AD 2000-25-11

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes, that requires repetitive inspections to detect fatigue cracking of the longeron splice fittings at stringer 11 on the left and right sides at body station 2598, and various follow-on actions. The actions specified by this AD are necessary to detect and correct fatigue cracking of the longeron splice fittings and subsequent damage to adjacent structure. Such damage could result in the inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the horizontal stabilizer. This action is intended to address the identified unsafe condition

Final rule

2000-25-11 BOEING: Amendment 39-12046. Docket 99-NM-326-AD. \n\n\tApplicability: Model 747-400 series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2419, Revision 1, dated September 21, 2000; certificated in any category. \n\n\tNote 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo detect and correct fatigue cracking of the longeron splice fittings and subsequent damage to adjacent structure, which could result in the inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the horizontal stabilizer; accomplish the following: \n\nInitial Detailed Visual Inspection \n\t(a) Perform a detailed visual inspection to detect cracking of the longeron fittings at stringer 11, on the left and right sides at body station 2598, at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2419, Revision 1, including Appendix A, dated September 21, 2000. \n\n\t\t(1) Inspect prior to the accumulation of 17,000 total flight cycles or 63,000 total flight hours, whichever occurs first. \n\n\t\t(2) Inspect within 24 months after the effective date of this AD.Note 2: Inspections, rework, and replacements accomplished prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-53A2419, dated December 17, 1998, are considered acceptable for compliance with the applicable action specified in this amendment. \n\n\tNote 3: Where there are differences between the AD and the service bulletin, the AD prevails. \n\n\tNote 4: For the purposes of this AD, a detailed visual 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\nRework/Replacement/Repetitive Inspections \n\t(b) If no cracking is detected during the inspection required by paragraph (a) of this AD, accomplish the requirements of either paragraph (b)(1), (b)(2), or (b)(3) of this AD. \n\n\t\t(1) Prior to further flight, rework all four longeron splice fittings on the left and right sides at body station 2598, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2419, Revision 1, including Appendix A, dated September 21, 2000. Repeat the inspection required by paragraph (a) of this AD one time at the later of the times specified in paragraphs (b)(1)(i) and (b)(1)(ii) of this AD, and thereafter at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first. \n\n\t\t\t(i) For airplanes on which the rework is accomplished prior to the accumulation of 7,000 total flight cycles and prior to the accumulation of 25,000 total flight hours: Inspect within 20,000 flight cycles or 72,000 flight hours after rework, whichever occurs first. \n\n\t\t\t(ii) For airplanes on which the rework is accomplished at or after the accumulation of 7,000 total flight cycles, or 25,000 total flight hours: Inspect within 10,000 flight cycles or 36,000 flight hours after rework, whichever occurs first. \n\n\t\t(2) Prior to further flight, replace all four longeron splice fittings on the left and right sides at body station 2598 with new fittings, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2419, Revision 1, including Appendix A, dated September 21, 2000. Repeat the inspection required by paragraph (a) of this AD one time within 20,000 flight cycles or 72,000 flight hours after the replacement, whichever occurs first; and thereafter at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first. \n\n\t\t(3) Repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first. \n\nCorrective Action/Repetitive Inspections \n\t(c) If any cracking is detected during any inspection required by paragraph (a) or (b)(3) of this AD, prior to further flight: Replace all four longeron splice fittings on the affected side in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2419, Revision 1, including Appendix A, dated September 21, 2000. Repeat the inspection on the affected side as required by paragraph (a) of this AD one time within 20,000 flight cycles or 72,000 flight hours after the replacement, whichever occurs first; and thereafter at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first. \n\n\t(d) If any cracking is detected during any inspection required by paragraph (b)(1), (b)(2), or (c) of this AD, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing CompanyDesignated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD. \n\n\tNote 5: There is no terminating action currently available for the inspections required by this AD. \n\nAlternative Methods of Compliance \n\t(e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNote 6: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\t(f) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\t(g) Except as provided by paragraph (d) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2419, Revision 1, including Appendix A, dated September 21, 2000. 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\t(h) This amendment becomes effective on January 30, 2001.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Boeing Model 747-400 series airplanes was published in the Federal Register on June 28, 2000 (65 FR 39828). That action proposed to require repetitive inspections to detect fatigue cracking of the longeron splice fittings at stringer 11 on the left and right sides at body station 2598, and various follow-on actions. \n\nComments \nInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nSupport for the Proposed Rule \nOne commenter supports the proposed rule. \n\nRequest to Reference New Service Bulletin \nOne commenter requests that the FAA revise the proposed rule to reference a new service bulletin, Boeing Alert Service Bulletin 747-53A2419, Revision 1, dated September 21, 2000. (The proposed rule referenced Boeing Alert Service Bulletin 747-53A2419, dated December 17, 1998, as the appropriate source of service information for certain proposed actions.) The commenter provides no justification for its request. \n\n\tThe FAA concurs with the commenter's request. Since the issuance of the proposed rule, the FAA has reviewed and approved Revision 1 of the service bulletin, including Appendix A. Revision 1 clarifies certain instructions and revises the effectivity listing to show changes in airplane operators. (No additional airplanes are added to the effectivity listing of Revision 1.) Therefore, the FAA has revised the applicability statement and paragraphs (a), (b)(1), (b)(2), and (c) of this final rule to reference Revision 1 of the service bulletin as the appropriate source of service information for the actions required by those paragraphs. The FAA also has added a new Note 2 to this AD (and reordered subsequent notes accordingly) to state that accomplishment of the actions required by this AD in accordance with the original issue of the service bulletin is acceptable for compliance with this AD. \n\nRequest to Follow Service Bulletin Instructions \nOne commenter requests that the FAA revise the proposed AD to reflect the service bulletin instructions for removal and replacement of the longeron splice fittings. The commenter notes that the service bulletin allows for removal and replacement of only those splice fittings that are cracked, provided that repetitive inspections of the remaining, uncracked, fittings continue. The proposed AD would require removal and replacement of all four fittings on the affected side if a single fitting is found to be cracked. \n\n\tThe FAA does not concur with the commenter's request. As explained in the "Differences Between Proposed Rule and Alert Service Bulletin" section of the proposal, the FAA finds it appropriate to mandate replacement of all longeron splice fittings on the affected side of the airplane if onefitting is found to be cracked. As pointed out in that same section of the proposal, the service bulletin recommends replacement of all four fittings on one side of the airplane at the same time (see Flag Note 1 of Figure 1 of the service bulletin). No change to the final rule is necessary in this regard. \n\nConclusion \nAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \nThere are approximately 490 Model 747-400 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 59 airplanes of U.S. registry will be affected by this AD. It will take approximately 2 work hours (1 hour per each side) per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this inspection on U.S. operators is estimated to be $7,080, or $120 per airplane, per inspection cycle. \n\n\tIt will take approximately 12 work hours (6 hours per each side) per airplane to accomplish the required rework or replacement, at an average labor rate of $60 per work hour. Required parts will cost between $731 and $7,906 per airplane. Based on these figures, the cost impact of this rework or replacement on U.S. operators is estimated to be between $1,451 and $8,626 per airplane. \n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \nThe 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\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (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. A final evaluationhas been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \n\nList of Subjects in 14 CFR Part 39 \nAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \nAccordingly, 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 \n1. The authority citation for part 39 continues to read as follows: \n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n2. Section 39.13 is amended by adding the following new airworthiness directive: