AD 95-20-05

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires repetitive inspections for cracking in the inboard strut-to-diagonal brace attach fittings, and repair or replacement, if necessary. This amendment requires an additional inspection of those attach fittings, and additional inspections in an area beyond that specified in the existing AD. This amendment also provides an optional terminating action for the required inspections, and expands the applicability of the existing AD to include additional airplanes. This amendment is prompted by reports of cracking and severing of the attach fittings. The actions specified by this AD are intended to prevent failure of the strut and separation of an engine from the airplane due to cracking of the inboard strut-to-diagonal brace attach fittings.

Final rule

95-20-05 BOEING: Amendment 39-9383. Docket 94-NM-255-AD. Supersedes AD 79-17-07, Amendment 39-3533. \n\n\tApplicability: Model 747 series airplanes, as listed in Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994; 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 otherwise 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 use the authority provided in paragraph (g) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent failure of the strut and subsequent loss of an engine, accomplish the following: \n\n\tNOTE 2: Paragraph (a) of this AD restates the requirements for initial and repetitive visual inspections contained in paragraphs A., and C., respectively, of AD 79-17-07, amendment 39-3583. Therefore, for operators who have previously accomplished at least the initial inspection in accordance with AD 79-17-07, paragraph (a) of this AD requires that the next scheduled inspection be performed within the intervals specified in (a)(1) or (a)(2), as applicable, after the last inspection performed in accordance with paragraph A. or C. of AD 79-17-07. \n\n\t(a)\tFor airplanes listed in Boeing Service Bulletin 747-54-2062, dated August 17, 1979: Prior to the accumulation of 5,000 total landings on the airplane, or within 500 hours time-in- service after September 4, 1979 (the effective date of AD 79-17-07, Amendment 39-3533), whichever occurs later, perform a visual inspection of the forward lower diagonal brace fittings of the inboard pylon to detect cracking, in accordance with Boeing Service Bulletin 747-54-2062, dated August 17, 1979, or Revision 7, dated December 21, 1994; or in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate. After the effective date of this AD, only Revision 7 of the service bulletin shall be used. \n\n\tNOTE 3: Inspections performed prior to the effective date of this AD are considered to be in compliance with paragraph (a) of this AD if performed in accordance with Boeing Service Bulletin 747-54-2062, August 17, 1979; Revision 1, dated November 13, 1980; Revision 2, dated March 19, 1981; Revision 3, dated August 28, 1981; Revision 4, dated June 30, 1982; Revision 5, dated June 1, 1984; Revision 6, dated October 2, 1986, or Revision 7, dated December 21, 1994. \n\n\t\t(1)\tIf no cracking is detected, repeat the inspections at intervals not to exceed 1,000 landings until all affected fittings are replaced with steel fittings in accordance with Revision 7 of the service bulletin. \n\n\t\t(2)\tIf any cracking is detected, prior to further flight, accomplish either paragraph (a)(2)(i) or (a)(2)(ii) of this AD until the inspections required by paragraph (b) of this AD are accomplished. \n\n\t\t\t(i)\tRepair or replace the cracked fitting in accordance with the \t\t\t\tservice bulletin; or \n\t\t\t(ii)\tRework the cracked fitting in accordance with the service bulletin as required by paragraph (b) of this AD. Thereafter, repeat the inspections at intervals not to exceed 250 landings until the reworked fitting is replaced with a serviceable fitting, or until the inspections required by paragraph (b) of this AD are accomplished. \n\n\t(b)\tFor airplanes as listed in Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994: Perform a detailed visual inspection and a surface high frequency eddy current (HFEC) inspection to detect cracking of the inboard strut-to-diagonal brace attach fittings, in accordance with Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994, at the time specified in either paragraph (b)(1) or (b)(2) of this AD, as applicable. \n\n\t\t(1)\tFor airplanes on which a cracked fitting has been reworked in accordance with Boeing Service Bulletin 747-54-2062, dated August 17, 1979: Perform the inspections within 250 landings since the last inspection performed in accordance with paragraph (a)(2)(ii) of this AD. \n\n\t\t(2)\tFor airplanes other than those identified in paragraph (b)(1) of this AD: Perform the inspections at the earlier of the times specified in paragraph (b)(2)(i) or (b)(2)(ii) of this AD. \n\t\t\t(i)\tPrior to the accumulation of 5,000 total landings on the airplane, or within 1,000 landings after the effective date of this AD, whichever occurs later; or \n\t\t\t(ii)\tWithin 1,000 landings since the last inspection performed in accordance with paragraph (a) of this AD. \n\n\t(c)\tIf no cracking is detected during the inspections required by paragraph (b) of this AD, repeat the inspections thereafter at intervals not to exceed 1,000 landings.\n \n\t(d)\tIf more than one crack is found during any inspection required by this AD, or if any crack is detected that is beyond the limits specified in Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994, prior to further flight, replace the attach fitting with a steel fitting in accordance with the service bulletin. \n\n\t(e)\tIf any transverse or longitudinal crack is found during the inspection required by paragraph (b) of this AD, and that crack is within the limits specified by Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994: Prior to further flight, stop drill the crack in accordance with the service bulletin, and accomplish the requirements of either paragraph (e)(1) or (e)(2) of this AD, as applicable. \n\n\t\t(1)\tFor any transverse crack that is found, accomplish the following: \n\t\t\t(i)\tPrior to further flight, remove the affected fastener and perform an open- hole HFEC inspection to detect cracking of the fastener hole, in accordance with the service bulletin. Thereafter, repeat this inspection within 125 landings. \n\n\t\t\t(ii)\tRepeat the inspections required by paragraph (b) of this AD within 125 landings after performing them initially. \n\n\t\t\t(iii)\tIf any crack is found during the inspections required by this paragraph and the crack is beyond the limits specified in the service bulletin, prior to further flight, replace the attach fitting with a steel fitting in accordance with the service bulletin. \n\n\t\t\t(iv)\tPrior to the accumulation of 250 landings following the detection of the transverse cracking, replace theattach fitting with a steel fitting in accordance with the service bulletin. \n\n\t\t(2)\tFor any longitudinal crack that is found, accomplish the following: \n\n\t\t\t(i)\tRepeat the inspection required by paragraph (b) of this AD at intervals not to exceed 250 landings. \n\n\t\t\t(ii)\tPrior to the accumulation of 1,000 landings following detection of the longitudinal cracking, replace the attach fitting with a steel fitting in accordance with the service bulletin. \n\n\t(f)\tReplacement of the attach fittings of the strut-to-diagonal brace with steel fittings, in accordance with Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994, constitutes terminating action for the requirements of this AD. \n\n\tNOTE 4: Replacement of the attach fittings of the strut to diagonal brace with steel fittings prior to the effective date of this AD is considered in compliance with paragraph (f) of this AD if performed in accordance with Boeing Service Bulletin 747-54-2062, Revision 1, dated November 13, 1980; Revision 2, dated March 19, 1981; Revision 3, dated August 28, 1981; Revision 4, dated June 30, 1982; Revision 5, dated June 1, 1984; or Revision 6, dated October 2, 1986. \n\n\tNOTE 5: This AD does not require certain additional work (to seal a gap between the fitting and the existing closure web, or replacement of the bushings in the diagonal brace fitting with anvil swaged bushings) as described in Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994. However, these installations are required to be accomplished as part of AD 95-10-16, amendment 39-9233 (60 FR 27008, May 22, 1995). Table 2 of Boeing Service Bulletin 747-54A2159, "Prior or Concurrent Service Bulletins" (which is cited in AD 95-10-16), specifies that Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994 (which is cited in this AD), must be accomplished prior to or concurrent with the installations required by AD 95-10-16. \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 6: 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 747-54-2062, Revision 7, dated December 21, 1994. 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(j)\tThis amendment becomes effective on November 2, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 79-17-07, amendment 39-3533 (44 FR 50033, August 27, 1979), which is applicable to certain Boeing Model 747 series airplanes, was published in the Federal Register on April 4, 1995 (60 FR 17030). The action proposed to continue to require repetitive visual inspections to detect cracking in the inboard strut-to-diagonal brace attach fittings, and replacement or repair of the cracking, if necessary. The action also proposed to add repetitive high frequency eddy current (HFEC) inspections to detect cracks of the attach fittings. Additionally, that action proposed to require that certain attach fittings with cracks be reinspected at shorter intervals, and to require subsequent replacement of the attach fittings of airplanes with certain known cracking. The action also proposed to expand the applicability of the rule to include additional affected airplanes, and provided an optional terminating action for the required inspections. \n\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\n\tOne commenter supports the proposed rule. \n\n\tThe Air Transport Association (ATA), on behalf of one of its members, requests that the FAA clarify that replacement of the aluminum attach fittings with steel ones, as described in revisions prior to Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994, is an acceptable terminating action for the requirements of this AD. \n\n\tThe FAA concurs. This AD does not require any further action for operators that have replaced the aluminum fittings with steel ones, in accordance with Revisions 1 through 7 of Boeing Service Bulletin 747-54-2062. A note has been added to the final rule to reflect this clarification. \n\n\tThe commenter also requests that the proposed rule be clarified to specify that, for airplanes on which the fitting replacement has been accomplished, additional work would not be required to terminate the requirements of the AD, i.e., installation of the closure web and installation of anvil swaged bushings. \n\n\tThe FAA concurs. The additional work referenced by the commenter is not required to be accomplished as part of this AD. However, the installation of the closure web and installation of anvil swaged bushings, as described in Revision 7 of the service bulletin, are required to be accomplished as part of the strut modification program, mandated by AD 95-10-16, amendment 39- 9233 (60 FR 27008, May 22, 1995), regardless of whether or not the aluminum attach fittings have been replaced with steel fittings. Table 2 of Boeing Service Bulletin 747-54A2159, "Prior or Concurrent Service Bulletins" (which is cited in AD 95-10-16), specifies that Boeing Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994 (which is cited in this AD), mustbe accomplished prior to or concurrent with the installations required by AD 95-10-16. A note has been added to the final rule to clarify this point. \n\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\n\tThere are approximately 367 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 152 airplanes of U.S. registry will be affected by this AD. \n\n\tThe new actions that are required by this AD will take approximately 11 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the total cost impact on U.S. operators of the new requirements of this AD is estimated to be $100,320, or $660 perairplane, per inspection cycle. This total cost impact figure is 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 terminating modification that would be provided by this AD action, it will take approximately 176 work hours per airplane to accomplishment it, at an average labor rate of $60 per work hour. Required parts will cost approximately $4,752 per airplane. Based on these figures, the total cost impact of the terminating modification will be $15,312 per airplane. \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, 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\n List 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 USC 106(g), 40101, 40113, 44701. § 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-3533 (44 FR 50033, August 27, 1979), and by adding a new airworthiness directive (AD), amendment 39-9383, to read as follows: