, whichever occurs later. \n\n\tNote 1: For the purposes of this AD, a detailed inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\nTerminating Action \n\n\t(b) For airplanes identified in paragraph (a)(1) of this AD, accomplishment of the one-time internal inspection for discrepancies (including cracks, corrosion, and delamination of the skin doublers) of the skin panels, as shown in Table 2 of Figure 2 of the Accomplishment Instructions of Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, terminates the repetitive inspection requirements of paragraph (a) of this AD. (For Zone A, an internal inspection is required. For Zone B, either an internal or external inspection is permissible.) \n\n\t(c) For airplanes identified in paragraph (a)(2) of this AD, accomplishment of the one-time internal inspection for discrepancies of the skin panels, as shown in Table 3 of Figure 2 of the Accomplishment Instructions Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, terminates the repetitive inspection requirements of paragraph (a) of this AD. (For Zone A, an internal inspection is required. For Zone B, either an internal or external inspection is permissible.) \n\nCorrective Action \n\n\t(d)If any crack is found during any inspection required by paragraph (a), (b), or (c) of this AD: Before further flight, repair in accordance with Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, except as provided by paragraph (e) of this AD. \n\n\t(e) Where Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001, specifies contacting Boeing for appropriate action: Before further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD. \n\nAlternative Methods of Compliance \n\n\t(f)(1) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, FAA, is authorized to approve alternative methods of compliance (AMOCs) for this AD. \n\n\t(2) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. \n\nIncorporation by Reference \n\n\t(g) Except as otherwise provided in this AD, the actions must be done in accordance with Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\nEffective Date \n\n\t(h) This amendment becomeseffective on July 14, 2003.

The FAA recently received a report of a significant number of cracks along the fuselage skin lap joint on a Boeing Model 737-300 series airplane with 35,710 total flight cycles. During scheduled maintenance, fatigue cracks were found on a lap joint of the skin that extends from aft of the flight deck to the wing front spar just above the passenger windows. Some of the cracks linked up to form a 10-inch crack. The premature cracks were attributed to delaminated skin doublers. Improper processing during phosphoric anodize application of the skin panel is the cause of the delaminated skin doublers. This condition, if not corrected, could result in fatigue cracks in the lap joints and consequent rapid decompression of the airplane. \n\n\tThe improperly processed panels were installed on certain airplanes during manufacturing and were available to the remaining airplanes as spare parts. Therefore, Model 737-200, -200C, -300, -400, and -500 series airplanes may be subject to the identified unsafe condition. \n\nRelated Rulemaking Activity \n\n\tWe have issued several ADs to require inspections of lap joints; however, those inspections are not required until various times defined in those ADs, which are substantially longer than the compliance time threshold of this AD such that those compliance times do not provide a sufficient level of safety to address the identified unsafe condition. \n\tIn addition, on June 26, 2003, we issued a supplemental notice of proposed rulemaking, Rules Docket No. 98-NM-11-AD (68 FR 39485, July 2, 2003). That proposed AD would apply to certain Boeing Model 737 series \nairplanes including those affected by this AD, and would require, among other things, repetitive inspections for cracking of the same bonded skin panels addressed in this AD to detect delamination of the skin doublers (tear straps) from the skin panels. That proposed AD would require accomplishment of the actions specified in Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001. \n\nExplanation of Relevant Service Information \n\n\tWe have reviewed and approved Boeing Service Bulletin 737-53-1179, Revision 2, dated October 25, 2001. That service bulletin describes procedures for, among other things, a one-time internal inspection for discrepancies (including cracks, corrosion, and delamination of skin doublers) of the lap joints on both sides of the airplane, and repair of any cracking found. \n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD requires repetitive external detailed inspections for cracks of the fuselage skin at the upper row of fasteners on all the lap joints from body station (BS) 259 to BS 1016. Inspection of the lap joints underneath the wing-to-body fairing is not required by this AD. This AD also provides for optional terminating action for the repetitive inspections. This optional terminating action consists of the one-time internal inspection described in the service bulletin discussed previously. \n\nDifference Between Proposed Rule and Service Bulletin \n\n\tAlthough the service bulletin specifies that operators may contact the manufacturer for disposition of certain repair conditions, this AD requires operators to repair those conditions per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings. \n\nInterim Action \n\n\tWe consider this AD interim action. As stated previously, we have issued a related proposed AD that is intended to require, among other things, additional inspections defined in Boeing Service Bulletin 737- 53-1179. This new AD provides for those additional inspections as optional terminating action for the repetitive inspections required by this AD. However, the planned compliance time for additional inspections would allow enough time to provide notice and opportunity for prior public comment on the merits of the modification. \n\nChanges to 14 CFR Part 39/Effect on the AD \n\n\tOn July 10, 2002, we issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance (AMOCs). Because we have now included this material in part 39, only the office authorized to approve AMOCs is identified in each individual AD. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tSubmit comments using the following format: \n\nOrganize comments issue-by-issue. For example, discuss a request to change the compliancetime and a request to change the service bulletin reference as two separate issues. \nFor each issue, state what specific change to the AD is being requested. \nInclude justification (e.g., reasons or data) for each request. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 2003-NM-165-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory ImpactThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may beobtained from the Rules Docket at the location provided under the caption ADDRESSES. \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 Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new airworthiness directive: