AD 2000-02-10

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires repetitive inspections to detect broken fasteners and cracking of the forward edge frame for main entry door number 3, and repair, if necessary. This amendment is prompted by reports of fatigue cracks at the inner chord and web of the body station 1265 edge frame between stringers 23 and 27. The actions specified by this AD are intended to detect and correct such cracking, which could result in rapid depressurization of the airplane.

Final rule.

2000-02-10 BOEING: Amendment 39-11529. Docket 98-NM-282-AD.\n\n\tApplicability: Model 747 series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2416, Revision 1, dated May 6, 1999; certificated in any category.\n\n\tNOTE 1: This AD also applies to airplanes that have been converted from a passenger configuration to a special freighter configuration.\n\n\tNOTE 2: 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 (d) 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\tTo detect and correct cracking of the inner chord and web of the body station 1265 edge frame between stringers 23 and 27, which could result in rapid depressurization of the airplane, accomplish the following: \n\nInspections\n\t(a)\tAccomplish the flight safety inspections of the frames at the floor intercostal to detect any broken fasteners and cracking of structure, in accordance with Figure 5 of Boeing Alert Service Bulletin 747-53A2416, Revision 1, dated May 6, 1999, at the applicable time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.\n\n\tNOTE 3: Accomplishment of the flight safety inspections of the frames at the floor intercostal on Group 2 airplanes prior to the effective date of this AD, in accordance with Boeing Alert Service Bulletin 747-53A2416, dated April 23, 1998, is considered acceptable for compliance with the actions required by paragraph (a) of this AD. However, Group 1 airplanes, as specified by paragraph (b) of this AD, that were inspected in accordance with the original release of the alert service bulletin are not exempt from the requirements of paragraph (b) of this AD. \n\n\tNOTE 4: Figure 5 of the alert service bulletin includes a detailed visual inspection for broken fasteners, an open hole high frequency eddy current (HFEC) inspection of certain fastener holes in the frame inner chord to detect any cracking of structure, and a surface HFEC inspection of the frame web to detect any cracking.\n\n\tNOTE 5: 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 supplementedwith 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\n\tNOTE 6: The alert service bulletin gives instructions to perform an open hole inspection, but does not give instructions to oversize the fastener hole after the inspection. This will keep sufficient material to oversize the hole at a later date when the modification work is accomplished.\n\n\t\t(1)\tFor airplanes that have accumulated fewer than 10,000 total flight cycles as of the effective date of this AD: Inspect prior to the accumulation of 10,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.\n\n\t\t(2)\tFor airplanes that have accumulated between 10,000 and 20,000 total flight cycles as of the effective date of this AD: Inspect prior to the accumulation of 11,000 total flight cycles, or within 750 flight cycles after the effective date of this AD, whichever occurs later.\n\n\t\t(3)\tFor airplanes that have accumulated more than 20,000 total flight cycles as of the effective date of this AD: Inspect prior to the accumulation of 20,750 total flight cycles, or within 500 flight cycles after the effective date of this AD, whichever occurs later.\n\n\t(b)\tFor Group 1 airplanes, as identified in Boeing Alert Service Bulletin 747-53A2416, Revision 1, dated May 6, 1999, on which the extended chord reinforcement strap modification specified in Boeing Service Bulletin 747-53-2066, dated June 28, 1972, has not been accomplished or on which the extended chord reinforcement strap modification was accomplished after the accumulation of 10,000 total flight cycles:\n\n\tAccomplish the surface HFEC inspection and the open hole HFEC inspection, as applicable, of the frames at the top of the inner chord reinforcement strap to detect any cracking of structure, in accordance with Figure 6 of thealert service bulletin at the applicable time specified in either paragraph (b)(1) or (b)(2) of this AD. Repeat the inspections thereafter at intervals not to exceed 800 flight cycles.\n\n\t\t(1)\tFor airplanes that have accumulated 20,000 total flight cycles or fewer as of the effective date of this AD: Inspect prior to the accumulation of 16,000 total flight cycles, or within 500 flight cycles after the effective date of this AD, whichever occurs later.\n\n\t\t(2)\tFor airplanes that have accumulated more than 20,000 total flight cycles as of the effective date of this AD: Inspect prior to the accumulation of 20,500 total flight cycles, or within 250 flight cycles after the effective date of this AD, whichever occurs later.\n\nRepair \n\n\t(c)\tIf any broken fastener or cracking of structure is detected during the inspections required by paragraph (a) or (b) of this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with 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 by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD.\n\nAlternative Methods of Compliance\n\n\t(d)\tAn 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 7: 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(e)\tSpecial 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\n\t(f)\tThe inspections shall be done in accordance with Boeing Alert Service Bulletin 747-53A2416, Revision 1, dated May 6, 1999. 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\n\t(g)\tThis amendment becomes effective on March 7, 2000.

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 series airplanes was published in the Federal Register on August 20, 1999 (64 FR 45466). That action proposed to require repetitive inspections to detect broken fasteners and cracking of the forward edge frame for main entry door number 3, and repair, if necessary. \n\nComments Received\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nRequest to Clarify Inspection Requirements for Group 2 Airplanes\n\tOne commenter states that the proposed AD should clarify that previous accomplishment of the inspections required for Group 2 airplanes, in accordance with Boeing Alert Service Bulletin 747-53A2416, dated April 23, 1998, is adequate for meeting the inspection requirements of the proposed rule. (Group 2 airplanes are identified in Revision 1, dated May 6, 1999, of the alert service bulletin.)\tThe commenter advises that all of its airplanes were included in the effectivity of the original release of the alert service bulletin and that the inspection requirements of the proposed AD, in accordance with the original release, have been accomplished. The commenter adds that no additional inspection requirements were added in Revision 1 of the alert service bulletin. For those reasons, the commenter requests changing the proposed AD to allow accomplishment of the flight safety inspections in accordance with the original release of the Boeing alert service bulletin instead of Revision 1 for Group 2 airplanes. \n\n\tThe FAA does not concur that it is necessary to change the proposed AD to cite the original release of the alert service bulletin rather than Revision 1 with regard to the inspections required for Group 2 airplanes. The FAA points out that the procedures in both of the alert service bulletins are identical for Group 2 airplanes. Therefore, the FAA agrees that inspections accomplished in accordance with the original release of the alert service bulletin meet the requirements of paragraph (a) of the proposed AD for Group 2 airplanes only. To clarify this, a note has been added to the final rule following paragraph (a).\n\nRequest to Clarify Certain Terminology in the Proposed Rule\n\tOne commenter requests minor editorial changes and clarification of certain terminology used in the proposed AD, as follows: \n\n In the second sentence of the "Explanation of Relevant Service Information," section and in Note 3 following paragraph (a) of the proposed AD, the commenter requests changing "inspection of certain fasteners" to "inspection of certain fastener holes." Although the "Explanation" section is not included in the final rule, the FAA concurs that such a change adds clarity to the inspection requirements, and has changed this phrase accordingly in Note 4 of the final rule. (Note 3 of the proposed rule is renumbered as Note 4 in the final rule.)\n\n In the first sentence of paragraph (c) of the proposed AD, the commenter requests changing "If any broken fastener or cracking" to "If any broken fasteners or cracking of structure." The FAA concurs with this request and has clarified this phrase accordingly in paragraphs (a), (b), and (c), and in Note 4, of the final rule. \n\n The commenter recommends that the heading preceding paragraph (c) of the proposed AD be called "Repair" or "Correction" rather than just "Repair." The commenter contends that "Correction" should be added to the heading because the statement of the unsafe condition specified that the action required is to detect and "correct" cracking. The FAA does not concur and considers that "Repair" is adequate for describing the action required to address the unsafe condition. For that reason, no change to the final rule is necessary in this regard.\n\nConclusion\n\tAfter 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\n\tThere are approximately 1,182 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 251 airplanes of U.S. registry will be affected by this AD.\n\n\tThe FAA estimates that it will take approximately 1 work hour per airplane to accomplish the inspection of the frames at the floor intercostal, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $15,060, or $60 per airplane, per inspection cycle.\n\n\tThe FAA also estimates that the inspection of the frames at the top of the inner chord reinforcement strap is required to be accomplished on 103 U.S.-registered airplanes. It is estimated that it will take approximately 1 work hour per airplane to accomplish the inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $6,180, or $60 per airplane, per inspection cycle. \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. \n\nRegulatory Impact\n\tThe 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 underExecutive 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 evaluation has 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\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment \n\tAccordingly, 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\t1. The authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended)\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: