AD 94-15-02

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 series airplanes, that currently requires inspections to verify the installation of shear pins, shear pin retainers, and shear pin retainer attaching parts in the aft end of the center pylon thrust link, and repair, if necessary. That AD was prompted by a report that both shear pins that attach the aft end of the center engine pylon thrust link to the tail pylon were missing. This amendment adds inspections to verify that the shear pin retainer attaching parts are tightened within specified limits; and adds a terminating modification for those inspections. This amendment also expands the applicability of the rule to include additional airplanes. The actions specified by this AD are intended to prevent structural damage to the engine mount structure, which could lead to loss of airplane components.

Final rule.

94-15-02 McDONNELL DOUGLAS: Amendment 39-8973. Docket 93-NM-216-AD. Supersedes AD 92-23-03, Amendment 39-8403. \n\n\tApplicability: Model MD-11 series airplanes; as listed in McDonnell Douglas MD-11 Alert Service Bulletin A54-31, dated September 17, 1992, and McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent structural damage to the engine mount structure, which could lead to loss of airplane components, accomplish the following: \n\n\t(a)\tFor airplanes listed in McDonnell Douglas MD-11 Alert Service Bulletin A54-31, dated September 17, 1992: Within 15 days after November 5, 1992 (the effective date of AD 92-23-03, amendment 39-8403), unless previously accomplished within the last 30 days, perform a visual inspection of the thrust link of the center engine forward mount to verify installation of the shear pins, the shear pin retainers, and the shear pin retainer attaching parts in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, dated September 17, 1992, or Revision 1, dated June 3, 1993. \n\n\t\t(1)\tIf shear pins, shear pin retainers, and shear pin retainer attaching parts are installed, repeat the visual inspection thereafter at intervals not to exceed 60 days until accomplishment of paragraph (c) or (d) of this AD. \n\n\t\t(2)\tIf any shear pin retainer or shear pin retainer attaching part is missing or loose, and if any shear pin has migrated, prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t\t(3)\tIf any shear pin retainer or shear pin retainer attaching part is missing or loose, and if no shear pin has migrated, prior to further flight, repair in accordance with "Condition II" of McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. \n\n\t(b)\tFor airplanes listed in McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993, and not subject to the requirements of paragraph (a) of this AD, accomplish the following: \n\n\t\t(1)\tFor airplanes specified as Groups III and IV in that service bulletin: Within 15 days after the effective date of this AD or prior to the accumulation of 60 days since the last visual inspection performed before the effective date of this AD in accordance McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993, or equivalent, whichever occurs later, perform a visual inspection of the thrust link of the center engine forward mount to verify installation of the shear pins, the shear pin retainers, and the shear pin retainer attaching parts in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. \n\n\t\t\t(i)\tIf shear pins, shear pin retainers, and shear pin retainer attaching parts are installed, repeat the visual inspection thereafter at intervals not to exceed 60 days until accomplishment of paragraph (c) or (d) of this AD. \n\n\t\t\t(ii)\tIf any shear pin retainer or shear pin retainer attaching part is loose or missing, and if any shear pin has migrated, prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t\t\t(iii)\tIf any shear pin retainer or shear pin retainer attaching part is loose or missing, and if no shear pin has migrated, prior to further flight, repair in accordance with "Condition II" of McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. \n\n\t\t(2)\tFor airplanes specified as Groups V and VI in that service bulletin: Accomplish the procedures specified in either paragraph (b)(2)(i) or (b)(2)(ii) of this AD: \n\n\t\t\t(i)\tAccomplish the visual inspection(s) and necessary follow-on procedures specified in paragraph (b)(1) of this AD. Or \n\n\t\t\t(ii)\tPrior to the accumulation of 18 months since the last verification for tightness of the shear pin retainer parts was accomplished, or within 6 months after the effective date of this AD, whichever occurs later, verify that the tightness of the shear pin retainer parts is within the limits specified in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. Repeat the verification for tightness thereafter at intervals not to exceed 18 months until the accomplishment of paragraph (d) of this AD. \n\n\t(c)\tFor all airplanes, except those subject to paragraph (b)(2)(ii) of this AD: Within 18 months after the effective date of this AD, verify that the tightness of the shear pin retainer attaching parts is within the limits specified in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. Repeat this verification thereafter at intervals not to exceed 18 months until accomplishment of paragraph (d) of this AD. Accomplishment of the verification for tightness required by this paragraph constitutes terminating action for the repetitive inspections for installation of parts required by paragraphs (a) and (b) of this AD. \n\n\t(d)\tFor all airplanes: Within 3 years after the effective date of this AD, replace the existing retainer and bolts with safety wire with a new retainer and new bolts with safety wire in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. Accomplishment of this replacement constitutes terminating action for the repetitive actions required by paragraphs (a), (b) and (c) of this AD. \n\n\t(e)\tWithin 15 days after detecting any discrepancy during any inspection or verification action required by this AD, submit a report of the inspection results to the Manager, Los Angeles ACO, FAA, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, California 90806-2425; fax (310) 988-5210. 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 \nNumber 2120-0056. \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 actions shall be done in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A54-31, dated September 17, 1992; and McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. The incorporation by reference of the former service bulletin was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of November 2, 1992 (57 FR 47991, October 21, 1992). The incorporation by reference of the latter service bulletin 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, CA 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(h)\tThis amendment becomes effective on August 19, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 92-23-03, amendment 39-8403 (57 FR 47991, October 21, 1992), which is applicable to certain McDonnell Douglas Model MD-11 series airplanes, was published in the Federal Register on March 17, 1994 (59 FR 12558). The action proposed to continue to require repetitive visual inspections to verify the installation of the shear pins, the shear pin retainers, and the shear pin retainer attaching parts in the aft end of the center engine (No. 2) pylon thrust link. It also proposed (1) to add repetitive inspections to verify that the shear pin retainer attaching parts are tightened within specified limits; (2) to delete the previously provided "optional terminating action" (which consists of a one-time verification for tightness of the nuts of the four shear pin retainer attaching bolts); and (3) to require eventual replacement of the existing retainer and attaching parts with a new retainer and attaching parts, as terminating action for the currently required repetitive visual inspections and the proposed repetitive verifications of tightness. \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\n\tOne commenter supports the proposal. \n\n\tThe Air Transport Association (ATA) of America, on behalf of one member operator, and the manufacturer request that the proposed AD be revised to indicate that the 60-day repetitive inspection specified in paragraph (a) and (b) be required only until either the initial verification for tightness (of the shear pin retainer attaching parts), the terminating action, or an FAA-approved repair is accomplished. These commenters state that the FAA already has approved repairs applicable to paragraphs (a) and (b) of the proposal, which have consisted of the installation of new parts. New parts obviously will be tightened upon installation; therefore, reinspection of the tightness of these parts within 60 days appears to be unwarranted. The commenters request that the repetitive interval for the inspection for installation of parts be revised to 18 months in order to be consistent with the recommendations of Phase 2 of the original issue of McDonnell Douglas Alert Service Bulletin A54-71. \n\n\tThe FAA concurs in part with the commenter's request. Upon further consideration of the procedures specified in the referenced service bulletin, the FAA concurs that a 60-day repetitive inspection interval is not necessary in certain situations, explained as follows: \n\n\tParagraphs (a)(1) and (b)(1)(i) of the final rule apply to situations where the shear pins, shear pin retainers, and shear pin retainer attaching parts have been inspected and found to be installed. The FAA finds that inspections to verify the installation of these parts must be repeated every 60 days, so long as there is no other action accomplished that will ensure the tightness of the attaching parts. These inspections for installation may be terminated, however, when the initial verification for tightness of the shear pin retainer attaching parts is accomplished in 18 months in accordance with paragraph (c) of the rule; or when the terminating modification described in paragraph (d) is installed, if earlier than 18 months. \n\n\tThe FAA has revised paragraphs (a)(2) and (b)(1)(ii) of the final rule, which apply to situations where any shear pin is missing or has migrated, and any shear pin retainer or shear pin retainer attaching part is missing. In such cases, an FAA-approved repair is required to be installed; the FAA has determined that these approved repairs will be such that no further inspections for installation of parts will be necessary once the approved repair is installed. The FAA has revised these paragraphs of the final rule to reflect this determination. \n\n\tAdditionally, the FAA has added new paragraphs (a)(3) and (b)(1)(iii), which specify that, in situations where the shear pin retainers or shear pin retainer attaching parts are missing or loose, and the shear pin has not migrated, operators may accomplish a repair in accordance procedures specified as "Condition II" in McDonnell Douglas Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. Subsequent to this repair, no further inspections for installation of parts are required. These paragraphs have been added in order to provide operators with an additional repair procedure that may be used in lieu of obtaining prior FAA-approval of repairs (which was the only option provided for in the proposal). \n\n\tThese same commenters contend that the 15-day compliance time for the initial inspection required by proposed paragraph (b) is not warranted for certain airplanes. The commenters point out that a tightness check was accomplished on airplanes in Groups V and VI (as specified in the referenced McDonnellDouglas service bulletin) prior to delivery; therefore, an initial inspection for installation of the subject parts should not be required for these airplanes. The commenters request that, for these airplanes, only a "re-verification" for tightness be required within 18 months. Additionally, the commenters point out that an initial visual inspection for installation of parts was accomplished on airplanes in Group III and IV prior to delivery; therefore, the compliance time for initial inspection for installation of parts required by this propose rule should be extended. The commenters suggest extending the initial compliance time to 60 days, since this is the compliance time recommended by the manufacturer in the referenced service bulletin. \n\n\tThe FAA concurs in part with the commenter's requests. The FAA acknowledges that it is appropriate to revise paragraph (b) of the final rule to differentiate between the requirements of the various groups of airplanes specified in the referenced service bulletin: \n\n\tAs for airplanes in Groups III and IV, the FAA does not concur with the commenter's request to extend the initial compliance time for the inspection for installation of parts on these airplanes. While these airplanes may have been inspected prior to delivery, and while the manufacturer's revised service bulletin recommends a repetitive inspection interval of 60 days, the FAA points out that the inspection procedures described in that service bulletin have not been mandated previously. Since the revised service bulletin was released over a year ago, there is no way to guarantee that affected airplanes have been repetitively inspected prior to the issuance of this final rule. In light of this, the FAA considers a compliance time of 15 days necessary in order to ensure that the accomplishment of what may be the first repetitive inspection for some airplanes is carried out in a timely manner. However, the FAA has revised the compliance terms of paragraph (b)(1) to provide a "grace period" for operators of airplanes that may have been visually (re-)inspected recently. The final rule now reflects a compliance time for the initial visual inspection as "within 15 days after the effective date of the AD, or prior to the accumulation of 60 days since the last visual inspection, whichever occurs later." \n\n\tAs for airplanes in Groups V and VI, the FAA concurs that these airplanes need not be subject to the initial inspection for installation of parts as required by paragraph (b), as long as repetitive verifications for tightness are conducted. Therefore, the FAA has revised paragraph (b) by adding a new paragraph (b)(2), which addresses these airplanes and allows them the option of either repetitively inspecting for installation of parts (as originally proposed), or conducting a verification for tightness within 18 months after the last verification was performed. If operators of these airplanes elect to perform the verification for tightness, it must be repeated every 18 months until the terminating modification is accomplished in accordance with paragraph (d) of the rule. \n\n\tThese same commenters request that proposed paragraph (c) be revised to indicate that accomplishment of the verification for tightness of the shear pin retainer attaching parts terminates the requirement for the repetitive visual inspections for installation of these same parts required by paragraph (a) and (b). The FAA concurs and has revised paragraph (c) of the final rule accordingly. \n\n\tThese commenters also request that proposed paragraph (d) be revised to extend the compliance time for accomplishment of the terminating modification from the proposed 3 years to 5 years. The commenters consider this modification to be only an "improvement change," and operators should be allowed to install it during a convenient and regularly scheduled maintenance period in order to avoid special scheduling of airplanes and additional associated costs.The FAA does not concur. In developing the compliance time for the terminating action, the FAA considered not only the safety implications, but the manufacturer's recommendations, the availability of required modification parts, and the practical aspects of an orderly modification of the fleet. In consideration of all of these items, the FAA determined that 3 years is an appropriate interval that will coincide with regularly scheduled maintenance periods ("C" checks) for the majority of the affected operators. However, under the provisions of paragraph (f) 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\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\n\tThere are approximately 94 Model MD-11 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 42 airplanes of U.S. registry will be affected by this AD. \n\n\tAccomplishment of the required inspections for installation of parts will take approximately 4 work hours per airplane, at an average labor rate of $55 per work hour. Based on these figures, the total cost impact of these requirements of this AD on U.S. operators is estimated to be $9,240, or $220 per airplane, per inspection. \n\n\tAccomplishment of the required verification for tightness of the shear pin retainer attaching parts will take approximately 6 work hours per airplane, at an average labor rate of $55 per work hour. Based on these figures, the total cost impact of these requirements of this AD on U.S. operators is estimated to be $13,860, or $330 per airplane, per verification. \n\n\tAccomplishment of the required terminating modification will take approximately 6 work hours per airplane, at an average labor rate of $55 per work hour. Required parts will be provided by the manufacturer at no cost to operators. Based on these figures, the total cost impact of these requirements of this AD on U.S. operators is estimated to be $13,860, or $330 per airplane. \n\n\tThe total 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\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 nothave 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.\tThe authority citation for part 39 continues to read as follows: \n\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\n\t2.\tSection 39.13 is amended by removing amendment 39-8403 (57 FR 47991, October 21, 1992), and by adding a new airworthiness directive (AD), amendment 39-8973, to read as follows: