AD 98-15-21

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-100 series airplanes, that currently requires repetitive inspections to detect cracking of the wing front spar web above engine numbers 2 and 3, and to detect cracked or broken fasteners in the web; and repair, if necessary. That AD also provides an optional terminating action for the repetitive inspections. This amendment requires various improved inspections. This amendment is prompted by a report indicating that the existing inspections do not adequately detect vertical cracks. The actions specified by this AD are intended to prevent fuel leakage onto an engine and a resultant fire due to cracked or broken fasteners in the wing front spar.

Final rule.

98-15-21 BOEING: Amendment 39-10672. Docket 97-NM-82-AD. Supersedes AD 95-02-15, Amendment 39-9134. \n\n\tApplicability: Model 747-100 series airplanes; as listed in Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995; 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 (g) 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 prevent fuel leakage onto an engine and a resultant fire, accomplish the following: \n\nRESTATEMENT OF REQUIREMENTS OF AD 95-02-15, AMENDMENT 39-9134: \n\n\t(a)\tFor airplanes on which the terminating action (fastener replacement) specified in Boeing Service Bulletin 747-57A2266, dated June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, dated June 10, 1993; has not been accomplished: Prior to the accumulation of 13,000 total flight cycles, or within 9 months after March 23, 1995 (the effective date of AD 95-02-15, amendment 39-9134), or within 2,000 flight cycles after the immediately preceding inspection accomplished in accordance with AD 92-07-11, amendment 39-8207, whichever occurs latest, accomplish the inspections specified in paragraphs (a)(1), (a)(2), and (a)(3) of this AD in accordance with Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994, or Revision4, dated November 3, 1994. Repeat these inspections thereafter at intervals not to exceed 2,000 flight cycles until the inspections required by paragraph (c) or (d) of this AD, as applicable, are accomplished. \n\n\t\t(1)\tPerform a detailed visual inspection to detect cracking of the wing front spar chords, stiffeners, and rib posts between the fastener heads between FSS 570 and FSS 684; and \n\n\t\t(2)\tPerform an ultrasonic inspection of the web under the upper and lower chord footprints to detect cracking of the wing front spar web between FSS 570 and FSS 684; and \n\n\t\t(3)\tPerform an ultrasonic inspection of the fasteners in the web-to-chords, and of the fasteners in the top two and bottom two rows in the web-to-stiffeners and web-to-rib posts of the wing front spar to detect cracked or broken fasteners between FSS 570 and FSS 684. \n\n\t(b)\tFor airplanes on which the terminating action (fastener replacement) specified in Boeing Service Bulletin 747-57A2266, dated June 6, 1991; Revision1, dated May 21, 1992; or Revision 2, dated June 10, 1993; has been accomplished: Within 18 months after accomplishing the terminating action specified in the original issue, Revision 1, or Revision 2 of the service bulletin, or within 9 months after March 23, 1995, whichever occurs later, accomplish the inspections specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD, in accordance with Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994, or Revision 4, dated November 3, 1994. Repeat these inspections thereafter at intervals not to exceed 2,000 flight cycles until the inspections required by paragraph (c) or (d) of this AD, as applicable, are accomplished. \n\n\t\t(1)\tPerform a detailed visual inspection of the wing front spar chords, stiffeners, and rib posts between the fastener heads between FSS 570 and FSS 684; and \n\n\t\t(2)\tPerform an ultrasonic inspection of the web under the upper and lower chord footprints to detect cracking of the wing front spar web between FSS 570 and FSS 636 and between FSS 675 and FSS 684; and \n\n\t\t(3)\tPerform an ultrasonic inspection of the fasteners in the web-to-chords, and of the fasteners in the top two rows and bottom two rows in the web-to-stiffeners and web-to-rib posts of the wing front spar to detect cracked or broken fasteners between FSS 570 and FSS 636 and between FSS 675 and FSS 684. NEW REQUIREMENTS OF THIS AD: \n\n\t(c)\tFor airplanes identified as Configuration A in Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995: Prior to the accumulation of 13,000 total flight cycles, or within 6 months after the effective date of this AD, or within 2,000 flight cycles after the immediately preceding inspection accomplished in accordance with paragraph (a) or (b) of this AD, whichever occurs latest, accomplish the inspections specified in paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of this AD, in accordance with Figure 3 of Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995. Repeat these inspections thereafter at intervals not to exceed 2,000 flight cycles. Accomplishment of these inspections terminates the inspections required by paragraphs (a) and (b) of this AD. \n\n\t\t(1)\tPerform a detailed visual inspection to detect damage and fuel leaks in the general area of the web of the wing front spar between FSS 570 and FSS 684. \n\n\t\t(2)\tPerform an eddy current inspection to detect cracks along the web near the edges of the vertical flange of the upper and lower chords of the wing front spar between FSS 570 and FSS 684. \n\n\t\t(3)\tPerform an ultrasonic inspection to detect cracks in the web around the first two fastener holes in the stiffeners and rib posts between FSS 570 and FSS 684. \n\n\t\t(4)\tPerform an ultrasonic inspection to detect cracked or broken fasteners in the fasteners attaching only the web to the chords, in the top two and bottom two rows of the fasteners attaching the web to the stiffeners, and in the top two and bottomtwo rows of the fasteners attaching the web to the rib posts. This inspection area is located between FSS 570 and FSS 684. \n\n\t(d)\tFor airplanes identified as Configuration B in Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995: Within 18 months following accomplishment of the terminating action (fastener replacement) specified in Boeing Service Bulletin 747-57A2266, dated June 6, 1991, Revision 1, dated May 21, 1992, or Revision 2, dated June 10, 1993; or within 12 months after the effective date of this AD; or within 2,000 flight cycles after the immediately preceding inspection accomplished in accordance with paragraph (a) or (b) of this AD; whichever occurs latest; accomplish the inspections specified in paragraphs (d)(1), (d)(2), (d)(3), and (d)(4) of this AD in accordance with Figure 4 of Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995. Repeat these inspections thereafter at intervals not to exceed 2,000 flight cycles. Accomplishment of these inspections terminates the inspections required by paragraphs (a) and (b) of this AD. \n\n\t\t(1)\tPerform a detailed visual inspection to detect damage and fuel leaks in the general area of the web of the wing front spar between FSS 570 and FSS 636 and between FSS 675 and FSS 684. \n\n\t\t(2)\tPerform an eddy current inspection to detect cracks along the web near the edges of the vertical flange of the upper and lower chords of the wing front spar between FSS 570 and FSS 636 and between FSS 675 and FSS 684. \n\n\t\t(3)\tPerform an ultrasonic inspection to detect cracks in the web around the first two fastener holes in the stiffeners and rib posts between FSS 570 and FSS 636 and between FSS 675 and FSS 684. \n\n\t\t(4)\tPerform an ultrasonic inspection to detect cracked or broken fasteners in the fasteners attaching only the web to the chords, in the top two and bottom two rows of the fasteners attaching the web to the stiffeners, and in the top two and bottom two rows of thefasteners attaching the web to the rib posts. This inspection area is located between FSS 570 and FSS 636 and between FSS 675 and FSS 684. \n\n\t(e)\tIf any discrepancy (i.e., cracking, fuel leakage, broken fasteners) is detected during any inspection required by this AD, prior to further flight, repair in accordance with paragraphs E. and H. (as applicable) of the Accomplishment Instructions of Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994; Boeing Service Bulletin 747-57A2266, Revision 4, dated November 3, 1994; or Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995. Thereafter, continue to inspect the remaining fasteners in accordance with paragraph (c) or (d) of this AD, as applicable, until the terminating action specified in paragraph (f) of this AD is accomplished. If any crack is found that cannot be removed by oversizing the fastener hole, prior to further flight, repair it in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t(f)\tReplacement of the fasteners in the web-to-chords and of the fasteners in the web-to- stiffeners and web-to-rib posts, as specified in Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994; Revision 4, dated November 3, 1994; or Revision 5, dated August 3, 1995; with oversized fasteners on each wing spar in accordance with the service bulletin constitutes terminating action for the repetitive inspections required by paragraphs (a), (b), (c), (d), and (e) of this AD. \n\n\t(g)\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 Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(h)\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\n\t(i)\tThe actions shall be done in accordance with Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994; Boeing Service Bulletin 747-57A2266, Revision 4, dated November 3, 1994; and Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995. \n\n\t\t(1)\tThe incorporation by reference of Boeing Alert Service Bulletin 747-57A2266, Revision 5, dated August 3, 1995, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. \n\n\t\t(2)\tThe incorporation by reference of Boeing Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994; and Boeing Service Bulletin 747-57A2266, Revision 4, dated November 3, 1994, was approved previously by the Director of the Federal Register as of March 23, 1995 (60 FR 9613, February 21, 1995). \n\n\t\t(3)\tCopies 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(j)\tThis amendment becomes effective on August 27, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 95-02-15, amendment 39-9134 (60 FR 9613, February 21, 1995), which is applicable to certain Boeing Model 747-100 series airplanes, was published in the Federal Register on April 14, 1998 (63 FR 18167). The action proposed to supersede AD 95-02-15 to continue to require repetitive inspections to detect cracking of the wing front spar web above engine numbers 2 and 3, and to detect cracked or broken fasteners in the web; and repair, if necessary. That action also continues to provide for an optional terminating action for the repetitive inspections. The action proposed to require various improved inspections. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received. \n\n\tThe commenter supports the proposed rule. \n\nConclusion \n\n\tAfter careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. \n\nCost Impact \n\n\tThere are approximately 190 Boeing Model 747-100 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 95 airplanes of U.S. registry will be affected by this AD. \n\n\tThe actions that are currently required by AD 95-02-15, and retained in this AD, take approximately 70 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required inspection on U.S. operators is estimated to be $399,000, or $4,200 per airplane, per inspection cycle. \n\n\tFor airplanes identified as Configuration A in the referenced alert service bulletin, the new actions that are required in this AD will take approximately 60 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the new inspection requirements of this AD on those U.S. operators is estimated to be $3,600 per airplane, per inspection cycle. \n\n\tFor airplanes identified as Configuration B in the referenced alert service bulletin, the new actions that are required in this AD will take approximately 40 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the new inspection requirements of this AD on U.S. operators is estimated to be $2,400 per airplane, per inspection cycle. \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. \n\n\tShould an operator elect to accomplish the optional terminating action (fastener replacement between FSS 570 and FSS 684) that is provided bythis AD action, it would take approximately 306 work hours to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $15,478. Based on these figures, the cost impact of the optional terminating action will be $33,838 per airplane. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \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, February26, 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\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\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\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by removing amendment 39-9134 (60 FR 9613, February 21, 1995), and by adding a new airworthiness directive (AD), amendment 39-10672, to read as follows: