AD 95-17-01

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 707 and 720 series airplanes, that currently requires repetitive visual and dye penetrant inspections to detect cracks in areas of the upper forward skin panels of the wing center section, and repair, if necessary. It also provides an optional terminating modification for the repetitive inspections. This amendment requires repetitive visual and eddy current inspections to detect cracks in areas of the upper forward skin panels of the wing center section, and repair, if necessary. This amendment is prompted by reports indicating that the inspections required by the existing AD are not effective in detecting fatigue cracks in a timely manner. The actions specified by this AD are intended to prevent fatigue cracking and subsequent failure of the upper forward skin panels of the wing center section.

Final rule

95-17-01 BOEING: Amendment 39-9330. Docket 94-NM-14-AD. Supersedes AD 68-18-03, Amendment 39-2056. \n\n\tApplicability: Model 707 and 720 series airplanes; as listed in Boeing Service Bulletin 2590, Revision 11, dated December 12, 1991; 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 use the authority provided in paragraph (g) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent fatigue cracking and subsequent failure of the upper forward skin panels of the wing center section, accomplish the following: \n\n\t(a)\tFor Model 707-100, -200, -300, -300B, -300C, and -400 series airplanes on which no bulb angle stiffeners have been installed in accordance with Boeing Service Bulletin 2590: Perform a visual inspection and an eddy current inspection to detect cracks in the areas of the upper forward skin of the wing center section specified in paragraphs b. and f.(1) of Part I of the Accomplishment Instructions of Boeing Service Bulletin 2590, Revision 8, dated June 2, 1972; Revision 9, dated March 14, 1975; Revision 10, dated January 31, 1991; or Revision 11, dated December 12, 1991. Perform the inspections at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable, in accordance with the procedures specified in the service bulletin. Repeat these inspections thereafter at intervals not to exceed 450 landings. \n\n\t\t(1)\tFor Model 707-300, -300B, -300C, and -400 series airplanes: Inspect 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)\tPrior to the accumulation of 6,000 total landings; or \n\t\t\t(ii)\tWithin 500 landings or 18 months after the effective date of this AD, whichever occurs first. \t\n\n\t\t(2)\tFor Model 707-100 and -200 series airplanes: Inspect at the later of the times specified in paragraphs (a)(2)(i) and (a)(2)(ii) of this AD. \n\t\t\t(i)\tPrior to the accumulation of 6,400 total landings; or \n\t\t\t(ii)\tWithin 500 landings or 18 months after the effective date of this AD, whichever occurs first. \n\n\t(b)\tFor Model 720 and 720B series airplanes on which no bulb angle stiffeners have been installed in accordance with Boeing Service Bulletin 2590: Perform a visual inspection and an eddy current inspection to detect cracks in the area of the upper forward skin of the wing center section specified in paragraph b. of Part I of the Accomplishment Instructions of Boeing Service Bulletin 2590, Revision 8, dated June 2, 1972; Revision 9, dated March 14, 1975; Revision 10, dated January 31, 1991; or Revision 11, dated December 12, 1991. Perform the inspections at the later of the times specified in paragraphs (b)(1) and (b)(2) of this AD, in accordance with the procedures specified in the service bulletin. Repeat these inspections thereafter at intervals not to exceed 450 landings. \n\n\t\t(1)\tPrior to the accumulation of 4,000 total landings; or \n\t\t(2)\tWithin 500 landings or 18 months after the effective date of this AD, \n\t\t\twhichever occurs first. \n\n\t(c)\tFor Model 720 and 720B, and 707-100, -200, -300, -300B, -300C, and -400 series airplanes on which bulb angle stiffeners have been installed, but on which the wing skin has not been replaced, in accordance with Boeing Service Bulletin 2590: Accomplish the inspections required by paragraph (c)(1), (c)(2), or (c)(3) of this AD, as applicable, in accordance with Boeing Service Bulletin 2590, Revision 11, dated December 12, 1991. Repeat these inspections thereafter at intervals not to exceed 1,000 landings. \n\n\tNOTE 2: Revision 11 of Boeing Service Bulletin 2590 is part of Boeing Service Bulletins 3484 (for Model 707-100 and -200 series airplanes), 3485 (for Model 720 and 720B series airplanes), and 3486 (for Model 707-300, -300B, -300C, and -400 series airplanes), all dated December 12, 1991. Boeing Service Bulletin 2590 references these service bulletins as additional sources of service information concerning accomplishment of the inspections required by paragraph (c) of this AD. \n\n\t\t(1)\tFor Model 720 and 720B series airplanes: Perform a visual and an eddy current inspection to detect cracks in the areas of the upper forward skin of the wing center section specified on pages 34 and 35 of Boeing Service Bulletin 3485, dated December 12, 1991, at the later of the times specified in paragraphs (c)(1)(i) and (c)(1)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 2,200 landings after installation of the bulb angle stiffeners; or \n\t\t\t(ii)\tWithin 500 landings or 18 months after the effective date of this AD, whichever occurs first. \n\n\t\t(2)\tFor Model 707-300, -300B, -300C, and -400 series airplanes: Perform a visual and an eddy current inspection to detect cracks in the areas of the upper forward skin of the wing center section specified on page 55 of Boeing Service Bulletin 3486, dated December 12, 1991, at the later of the times specified in paragraphs (c)(2)(i) and (c)(2)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 2,200 landings after installation of the bulb angle stiffeners; or \n\t\t\t(ii)\tWithin 500 landings or 18 months after the effective date of this AD, whichever occursfirst.\n \t\n\t\t(3)\tFor Model 707-100 and -200 series airplanes: Perform a visual and an eddy current inspection to detect cracks in the areas of the upper forward skin of the wing center section specified on pages 37 and 38 of Boeing Service Bulletin 3484, dated December 12, 1991, at the later of the times specified in paragraphs (c)(3)(i) and (c)(3)(ii) of this AD. \n\n\t\t\t(i)\tPrior to the accumulation of 2,200 landings after installation of the bulb angle stiffeners; or \n\t\t\t(ii)\tWithin 500 landings or 18 months after the effective date of this AD, whichever occurs first. \n\n\t(d)\tIf any crack is found during any inspection required by paragraph (a), (b), or (c) of this AD, prior to further flight, repair in accordance with Part II of the Accomplishment Instructions of Boeing Service Bulletin 2590, Revision 7, dated September 22, 1969; Revision 8, dated June 2, 1972; Revision 9, dated March 14, 1975; Revision 10, dated January 31, 1991; or Revision 11, dated December 12, 1991. \n\n\t(e)\tFor Model 707 series airplanes: Accomplishment of the "Reinforcing Stiffener Installation and Skin Panel Replacement" in accordance with Part III of the Accomplishment Instructions of Boeing Alert Service Bulletin 2590, Revision 6, dated July 8, 1968; Boeing Service Bulletin 2590, Revision 7, dated September 22, 1969, Revision 8, dated June 2, 1972, Revision 9, dated March 14, 1975, Revision 10, dated January 31, 1991, or Revision 11, dated December 12, 1991; constitutes terminating action for the inspections required by paragraphs (a), (b), and (c) of this AD. Accomplishment of the reinforcement and replacement in accordance with Boeing Alert Service Bulletin 2590, Revision 5, dated September 20, 1967, also is considered acceptable for compliance with paragraph (e) of this AD provided that the forward skin panel also is replaced in accordance with that service bulletin. \n\n\t(f)\tFor Model 720 series airplanes: Accomplishment of the "Reinforcing Stiffener Installation and Skin Panel Replacement" in accordance with Part III of the Accomplishment Instructions of Boeing Alert Service Bulletin 2590, Revision 6, dated July 8, 1968; Boeing Service Bulletin 2590, Revision 7, dated September 22, 1969, Revision 8, dated June 2, 1972, Revision 9, dated March 14, 1975, Revision 10, dated January 31, 1991, or Revision 11, dated December 12, 1991; constitutes terminating action for the inspections required by paragraphs (a), (b), and (c) of this AD. Accomplishment of the reinforcement and replacement in accordance with Boeing Alert Service Bulletin 2590, Revision 4, dated May 26, 1967, or Revision 5, dated September 20, 1967, also is considered acceptable for compliance with paragraph (f) of this AD provided that the forward skin panel also is replaced in accordance with that service bulletin. \n\n\t(g)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(h)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location here the requirements of this AD can be accomplished. \n\n\t(i)\tThe actions shall be done in accordance with the following service documents: \n\n\tBoeing Alert Service Bulletin 2590, Revision 4, dated May 26, 1967; \n\tBoeing Alert Service Bulletin 2590, Revision 5, dated September 20, 1967; \n\tBoeing Alert Service Bulletin 2590, Revision 6, dated July 8, 1968; \n\tBoeing Service Bulletin 2590, Revision 7, dated September 22, 1969; \n\tBoeing Service Bulletin 2590, Revision 8, dated June 2, 1972; \n\tBoeing Service Bulletin 2590, Revision 9, dated March 14, 1975; \n\tBoeing Service Bulletin 2590, Revision 10, dated January 31, 1991; \n\tBoeing Service Bulletin 2590, Revision 11, dated December 12, 1991; \n\tpages 37 and 38 of Boeing Service Bulletin 3484, dated December 12, 1991; \n\tpages 34 and 35 of Boeing Service Bulletin 3485, dated December 12, 1991; and \n\tpages 55 and 56 of Boeing Service Bulletin 3486, dated December 12, 1991. \n\tBoeing Alert Service Bulletin 2590, Revision 6, dated July 8, 1968, contains the following specified effective pages: \n\n\n\nPage Number\nRevision Level\nShown on Page\nDate \nShown on Page\n1, 3-5, 7, 9, 10, 14, 16 \n6\nJuly 8, 1968\n2, 6, 8, 11-13, 15\t\n5\nSeptember 20, 1967 \n\nThis incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(j)\tThis amendment becomes effective on September 13, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Boeing Model 707 and 720 series airplanes, was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on February 7, 1995 (60 FR 7143). That supplemental NPRM proposed to supersede AD 68-18-03, amendment 39-2056. That AD currently requires repetitive visual and dye penetrant inspections to detect cracks on the upper forward skin panels of the wing center section, and repair, if necessary. It also provides an optional terminating modification for the repetitive inspections. The supplemental NPRM proposed to require repetitive visual and eddy current inspections to detect cracks on the upper forward skin panels of the wing center section, and repair, if necessary.\n \n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received. \n\n\tThe commenter requests that paragraph (e) of the proposal be revised to allow that the terminating action specified in that paragraph be accomplished in accordance with procedures contained in revisions prior to Revision 6 of Boeing Service Bulletin 2590, provided that, in addition to the installation of reinforcing stiffeners, the forward skin panel is replaced. The commenter indicates that the modifications described in these earlier revisions of the service bulletin are identical to those specified in Revisions 6 and subsequent. The commenter adds that the "aging fleet document" (Boeing Document D6-54496), which addresses the affected airplanes, specifies that modifications accomplished in accordance with the original issue through Revision 8 of Boeing Service Bulletin 2590 are considered to be terminating action, provided that new forward skin panels are installed. The commenter states that the inconsistency between theproposal and the "aging fleet document" in this regard has caused confusion among some operators as to whether airplanes modified in accordance with earlier revisions of the service bulletin are considered to be in compliance with the proposed AD. \n\n\tThe FAA concurs partially. The FAA has re-examined the earlier revisions of the service bulletin, and has determined that the original issue and Revisions 1 through 3 of the service bulletin were issued as telegraphic documents. These revisions do not adequately address procedures for accomplishing the terminating modifications in sufficient detail. Therefore, the FAA does not consider these revisions to be acceptable for accomplishment of the terminating modification specified in this AD. However, Revision 4 does provide adequate procedures for accomplishing the terminating modification for Model 720 series airplanes, provided that the forward skin panel also is replaced in accordance with the service bulletin. In addition, Revision 5 contains adequate information for accomplishment of the terminating modification for both Model 707 and 720 series airplanes, provided that the forward skin panel also is replaced in accordance with the service bulletin. These determinations have been specified in paragraphs (e) and (f) of the final rule for Models 707 and 720 series airplanes, respectively. \n\n\tCertain service bulletin titles were referenced incorrectly in NOTE 2 and paragraphs (c)(1), (c)(2), and (c)(3) of the supplemental NPRM as "Boeing Master Inspection Service Bulletins." The appropriate titles for these service documents are "Boeing Service Bulletins." The FAA has revised the note and those paragraphs of the final rule accordingly. In addition, the FAA has added references to specific page numbers of those service bulletins for the convenience of operators. \n\n\tIn addition, paragraph (e) of the supplemental NPRM did not specify that Revision 6 of Boeing Service Bulletin 2590 was issued as an alert service bulletin. The final rule has been revised accordingly. \n\n\tAfter careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\n\tThere are approximately 416 Model 707 and 720 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 82 airplanes of U.S. registry will be affected by this AD, that it will take approximately 32 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $157,440, or $1,920 per airplane, per inspection cycle. \n\n\tThe total 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 \n\tShould an operator elect to accomplish the optional terminating action that is provided by this AD action, it will take approximately 1,250 work hours to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts is approximately $45,000 per airplane. Based on these figures, the total cost impact of the optional terminating action is estimated to be $120,000 per airplane. \n\n\tThe regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \n\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:PART 39 - AIRWORTHINESS DIRECTIVES\n \n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40101, 40113, 44701. § 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-2056, and by adding a new airworthiness directive (AD), amendment 39-9330, to read as follows: