AD 97-14-06

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing 747 series airplanes, that currently requires replacement of certain fuse pins on the upper link of the inboard and outboard struts. That AD also requires inspections to detect corrosion or cracks of certain fuse pins, and replacement, if necessary. This amendment reduces the compliance times of actions associated with certain fuse pins and provides for optional terminating action for the requirements of this AD. This amendment is prompted by a report of fracturing of a bulkhead style fuse pin located in the inboard strut at the forward end of the upper link. The actions specified in this AD are intended to prevent failure of the strut and separation of an engine from the airplane due to fracturing of the fuse pins.

Final rule; request for comments

97-14-06 BOEING: Amendment 39-10064. Docket 97-NM-94-AD. Supersedes AD 95-06-02, Amendment 39-9172. \n\n\tApplicability: Model 747 and 747-400 series airplanes, line numbers 1 through 967 inclusive, and 969 through 992 inclusive; certificated in any category; excluding airplanes equipped with Pratt & Whitney PW4000 or General Electric CF6-80C2 series engines; and excluding airplanes on which the strut/wing modification has been accomplished in accordance with AD 95-13-05, amendment 39-9285, AD 95-13-07, amendment 39-9287; or AD 95-10-16, amendment 39-9233. \n\n\tNOTE 1: This AD does not require that the actions be accomplished on those airplanes having pylons on which 15-5 corrosion resistant steel (third generation) fuse pins are installed through the upper link of the inboard and outboard struts. \n\n\tNOTE 2: 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 otherwise 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 (h) 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 failure of the strut and loss of an engine due to corrosion or cracking of the fuse pins, accomplish the following: \n\n\t(a)\tFor airplanes having bottle bore style fuse pins in the forward position on the upper link: Replace any bottle bore style fuse pin with a new bulkhead style fuse pin in the forward position, or with 15-5 corrosion resistant steel (third generation) fuse pins in the forward position, in accordance with Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997, at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD. \n\n\t\t(1)\tPrior to the accumulation of 5,000 total landings on the fuse pin, or within 5 years since installation of the pin, whichever occurs first. Or \n\t\t(2)\tWithin 6 months after April 13, 1995 (the effective date of AD 95-06-02, amendment 39-9172). \n\n\tNOTE 3: Third generation fuse pins are installed in pairs (in the forward and aft positions). Therefore, replacement of an individual upper link fuse pin in the forward position with a third generation pin also would necessitate replacement of the pin in the aft position. \n\n\tNOTE 4: The alert service bulletin references Boeing Service Bulletin 747-54-2155, dated September 23, 1993, as an additional source of service information for replacement of the fuse pinswith 15-5 corrosion resistant steel (third generation) fuse pins. Installation of these third generation fuse pins is preferred over installation of bulkhead style fuse pins. \n\n\t(b)\tFor airplanes having bulkhead style fuse pins in the forward position on the upper link: Perform a detailed visual inspection to detect corrosion of the pins, and a magnetic particle inspection to detect cracks, in accordance with Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997, at the earlier of the times specified in paragraphs (b)(1) and (b)(2) of this AD.\n\n\t\t(1)\tPerform the inspections at the later of the times specified in paragraphs (b)(1)(i) and (b)(1)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 8,000 total landings on the fuse pin, or within 8 years since installation of the pin, whichever occurs first. Or \n\n\t\t\t(ii)\tWithin 12 months after April 13, 1995. \n\n\t\t(2)\tPerform the inspections at the later of the times specified in paragraphs (b)(2)(i) and (b)(2)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 5,000 total landings on the fuse pin, or within 5 years since installation of the pin, whichever occurs first. Or \n\n\t\t\t(ii)\tWithin 90 days after the effective date of this AD. \n\n\t(c)\tFor the inboard and outboard struts on airplanes other than those identified in paragraph (d) of this AD: If no corrosion or crack is found during the inspection required by paragraph (b) of this AD, repeat the inspection thereafter, in accordance with Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997, at the time specified in paragraph (c)(1) or (c)(2) of this AD, as applicable. \n\n\t\t(1)\tFor airplanes on which the initial inspection required by paragraph (a) or (b) of AD 95-06-02 has been accomplished prior to the effective date of this AD: Repeat the inspection within 1,000 landings since the last inspection in accordance with AD 95-06-02, or within 500 landings after the effective date of this AD, whichever occurs first, and thereafter at intervals not to exceed 500 landings. \n\n\t\t(2)\tFor airplanes other than those identified in paragraph (c)(1) of this AD: Repeat the inspection thereafter at intervals not to exceed 500 landings. \n\n\t(d)\tFor the outboard struts on airplanes equipped with Rolls-Royce RB211-524G or -524H series engines: If no corrosion or crack is found during the inspection required by paragraph (b) of this AD, repeat the inspection thereafter in accordance with Boeing Alert Service Bulletin 747- 54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997, at the time specified in paragraph (d)(1) or (d)(2) of this AD, as applicable. \n\n\t\t(1)\tFor airplanes on which the initial inspection required by paragraph (a) or (b) of AD 95-06-02 has been accomplished prior to the effective date of this AD: Repeat the inspection within 2,000 landings since the last inspection in accordance with AD 95-06-02, or within 1,000 landingsafter the effective date of this AD, whichever occurs first, and thereafter at intervals not to exceed 500 landings. \n\n\t\t(2)\tFor airplanes other than those identified in paragraph (d)(1) of this AD: Repeat the inspection thereafter at intervals not to exceed 500 landings. \n\n\tNOTE 5: The outboard struts of airplanes equipped with Rolls-Royce RB211-524G or -524H series engines are equipped with thick wall "4330 steel" bulkhead style fuse pins in the forward position of the upper link. Crack propagation to critical length in these thick wall pins is slower than for pins installed on the struts of airplanes equipped with engines other than the Rolls-Royce RB211-524G or -524H series. \n\n\t(e)\tIf any corrosion or crack is found during any inspection required by this AD, prior to further flight, replace the corroded or cracked pin with either a new bulkhead style fuse pin in the forward position of the upper link, or with 15-5 corrosion resistant steel (third generation) fuse pins inthe forward and aft positions of the upper link; in accordance with Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997. Accomplish inspections, if applicable, as specified in paragraph (e)(1) or (e)(2). \n\n\t\t(1)\tIf the corroded or cracked fuse pin is replaced with a new bulkhead style fuse pin, prior to the accumulation of 5,000 total landings on the new pin, or within 5 years since installation of the new pin, whichever occurs first, perform a detailed visual inspection to detect corrosion of the new pin, and a magnetic particle inspection to detect cracks of the new pin, in accordance with the alert service bulletin. Repeat these inspections thereafter at the interval specified in paragraph (e)(1)(i) or (e)(1)(ii) of this AD, as applicable. \n\n\t\t\t(i)\tFor the inboard and outboard struts on airplanes other than those identified in paragraph (e)(1)(ii) of this AD: Repeat the inspections at intervals not to exceed 500 landings. \n\n\t\t\t(ii)\tFor the outboard struts on airplanes equipped with Rolls-Royce RB211-524G or -524H series engines: Repeat the inspections at intervals not to exceed 1,000 landings. \n\n\t\t(2)\tIf the corroded or cracked fuse pin is replaced with a 15-5 corrosion resistant steel (third generation) fuse pin, no further action is required by this AD. \n\n\t(f)\tAccomplishment of the strut/wing modification in accordance with Boeing Alert Service Bulletin 747-54A2166, Revision 1, dated May 1, 1997, constitutes terminating action for the requirements of this AD. \n\n\tNOTE 6: Boeing Alert Service Bulletin 747-54A2166, Revision 1, references Boeing Alert Service Bulletins 747-54A2157, 747-54A2158, and 747-54A2159 as additional sources of service information for accomplishment of the strut/wing modification. \n\n\t(g)\tInstallation of 15-5 corrosion resistant steel (third generation) fuse pins in the forward and aft positions of the upper link on the inboard or outboard strut in accordance with Boeing Alert Service Bulletin 747-54A2166, Revision 1, dated May 1, 1997, constitutes terminating action for the requirements of this AD. \n\n\t(h)\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 7: 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(i)\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(j)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, or Revision 1, dated May 1, 1997. The incorporation by reference of Boeing Alert Service Bulletin 747-54A2166, dated April 28, 1994, 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 April 13, 1995 (60 FR 13618, March 14, 1995). The incorporation by reference of Boeing Alert Service Bulletin 747-54A2166, Revision 1, dated May 1, 1997, 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(k)\tThis amendment becomes effective on July 18, 1997.

On March 3, 1995, the FAA issued AD 95-06-02, amendment 39-9172 (60 FR 13618, March 14, 1995), to require replacement of certain fuse pins on the upper link of the inboard and outboard struts. That AD also currently requires inspections to detect corrosion or cracks of certain fuse pins, and replacement, if necessary. (A correction of the rule was published in the Federal Register on April 19, 1995 (60 FR 19492).) That action was prompted by reports of cracked or corroded fuse pins on the upper link of the inboard and outboard struts, which could result in fracturing of the pins. \n\nActions Since Issuance of Previous Rule \n\n\tSince the issuance of AD 95-06-02, the FAA received a report indicating that a fracture of a bulkhead style fuse pin located in the inboard strut at the forward end of the upper link had occurred on a Boeing Model 747 series airplane. The bulkhead style fuse pin had accumulated 7,750 flight cycles and 42,027 flight hours. Metallurgical analysis of this pin indicated that the cause of the cracking was fatigue. Fracturing of the fuse pins, if not corrected, could result in failure of the strut and separation of an engine from the airplane. \n\nExplanation of Relevant Service Information\n\n\tSince the issuance of the previous rule, the FAA has reviewed and approved Boeing Alert Service Bulletin 747-54A2166, Revision 1, dated May 1, 1997, which reduces the recommended times for actions associated with certain fuse pins. The alert service bulletin references Boeing Alert Service Bulletins 747-54A2157, 747-54A2158, and 747-54A2159, which describe procedures for modification of the strut/wing. The alert service bulletin also references Boeing Service Bulletin 747-54-2155, which describes procedures for installation of 15-5 corrosion resistant steel (third generation) fuse pins in the forward and aft positions of the upper link on the inboard or outboard strut. Accomplishment of either the strut/wing modification or installation of 15-5 fuse pins eliminates the need for additional inspections or replacement of fuse pins. \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 95-06-02 to continue to require replacement of certain fuse pins on the upper link of the inboard and outboard struts. This AD also continues to require inspections to detect corrosion or cracks of certain fuse pins, and replacement, if necessary. This amendment reduces the compliance times of actions associated with certain bulkhead fuse pins. This amendment also provides for optional terminating action for the requirements of this AD. \n\n\tThis is considered to be interim action. The FAA may consider further rulemaking action to require the accomplishment of the optional terminating action (installation of 15-5 corrosion resistant steel (third generation) fuse pins) currently specified in this AD. However, the proposed compliance time for accomplishment of that action is sufficiently long so that prior notice and time for public comment will be practicable. \n\nDetermination 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. \n\nComments Invited \n\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-94-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 Adoption 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\n PART 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 39-9172 (60 FR 13618, March 14, 1995), and by adding a new airworthiness directive (AD), amendment 39-10064, to read as follows: