AD 99-06-13

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, that currently requires inspection(s) to detect fatigue cracking of the shock strut cylinder of the main landing gear (MLG), and replacement of any cracked shock strut cylinder with a serviceable part. That AD also provides for installation of brake line hydraulic restrictors on the MLG brake systems, which, if accomplished, terminates the repetitive inspections. This amendment requires that the subject inspection be accomplished repetitively following installation of brake line hydraulic restrictors. This amendment is prompted by an additional report of fatigue cracking and subsequent fracturing of the shock strut cylinder of the MLG. The actions specified by this AD are intended to prevent collapse of the MLG due to fracturing of the shock strut cylinder.

Final rule

99-06-13 MCDONNELL DOUGLAS: Amendment 39-11077. Docket 97-NM-292-AD. Supersedes AD 95-22-06, Amendment 39-9413.\n\n\tApplicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) series airplanes, and Model MD-88 airplanes; as listed in McDonnell Douglas Alert Service Bulletin MD80-32A286, dated September 11, 1995; 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)(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 collapse of the main landing gear (MLG) due to fracturing of the shock strut cylinder, accomplish the following: \n\n\tNOTE 2: Where there are differences between the referenced alert service bulletin and the AD, the AD prevails.\nInspections\n\n\t(a)\tPerform dye penetrant and magnetic particle inspections to detect cracking of the shock strut cylinder of the MLG, in accordance with McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 03, dated May 28, 1998; at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. \n\n\tNOTE 3: Inspections accomplished prior to the effective date of this AD in accordance with McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 02, dated October 2, 1997, are considered acceptable for compliance with paragraph (a) of this AD. \n\n\t\t(1)\tFor MLG shock strut cylinders that, as of the effective date of this AD, have accumulated less than 1,200 landings since accomplishment of the brake line hydraulic restrictor installation: Inspect within 1,200 landings after the effective date of this AD. Repeat the inspections thereafter at intervals not to exceed 1,200 landings for a total of 4 inspections. \n\n\t\t(2)\tFor MLG shock strut cylinders that, as of the effective date of this AD, have accumulated greater than or equal to 1,200 landings and less than 2,400 landings since accomplishment of the brake line hydraulic restrictor installation: Inspect within 1,200 landings after the effective date of this AD. Repeat the inspections thereafter at intervals not to exceed 1,200 landings for a total of 3 inspections. \n\n\t\t(3)\tFor MLG shock strut cylinders that, as of the effective date of this AD, have accumulated greater than or equal to 2,400 landings since accomplishment of the brake line hydraulic restrictor installation: Inspect within 1,200 landings after the effective date of this AD. Repeat the inspections thereafter at intervals not to exceed 1,200 landings for a total of 2 inspections.\n\nCorrective Actions\n\n\t(b)\tIf any cracking is detected during any inspection required by paragraph (a) of this AD, prior to further flight, accomplish either paragraph (b)(1) or (b)(2) of this AD in accordance with McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 03, dated May 28, 1998. \n\n\t\t(1)\tReplace the shock strut cylinder with a crack-free serviceable part and, thereafter, repeat the inspections required by paragraph (a) of this AD, at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. Or \n\n\t\t(2)\tReplace the shock strut cylinder with a new shock strut cylinder. Accomplishment of the replacement constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD. \n\n\tNOTE 4: Replacements accomplished prior to the effective date of this AD in accordance with McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 02, dated October 2, 1997, are considered acceptable for compliance with paragraph (b) of this AD. \n\nSpares \n\n\t(c)\tAs of the effective date of this AD, no person shall install on any airplane an MLG shock strut cylinder or MLG assembly unless that part has been inspected and found to be crack free, in accordance with McDonnell Douglas Alert Service MD80-32A286, Revision 02, dated October 2, 1997, or Revision 03, dated May 28, 1998.\n\nAlternative Methods of Compliance \n\n\t(d)\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\tNOTE 5: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\n\t\t(2)\tAlternative methods of compliance, approved previously in accordance with AD 95-22-06, amendment 39-9413, are approved as alternative methods of compliance with this AD.\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)\tThe actions shall be done in accordance with McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 03, dated May 28, 1998. 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. Copies 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(g)\tThis amendment becomes effective on April 22, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 95-22-06, amendment 39-9413 (60 FR 54417, October 24, 1995), which is applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, was published in the Federal Register on July 30, 1998 (63 FR 40666). The action proposed to continue to require inspection(s) to detect fatigue cracking of the shock strut cylinder of the main landing gear (MLG), and replacement of any cracked shock strut cylinder with a serviceable part. That action also proposed to continue to provide for installation of brake line hydraulic restrictors on the MLG brake systems, which, if accomplished, terminates the repetitive inspections. That action proposed to require that the subject inspection be accomplished repetitively following installation of brake line hydraulic restrictors. \n\nComments Received \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 Proposed Rule \n\n\tSeveral commenters support the proposed rule. \n\nRequest to Revise Wording \n\n\tOne commenter requests that the phrase "for airplanes" in paragraphs (a)(1), (a)(2), and (a)(3) of the proposed AD be revised to "for MLG shock strut cylinders." The commenter points out that MLG's are replaceable units that can be "time continued" on a different airplane. The FAA concurs. The FAA's intent was that compliance time of those paragraphs be specified in the landings accumulated on MLG's since accomplishment of the brake line hydraulic restrictor installation, rather than the landings that an airplane had accumulated. Therefore, the FAA has revised paragraphs (a)(1), (a)(2), and (a)(3) of the final rule to clarify this point. \n\nRequests to Revise Repetitive Inspection Intervals \n\n\tOne commenter requests that the repetitive inspectioninterval of the proposed AD be extended from 1,200 landings to 2,000 landings. The commenter states that such an extension would allow most inspections to occur within its check hangar environment. \n\n\tThe FAA does not concur with the commenter's request. The commenter provided no technical justification for revising this interval as requested. Fatigue cracking and subsequent fracturing of the shock strut cylinder of the MLG is a significant safety issue, and the FAA has determined that the inspection interval, as proposed, is warranted, based on the effectiveness of the inspection procedure to detect cracks, and the rate of crack growth in the shock strut cylinder of the MLG. The FAA considered not only those safety issues in developing an appropriate compliance time for this action, but the recommendations of the manufacturer, the availability of any necessary repair parts, and the practical aspect of accomplishing the required inspection within an interval of time that parallels normal scheduled maintenance for the majority of affected operators. However, under the provisions of paragraph (d)(1) of the final rule, the FAA may approve requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. \n\n\tOne commenter requests that the FAA revise the proposed AD to simplify and clarify that inspections should be performed at a minimum of 4,800 cycles past restrictor installation. The commenter suggests that the proposed AD be revised to read, "Perform repetitive inspections at intervals not to exceed 1,200 landings until a minimum of 4,800 landings has accumulated since brake line restrictor installation. A minimum of two (2) repetitive inspections, with at least 1,000 cycles accrued between inspections, shall be performed regardless of the total number of cycles accumulated since restrictor installation." The commenter states that such a statement will ensure that inspections are performed past 4,800 cycles from restrictor installation and will allow credit for inspections performed prior to issuance of McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 02, dated October 2, 1997. \n\n\tThe FAA does not concur with the commenter's request. The FAA points out that the subject repetitive inspection intervals are essentially identical to those specified in McDonnell Douglas Alert Service Bulletin MD80-32A286, Revision 03, dated May 28, 1998 (which is referenced in the proposed AD as the appropriate source of service information for accomplishment of the required actions). The FAA finds that using wording that is significantly different from that of the alert service bulletin may cause more confusion to operators. Therefore, the FAA finds that no change to the final rule is necessary. \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 1,011 McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 625 airplanes of U.S. registry will be affected by this AD. \n\n\tThe dye penetrant and magnetic particle inspections that are required in this AD action will 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 dye penetrant and magnetic particle inspections required by this AD on U.S. operators is estimated to be $150,000, or $240 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 therequirements 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 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 39-9413 (60 FR 54417, October 24, 1995), and by adding a new airworthiness directive (AD), amendment 39-11077, to read as follows: