AD 99-21-06

This amendment supersedes an existing airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-9-81, -82, -83, and -87 series airplanes (MD-81, -82, -83, and -87), and Model MD-88 airplanes, that currently requires visual or eddy current inspections to detect cracks of the actuator cylinder support brackets of the slat drive mechanism assembly, and replacement of any cracked brackets. This amendment continues to require repetitive eddy current inspection, adds an inspection requirement, and expands the area of inspection. This amendment also provides terminating action for the repetitive inspections. This amendment is prompted by reports indicating that additional cracking was found outside the original inspection area. The actions specified by this AD are intended to prevent inadvertent slat retraction in flight.

Final rule.

99-21-06 MCDONNELL DOUGLAS: Amendment 39-11349. Docket 98-NM-267-AD. Supersedes AD 91-21-11, Amendment 39-8058. \n\n\tApplicability: All Model DC-9-81, -82, -83, and -87 series airplanes (MD-81, -82, -83, and -87); and Model MD-88 airplanes; 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 (h)(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 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 inadvertent slat retraction in flight, accomplish the following: \n\nRESTATEMENT OF CERTAIN REQUIREMENTS OF AD 91-21-11, AMENDMENT 39-8058 \n\t(a)\tPrior to the accumulation of 10,000 total landings or within 30 days after October 30, 1991 (the effective date of AD 91-21-11), whichever occurs later, perform a visual or eddy current inspection to detect cracks of the actuator cylinder support brackets of the slat drive mechanism assembly, part numbers 5938886--(any configuration) and 5938887--(any configuration), in accordance with the instructions in McDonnell Douglas MD-80 Alert Service Bulletin A27-322, dated August 22, 1991 (hereinafter referred to as "A27-322"). \n\n\t(b)\tIf no crack is found during the inspection required by paragraph (a) of this AD, repeat the inspection at the following intervals: \n\n\t\t(1)\tIf the immediately preceding inspection was accomplished using visual means, conduct the next inspection within 1,000 landings. \n\n\t\t(2)\tIf the immediately preceding inspection was accomplished using eddy current means, conduct the next inspection within 3,000 landings. \n\n\t(c)\tIf any crack is found during any inspection required by paragraph (a) or (b) of this AD, prior to further flight, remove and replace the slat drive mechanism with a new part, part numbers 5938887--(any configuration) and 5938886-- (any configuration), in accordance with A27-322. \n\nNEW REQUIREMENTS OF THIS AD \nInitial and Repetitive Inspections \n\t(d)\tPerform visual and/or eddy current inspections, as applicable, to detect cracks of the actuator cylinder support brackets of the slat drive mechanism assembly, in accordance with McDonnell Douglas Alert Service Bulletin MD80-27-A322, Revision 03, dated August 4, 1998, at the time specified in paragraph (d)(1), (d)(2), or (d)(3), as applicable, of this AD. \n\n\t\t(1)\tFor airplanes on which no inspection has been performed in accordance with AD 91-21-11: Perform both visual and eddy current inspections prior to the accumulation of 10,000 total landings or within 30 days after the effective date of this AD, whichever occurs later. \n\n\t\t(2)\tFor airplanes on which the immediately preceding inspection was performed using visual means in accordance with AD 91-21-11, accomplish the requirements of paragraphs (d)(2)(i) and (d)(2)(ii) of this AD. \n\n\t\t\t(i)\tWithin 1,000 landings after the immediately preceding visual inspection, perform a visual inspection; and \n\n\t\t\t(ii)\tWithin 6 months after the last visual inspection required by paragraph (d)(2)(i) of this AD, perform an eddy current inspection. \n\n\t\t(3)\tFor airplanes on which the immediately preceding inspection was performed using eddy current means in accordance with AD 91-21-11: Perform an eddy current inspection within 3,000 landings after the last eddy current inspection. \n\n\t(e)\tIf no crack is found during any inspection required by paragraph (d) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 3,000 landings until the actions specified in paragraph (g) of this AD are accomplished for both actuator cylinder support brackets of the slat drive mechanism assembly. \n\nCorrective/Terminating Action \n\t(f)\tIf any cracking is found during any inspection required by paragraph (d) or (e) of this AD, prior to further flight, modify the actuator cylinder support bracket of the slat drive mechanism assembly (Option 1 or 2 for Group 1 or 2 airplanes, as applicable) in accordance with McDonnell Douglas Service Bulletin MD80-27-322, Revision 02, dated February 11, 1998, as specified in paragraph (f)(1) or (f)(2), as applicable, of this AD. \n\n\t\t(1)\tFor airplanes identified as Group 1 in the service bulletin: Accomplish the actions as identified in the service bulletin as Group 1 Option 1 or Group 1 Option 2. \n\n\t\t(2)\tFor airplanes identified as Group 2 in the service bulletin: Accomplish the actions as identified in the service bulletin as Group 2 Option 1 or Group 2 Option 2. \n\n\t(g)\tAccomplishment of the modification of the actuator cylinder support bracket specified in paragraph (f) of this AD constitutes terminating action for the repetitive inspections required by this AD, provided that both actuator cylinder support brackets are modified. Alternative Methods of Compliance \n\n\t(h)\t(1)\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, Los Angeles 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, Los Angeles ACO. \n\n\t\t(2)\tAlternative methods of compliance, approved previously in accordance with AD 91-21-11, amendment 39-8058, are approved as alternative methods of compliance for this AD. \n\n\tNOTE 2:Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\nSpecial Flight Permits \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\nIncorporation by Reference \n\t(j)\tThe actions shall be done in accordance with McDonnell Douglas MD-80 Alert Service Bulletin A27-322, dated August 22, 1991; McDonnell Douglas Service Bulletin MD80-27-322, Revision 02, dated February 11, 1998; or McDonnell Douglas Alert Service Bulletin MD80-27-A322, Revision 03, dated August 4, 1998; as applicable. \n\n\t\t(1)\tThe incorporation by reference of McDonnell Douglas Alert Service Bulletin MD80-27-A322, Revision 03, dated August 4, 1998; and McDonnell Douglas Service Bulletin MD80-27-322, Revision 02, dated February 11, 1998,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 McDonnell Douglas MD-80 Alert Service Bulletin A27-322, dated August 22, 1991, was approved previously by the Director of the Federal Register as of October 30, 1991 (56 FR 51645, October 15, 1991). \n\n\t\t(3)\tCopies may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; 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 November 12, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 91-21-11, amendment 39-8058 (56 FR 51645, October 15, 1991), which is applicable to all McDonnell Douglas Model DC-9-81, -82, -83, and -87 Series Airplanes (MD-81, -82, -83, and -87), and Model MD-88 airplanes, was published in the Federal Register on July 21, 1999 (64 FR 39097). The action proposed to continue to require eddy current inspections to detect cracks of the actuator cylinder support brackets of the slat drive mechanism assembly, and replacement of any cracked brackets. That action also proposed to add an inspection requirement, and expand the area of inspection. That action also proposed to provide terminating action for the repetitive inspections. \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 single comment received. \n\n\tThe commenter supports the proposed rule. \n\nConclusion \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 as proposed. \n\nCost Impact \n\n\tThere are approximately 1,180 airplanes of the affected design in the worldwide fleet. The FAA estimates that 787 airplanes of U.S. registry will be affected by this AD. \n\n\tThe inspections that are currently required by AD 91-21-11 take approximately 3 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 $141,660, or $180 per airplane, per inspection cycle. \n\n\tThe one-time visual inspection that is required by this AD will take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the requirements of this AD on U.S. operators is estimated to be $47,220, or $60 per airplane. \n\n\tThe inspections of the expanded area that are required by this AD will take approximately 2 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 requirements of this AD on U.S. operators is estimated to be $94,440, or $120 per airplane, per inspection cycle. \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. \n\n\tShould an operator be required or elect to accomplish the terminating modification that is provided by this AD action, it will take between 130 and 162 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost $22,574 per airplane. Based on these figures, the cost impact of the optional terminating modification, is estimated to be between $30,374 and $32,294 per airplane. \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\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\nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-8058 (56 FR 51645, October 15, 1991), and by adding a new airworthiness directive (AD), amendment 39-11349, to read as follows: