AD 2000-11-07

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-200, -300, and -400 series airplanes, that currently requires repetitive high frequency eddy current (HFEC) inspections to detect cracking of the front spar web of the center section of the wing, and repair, if necessary. This amendment requires that the existing inspection be accomplished at a reduced threshold, and adds a requirement that the existing HFEC inspection be accomplished on repaired areas. This amendment is prompted by reports of cracking in repaired areas of the front spar web and cracking of the front spar web on an airplane that had accumulated fewer flight cycles than the inspection threshold of the existing AD. The actions specified by this AD are intended to prevent the leakage of fuel into the forward cargo bay, as a result of fatigue cracking in the front spar web, which could result in a potential fire hazard.

Final rule

2000-11-07 BOEING: Amendment 39-11755. Docket 99-NM-30-AD. Supersedes AD 97-05-01, Amendment 39-9945. \n\n\tApplicability: Model 747-200, -300, and -400 series airplanes; up to and including line number 744; 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 (d) 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 the leakage of fuel into the forward cargo bay, as a result of fatigue cracking in the front spar web, which could result in a potential fire hazard, accomplish the following: \n\nRESTATEMENT OF REQUIREMENT OF AD 97-05-01 \nRepetitive Inspections \n\n\t(a)\tPerform a high frequency eddy current (HFEC) inspection to detect cracking of the front spar web of the center section of the wing, in accordance with Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996; Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997; or Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999; at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable, until accomplishment of the requirements of paragraph (b) of this AD. \n\n\t\t(1)\tFor airplanes that have accumulated 12,000 to 17,999 total landings as of April 2, 1997 (the effective date of AD 97-05-01, amendment 39-9945): Perform the initial inspection within 12 months after April 2, 1997, unless previously accomplished within the last 12 months prior to April 2, 1997. Perform this inspection again prior to the accumulation of 18,000 total landings or within 1,400 landings, whichever occurs later; after accomplishing the initial inspection, and thereafter at intervals not to exceed 1,400 landings. \n\n\t\t(2)\tFor all other airplanes: Perform the initial inspection prior to the accumulation of 18,000 total landings or within 12 months after April 2, 1997, whichever occurs later. Repeat this inspection thereafter at intervals not to exceed 1,400 landings. \n\nNEW REQUIREMENTS OF THIS AD \nRepetitive Inspections \n\n\t(b)\tPrior to accumulation of 12,000 total landings, or within 12 months after the effective date of this AD, whichever occurs later, perform an HFEC inspection to detect cracking of the front spar web of the center section of the wing, in accordance with Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997; or Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999. Repeat the HFEC inspection thereafter at intervals not to exceed 1,400 landings. Accomplishment of the HFEC inspection constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD. \n\n\tNote 2: Inspections accomplished prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996, are acceptable for compliance with the initial inspection required by paragraph (b) of this AD, provided that the airplane does not have a repair installed in the inspection area. Repair \n\n\t(c)\tIf any cracking is detected during any inspection required by paragraph (a) or (b) of this AD, prior to further flight, confirm the cracking with secondary procedures in accordance with Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997, or Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999. Thereafter repeat the HFEC inspection required by paragraph (a) or (b) of this AD at intervals not to exceed 1,400 landings. \n\n\t\t(1)\tIf any vertical crack is found that is less than 10 inches in length and has not extended in a diagonal direction, prior to further flight, repair in accordance with the service bulletin. \n\n\t\t(2)\tIf any vertical crack is found that is 10 inches or greater in length; or if any crack is found that has extended in a diagonal direction (regardless of the length); or if any crack is found that would affect an existing repair, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Designated Engineering Representative who has been authorized by the FAA to make such findings. Fora repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD. \n\nAlternative Methods of Compliance \n\n\t(d)\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\n\tNote 3: 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(e)\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\nIncorporation by Reference \n\n\t(f)\tExcept as provided by paragraph (c)(2) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996; Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997; or Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999; as applicable. 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. \n\n\t\t(1)\tThe incorporation by reference of Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997; and Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999; is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. \n\n\t\t(2)\tThe incorporation by reference of Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996; was approved previously by the Director of the Federal Register as of April 2, 1997(62 FR 8613, February 26, 1997). \n\n\t\t(3)\tCopies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\nEffective Date \n\n\t(g)\tThis amendment becomes effective on July 6, 2000.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 97-05-01, amendment 39-9945 (62 FR 8613, February 26, 1997), which is applicable to certain Boeing Model 747-200, -300, and -400 series airplanes, was published in the Federal Register on December 21, 1999 (64 FR 71336). The action proposed to require that the repetitive high frequency eddy current (HFEC) inspections to detect cracking of the front spar web of the center section of the wing required by the existing AD be accomplished at a reduced threshold. The action also proposed to require that the HFEC inspection be accomplished on repaired areas. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nSupport for the Proposal \n\n\tOne commenter supports the proposed rule. Request to Reference Additional Source of Service Information \n\n\tOne commenter requests that the FAA revise paragraph (b) of the proposed rule to allow the HFEC inspection described in that paragraph to be accomplished in accordance with Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996. (The proposed rule references Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997, and Revision 3, dated January 7, 1999, as appropriate sources of service information for accomplishment of the actions required by paragraph (b).) The commenter states that the inspection method to detect cracking of the forward side of the front spar web in Revision 1 of the alert service bulletin is identical to the method described in Revisions 2 and 3. The commenter also states that operators who have accomplished the HFEC inspection in accordance with paragraph (a)(1) of AD 97-05-01 (which is restated as paragraph (a)(1) of this AD) should be given credit for performing the inspection. To this end, the commenter requests that the compliance time of paragraph (b) of this AD be revised from "Prior to accumulation of 12,000 total landings, or within 12 months after the effective date of this AD, whichever occurs later," to incorporate an option for the inspection to be accomplished "within 1,400 landings after the previous HFEC inspection." \n\n\tThe FAA partially concurs with the commenter's request. Although the inspection method is identical in Revisions 1, 2, and 3 of the service bulletin, as explained in the preamble of the proposed rule, Revisions 2 and 3 of the service bulletin describe an inspection of the aft side of the front spar web for areas where a repair is located on the forward side. For this reason, paragraph (b) of the proposed rule requires inspection in accordance with Revision 2 or 3 of the service bulletin. However, because the inspection is the same for airplanes without repairs in the area of the inspection, the FAA finds that inspections accomplished prior to the effectivedate of this AD in accordance with Revision 1 of the alert service bulletin are acceptable for compliance with the initial inspection required by paragraph (b) of this AD, provided that the airplane does not have a repair installed in the inspection area. A new "Note 2" has been added to this final rule accordingly. However, the FAA has determined that the accomplishment instructions in Revisions 2 and 3 of the service bulletin are clearer than those in Revision 1 of the alert service bulletin; therefore, inspections in accordance with paragraph (b) of this AD accomplished after the effective date of this AD are required to be accomplished in accordance with Revision 2 or 3 of the service bulletin. \n\n\tWith regard to the commenter's request to revise the compliance time for the actions required by paragraph (b) of this AD, the FAA finds that no change to the final rule is required beyond the inclusion of the new "Note 2," as described above. Credit is always given for actions accomplished prior to the effective date of an AD by means of the phrase, "Compliance: Required as indicated, unless accomplished previously." \n\nRequest to Revise Cost Impact Information \n\n\tOne commenter requests that the FAA revise the estimated number of work hours stated in the cost impact section of the preamble of the proposed rule from 8 work hours to 48 work hours per airplane. The commenter points out that the manufacturer estimates 48 work hours per airplane in Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999. The commenter states that, based on its experience, the proposed actions take approximately 48 work hours. \n\n\tThe FAA does not concur with the commenter's request. The estimate of 48 work hours given in the service bulletin includes time for gaining access and closing up. The cost analysis in AD rulemaking actions, however, 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 actions. Because incidental costs may vary significantly from operator to operator, they are almost impossible to calculate. The number of work hours necessary to accomplish the required actions, specified as 8 in the cost impact information in the proposal and restated below, represents the time necessary to perform only the actions actually required by this AD (that is, the inspection). No change to the final rule is necessary in this regard. \n\nRequest to Clarify "Terminating Action" Statement in Paragraph (b) \n\n\tOne commenter, the airplane manufacturer, states that one operator was confused by the statement in paragraph (b) of the proposed rule that, "Accomplishment of the HFEC inspection constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD." The operator was confused because paragraph (a) of the proposed rule specifies repetitive inspections at intervals not to exceed 1,400 landings. The operator found these statements contradictory. \n\n\tThe commenter makes no specific request for a change to the proposed rule. The FAA infers that the operator to whom the commenter refers does not understand the meaning of "terminating action." Paragraph (a) of this AD states that the inspection in that paragraph is to be performed "at the time specified in paragraph (a)(1) or (a)(2) of this AD, .until accomplishment of the requirements of paragraph (b) of this AD." As stated previously, paragraph (b) of this AD states that "Accomplishment of the HFEC inspection constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD." Once the initial inspection in accordance with paragraph (b) of this AD has been accomplished, the repetitive inspections in paragraph (a) of this AD are no longer necessary and need not be accomplished. The repetitive inspections specified in paragraph (b) of this AD must be accomplished at intervals not to exceed 1,400 landings (as stated in that paragraph). The FAA finds that no further clarification is necessary, and no change to the final rule is necessary in this regard. \n\nRequest to Revise AD Referencing Supplemental Structural Inspection Items \n\n\tOne commenter requests that the FAA revise AD 94-15-18, amendment 39-8989 (59 FR 41233, August 11, 1994), to exclude Supplemental Structural Inspection Document (SSID) Items W-3A and W-3B on SSID-candidate airplanes that are included in the effectivity listing of Boeing Service Bulletin 747-57A2298. The commenter states that the SSID inspections allow detailed visual and surveillance inspections of the front spar web at "D"-check intervals using sampling methods. This AD requires HFEC inspections of the front spar web at intervals not to exceed 1,400 landings for all airplanes included in the applicability of this AD. \n\n\tThe FAA does not concur with the commenter's request. The commenter's request is not relevant to this proposed rule. In the future, should the FAA consider further rulemaking to revise AD 94-15-18, the issue raised by the commenter would be appropriate to address. No change to the final rule is necessary in this regard. \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 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\nCost Impact \n\n\tThere are approximately 485 Model 747-200, -300, and -400 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 105 airplanes of U.S. registry will be affected by this AD. \n\n\tThe inspections that are currently required by AD 97-05-01 and retained in this AD, take approximately 8 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 actions on U.S. operators is estimated to be $50,400, or $480 per airplane, per inspection cycle. \n\n\tThe cost impact figure discussed above 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\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\t1. The authority citation for part 39 continues to read as follows: \nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n§ 39.13 (Amended) \n\t2. Section 39.13 is amended by removing amendment 39-9945 (62 FR 8613, February 26, 1997), and by adding a new airworthiness directive (AD), amendment 39-11755, to read as follows: