AD 97-12-03

This amendment supersedes two existing airworthiness directives (AD) that are applicable to certain Boeing Model 747 series airplanes. One of those AD's currently requires inspections for cracking, corrosion, and fracturing of the lower horizontal clevis of the strut midspar fittings, and replacement of discrepant parts with new or serviceable parts, or repair, if necessary. That AD also requires inspection for removal of broken sealant of the clevis and the fasteners, and various follow-on actions. It also provides for optional terminating actions for the inspections. The other AD currently requires inspection for cracking of certain fastener holes of the upper and lower horizontal clevis legs. This amendment continues to require inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis; and adds corresponding inspections of the upper horizontal clevis, and replacement of discrepant parts with new parts, or rework, if necessary. This amendment also removes certain optional terminating actions. This amendment is prompted by reports of cracking of the lower and upper leg of the horizontal clevis of the midspar fitting. The actions specified in this AD are intended to detect and correct cracking and fracturing of the clevis, which could result in drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the airplane.

Final rule; request for comments

97-12-03 BOEING: Amendment 39-10045. Docket 97-NM-70-AD. Supersedes AD 87-04-13 R1, amendment 39-5836; and AD 96-25-01, amendment 39-9842. \n\n\tApplicability: Model 747 series airplanes as listed in Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996; certificated in any category, except for airplanes on which the strut/wing modification has been accomplished in accordance with the following Boeing alert service bulletins: \n\n\t1. Boeing Alert Service Bulletin 747-54A2157, dated January 12, 1995; Revision 1, dated August 3, 1995; or Revision 2, dated November 14, 1996; \n\n\t2. Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994; Revision 1, dated August 17, 1995; or Revision 2, dated August 15, 1996; or \n\n\t3. Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994; Revision 1, dated June 1, 1995; or Revision 2, dated March 14, 1996. \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 request approval for an alternative method of compliance in accordance with paragraph (n) 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 drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the airplane due to cracking or fracturing of the midspar fitting clevis, accomplish the following: \n\nRestatement of Requirements of AD 96-25-01 \n\n\t(a)\tFor all airplanes: Except as provided by paragraph (d) of this AD, perform a detailed visual borescope inspection to detect cracking, corrosion, and/or fracturing of the lower horizontal clevis of both midspar fittings of the inboard struts, in accordance with Boeing Alert Service Bulletin 747-54A2179, dated June 27, 1996, or Revision 1, dated November 27, 1996, at the time specified in paragraph (a)(1), (a)(2), (a)(3), or (a)(4) of this AD, as applicable. \n\n\t\t(1)\tFor airplanes identified as Group 1 or Group 6 in the alert service bulletin: Perform the initial inspection at the time specified in paragraph (a)(1)(i) or (a)(1)(ii), as applicable. Thereafter, repeat this inspection at intervals not to exceed every 150 flight cycles, or every 3 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 150 flight cycles or 60 days after January 2, 1997 (the effective date of AD 96-25-01, amendment 39-9842), whichever occurs first. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 500 flight cycles prior to January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 500 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\n\t\t(2)\tFor airplanes identified as Group 2 or Group 4 in the alert service bulletin: Perform the initial inspection at the time specified in paragraph (a)(2)(i) or (a)(2)(ii) of this AD, as applicable. Thereafter, repeat this inspection at intervals not to exceed every 300 flight cycles or 6 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 150 flight cycles or 60 days after January 2, 1997, whichever occurs first. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 1,000 flight cycles prior to January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\t\t(3)\tFor airplanes identified as Group 3 in the alert service bulletin: Perform the initial inspection at the time specified in paragraph (a)(3)(i) or (a)(3)(ii) of this AD, as applicable. Thereafter, repeat this inspection at intervals not to exceed every 350 flight cycles or 6 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 150 flight cycles or 60 days after January 2, 1997, whichever occurs first. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 1,000 flight cycles prior to January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\t\t(4)\tFor airplanes identified as Group 5 in the alert service bulletin: Perform the initial inspection at the time specified in paragraph (a)(4)(i) or (a)(4)(ii) of this AD, as applicable. Thereafter, repeat the inspection at intervals not to exceed every 300 flight cycles or 6 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 150 flight cycles or 60 days after January 2, 1997, whichever occurs first. \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 800 flight cycles prior to January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 800 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\n\t(b)\tFor airplanes identified as Group 1 in Boeing Alert Service Bulletin 747-54A2179, dated June 27, 1996, or Revision 1, dated November 27, 1996: Except as provided by paragraph (e) of this AD, perform a detailed visual borescope inspection to detect cracking, corrosion, and/or fracturing of the lower horizontal clevis of both midspar fittings of the outboard struts, in accordance with Boeing Alert Service Bulletin 747-54A2179, dated June 27, 1996, or Revision 1, dated November 27, 1996, at the time specified in paragraph (b)(1) or (b)(2) of this AD, as applicable. Thereafter, repeat the inspection at intervals not to exceed every 300 flight cycles or 6 months, whichever occurs first. \n\n\t\t(1)\tWithin 200 flight cycles or 60 days after January 2, 1997, whichever occurs first. Or \n\n\t\t(2)\tFor airplanes on which the terminating action has been accomplished within the last 1,000 flight cycles prior to January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \nNew Requirements of this AD \n\n\t(c)\tFor all airplanes: After the effective date of this AD, prior to the accomplishment of each inspection required by paragraph (a), (b), (d), or (e), of this AD, remove the sealant common to the lower leg of the horizontal clevis of the inboard (for all airplanes) midspar fittings, and the outboard (for Groups 1 and 6 airplanes) and clean the midspar fittings, in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. Prior to further flight following accomplishment of these actions, apply corrosion inhibitive compound BMS 3-23 to any area where the original sealant was removed or disturbed, in accordance with Boeing Standard Operational Procedures (BSOP) 20-41-05 for Model 747 series airplanes. \n\n\t(d)Accomplishment of the actions specified in this paragraph is an alternative to compliance with paragraph (a) of this AD. Perform an ultrasonic/detailed visual inspection to detect cracking, corrosion, and/or fracturing of the lower horizontal clevis of both midspar fittings of the inboard struts, in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, at the time specified in paragraph (d)(1), (d)(2), (d)(3), or (d)(4)as applicable. \n\n\t\t(1)\tFor airplanes identified as Group 1 or 6 in the alert service bulletin: Perform the inspections at the time specified in paragraph (d)(1)(i) or (d)(1)(ii) of this AD. Thereafter, repeat the inspections at intervals not to exceed every 1,000 flight cycles or 18 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 150 flight cycles or 3 months after accomplishing the last inspection required by paragraph (b) of AD 96-25-01 or paragraph (a) of this AD. \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 500 flight cycles after January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 500 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\n\t\t(2)\tFor airplanes identified as Group 2 or 4 in the alert service bulletin: Perform the inspection at the time specified in paragraph (d)(2)(i) or (d)(2)(ii) of this AD, as applicable. Thereafter, repeat this inspection at intervals not to exceed every 1,500 flight cycles or 18 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 300 flight cycles or 6 months after accomplishing the last inspection required by paragraph (b) of AD 96-25-01 or paragraph (a) of this AD. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 1,000 flight cycles after January 2, 1997, in accordancewith Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\t\t(3)\tFor airplanes identified as Group 3 in the alert service bulletin: Perform the inspection at the time specified in paragraph (d)(3)(i) or (d)(3)(ii) of this AD, as applicable. Thereafter, repeat the inspection at intervals not to exceed every 2,500 flight cycles or 18 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 350 flight cycles or 6 months after accomplishing the last inspection required by paragraph (b) of AD 96-25-01 or paragraph (a) of this AD. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 1,000 flight cycles after January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\t\t(4)\tFor airplanes identified as Group 5 in the alert service bulletin: Perform the inspection at the time specified in paragraph (d)(4)(i) or (d)(4)(ii) of this AD, as applicable. Thereafter, repeat the inspection at intervals not to exceed every 1,500 fight cycles or 18 months, whichever occurs first. \n\n\t\t\t(i)\tWithin 300 flight cycles or 6 months after accomplishing the last inspection required by paragraph (b) of AD 96-25-01 or paragraph (a) of this AD. Or \n\n\t\t\t(ii)\tFor airplanes on which terminating action has been accomplished within 800 flight cycles after January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection within 800 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\n\t(e)\tFor airplanes identified as Group 1 in Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996: Accomplishment of the actions specified in this paragraph is an alternative to compliance with paragraph (b) of this AD. Perform an ultrasonic/detailed visual inspection to detect cracking, corrosion, and/or fracturing of the lower horizontal clevis of both midspar fittings of the outboard struts, in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, at the time specified in paragraph (e)(1) or (e)(2) of this AD, as applicable. Thereafter, repeat the inspection at intervals not to exceed every 2,000 flight cycles or 18 months, whichever occurs first. \n\t\t(1)\tWithin 300 flight cycles or 6 months after accomplishing the last inspection required by paragraph (c) of AD 96-25-01 or paragraph (b) of this AD. Or \n\n\t\t(2)\tFor airplanes on which terminating action has been accomplished within 1,000 flight cycles after January 2, 1997, in accordance with Boeing Service Bulletin 747-54-2118, Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the inspection within 1,000 flight cycles or 12 months after January 2, 1997, whichever occurs first. \n\n\t(f)\tFor all airplanes: After the effective date of this AD, prior to the accomplishment of each inspection required by paragraphs (g), (h), or (i), of this AD, remove the sealant of the upper horizontal leg surface and clean the midspar fittings in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. Prior to further flight following accomplishment of these actions: Restore the sealant of the upper horizontal leg surface in accordance with the alert service bulletin. \n\n\t(g)\tFor all airplanes: Within90 days after the effective date of this AD, perform an ultrasonic/detailed visual inspection to detect cracking, corrosion, and/or fracturing of the upper horizontal clevis of both midspar fittings of the inboard struts, in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. Repeat the ultrasonic/detailed visual inspection thereafter at the time specified in paragraph (g)(1), (g)(2), or (g)(3), as applicable. \n\n\t\t(1)\tFor airplanes identified as Group 1 or 6 in the alert service bulletin: Repeat at intervals not to exceed every 1,000 flight cycles or 18 months, whichever occurs first. \n\t\t(2)\tFor airplanes identified as Group 2, 4, or 5 in the alert service bulletin: Repeat at intervals not to exceed every 1,500 flight cycles or 18 months, whichever occurs first. \n\t\t(3)\tFor airplanes identified as Group 3 in the alert service bulletin: Repeat at intervals not to exceed every 2,500 flight cycles or 18 months, whichever occurs first.(h)\tFor airplanes identified as Group 1 in Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996: Within 90 days after the effective date of this AD, perform an ultrasonic/detailed visual inspection of the upper horizontal clevis of both midspar fittings of the outboard strut to detect cracking, corrosion, and/or fracturing, in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed every 2,000 flight cycles or 18 months, whichever occurs first.\n \n\t(i)\tFor airplanes specified in paragraph (i)(1) or (i)(2) of this AD: Perform the actions specified in paragraph (a), (b), (d), (e), (f), (g), or (h) of this AD, as applicable, at the time specified in paragraph (i)(1) or (i)(2) of this AD, as applicable. Thereafter, perform the repetitive inspections at the time specified in paragraph (a), (b), (d), (e), (f), (g), or (h) of this AD, as applicable. \n\n\t\t(1)\tFor airplanes on which rework of all the fastener holeshas been accomplished in accordance with Boeing Alert Service Bulletin 747-54A2179, dated June 27, 1996, Revision 1, dated November 27, 1996, or Boeing Service Bulletin 747-54-2118, dated July 25, 1986: Perform the initial inspection at the later of the times specified in paragraphs (i)(1)(i) and (i)(1)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 3,000 total landings, or within 3 years after accomplishment of the rework, whichever occurs first. Or \n\n\t\t\t(ii)\tWithin 90 days after the effective date of this AD. \n\t\t(2)\tFor airplanes on which the midspar fittings have been replaced in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, or Boeing Service Bulletin 747-54-2118, dated July 25, 1986; Revision 1, dated May 21, 1987; Revision 2, dated April 21, 1988; Revision 3, dated September 29, 1988; or Revision 4, dated May 11, 1989: Perform the initial inspection at the later of the times specified in paragraphs (i)(2)(i) and (i)(2)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 5,000 landings, or within 5 years after the fitting has been replaced, whichever occurs first. Or \n\n\t\t\t(ii)\tWithin 90 after the effective date of this AD. \n\n\t(j)\tFor all airplanes: If any cracking, corrosion, or fracturing is detected during any inspection required by this AD that is outside the limits specified in Boeing Alert Service Bulletin 757-54A2179, Revision 1, dated November 27, 1996, and the damaged area is within the area limits specified in the alert service bulletin, prior to further flight, accomplish the requirements of paragraph (j)(1) or (j)(2) of this AD. \n\n\t\t(1)\tAccomplish the strut/wing modification specified in paragraph (j)(1)(i), (j)(1)(ii), or (j)(1)(iii) of this AD, as applicable. Following accomplishment of that action, no further action is required by this AD. \n\n\t\t\t(i)\tFor airplanes equipped with Rolls Royce Model RB211 series engines: Accomplish the strut/wing modification in accordance with Boeing Alert Service Bulletin 747- 54A2157, Revision 2, dated November 14, 1996. Accomplishment of this paragraph terminates the requirements of AD 95-13-05, amendment 39-9285. \n\n\t\t\t(ii)\tFor airplanes equipped with General Electric Model CF6-45 or -50 series engines, or Pratt & Whitney Model JT9D-70 series engines: Accomplish the strut/wing modification in accordance with Boeing Alert Service Bulletin 747-54A2158, Revision 2, dated August 15, 1996. Accomplishment of this paragraph terminates the requirements of AD 95-13-07, amendment 39-9287. \n\n\t\t\t(iii)\tFor airplanes equipped with Pratt & Whitney Model JT9D series engines (excluding Model JT9D-70 engines): Accomplish the strut/wing modification in accordance with Boeing Alert Service Bulletin 747-54A2159, Revision 2, dated March 14, 1996. Accomplishment of this paragraph terminates the requirements of AD 95-10-16, amendment 39-9233. \n\n\t\t(2)\tReplace the midspar fittings of the strut with new fittings in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. Repeat the inspections thereafter at the intervals specified in paragraph (i)(2) of this AD. \n\n\t(k)\tIf any cracking, corrosion, or fracturing is detected during any inspection required by this AD that is outside the limits specified in Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, and the damaged area is outside the area limits specified in the alert service bulletin, prior to further flight, accomplish the requirements of either paragraph (j)(1) or (j)(2) of this AD, or repair in accordance with a method approved by the Manager, Seattle ACO.\n \n\t(l)\tFor all airplanes: If any cracking, corrosion, or fracturing is detected during any inspection required by this AD and it is within the limits specified in Boeing Alert Service Bulletin 757-54A2179, Revision 1, dated November 27, 1996: Prior to further flight, accomplish the requirements of paragraph (l)(1), (l)(2), (l)(3), or (l)(4) of this AD. \n\n\t\t(1)\tRework any discrepant area in accordance with the alert service bulletin. Following the rework, repeat the actions required by paragraph (a), (b), (d), (e), (f), (g), or (h) of this AD, as applicable, at the intervals specified in those paragraphs. \n\n\t\t(2)\tRework all the fastener holes in accordance with the alert service bulletin. Within 3,000 flight cycles or 3 years after reworking all the fastener holes, whichever occurs first: Repeat the actions required by paragraph (i)(1) of this AD, and accomplish the repetitive inspections required by paragraph (i) of this AD. \n\n\t\t(3)\tReplace the midspar fittings in accordance with the alert service bulletin. Within 5,000 flight cycles or 5 years after replacing the midspar fittings, whichever occurs first: Repeat the actions required by paragraph (i)(2) of this AD, and accomplish the repetitive inspections required by paragraph (i) of this AD. \n\n\t\t(4)\tAccomplish the strut/wing modification specified inparagraph (j)(1)(i), (j)(1)(ii), or (j)(1)(iii) of this AD, as applicable. Following accomplishment of that action, no further action is required by this AD. \n\n\t(m)\tAccomplishment of the strut/wing modification specified in paragraph (j)(1)(i), (j)(1)(ii), or (j)(1)(iii) of this AD constitutes terminating action for the requirements of this AD. \n\n\t(n)\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\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(o)\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(p)\tCertain actions shall be done in accordance with the Boeing Alert Service Bulletins listed in the following table. The incorporation by reference of those documents was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of the dates specified in the table below: \n\n\nReferenced Service\nBulletin and Date\nApproval Date \nand Federal Register Citation \n747-54A2157,\nJanuary 12, 1995\nJuly 28, 1995\n(60 FR 33333, June 28, 1995)\n747-54A2158, \nNovember 30, 1994\nJuly 28, 199\n(60 FR 33336, July 28, 1995)\n747-54A2159,\nNovember 3, 1994\nJune 21, 1995\n(60 FR 27008, May 22, 1995)\n\nCertain other actions shall be done in accordance with the Boeing Alert Service Bulletins listed in the following table. The incorporation by reference of those documents was approved previously by the Director of the Federal Registeron January 22, 1997 (61 FR 66201, December 12, 1996), in accordance with 5 U.S.C. 552(a) and 1 CFR part 51: \n\n\nReferenced Service Bulletin\n\nRevision Level\n\nDate \n747-54A2179\nOriginal\t\nJune 27, 1996 \n747-54A2157\n1 \nAugust 3, 1995 \n747-54A2157\n2\nNovember 14, 1996\n747-54A2158\n1\nAugust 17, 1995 \n747-54A2158\n2\nAugust 15, 1996\n747-54A2159\n1\nJune 1, 1995\n747-54A2159 \n2 \nMarch 14, 1996 \n\nCertain other actions shall be done in accordance with Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. 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(q)\tThis amendment becomes effective on June 24, 1997.

On January 13, 1988, the FAA issued AD 87-04-13 R1, amendment 39-5836 (53 FR 2005, January 26, 1988), applicable to certain Boeing Model 747 series airplanes. That AD revised an existing AD to require inspection for cracking, and repair or replacement, as necessary, of the horizontal clevis of the pylon midspar attach fitting. That action was prompted by reports of cracking and corrosion in the fastener holes of the midspar attach fitting of the engine pylon. The actions required by that AD are intended to detect and correct such cracking/corrosion of the attach fitting, which could cause possible separation of the pylon and engine from the wing. \n\n\tIn addition, on November 25, 1996, the FAA issued AD 96-25-01, amendment 39-9842 (61 FR 66201, December 17, 1996), applicable to certain Boeing Model 747 series airplanes, to require inspections to detect broken sealant common to the lower horizontal clevis of the inboard and outboard strut midspar fittings and of the fasteners, and various follow-on actions. That action also requires inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis, and replacement of discrepant parts with new or serviceable parts, or repair, if necessary. That action also provides for optional terminating actions for the repetitive inspections. That action was prompted by reports of fatigue cracking, stress corrosion cracking, and fracturing of the horizontal clevis of the inboard midspar fitting of the number three strut. The actions required by that AD are intended to detect and correct such cracking and fracturing, which could result in drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the airplane. \n\nOther Relevant Rulemaking \n\n\tThe FAA has previously issued several other AD's that address cracking in the midspar fitting clevis on Boeing Model 747 series airplanes: \n\n\t1. AD 90-06-06, amendment 39-6490 (55FR 8374, March 7, 1990): Among various other actions, this AD requires structural modification, among various other actions, in accordance with Boeing Document No. D6-35999, dated March 31, 1989. The FAA has approved an alternative method of compliance that extends the compliance time threshold to a maximum of three years after the airplane reaches 20,000 total flight cycles, or until the mandated strut/wing modification is accomplished, whichever occurs first. Additionally, ultrasonic inspections to detect cracking of the fastener holes are required at intervals not to exceed 1,000 flight cycles in accordance with Boeing Service Bulletin 747-54-2118, dated July 26, 1986. If cracking or corrosion is detected during those inspections, rework or replacement of the midspar fitting with a new or serviceable part is required, in accordance with that service bulletin. \n\n\tThe FAA has approved Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, of as an alternative method of compliance for the requirements specified in AD 90-06-06, which references Boeing Service Bulletin 747-54-2118 as the appropriate source of service information. \n\n\t2. AD 95-10-16, amendment 39-9233 (60 FR 27008, May 5, 1995): For airplanes equipped with Pratt & Whitney Model JT9D engines (excluding Model JT9D-70 engines), that AD requires modification of the nacelle strut and wing structure, and inspections of the adjacent structure that has not been replaced by the modification, in accordance with Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994. As a condition to extend the compliance time from 32 to 56 months, AD 95-10-16 also requires repetitive ultrasonic inspections to detect cracking of the aft- most two fastener holes in both strut midspar fittings on the inboard and outboard nacelle struts, or modification of the aft-most two fastener holes as described in Boeing Service Bulletin 747-54-2118. \n\n\tThe FAA has approved the inspections of the upper and lower horizontal legs of the strut midspar fittings and compliance times for those inspections specified in Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 29, 1996, as an alternative to those actions specified in paragraphs (a)(2)(ii)(a) and (a)(2)(iv)(a) of AD 95-10-16. \n\n\tSince the issuance of that AD, Boeing Alert Service Bulletin 747-54A2159, Revision 1, dated June 1, 1995, and Revision 2, dated March 14, 1996, have been approved as alternative methods of compliance with that AD. \n\n\t3. AD 95-13-05, amendment 39-9285 (60 FR 33333, June 28, 1995): For airplanes equipped with Rolls Royce Model RB211 series engines, that AD requires modification of the strut/wing in accordance with Boeing Alert Service Bulletin 747-54A2157, dated January 12, 1995.\n\n\tSince the issuance of that AD, Boeing Alert Service Bulletin 747-54A2157, Revision 1, dated August 3, 1995, and Revision 2, dated November 14, 1996, have been approved as alternative methods of compliance with the AD. \n\n\t4. AD 95-13-07, amendment 39-9287 (60 FR 33336, July 28, 1995): For airplanes equipped with General Electric Model CF6-45 or -50 series engines, that AD requires modification of the strut/wing in accordance with Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994. \n\n\tSince issuance of that AD, Boeing Alert Service Bulletin 747-54A2158, Revision 1, dated August 17, 1995, and Revision 2, dated August 15, 1996, have been approved as alternative methods of compliance with that AD.\n\n Actions Since Issuance of AD 87-04-13 R1 and AD 96-25-01 \n\n\tSince the issuance of AD 96-25-01, the FAA has received reports indicating that cracking was found of the lower and upper leg of the horizontal clevis of the midspar fitting on Boeing Model 747 series airplanes. The cracking was detected during inspections that were conducted in accordance with AD 96-25-01. \n\n\tOne operator reported that a midspar fitting at the number three pylon was cracked at the fourth row of fasteners from the aft end on the upper leg of the horizontal clevis of the midspar fitting. This operator also reported a crack on the lower leg of the midspar fitting at the number two pylon at the second row from the aft end. Metallurgical analysis accomplished on the midspar fitting at the number three pylon indicates that the cause of the cracking was stress corrosion. \n\n\tThe FAA also received another report indicating that cracking was detected on the upper leg of the horizontal clevis of the midspar fitting at the second row of fasteners from the aft end at the number three pylon. In addition, this report indicated that cracking was also detected on that same airplane at the number 3 pylon at the second row from the aft end of the lower leg. The report also indicated that terminating action specified Boeing Service Bulletin 747-54-2118, dated July 25, 1986, had been accomplished on the affected airplane; this service bulletin was referenced in AD 96-25-01 as the appropriate source of service information. \n\n\tCracking or fracturing of the lower or upper horizontal clevis of the inboard and outboard strut midspar fittings, if not detected and corrected in a timely manner, could result in drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the airplane. \n\nExplanation of New Relevant Service Information \n\n\tSince the issuance of AD 87-04-13 R1 and AD 96-25-01, the FAA has reviewed and approved Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996. \nThis alert service bulletin describes procedures for the following: \n\n\t1. Removing sealant common to the lower and upper horizontal legs of the clevis of the outboard (for certain airplanes) and the inboard (for all airplanes) midspar fittings, and cleaning the midspar fittings. \n\n\t2. Performing detailed visual borescope inspections or alternative ultrasonic/detailed visual inspections to detect cracking, corrosion, and/or fracturing of the lower horizontal legs of the clevis of the strut midspar fittings, and repair, if necessary. \n\n\t3. Performing ultrasonic and detailed visual inspections to detect cracking, corrosion, and/or fracturing of the upper horizontal leg of the strut midspar fittings, and repair, if necessary. \n\n\t4. Reworking only the discrepant areas or hole. \n\n\t5. Reworking all fastener holes, or replacing the midspar fitting with new fittings, as applicable, if any discrepancy is detected; this eliminates the need for repetitive inspections. \n\n\tAdditionally, for all airplanes, the service bulletin references replacement of the midspar fittings, which involves modification of the strut/wing in accordance with the following Boeing service bulletins, as applicable. Accomplishment of this modification eliminates the need for repetitive inspections. \n\n\t1. Boeing Alert Service Bulletin 747-54A2157, dated January 12, 1995; Revision 1, dated August 3, 1995; or Revision2, dated November 14, 1996 (for airplanes equipped with Rolls Royce RB211 engines); \n\n\t2. Boeing Alert Service Bulletin 747-54-A2158, dated November 30, 1994; Revision 1, dated August 17, 1995; or Revision 2, dated August 15, 1996 (for airplanes equipped with General Electric CFC-45/-50 or Pratt & Whitney JT9D-70 engines); and \n\n\t3. Boeing Service Bulletin 747-54A2159, dated November 3, 1994; Revision 1, dated June 1, 1995; or Revision 2, dated March 14, 1996 (for airplanes equipped with Pratt & Whitney engines). \n\nExplanation of Requirements of Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 87-04-13 R1 and AD 96-25-01, as follows: \n\n\tFirst, this AD requires removal of certain sealant common to the lower and upper horizontal legs of the outboard (for certain airplanes) and the inboard (for all airplanes) midspar fittings, and cleaning the midspar fittings. \n\n\tThisAD continues to require repetitive detailed visual borescope inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis of the inboard and outboard strut midspar fittings. Replacement of discrepant fittings with new fittings is also required, or rework, as applicable. This AD adds ultrasonic/detailed visual inspections as an alternative method of accomplishing those inspections. \n\n\tThis AD adds repetitive ultrasonic/detailed visual inspections of the upper horizontal clevis of the inboard and outboard strut midspar fittings, and replacement of discrepant fittings with new fittings, or rework, if necessary. \n\n\tFor airplanes on which any cracking, corrosion, or fracturing is detected that is outside certain limits, this AD requires accomplishment of the strut/wing modification, replacement of the midspar fittings of the strut with new fittings, or repair in accordance with a method approved by the FAA, as applicable. \n\n\tAccomplishment of the strut/wing modification constitutes terminating action for the repetitive inspection requirements of this AD. \n\n\tCertain actions are required to be accomplished in accordance with Boeing Alert Service Bulletin 747-A2179, Revision 1, dated November 27, 1996, described previously. Certain other actions are required to be accomplished in accordance with a method approved by the FAA.\n\n Difference Between This AD and the Alert Service Bulletin \n\n\tOperators should note that, while the alert service bulletin advises operators to contact the manufacturer if the damaged area is beyond the specified limits, this AD requires operators to repair any such damage in accordance with a method approved by the FAA, Transport Airplane Directorate. \n\n\tOperators also should note that airplanes on which reworking of the upper and lower horizontal clevis of the midspar fittings has been accomplished in accordance with Boeing Service Bulletin 747-54-2118, dated July 25, 1986, have not been included in the effectivity of the alert service bulletin. However, the FAA has determined that, in light of the recent reports of cracking, the rework is not sufficient to provide adequate assurance of permanent correction of the unsafe condition addressed by this action. Therefore, the FAA has removed the provision for reworking from AD 96-25-01 as an optional terminating action for the repetitive inspection requirements of this AD. \n\n\tAdditionally, Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated November 27, 1996, describes the replacement of the midspar fittings of the strut as an optional method of eliminating the repetitive inspections. The alert service bulletin also references replacement of the midspar fittings of the strut in accordance with either the alert service bulletin or Boeing Service Bulletin 747-54-2118, Revision 4, dated May 11, 1989, as an optional terminating action, which eliminates the need for repetitive inspections. \n\n\tHowever, the FAA has determined that,in light of the recent reports of cracking discussed previously, neither the replacement nor the rework is sufficient to provide adequate assurance of permanent correction of the unsafe condition. Therefore, the FAA also has removed those optional terminating actions from this AD.\n\n Determination 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. Comments Invited \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\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 97-NM-70-AD." The postcard will be date stamped and returned to the commenter. \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\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 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: \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 39-5836 (53 FR 2005, January 26, 1988) and amendment 39-9842 (61 FR 66201, December 17, 1996), and by adding a new airworthiness directive (AD), amendment 39-10045, to read as follows: