AD 99-21-07

This amendment supersedes two existing airworthiness directives (AD), applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes, that currently require installation of hydraulic line restrictors in the main landing gear (MLG), and modification or replacement of the left and right MLG hydraulic damper assemblies. This amendment requires an additional modification of the MLG hydraulic damper assemblies, or replacement of the MLG hydraulic damper assemblies with modified and reidentified hydraulic damper assemblies. This amendment is prompted by reports indicating that MLG hydraulic damper assemblies removed for overhaul had failed or damaged spring retainers, due to insufficient material thickness of the spring retainers. The actions specified by this AD are intended to prevent failure of the hydraulic damper assemblies of the MLG, which could result in vibration damage and collapse of the MLG.

Final rule.

99-21-07 MCDONNELL DOUGLAS: Amendment 39-11350. Docket 98-NM-268-AD. Supersedes AD 96-01-09, Amendment 39-9485; and AD 96-21-01, Amendment 39-9777. \n\n\tApplicability: Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83), and -87 (MD-87) series airplanes, and Model MD-88 airplanes; as listed in McDonnell Douglas Service Bulletins MD80-32-276 and MD80-32-278, both dated March 31, 1995; and Model DC-9-10, -20, -30, -40, and -50; and C-9 (military) series airplanes, as listed in McDonnell Douglas Service Bulletin DC9-32-289, dated March 7, 1996; 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) 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 hydraulic damper assemblies of the MLG, which could result in vibration damage and collapse of the MLG, accomplish the following: \n\nRESTATEMENT OF REQUIREMENTS OF AD 96-01-09:\nModifications \n\t(a)\tFor airplanes listed in McDonnell Douglas MD-80 Service Bulletin MD80-32-276, dated March 31, 1995, that have not been previously modified (installation of brake line restrictors) in accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-246: Within 9 months after February 26, 1996 (the effective date of AD 96-01-09, amendment 39-9485), install filtered brake line restrictors in the MLG hydraulic brake system in accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-276, dated March 31, 1995, or Revision 1, dated October 17, 1995. \n\n\tNOTE 2: Installation of filtered restrictors in accordance with the instructions specified in McDonnell Douglas MD-80 Alert Service Bulletin, MD80-A32-286, dated September 11, 1995, is considered acceptable for compliance with paragraph (a) of this AD. \n\n\t(b)\tFor airplanes listed in McDonnell Douglas MD-80 Service Bulletin MD80-32-278, dated March 31, 1995: Within 36 months after February 26, 1996, modify the hydraulic damper assembly (by removing shims, increasing bolt torque, and incorporating changes to increase the volume of fluid passing between the two damper chambers) in accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-278, dated March 31, 1995, or Revision 1, dated September 6, 1995. \n\nRESTATEMENT OF REQUIREMENTS OF AD 96-21-01: \nReplacement or Modification \n\t(c)\tFor airplanes listed in McDonnell Douglas Service Bulletin DC9-32-289, dated March 7, 1996: Within 24 months after November 14, 1996 (the effective date of AD 96-21-01, amendment 39-9777), either replace or modify the MLG hydraulic damper assembly, in accordance with the procedures specified as either "Option 1" or "Option 2," respectively, of the service bulletin. \n\nNEW REQUIREMENTS OF THIS AD: \nReplacement or Modification \n\t(d)\tFor McDonnell Douglas Model DC-9 series airplanes, and C-9 (military) series airplanes (as listed in McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01): Within 18 months after the effective date of this AD, accomplish the requirements specified in either paragraph (d)(1) or (d)(2) of this AD in accordance with McDonnell Douglas Service Bulletin DC9-32-311, dated July 6, 1998, or McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01, dated March 8, 1999. \n\n\t\t(1)\tModify the left and right MLG hydraulic damper assemblies. \n\n\t\t(2)\tReplace the left and right MLG hydraulic damper assemblies with modified and reidentified hydraulic damper assemblies having part number (P/N) SR09320057-7005, SR09320057-7007, SR09320057-7009, or 5923142-5513. \n\n\t(e)\tFor McDonnell Douglas Model DC-9-80 series airplanes, and MD-88 airplanes (as listed in McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01): Within 3,000 flight cycles after incorporation of the latest configuration of the left and right MLG hydraulic damper assemblies, or within 9 months after the effective date of this AD, whichever occurs later; accomplish the requirements specified in either paragraph (d)(1) or (d)(2) of this AD in accordance with McDonnell Douglas Service Bulletin DC9-32-311, dated July 6, 1998, or McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01, dated March 8, 1999. \n\n\t(f)\tParagraph (b) or (c) of this AD, as applicable, must be accomplished prior to or concurrent with the accomplishment of either paragraph (d) or (e)of this AD, as applicable. \n\nSpares \n\t(g)\tAs of the effective date of this AD, no person shall install on any airplane a damper sub assembly having P/N SR09320057-9, SR09320057-17, or 5923142-5017; or a damper assembly having P/N SR09320057-7001, SR09320057-7003, or 5923142-5511, unless the part has been modified and reidentified in accordance with paragraph (d)(2) of this AD. \n\nAlternative Methods of Compliance \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, 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\tNOTE 3: 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 Service Bulletin MD80-32-276, dated March 31, 1995; McDonnell Douglas MD-80 Service Bulletin MD80-32-276, Revision 1, dated October 17, 1995; McDonnell Douglas MD-80 Service Bulletin MD80-32-278, dated March 31, 1995; McDonnell Douglas MD-80 Service Bulletin MD80-32-278, Revision 1, dated September 6, 1995; McDonnell Douglas Service Bulletin DC9-32-289, dated March 7, 1996; McDonnell Douglas Service Bulletin DC9-32-311, dated July 6, 1998; or McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01, dated March 8, 1999; as applicable. \n\n\t\t(1)\tThe incorporation by reference of McDonnell Douglas Service Bulletin DC9-32-311, dated July 6, 1998; or McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01, dated March 8, 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 McDonnell Douglas MD-80 Service Bulletin MD80-32-276, dated March 31, 1995, McDonnell Douglas MD-80 Service Bulletin MD80-32-276, Revision 1, dated October 17, 1995; McDonnell Douglas MD-80 Service Bulletin MD80-32-278, dated March 31, 1995; and McDonnell Douglas MD-80 Service Bulletin MD80-32-278, Revision 1, dated September 6, 1995; was approved previously by the Director of the Federal Register as of February 26, 1996 (61 FR 2407, January 26, 1996). \n\n\t\t(3)\tThe incorporation by reference of McDonnell Douglas Service Bulletin DC9-32-289, dated March 7, 1996, was approved previously by the Director of the Federal Register as of November 14, 1996 (61 FR 53042, October 10, 1996). \n\n\t\t(4)\tCopies may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846. 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 96-01-09, amendment 39-9485 (61 FR 2407, January 26, 1996), and AD 96-21-01, amendment 39-9777 (61 FR 53042, October 10, 1996), which are applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes, was published in the Federal Register on July 23, 1999 (64 FR 39944). The action proposed to require an additional modification of the main landing gear (MLG) hydraulic damper assemblies, or replacement of the MLG hydraulic damper assemblies with modified and reidentified hydraulic damper assemblies. \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 2,015 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,145 airplanes of U.S. registry will be affected by this AD. \n\n\tThe installation that is currently required by AD 96-01-09, and retained in this AD, takes approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $928 per airplane. Based on these figures, the cost impact of the currently required installation on U.S. operators is estimated to be $1,168 per airplane. \n\n\tThe modification that is currently required by AD 96-01-09, and retained in this AD, takes approximately 6 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $4,000 per airplane. Based on these figures, thecost impact of the currently required modification on U.S. operators is estimated to be $4,360 per airplane. \n\n\tThe replacement that is currently required by AD 96-21-01, and retained in this AD, takes approximately 6 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $11,139 per airplane (two assemblies at $5,569 each). Based on these figures, the cost impact of the currently required replacement on U.S. operators is estimated to be $11,499 per airplane. \n\n\tThe modification that is currently required by AD 96-21-01, and retained in this AD, takes approximately 11 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $2,907 per airplane. Based on these figures, the cost impact of the currently required modification on U.S. operators is estimated to be $3,567 per airplane. \n\n\tThe modification or replacement that is required in this AD action will take approximately 18 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $608 per airplane. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be $1,932,760, or $1,688 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. \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 thepreparation 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 39-9485 (61 FR 2407, January 26, 1996), and amendment 39-9777 (61 FR 53042, October 10, 1996), and by adding a new airworthiness directive (AD), amendment 39-11350, to read as follows: