99-30370. Airworthiness Directives; Boeing Model 737-200 and -300 Series Airplanes Equipped With Cargo Doors Installed in Accordance With Supplemental Type Certificate (STC) SA2969SO  

  • [Federal Register Volume 64, Number 224 (Monday, November 22, 1999)]
    [Proposed Rules]
    [Pages 63757-63759]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 99-30370]
    
    
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    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 39
    
    [Docket No. 99-NM-85-AD]
    RIN 2120-AA64
    
    
    Airworthiness Directives; Boeing Model 737-200 and -300 Series 
    Airplanes Equipped With Cargo Doors Installed in Accordance With 
    Supplemental Type Certificate (STC) SA2969SO
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Notice of proposed rulemaking (NPRM).
    
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    SUMMARY: This document proposes the supersedure of an existing 
    airworthiness directive (AD), applicable to certain Boeing Model 737-
    200 and -300 series airplanes, that currently requires repetitive 
    inspections to detect cracking in the radii on the support angles on 
    the lower jamb (latch lug fittings) of the main deck cargo door, and 
    replacement of cracked parts. This action would add a requirement for 
    installation of redesigned lower jamb latch support angles in the main 
    cargo door surround structure, which would terminate the repetitive 
    inspections. This proposal is prompted by the development of a 
    modification that will provide better protection of the subject area 
    against effects of structural fatigue. The actions specified by the 
    proposed AD are intended to prevent in-flight separation of the main 
    deck cargo door from the airplane due to fatigue cracking on the 
    support angles on the lower door jamb.
    
    DATES: Comments must be received by January 6, 2000.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), Transport Airplane Directorate, ANM-114, 
    Attention: Rules Docket No. 99-NM-85-AD, 1601 Lind Avenue, SW., Renton, 
    Washington 98055-4056. Comments may be inspected at this location 
    between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
    holidays.
        The service information referenced in the proposed rule may be 
    obtained from Pemco Aeroplex, Inc., P.O. Box 2287, Birmingham, Alabama 
    35201-2287. This information may be examined at the FAA, Transport 
    Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at 
    the FAA, Small Airplane Directorate, Atlanta Aircraft Certification 
    Office, One Crown
    
    [[Page 63758]]
    
    Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia.
    
    FOR FURTHER INFORMATION CONTACT: Paul Sconyers, Manager, Airframe and 
    Propulsion Branch, ACE-117A; FAA, Small Airplane Directorate, Atlanta 
    Aircraft Certification Office, One Crown Center, 1895 Phoenix 
    Boulevard, suite 450, Atlanta, Georgia 30337-2748; telephone (770) 703-
    6076; fax (770) 703-6097.
    
    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 99-NM-85-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-114, Attention: Rules 
    Docket No. 99-NM-85-AD, 1601 Lind Avenue, SW., Renton, Washington 
    98055-4056.
    
    Discussion
    
        On December 29, 1994, the FAA issued AD 95-01-06, amendment 39-9117 
    (60 FR 2323, January 9, 1995), as revised by AD 95-01-06 R1, amendment 
    39-9449 (60 FR 62192, December 5, 1995), applicable to certain Boeing 
    Model 737-200 and -300 series airplanes [those equipped with main deck 
    cargo doors installed in accordance with supplemental type certificate 
    (STC) SA2969SO]. That AD requires repetitive visual inspections to 
    detect cracking in the radii on the support angles on the lower jamb 
    (latch lug fittings) of the main deck cargo door, and replacement of 
    cracked parts with new parts. That action was prompted by reports of 
    premature fatigue cracking on the support angles on the lower jamb of 
    the main deck cargo door. The requirements of that AD are intended to 
    prevent in-flight separation of the main deck cargo door from the 
    airplane due to fatigue cracking on the support angles on the lower 
    door jamb.
    
    Actions Since Issuance of Previous Rule
    
        When the FAA originally issued AD 95-01-06R1, it was noted in the 
    preamble that the AD was considered interim action until final action 
    was identified, at which time the FAA might consider further 
    rulemaking. Since the issuance of that AD, the STC holder for the cargo 
    door airplane modification has generated a design change for the lower 
    latch lug fitting support angles for the main cargo door surround 
    structure. This design change, consisting of the installation of new 
    lower jamb latch support angles in the main cargo door surround 
    structure, would eliminate the need for the repetitive inspections (as 
    required by AD 95-01-06R1). Upon consideration, the FAA has determined 
    that installation of the design change is necessary to correct the 
    unsafe condition addressed by AD 95-01-06R1.
        The FAA has determined that long-term continued operational safety 
    will be better assured by modifications or design changes to remove the 
    source of the problem, rather than by repetitive inspections. Long term 
    inspections may not be providing the degree of safety assurance 
    necessary for the transport airplane fleet. This, coupled with a better 
    understanding of the human factors associated with numerous repetitive 
    inspections, has led the FAA to consider placing less emphasis on 
    special procedures and more emphasis on design improvements. The 
    proposed design change requirement is in consonance with these 
    considerations.
        The actions specified by the proposed AD are intended to prevent 
    in-flight separation of the main deck cargo door from the airplane due 
    to fatigue cracking on the support angles on the lower door jamb.
    
    Explanation of Relevant Service Information
    
        The FAA has reviewed and approved Pemco Service Bulletin 737-53-
    0003, Revision 4, dated February 22, 1995, and Revision 5, dated March 
    25, 1999, which describe, among other things, procedures for 
    installation of new, improved lower jamb latch support angles in the 
    main cargo door surround structure. Accomplishment of the actions 
    specified in the service bulletin is intended to adequately address the 
    identified unsafe condition.
    
    Explanation of Requirements of Proposed Rule
    
        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 95-01-06 R1 to continue to require the 
    repetitive visual inspections to detect cracking in the radii on the 
    support angles on the lower jamb (latch lug fittings) of the main deck 
    cargo door, and replacement of cracked parts with new parts. The 
    proposed AD would also add a requirement for accomplishment of the 
    design change specified in the service bulletins described previously, 
    which would terminate the repetitive visual inspections. The actions 
    would be required to be accomplished in accordance with the service 
    information described previously, except as discussed below.
        The FAA has clarified the inspection requirement contained in AD 
    95-01-06 R1. Whereas that AD specified a visual inspection, the FAA has 
    revised this proposed AD to clarify that its intent is to require a 
    detailed visual inspection. Additionally, a note has been added to the 
    proposed rule to define that inspection.
    
    Differences Between Proposed Rule and Service Information
    
        Operators should note that, unlike the procedures described in 
    Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 
    1994, this proposed AD would not permit further flight if cracks are 
    detected in the affected area of the cargo door installation. The FAA 
    has determined that, because of the safety implications and 
    consequences associated with such cracking, any affected area of the 
    cargo door installation that is found to be cracked must be repaired or 
    modified prior to further flight.
    
    Cost Impact
    
        There are approximately 32 airplanes of the affected design in the 
    worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry 
    would be affected by this proposed AD.
        The inspection that is currently required by AD 95-01-06 R1 and 
    retained in this proposed AD takes approximately 8 work hours per
    
    [[Page 63759]]
    
    airplane to accomplish, at an average labor rate of $60 per work hour. 
    Based on these figures, the cost impact of the currently required 
    actions on U.S. operators is estimated to be $480 per airplane, per 
    inspection cycle.
        The new installation that is proposed in this AD action would take 
    approximately 500 work hours per airplane to accomplish, at an average 
    labor rate of $60 per work hour. Required parts would cost 
    approximately $9,700 per airplane. Based on these figures, the cost 
    impact of the proposed requirements of this AD on U.S. operators is 
    estimated to be $79,400, or $39,700 per airplane.
        The cost impact figures discussed above are based on assumptions 
    that no operator has yet accomplished any of the current or proposed 
    requirements of this AD action, and that no operator would accomplish 
    those actions in the future if this AD were not adopted.
    
    Regulatory Impact
    
        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 
    part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
    follows:
    
    PART 39--AIRWORTHINESS DIRECTIVES
    
        1. The authority citation for part 39 continues to read as follows:
    
        Authority: 49 U.S.C. 106(g), 40113, 44701.
    
    
    Sec. 39.13  [Amended]
    
        2. Section 39.13 is amended by removing amendment 39-9449 (60 FR 
    62192, December 5, 1995), and by adding a new airworthiness directive 
    (AD), to read as follows:
    
    Boeing: Docket 99-NM-85-AD. Supersedes AD 95-01-06 R1, Amendment 39-
    9449.
    
        Applicability: Model 737-200 and -300 series airplanes equipped 
    with main deck cargo doors installed in accordance with supplemental 
    type certificate (STC) SA2969SO, certificated in any category.
    
        Note 1: This AD applies to each airplane identified in the 
    preceding applicability provision, regardless of whether it has been 
    otherwise 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 use the authority 
    provided in paragraph (c)(1) of this AD to request approval from the 
    FAA. This approval may address either no action, if the current 
    configuration eliminates the unsafe condition; or different actions 
    necessary to address the unsafe condition described in this AD. Such 
    a request should include an assessment of the effect of the changed 
    configuration on the unsafe condition addressed by this AD. In no 
    case does the presence of any modification, alteration, or repair 
    remove any airplane from the applicability of this AD.
    
        Compliance: Required as indicated, unless accomplished 
    previously.
        To prevent in-flight separation of the main deck cargo door from 
    the airplane, accomplish the following:
    
        Note 2: This AD references Pemco Alert Service Letter 737-53-
    0003, Revision 3, dated December 22, 1994; Pemco Service Bulletin 
    737-53-0003, Revision 4, dated February 22, 1995; and Pemco Service 
    Bulletin 737-53-0003, Revision 5, dated March 25, 1999; for 
    information concerning inspection and replacement procedures. In 
    addition, this AD specifies replacement requirements different from 
    those included in the service letter or service bulletin. Where 
    there are differences between the AD and the service letter or 
    service bulletin, the AD prevails.
    
    Restatement of Requirements of AD 95-01-06R1, Amendment 39-9449
    
    Repetitive Inspections
    
        (a) Within 50 flight cycles after January 24, 1995 (the 
    effective date of AD 95-01-06, amendment 39-9117), or within 50 
    flight cycles after installation of STC SA2969SO, whichever occurs 
    later, perform a detailed visual inspection to detect cracking in 
    the radii on the support angles on the lower jamb of the main deck 
    cargo door, in accordance with Pemco Alert Service Letter 737-53-
    0003, Revision 3, dated December 22, 1994.
        (1) If no cracking is detected, repeat the detailed visual 
    inspection thereafter at intervals not to exceed 450 flight cycles.
        (2) If any cracking is detected, prior to further flight, 
    replace the cracked part with a new part in accordance with the 
    alert service letter. Repeat the detailed visual inspection 
    thereafter at intervals not to exceed 450 flight cycles.
    
        Note 3: For the purposes of this AD, a detailed visual 
    inspection is defined as: ``An intensive visual examination of a 
    specific structural area, system, installation, or assembly to 
    detect damage, failure, or irregularity. Available lighting is 
    normally supplemented with a direct source of good lighting at 
    intensity deemed appropriate by the inspector. Inspection aids such 
    as mirror, magnifying lenses, etc., may be used. Surface cleaning 
    and elaborate access procedures may be required.''
    
    New Requirements of This AD
    
    Terminating Action
    
        (b) Within 1,500 flight cycles after the effective date of this 
    AD, install redesigned lower jamb latch lug support angles in the 
    main cargo door surround structure in accordance with Pemco Service 
    Bulletin 737-53-0003, Revision 4, dated February 22, 1995, or 
    Revision 5, dated March 25, 1999. This action constitutes 
    terminating action for the requirements of this AD.
    
    Alternative Methods of Compliance
    
        (c)(1) 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, FAA, Small Airplane Directorate, 
    Atlanta Aircraft Certification Office (ACO). Operators shall submit 
    their requests through an appropriate FAA Principal Maintenance 
    Inspector, who may add comments and then send it to the Manager, 
    Atlanta ACO.
        (c)(2) Alternative methods of compliance, approved previously in 
    accordance with AD 95-01-06 R1, amendment 39-9449, are approved as 
    alternative methods of compliance with paragraphs (a) and (b) of 
    this AD.
    
        Note 4: Information concerning the existence of approved 
    alternative methods of compliance with this AD, if any, may be 
    obtained from the Atlanta ACO.
    
    Special Flight Permits
    
        (d) Special flight permits may be issued in accordance with 
    Secs. 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.
    
        Issued in Renton, Washington, on November 16, 1999.
    D.L. Riggin,
    Acting Manager, Transport Airplane Directorate, Aircraft Certification 
    Service.
    [FR Doc. 99-30370 Filed 11-19-99; 8:45 am]
    BILLING CODE 4910-13-U
    
    
    

Document Information

Published:
11/22/1999
Department:
Federal Aviation Administration
Entry Type:
Proposed Rule
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
99-30370
Dates:
Comments must be received by January 6, 2000.
Pages:
63757-63759 (3 pages)
Docket Numbers:
Docket No. 99-NM-85-AD
RINs:
2120-AA64: Airworthiness Directives
RIN Links:
https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives
PDF File:
99-30370.pdf
CFR: (1)
14 CFR 39.13