AD 96-14-04

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-10 and MD-11 series airplanes, and KC-10A (military) airplanes, that requires identifying and replacing certain lock link bolts in the nose landing gear (NLG). This amendment is prompted by a report indicating that certain bolts were improperly heat-treated during manufacturing, which makes them prone to failure. The actions specified by this AD are intended to prevent failure of the lock link bolts in the NLG, which could result in the collapse of the NLG.

Final rule.

96-14-04 MCDONNELL DOUGLAS: Amendment 39-9686. Docket 95-NM-254-AD. \n\n\tApplicability: Model DC-10-10, -15, -30, and -40 series airplanes, and KC-10A airplanes, as listed in McDonnell Douglas Service Bulletin DC10-32-242, dated November 1, 1995; and Model MD-11 series airplanes as listed in McDonnell Douglas Service Bulletin MD11-32-060, dated November 6, 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 (e) 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 nose landing gear as a result of failure of the lock link bolt, accomplish the following: \n\n\t(a)\tWithin 24 months after the effective date of this AD, perform a either a visual inspection or a records search to determine the serial number of the lock link bolt, part number (P/N) ACG7079-1, installed in the nose landing gear (NLG). If the visual inspection is accomplished, it must be conducted in accordance with procedures specified in McDonnell Douglas Service Bulletin DC10-32-242, dated November 1, 1995, for Model DC-10 series airplanes; or McDonnell Douglas Service Bulletin MD11-32-060, dated November 6, 1995, for Model MD-11 series airplanes. \n\n\t(b)\tIf the serial number of the lock link bolt is not AP001 through AP036 inclusive, or AP200through AP344 inclusive: No further action is required by this AD. \n\n\t(c)\tIf the serial number of the lock link bolt is AP001 through AP036 inclusive, or AP200 through AP344 inclusive: Within 24 months after the effective date of this AD, replace the lock link bolt with a bolt, P/N ACG7079-1, that does not have one of those serial numbers. \n\n\t(d)\tAs of the effective date of this AD, no person shall install a lock link bolt, part number (P/N) ACG7079-1, having a serial number of AP001 through AP036 inclusive, or AP200 through AP344 inclusive, on any airplane. \n\n\t(e)\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 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\n\t(f)\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\n\t(g)\tThe inspection shall be done in accordance with McDonnell Douglas Service Bulletin DC10-32-242, dated November 1, 1995, for Model DC-10 series airplanes; and McDonnell Douglas Service Bulletin MD11-32-060, dated November 6, 1995, for Model MD-11 series airplanes. 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, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 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(h)\tThis amendment becomes effective on August 13, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-10 and MD-11 series airplanes, and KC-10A (military) airplanes was published in the Federal Register on March 18, 1996 (61 FR 10907). That action proposed to require a one-time visual inspection to identify suspect lock link bolts, and the replacement of those bolts with new serviceable bolts. \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 Proposal \n\n\tFour commenters support the proposal. \n\nRequest to Allow Records Search in Lieu of Inspection \n\n\tOne commenter requests that the proposed rule be revised to allow operators to conduct a records search to determine if airplanes are equipped with the suspect bolt, rather than conduct an inspection of every airplane in order to determine if the bolt is installed. This commenter states that, for some operators, the NLG lock link bolts are required to have a tracking history (i.e., records track the bolt by serial number). For these operators, it would be more economically feasible, and just as productive, to conduct a records search in lieu of an inspection. \n\n\tThe FAA concurs. Paragraph (a) of the final rule has been revised to provide for the option of conducting a records search. \n\nRequest to Extend the Compliance Time for Replacement \n\n\tSeveral commenters request that the proposed rule be revised to allow operators to replace suspect bolts at a later time. These commenters request that, instead of requiring that a suspect bolt be replaced prior to further flight after the inspection is accomplished, the proposed rule should permit operators to replace the bolt at any time after the inspection, but prior to the end of the 24-month compliance time. These commenters consider that this extension of the replacement time will obtain the same result as intended by the FAA, and will have a less disruptive impact on operators' schedules. \n\n\tThe FAA concurs that the bolts need not be replaced prior to further flight after the inspection (or records search) is accomplished. The FAA makes this finding based on the following data pertinent to the configuration of the suspect bolts themselves: \n\n\t1. None of the suspect bolts were manufactured prior the initial production of the Model MD-11 series airplanes (in 1991). In light of this, the FAA is confident that none of the suspect bolts was installed as original equipment on any of the affected Model DC-10 series airplanes. (Model DC-10's have been produced since 1971.) \n\n\t2. The suspect bolts were manufactured using a process that did not affect their static strength requirement, but did reduce their fatigue life. These bolts should have a fatigue life in the range of 58,281 landings; due to the manufacturing process used, however, the fatigue life of the suspect bolts has been reduced to approximately 24,638 landings. \n\n\t3. A review of the utilization rates of the current worldwide fleet indicates that the highest number of landings accumulated on any Model MD-11 series airplane is approximately 5,000 landings. \n\n\t4. The average annual utilization rate of the airplanes affected by this AD is between 1,000 and 1,200 landings. \n\n\tThese data indicate that, if any suspect bolt had been installed as original equipment on a Model MD-11 (even those airplanes with the highest number of landings accumulated so far), or installed as a replacement component on a Model DC-10, the fatigue life "remaining" on any suspect bolt is long enough to permit continued use of that bolt for a 24-month period. \n\n\tBased on these factors, the FAA has determined that a large enough margin of safety exists so that replacement of the suspect bolts may be accomplished within 24 months after the effective date of this AD, regardless of when the inspection (or records search) is performed. Paragraph (c) of the final rule has been revised to specify this. \n\nRequest to Permit Replacement with Other Than New Bolts \n\n\tOne commenter, the airframe manufacturer, requests that the proposed rule be revised to delete the requirement that a "new" bolt be used as a replacement bolt. This commenter states that the use of the term "new" excludes the use of refurbished or serviceable bolts that do not have one of the suspect serial numbers. \n\n\tThe FAA concurs. Serviceable (non-suspect) bolts are acceptable as replacement parts. Accordingly, paragraph (c) of the final rule has been revised to delete the word "new" from the description of required replacement bolts. \n\nRequest to Ensure Availability of Replacement Parts \n\n\tOne commenter expresses concerns that the replacement bolts will not be available in a timely manner. This commenter states that several service bulletins recently have been released by McDonnell Douglas that recommend inspections and replacement of high-strength landing gear parts that were improperly heat-treated. This commenter is concerned that the bolt suppliers may not be able to meet the concurrent demand for the large quantity of parts needed for the entire affected fleet. \n\n\tThe FAA acknowledges this commenter's concerns, and just recently contacted the manufacturer on this very subject. The manufacturer has assured the FAA that its suppliers stand ready to meet the demand for parts for the total fleet. \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 565 Model DC-10 and MD-11 series airplanes and KC-10A (military airplanes) of the affected design in the worldwide fleet. The FAA estimates that 334 airplanes of U.S. registry will be affected by this proposed AD. \n\n\tIt will take approximately .5 work hour per airplane to accomplish either a one-time inspection or a commensurate records search, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $10,020, or $30 per airplane. \n\n\tIf a suspect lock link bolt is found to be installed on an airplane, its removal and replacement will take approximately 3 work hours to accomplish, at an average labor rate of $60 per work hour. (For operators of Model MD-11 series airplanes, the manufacturer has indicated that it will reimburse operators for certain of these labor costs as a labor credit allowance.) Replacement parts will be supplied by the manufacture at no charge to operators. Based on these figures, the cost impact of the replacement action on U.S. operators is estimated to be $180 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 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 adding the following new airworthiness directive: