AD 2001-23-15

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires repetitive detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. That AD also provides for an optional terminating modification for the repetitive inspections. This amendment continues to require repetitive detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. This amendment mandates accomplishment of the previously optional terminating modification. The actions specified by this AD are intended to find and fix discrepancies of the installation of the midspar fuse pins, which could result in loss of the secondary retention capability of the fuse pins, migration of the fuse pins, and consequent loss of the strut and engine from the airplane. This action is intended to address the identified unsafe condition.

Final rule.

2001-23-15 Boeing: Amendment 39-12514. Docket 2001-NM-02-AD. Supersedes AD 2001-05-05, amendment 39-12141. \n\n\tApplicability: Model 747 series airplanes, line numbers 1 through 1046 that have accomplished Airworthiness Directives 95-10-16, 95-13-05, 95-13-06, or 95-13-07; and line numbers 1047 through 1271 inclusive; 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 (c)(1) 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 conditionhas 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 find and fix discrepancies of the installation of the midspar fuse pins of the inboard and outboard strut, which could result in loss of the secondary retention capability of the fuse pins, migration of the fuse pins, and consequent loss of the strut and engine from the airplane; accomplish the following: \n\nRestatement of the Requirements of AD 2001-05-05 \n\nInspections/Follow-On Actions \n\n\t(a) At the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable: Do a detailed visual inspection to find discrepancies (e.g., incorrect thread protrusion, which is less than two threads protruding from the nut between the nut and the secondary retention washer; incorrect gap between the fuse pin primary nut and secondary retention washer; cracked or broken torque stripe) of the installation of the midspar fuse pins of the inboard and outboard struts, per Figure 2 of Boeing Service Bulletin 747-54A2206, Revision 1, dated February 22, 2001, or Revision 2, dated May 17, 2001. \n\n\t\t(1) For airplanes having the production equivalent of one of the AD's listed in Table 1 of this AD: Do the inspection at the later of the times specified in paragraphs (a)(1)(i) and (a)(1)(ii) of this AD. \n\n\t\t\t(i) Before the accumulation of 8,000 total flight hours, or within 24 months since manufacture of the airplane, whichever occurs first. \n\n\t\t\t(ii) Within 90 days after March 21, 2001 (the effective date of AD 2001-05-05, amendment 39-12141). \n\n\t\t(2) For airplanes modified per one of the AD's listed in Table 1 of this AD: Do the inspection at the later of the times specified in paragraphs (a)(2)(i) and (a)(2)(ii) of this AD. Table 1 follows: \n\n\tTable 1\n\nAD No.\nAmendment No. \nAD 95-10-16\n39-9233 \nAD 95-13-05\n39-9285\nAD 95-13-06\n39-9286 \nAD 95-13-07\n39-9287\n\n\t\t\t(i) Within 8,000 flight hours or 24 months after the modification, whichever occurs first. \n\n\t\t\t(ii) Within 90 days after March 21, 2001. \n\n\tNote 2: Where there are differences between the AD and the service bulletin, the AD prevails. \n\n\tNote 3: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\n\t\t\t(A) If no discrepancy is found: Repeat the inspection at intervals not to exceed 8,000 flight hours or 24 months, whichever occurs first, until you do the terminating modification specified in paragraph (b) of this AD. \n\n\t\t\t(B) If any discrepancy is found, and the primary nut has backed off and contacts the secondary retention washer: Before further flight, do the terminating modification specified in paragraph (b) of this AD. \n\n\t\t\t(C) If any discrepancy is found, and the primary nut does not contact the secondary retention washer: Repeat the inspection at intervals not to exceed 90 days. Within 18 months after the initial finding, or before March 21, 2001, whichever occurs later, do the terminating modification specified in paragraph (b) of this AD. \n\n\tNote 4: Inspections done prior to the effective date of this AD per Boeing Alert Service Bulletin 747-54A2206, dated October 19, 2000, are acceptable for compliance with the inspections required by paragraph (a) of this AD. \n\nNew Requirements of This AD \n\nTerminating Action \n\n\t(b) Within 6 years after the effective date of this AD: Do the terminating modification (replacement of the primary nut of the midspar fuse pin, installation of torque strip, a detailed visual inspection of the fuse pin threads fordamage, and replacement, if necessary) per Figure 3 of Boeing Service Bulletin 747-54A2206, Revision 1, dated February 22, 2001, or Figure 3 of Boeing Service Bulletin 747-54A2206, Revision 2, dated May 17, 2001. Doing this modification ends the repetitive inspections required by this AD. \n\n\tNote 5: Doing the terminating modification prior to the effective date of this AD per Boeing Alert Service Bulletin 747-54A2206, dated October 19, 2000, is acceptable for compliance with the terminating action required by paragraph (b) of this AD. \n\nAlternative Methods of Compliance \n\n\t(c)\t(1) An 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. 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\t\t(2) Any alternative methodof compliance which was approved previously in accordance with AD 2001-05-05 is approved for compliance with this AD. \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\nSpecial Flight Permits \n\n\t(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(e) The actions shall be done in accordance with Boeing Service Bulletin 747-54A2206, Revision 1, dated February 22, 2001; or Boeing Service Bulletin 747-54A2206, Revision 2, dated May 17, 2001. \n\n\t\t(1) The incorporation by reference of Boeing Service Bulletin 747-54A2206, Revision 2, dated May 17, 2001, is approved by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.(2) The incorporation by reference of Boeing Service Bulletin 747-54A2206, Revision 1, dated February 22, 2001, was approved previously by the Director of the Federal Register as of March 21, 2001 (66 FR 13424, March 6, 2001). \n\n\t\t(3) 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\nEffective Date \n\n\t(f) This amendment becomes effective on December 31, 2001.

Existing airworthiness directive AD 2001-05-05, amendment 39-12141 (66 FR 13424), applicable to certain Boeing Model 747 series airplanes, was published in the Federal Register on March 6, 2001 as a final rule with request for comments. This AD requires repetitive detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. This AD also provides for an optional terminating modification for the repetitive inspections. The rule became effective on March 21, 2001. \n\n\tA proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 2001-05-05 was published in the Federal Register on April 26, 2001 (66 FR 20950). The action proposed to continue to require repetitive detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. The action also proposed to mandate accomplishment of the previously optional terminating modification. \n\nActions Since the Issuance of the NPRM \n\n\tSince the issuance of the NPRM, the FAA has reviewed and approved Boeing Service Bulletin 747-54A2206, Revision 2, dated May 17, 2001. Revision 2 describes procedures for use of an alternate replacement nut, in addition to the replacement nut specified in Revision 1, dated February 22, 2001. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this rule. The FAA received comments regarding both AD 2001-05-05 and the proposed rule having Docket Number 2001-NM-02-AD. These comments and our response are presented below. \n\nI. Comments to AD 2001-05-05 \n\nRequest for Use of an Alternate Replacement Nut \n\n\tOne commenter requests that the FAA provide for use of an alternate replacement for the primary retention nut having part number (P/N) BACN10JC24CD, which is listed in Boeing Service Bulletin 747-54A2206, Revision 1, dated February 22, 2001. The commenter states that the replacement nuts specified in AD 2001-05-05 are not readily available from the manufacturer. \n\n\tThe FAA concurs, and has changed this final rule accordingly by approving Boeing Service Bulletin 747-54A2206, Revision 2, dated May 17, 2001, which provides for use of an alternate replacement nut. \n\nRequest for Increase of Repetitive Inspection Interval \n\n\tAnother commenter asks that the repetitive inspection interval specified in paragraph (a) be increased from 8,000 flight hours to 8,500 flight hours to facilitate inspections at the C-check. \n\n\tThe FAA does not concur because the specified repetitive interval is based on the recommendation of the manufacturer and on the C-check schedule of the majority of operators. However, the FAA notes that the commenter may apply for an alternative method of compliance, in accordance with paragraph (c)(1) of this AD. \n\nII. Comments to 2001-NM-02-AD \n\nRequest To Continue Terminating Action as Optional \n\n\tOne commenter objects to the proposal to mandate accomplishment of the previously optional terminating action. The commenter cites two reasons for its objection: (1) It has found no instances of backed-off primary retention nuts for the midspar fuse pins on the inboard and the outboard strut, and (2) there are two fuse pin retention devices in place, which are designed to prevent midspar fuse pin migration. \n\n\tThe FAA does not concur that the previously optional terminating action should remain optional. The unsafe condition has resulted in at least three incidents of the primary retention nut on the midspar fitting fuse pin backing off. In one of these incidents, the primary retention nut contacted the secondary retention washer. This action will require that the terminating action be performed within 6 years. If the repetitive inspections reveal a discrepancy, the terminating action must be performed sooner. Therefore, no change to the final rule has been made in response to this comment. \n\nRequest for Clarification of Applicability \n\n\tThe manufacturer requests that the wording in paragraph (a)(1) of the proposed AD be changed from "For airplanes modified per the production equivalent of one of the AD's listed in Table 1 of this AD:" to "For airplanes having the production equivalent of one of the AD's listed in Table I of this AD:" and that AD 99-10-10 be removed from Table 1. \n\n\tThe FAA agrees that these changes will provide clarification and has changed paragraph (a)(1) of this AD accordingly. In line with this change, the FAA has also revised the applicability of this AD to specify this clarification. \n\nRequest To Revise Cost Impact \n\n\tOne commenter requests that the FAA revise the Cost Impact paragraph to reflect that at least 12 work-hours may be necessary to perform the required action rather than the 4 work-hours cited in the proposed rule. \n\n\tThe FAA does not concur. The cost analysis of the AD is limited to the cost of actions actually required by the rule. It does not consider the costs of "on condition" actions, such as replacing a nut, if replacement is needed during a required inspection. Such "on-condition" actions would be required to be accomplished, regardless of AD direction, in order to correct an unsafe condition identified in an airplane and to ensure operation of that airplane in an airworthy condition, as required by the Federal Aviation Regulations. In addition, the FAA recognizes that, in accomplishing the requirements of any AD, operators may incur "incidental" costs in addition to the "direct" costs that are reflected in the cost analysis presented in the AD preamble. However, the cost analysis in AD rulemaking actions typically does not include incidental costs, such as the time required to gain access and close up; planning time; or time necessitated by other administrative requirements. No change to the cost impact is necessary in the final rule. \n\nConclusion \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 described above. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 1,111 Boeing Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 256 airplanes of U.S. registry will be affected by this AD. \n\n\tThe inspections that are currently required by AD 2001-05-05 take approximately 4 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 inspections on U.S. operators is estimated to be $61,440, or $240 per airplane, per inspection cycle. \n\n\tThe terminating modification that is required by this new AD will take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,000 per airplane. Based on these figures, the cost impact of the modification required by this AD on U.S. will be $317,440, or $1,240 per airplane. \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. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) Is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\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: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-12141 (66 FR 13424, March 6, 2001), and by adding a new airworthiness directive (AD), amendment 39-12514, to read as follows: