AD 94-09-01

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This action requires an eddy current inspection to detect defects in the upper and lower lock links on the nose landing gear (NLG), and rework or replacement of any defective link found. This amendment is prompted by reports of cracking and subsequent failure of certain lock links on these airplanes, which have been attributed to forging defects in the lock links. The actions specified in this AD are intended to prevent collapse of the NLG.\n\n\tThe incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of May 5, 1994.\n\n\tComments for inclusion in the Rules Docket must be received on or before June 20, 1994.

Final rule; request for comments.

94-09-01 MCDONNELL DOUGLAS: Amendment 39-8889. Docket 94-NM-45-AD.\n\n\tApplicability: Model MD-11 series airplanes; as listed in McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994; certificated in any category.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo prevent collapse of the nose landing gear (NLG), accomplish the following:\n\n\t(a)\tWithin 120 days after the effective date of this AD, perform an eddy current inspection to detect defects in the upper lock links, part number ACG7396-1, and lower lock links, part number ACG7237-1, on the NLG; in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994.\n\n\t(b)\tIf no defect is found, prior to further flight, identify the inspected lock link in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994.\n\n\t(c)\tIf any defect is found, prior to further flight, accomplish either paragraph (c)(1) or (c)(2) ofthis AD in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994.\n\n\t\t(1)\tRework and identify the lock link. Or\n\n\t\t(2)\tReplace the defective lock link with a serviceable lock link that has been inspected and identified in accordance with paragraphs (a) and (b) of this AD.\n\n\t(d)\tWithin 10 days after accomplishing the inspection required by paragraph (a) of this AD, submit a report of inspection findings to the Manager, Los Angeles Aircraft Certification Office (ACO), 3229 East Spring Street, Long Beach California 90806-2425; fax (310) 988-5210. The report must include the inspection results, a description of any discrepancy found, the part numbers of all links inspected, the airplane serial number, and the number of landings and flight hours on the airplane. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.\n\n\t(e)\tAs of the effective date of this AD, no person shall install an upper lock link, part number ACG7396-1, or a lower lock link, part number ACG7237-1, on the NLG of any airplane unless that lock link has been inspected and identified in accordance with paragraphs (a) and (b) of this AD.\n\n\t(f)\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: 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(g)\tSpecial flight permits may be issuedin accordance with Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.\n\n\t(h)\tThe actions shall be done in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994. 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 McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, California 90801-1771, Attention: Business Unit Manager, Technical Administrative Support, Dept. L51, M.C. 2-98. 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, 3229 East Spring Street, Long Beach, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.\n\n\t(i)\tThisamendment becomes effective on May 5, 1994.

The FAA has received a report of cracking and subsequent failure of an upper lock link on the center landing gear (CLG) of a McDonnell Douglas Model MD-11 series airplane. Results of a subsequent analysis attributed the failure to forging defects in the lock link. An investigation conducted by the manufacturer revealed two additional upper links on the CLG with similar forging defects. The lower lock link on the CLG and the upper and lower lock links on the nose landing gear (NLG) are similar in design and are manufactured by the same supplier as the upper lock link on the CLG; therefore, defective lock links could be installed at any of these locations. Failure of the lock links on the CLG would result in collapse of the CLG; collapse of the CLG would not present an unsafe condition. However, cracking and subsequent failure of the lock links on the NLG, if not corrected, could result in collapse of the NLG. This situation could result in reduced controllability of the airplane during takeoff or landing.\n\n\tThe FAA has reviewed and approved McDonnell Douglas MD-11 Alert Service Bulletin A32-44, dated March 22, 1994, that describes procedures for an eddy current inspection to detect defects in the lock links of the NLG and CLG on certain airplanes, and rework or replacement of any defective lock link found. Reworking or replacing the lock links will minimize the possibility of failure of the lock links on NLG and CLG and subsequent collapse of a landing gear.\n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other Model MD-11 series airplanes of the same type design, this AD is being issued to prevent collapse of the NLG. This AD requires an eddy current inspection to detect defects in the upper and lower lock links on the NLG, and rework or replacement of any defective link found. The actions are required to be accomplished in accordance with the alert service bulletin described previously.This AD also requires that operators submit a report of inspection findings to the FAA.\n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.\n\n\tThe required compliance time of 120 days is usually sufficient to allow for a brief comment period before adoption of a final rule. In this AD, however, that compliance time was selected because of a short-term problem with availability of sufficient replacement parts if defects are found; a shorter compliance time might have resulted in the unnecessary removal of airplanes from service pending delivery of replacement parts. Nevertheless, the FAA has determined that immediate adoption is necessary in this case because of the importance of initiating the required inspections as soon as possible.\n\nComments Invited\n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.\n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.\n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 94-NM-45-AD." The postcard will be date stamped and returned to the commenter.\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\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment \n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations as follows:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\t1.\tThe authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.\n\n§ 39.13 - (Amended)\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: