94-6210. Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes  

  • [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
    
    
    

Document Information

Published:
03/17/1994
Department:
Federal Aviation Administration
Entry Type:
Uncategorized Document
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
94-6210
Dates:
Comments must be received by May 10, 1994.
Pages:
0-0 (1 pages)
Docket Numbers:
Federal Register: March 17, 1994, Docket No. 93-NM-216-AD
CFR: (1)
14 CFR 39.13