[Federal Register Volume 59, Number 52 (Thursday, March 17, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-6210] [[Page Unknown]] [Federal Register: March 17, 1994] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 93-NM-216-AD] Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the supersedure of 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 also provides an optional terminating action, which, if accomplished, would terminate the repetitive inspections. 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 action would add inspections to verify that the shear pin retainer attaching parts are tightened within specified limits; and a terminating modification for those inspections. This action would also remove the optional terminating action, and expand the applicability of the rule to include additional airplanes. The actions specified by the proposed AD are intended to prevent structural damage to the engine mount structure, which could lead to loss of airplane components. DATES: Comments must be received by May 10, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-216-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule 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. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office (ACO), 3229 East Spring Street, Long Beach, California. FOR FURTHER INFORMATION CONTACT: Wahib Mina, Aerospace Engineer, Airframe Branch, ANM-121L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office (ACO), 3229 East Spring Street, Long Beach, California 90806-2425; telephone (310) 988-5324; fax (310) 988-5210. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters 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 93-NM-216-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-216-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion On October 14, 1992, the FAA issued AD 92-23-03, Amendment 39-8403 (57 FR 47991, October 21, 1992), applicable to certain McDonnell Douglas Model MD-11 series airplanes, to require repetitive visual inspections to verify the installation of shear pins, shear pin retainers, and shear pin retainer attaching parts at the aft end of the center engine (No. 2) pylon thrust link; repair of any discrepancy found; and submission of a report of inspection findings to the FAA. That AD also provides an optional terminating action for the repetitive inspections. 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. The requirements of that AD are intended to prevent structural damage to the engine mount structure, which could lead to loss of airplane components. Since the issuance of AD 92-23-03, one operator has reported that, during the initial visual inspection conducted in accordance with that AD, all bolts and nuts were found installed; however, during a subsequent repetitive inspection, one nut and one bolt that attach the retainer were missing. If the retainers are missing, the shear pins may also be missing and the engine thrust loads will be improperly distributed to the airplane structure. This condition, if not corrected, could result in structural damage to the engine mount structure, which could lead to loss of airplane components. The FAA has reviewed and approved McDonnell Douglas MD-11 Alert Service Bulletin A54-31, Revision 1, dated June 3, 1993. This service bulletin revision adds procedures for performing repetitive inspections to verify that the shear pin retainer attaching parts are tightened within specific limits. This service bulletin revision also describes procedures for replacement of the existing retainer and attaching parts with a new retainer and attaching parts. Incorporation of this replacement eliminates the need for repetitive visual inspections and repetitive tightness verifications. The effectivity listing of this service bulletin revision includes 34 additional airplanes identified as being subject to the addressed unsafe condition. Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 92-23-03 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. The proposed AD would add repetitive inspections to verify that the shear pin retainer attaching parts are tightened within specified limits. If any shear pin, shear pin retainer, or shear pin retainer attaching part is missing during any inspection, this proposal would continue to require repair in accordance with a method approved by the FAA. The ``optional terminating action'' provided by AD 92-23-03, which consists of a one-time verification for tightness of the nuts of the four shear pin retainer attaching bolts, would no longer be provided in the proposed rule. The proposed AD would also require eventual replacement of the existing retainer and attaching parts with a new retainer and attaching parts. When accomplished, this replacement would be considered terminating action for the currently required repetitive visual inspections and the proposed repetitive verifications of tightness. The actions would be required to be accomplished in accordance with the revised alert service bulletin described previously. This proposal would also require that operators submit a report to the FAA of any discrepancy found during any inspection. Additionally, this proposal would expand the applicability of the rule to include additional airplanes that have been identified as being subject to the addressed unsafe condition. There 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 would be affected by this proposed AD, that it would take approximately 16 work hours per airplane to accomplish the proposed actions and that the average labor rate is $55 per work hour. Required parts would be provided at no cost to operators. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $36,960, or $880 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by removing amendment 39-8403 (57 FR 47991, October 21, 1992), and by adding a new airworthiness directive (AD), to read as follows: McDonnell Douglas: Docket 93-NM-216-AD. Supersedes AD 92-23-03, Amendment 39-8403. Applicability: 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. Compliance: Required as indicated, unless accomplished previously. - To prevent structural damage to the engine mount structure, which could lead to loss of airplane components, accomplish the following: (a) For 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. (1) If shear pins, shear pin retainers, and shear pin retainer attaching parts are installed, repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 60 days in accordance with the service bulletin until accomplishment of paragraph (d) of this AD. (2) If any shear pin, shear pin retainer, or shear pin retainer attaching part is missing, prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 60 days in accordance with the service bulletin until accomplishment of paragraph (d) of this AD. (b) For 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: Within 15 days after the effective date of this AD, 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, Revision 1, dated June 3, 1993. (1) If shear pins, shear pin retainers, and shear pin retainer attaching parts are installed, repeat the inspection required by paragraph (b) of this AD thereafter at intervals not to exceed 60 days in accordance with the service bulletin until accomplishment of paragraph (d) of this AD. (2) If any shear pin, shear pin retainer, or shear pin retainer attaching part is missing, prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Repeat the inspection required by paragraph (b) of this AD thereafter at intervals not to exceed 60 days in accordance with the service bulletin until accomplishment of paragraph (d) of this AD. (c) 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 the verification required by paragraphs (c) of this AD thereafter at intervals not to exceed 18 months in accordance with the service bulletin until accomplishment of paragraph (d) of this AD. (d) 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. (e) Within 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 Number 2120-0056. (f) An 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 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. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. - (g) Special flight permits may be issued in 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. Issued in Renton, Washington, on March 11, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-6209 Filed 3-16-94; 8:45 am] BILLING CODE 4910-13-U ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-05-AD] Airworthiness Directives; Boeing Model 747 Series Airplanes Equipped With Pratt & Whitney JT9D-3 or JT9D-7 Series Engines, Excluding JT9D-70 Series Engines AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require inspections of the inboard and outboard strut chords, stiffeners, and web to detect cracks and loose fasteners; repair of the chords, stiffeners, or web, if necessary; and replacement of any loose fastener. This proposal is prompted by reports of fatigue cracks and loose fasteners found in the forward lower spar web of the inboard strut on Model 747 series airplanes equipped with Pratt & Whitney JT9D-3 and JT9D-7 series engines. The actions specified by the proposed AD are intended to prevent separation of the strut from the wing of the airplane due to fatigue cracking. DATES: Comments must be received by May 10, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-05-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: Tim Backman, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2776; fax (206) 227-1181. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters 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-05-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-05-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The FAA has received six reports of fatigue cracks and one report of loose fasteners found in the forward lower spar web of the inboard strut on Model 747 series airplanes equipped with Pratt & Whitney JT9D- 3 and JT9D-7 series engines. The cracks were found in the area under the stiffeners and baffle and along the web chord. The airplanes on which these cracks were found had accumulated between 6,451 and 18,350 flight cycles and between 17,797 and 83,960 flight hours. All cracks reported have been found on the web of the inboard strut. During investigation of a recent in-flight engine loss, a similar crack of approximately two inches in length was found on the forward lower spar web. Although the in-inflight engine loss incident is still under investigation, the crack in the web was determined to be a contributing cause of the accident. Cracking in the forward lower spar web of the inboard strut could reduce the lateral strength of the strut. This condition, if not detected and corrected in a timely manner, could result in separation of the strut from the wing of the airplane due to fatigue cracking. Although all cracks reported were found on the web of the inboard strut, given standard design tolerances, little difference exists between the thickness of the web of the inboard strut (0.025 inch) and that of the outboard strut (0.032 inch). Additionally, the inboard and outboard webs are similar in configuration and loading environments. For these reasons, the FAA finds that the outboard strut web is subject to the same unsafe condition as the inboard strut web. The FAA has reviewed and approved Boeing Service Bulletin 747-54- 2160, dated September 9, 1993, that describes procedures for repetitive detailed visual inspections of the inboard strut chords, stiffeners, and web to detect cracks and loose fasteners; repair of the chords, stiffeners, or web, if necessary; and replacement of any loose fastener found. These same procedures are effective for inspecting the outboard strut chord. Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require repetitive detailed visual inspections of the inboard and outboard strut chords, stiffeners, and web to detect cracks and loose fasteners; repair of the chords, stiffeners, or web, if necessary; and replacement of any loose fastener. The actions would be required to be accomplished in accordance with the procedures specified in the service bulletin described previously. This is considered to be interim action. The manufacturer has advised that it is currently developing a modification program for the engine strut that will positively address the unsafe condition addressed by this AD. Once this modification program is developed, approved, and available, the FAA may consider additional rulemaking. There are approximately 380 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 140 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 22 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $169,400, or $1,210 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: Boeing: Docket 94-NM-05-AD. Applicability: Model 747 series airplanes equipped with Pratt & Whitney JT9D-3 or JT9D-7 series engines, excluding JT9D-70 series engines; line numbers 001 through 510 inclusive; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent separation of the strut from the wing of the airplane due to fatigue cracking, accomplish the following: (a) Perform a detailed visual inspection of the inboard and outboard strut forward lower spar chords, stiffeners, and web to detect cracks and loose fasteners, in accordance with the procedures described in Boeing Service Bulletin 747-54-2160, dated September 9, 1993, at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. Repeat this inspection thereafter at intervals not to exceed 2,000 landings or 8,000 hours time-in- service, whichever occurs first. (1) For airplanes that have accumulated less than 6,000 total landings as of the effective date of this AD: Perform the initial inspection at the later of the times specified in paragraphs (a)(1)(i) and (a)(1)(ii) of this AD. (i) Prior to the accumulation of 6,000 total landings on the strut. Or (ii) Within 8 months after the effective date of this AD. (2) For airplanes that have accumulated 6,000 or more total landings, but less than 15,000 total landings, as of the effective date of this AD: Perform the initial inspection within 6 months after the effective date of this AD. (3) For airplanes that have accumulated 15,000 or more total landings as of the effective date of this AD: Perform the initial inspection within 4 months after the effective date of this AD. (b) If any crack is found during any inspection required by paragraph (a) of this AD, prior to further flight, repair in accordance with procedures specified in Chapter 54-10-03 of the 747 Structural Repair Manual. (c) If any loose fastener is found during any inspection required by paragraph (a) of this AD, prior to further flight, replace the fastener in accordance with procedures specified in Chapter 51-30-02 of the 747 Structural Repair Manual. (d) An 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, Seattle 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, Seattle ACO. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (e) Special flight permits may be issued in 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. Issued in Renton, Washington, on March 11, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-6210 Filed 3-16-94; 8:45 am] BILLING CODE 4910-13-U