99-682. Airworthiness Directives; Boeing Model 737 Series Airplanes  

  • [Federal Register Volume 64, Number 8 (Wednesday, January 13, 1999)]
    [Proposed Rules]
    [Pages 2161-2164]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 99-682]
    
    
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    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 39
    
    [Docket No. 98-NM-383-AD]
    RIN 2120-AA64
    
    
    Airworthiness Directives; Boeing Model 737 Series Airplanes
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Notice of proposed rulemaking (NPRM).
    
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    SUMMARY: This document proposes the adoption of a new airworthiness 
    directive (AD) that is applicable to all Boeing Model 737 series 
    airplanes. This proposal would require repetitive displacement tests of 
    the secondary slide in the dual concentric servo valve of the power 
    control unit (PCU) for the rudder, and replacement of the valve 
    assembly with a modified valve assembly, if necessary. This proposal is 
    prompted by reports of cracking found in PCU secondary servo valve 
    slides. The actions specified by the proposed AD are intended to 
    prevent failure of the secondary slide and consequent rudder hardover 
    and reduced controllability of the airplane.
    
    DATES: Comments must be received by February 12, 1999.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), Transport Airplane Directorate, ANM-114, 
    Attention: Rules Docket No. 98-NM-383-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 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: R.C. Jones, Aerospace Engineer, 
    Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
    Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
    SW., Renton, Washington 98055-4056; telephone (425) 227-1118; fax (425) 
    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.
    
    [[Page 2162]]
    
        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 98-NM-383-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. 98-NM-383-AD, 1601 Lind Avenue, SW., Renton, Washington 
    98055-4056.
    
    Discussion
    
        The FAA has received reports of cracking found on Boeing Model 737 
    series airplanes on one of the two legs of the clevis of the secondary 
    slide, which is a component of the dual servo valve in the power 
    control unit (PCU) of the rudder. Most of the cracks were found during 
    the manufacturing process by the PCU supplier. However, some of the 
    cracks were found on servo valve assemblies by operators; those 
    assemblies had not yet been installed in PCU's. Test results have 
    indicated that a crack in one leg of the secondary slide is not in 
    itself an unsafe condition. However, a crack in the other leg of that 
    same slide could cause the slide to break apart and allow a loose part 
    to jam both the primary and secondary slides within the valve assembly. 
    This condition, if not corrected, could result in rudder hardover and 
    reduced controllability of the airplane.
    
    Other Relevant Rulemaking
    
        Related AD 97-14-04, amendment 39-10061 (62 FR 35068, June 30, 
    1997), applicable to all Boeing Model 737-100, -200, -300, -400, and -
    500 series airplanes, requires the following actions:
         Tests of the main rudder PCU to detect excessive internal 
    leakage of hydraulic fluid, stalling, or reversal, and to verify proper 
    operation of the PCU;
         Replacement of the PCU with a unit having a different part 
    number, if necessary (the new PCU incorporates a redesigned valve 
    assembly);
         Replacement of the PCU and the vernier control rod bolts 
    with newly designed units; and
         Leak tests of the PCU, and replacement of the PCU with a 
    serviceable or newly designed unit, if necessary.
    
    Explanation of Relevant Service Information
    
        The FAA has reviewed and approved a draft of Boeing Alert Service 
    Bulletin 737-27A1221, dated January 14, 1999 (for Boeing Model 737-100, 
    -200, -300, -400, and -500 series airplanes); and a draft of Boeing 
    Alert Service Bulletin 737-27A1222, dated January 14, 1999 (for Boeing 
    Model 737-600, -700, and -800 series airplanes). [Although these alert 
    service bulletins will not be published until after this proposed AD 
    has been issued, they are not expected to be substantively different 
    from the drafts that have been approved. Copies of these drafts have 
    been placed in the rulemaking docket.] These draft alert service 
    bulletins describe procedures for a displacement test of the secondary 
    slide in the dual concentric servo valve of the rudder PCU, criteria 
    for passing the test, and procedures for replacement of any discrepant 
    valve assembly with one having a slide that passes the displacement 
    test. Accomplishment of the actions specified in the draft alert 
    service bulletins is intended to adequately address the identified 
    unsafe condition.
        Boeing Alert Service Bulletin 737-27A1222 refers to Parker Service 
    Bulletin 381500-27-01, dated December 22, 1998, as an additional source 
    of service information for accomplishment of the displacement test for 
    Model 737-600, -700, -800, and -900 series airplanes.
    
    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 require accomplishment of the actions specified in 
    the draft alert service bulletins described previously, except as 
    discussed in the ``Differences Between Proposed Rule and Draft Alert 
    Service Bulletins'' section of this proposed AD. The proposed AD also 
    would require that operators report results of inspection findings to 
    the FAA and submit failed valve assemblies to Parker Hannifin 
    Corporation (the PCU manufacturer).
    
    Interim Action
    
        This is considered to be interim action until final action is 
    identified, at which time the FAA may consider further rulemaking.
    
    Differences Between Proposed Rule and Draft Alert Service Bulletins
    
        Operators should note that, while the draft alert service bulletins 
    do not recommend that the displacement test be repeated, the FAA has 
    determined that the proposed AD should be considered interim action 
    until the root cause of the cracking can be determined or a final 
    action identified. As a result, the proposed AD would require 
    accomplishment of the displacement test at regular intervals.
        In addition, while this proposed AD is applicable to all Boeing 
    Model 737 series airplanes, the effectivity of the alert service 
    bulletins is limited to airplanes with certain line numbers. Because 
    this proposed AD is interim action and a final action has not yet been 
    identified to adequately address the identified unsafe condition, it 
    will be necessary to repeat the displacement test on all Model 737 
    series airplanes, including airplanes that are produced subsequent to 
    those with line numbers specified in the draft alert service bulletins.
        Further, although draft Boeing Alert Service Bulletin 737-27A1221 
    specifies that the manufacturer may be contacted for disposition of 
    certain corrective actions, this proposal would require those 
    corrective actions to be accomplished in accordance with a method 
    approved by the FAA.
    
    Cost Impact
    
        There are approximately 3,059 airplanes of the affected design in 
    the worldwide fleet. The FAA estimates that 1,334 airplanes of U.S. 
    registry would be affected by this proposed AD, that it would take 
    approximately 1 work hour per airplane to accomplish the proposed 
    displacement test, and that the average labor rate is $60 per work 
    hour. Based on these figures, the cost impact of the proposed AD on 
    U.S. operators is estimated to be $80,040, or $60 per airplane, per 
    test cycle.
        The 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 proposed test requires that the PCU be removed from the 
    airplane. It would take approximately 9 work hours to remove and 
    reinstall or replace the PCU. For Model 737-100, -200, -300, -400, and 
    -500 series airplanes, concurrent accomplishment of this proposed AD 
    and AD 97-14-04 would preclude the necessity to accomplish this 
    replacement action twice, thereby offsetting the cost impact on 
    operators.
    
    Regulatory Impact
    
        The regulations proposed herein would not have substantial direct 
    effects on the States, on the relationship
    
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    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 adding the following new 
    airworthiness directive:
    
    Boeing: Docket 98-NM-383-AD.
    
        Applicability: All Model 737 series airplanes, certificated in 
    any category.
    
        Note 1: This AD applies to each airplane identified in the 
    preceding applicability provision, regardless of whether it has been 
    modified, altered, or repaired in the area subject to the 
    requirements of this AD. For airplanes that have been modified, 
    altered, or repaired so that the performance of the requirements of 
    this AD is affected, the owner/operator must request approval for an 
    alternative method of compliance in accordance with paragraph (e) of 
    this AD. The request should include an assessment of the effect of 
    the modification, alteration, or repair on the unsafe condition 
    addressed by this AD; and, if the unsafe condition has not been 
    eliminated, the request should include specific proposed actions to 
    address it.
    
        Compliance: Required as indicated, unless accomplished 
    previously.
        To prevent failure of the secondary servo valve slide in the 
    rudder power control unit (PCU) due to cracking of the slide, and 
    consequent rudder hardover and reduced controllability of the 
    airplane, accomplish the following:
        (a) Perform a displacement test of the secondary slide in the 
    dual servo valve in the rudder PCU, in accordance with Boeing Alert 
    Service Bulletin 737-27A1221, dated January 14, 1999 (for Model 737-
    100, -200, -300, -400, and -500 series airplanes); or 737-27A1222, 
    dated January 14, 1999 (for Model 737-600, -700, -800, and -900 
    series airplanes); at the applicable time specified by paragraph 
    (a)(1), (a)(2), (a)(3), (a)(4), or (a)(5) of this AD. Repeat the 
    displacement test on that PCU thereafter at intervals not to exceed 
    12,000 flight hours.
        (1) For Model 737-100, -200, -300, -400, and -500 series 
    airplanes on which the PCU replacement required by paragraph (d)(1) 
    of AD 97-14-04, amendment 39-10061 (62 FR 35068, June 30, 1997), has 
    been accomplished prior to the effective date of this AD: Conduct 
    the displacement test within 4 months after the effective date of 
    this AD.
        (2) For Model 737-100, -200, -300, -400, and -500 series 
    airplanes on which the PCU installation required by paragraph (d)(1) 
    of AD 97-14-04 has not been accomplished prior to the effective date 
    of this AD: Prior to installing the PCU required by AD 97-14-04, 
    conduct the displacement test on that PCU as required by this 
    paragraph of this AD.
        (3) For airplanes equipped with a PCU having part number 65-
    44861-12 and having serial number (S/N) 3509A or lower: Conduct the 
    displacement test within 4 months after the effective date of this 
    AD.
        (4) For Model 737-600, -700, and -800 series airplanes having 
    line numbers 1 through 222 inclusive: Conduct the displacement test 
    within 4 months after the effective date of this AD.
        (5) For all other airplanes: Conduct the displacement test prior 
    to the accumulation of 12,000 flight hours on the PCU, or within 30 
    days after the effective date of this AD, whichever occurs later.
        (b) If the results of the displacement test required by 
    paragraph (a) of this AD are outside the limits specified by Boeing 
    Alert Service Bulletin 737-27A1221, dated January 14, 1999 (for 
    Model 737-100, -200, -300, -400, and -500 series airplanes), or 737-
    27A1222, dated January 14, 1999 (for Model 737-600, -700, -800, and 
    -900 series airplanes): Prior to further flight, accomplish the 
    actions specified in paragraphs (b)(1) and (b)(2) of this AD.
        (1) Replace the valve assembly, in accordance with the 
    applicable alert service bulletin, with a serviceable valve 
    assembly. And
        (2) Following installation of the replacement valve assembly in 
    accordance with paragraph (b)(1) of this AD, perform the 
    displacement test required by paragraph (a) of this AD on that 
    assembly, in accordance with the applicable alert service bulletin. 
    If the test results are outside the limits specified by the 
    applicable alert service bulletin, prior to further flight, perform 
    corrective action in accordance with a method approved by the 
    Manager, Seattle Aircraft Certification Office, FAA, Transport 
    Airplane Directorate.
    
        Note 2: Boeing Alert Service Bulletin 737-27A1222 refers to 
    Parker Service Bulletin 381500-27-01, dated December 22, 1998, as an 
    additional source of service information for accomplishment of the 
    displacement test for Model 737-600, -700, -800, and -900 series 
    airplanes.
    
        (c) As of the effective date of this AD, no person shall install 
    on any airplane a main rudder PCU having serial number (S/N) 3509A 
    or lower (for Model 737-100, -200, -300, -400, and -500 series 
    airplanes) or S/N 0299 or lower (for Model 737-600, -700, -800, and 
    -900 series airplanes) unless that PCU's nameplate has been vibro-
    engraved with the letter ``C'' following the serial number.
        (d)(1) Within 10 days after accomplishing the displacement test 
    required by paragraph (a) of this AD: Submit a report of inspection 
    findings to the Manager, Seattle Aircraft Certification Office 
    (ACO), FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., 
    Renton, Washington 98055-4056; fax (425) 227-1181. The report must 
    include the inspection results (both positive and negative 
    findings), test data for any failed actuators, a description of any 
    discrepancies found, the part number and serial number of each 
    actuator tested, and the airplane serial number.
        (2) Within 10 days after accomplishing the displacement test 
    required by paragraph (a) of this AD: Submit failed valve assemblies 
    for analysis to Parker Hannifin Corporation, Chief Engineer, 
    Customer Support Operations, 16666 Von Karman Avenue, Irvine, 
    California 92606.
        (3) 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.
        (e) 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 ACO. 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 3: Information concerning the existence of approved 
    alternative methods of compliance with this AD, if any, may be 
    obtained from the Seattle ACO.
    
        (f) Special 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.
    
    
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        Issued in Renton, Washington, on January 6, 1999.
    John J. Hickey,
    Acting Manager, Transport Airplane Directorate, Aircraft Certification 
    Service.
    [FR Doc. 99-682 Filed 1-12-99; 8:45 am]
    BILLING CODE 4910-13-U
    
    
    

Document Information

Published:
01/13/1999
Department:
Federal Aviation Administration
Entry Type:
Proposed Rule
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
99-682
Dates:
Comments must be received by February 12, 1999.
Pages:
2161-2164 (4 pages)
Docket Numbers:
Docket No. 98-NM-383-AD
RINs:
2120-AA64: Airworthiness Directives
RIN Links:
https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives
PDF File:
99-682.pdf
CFR: (1)
14 CFR 39.13