98-29603. Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines  

  • [Federal Register Volume 63, Number 214 (Thursday, November 5, 1998)]
    [Proposed Rules]
    [Pages 59743-59746]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 98-29603]
    
    
    =======================================================================
    -----------------------------------------------------------------------
    
    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 39
    
    [Docket No. 98-ANE-66-AD]
    RIN 2120-AA64
    
    
    Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
    Engines
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Notice of proposed rulemaking (NPRM).
    
    -----------------------------------------------------------------------
    
    SUMMARY: This proposal would require revisions to the Time Limits 
    Section (TLS) of the manufacturer's Engine Manuals (EMs) for Pratt & 
    Whitney (PW) PW4000 series turbofan engines to include required 
    enhanced inspection of selected critical life-limited parts at each 
    piece-part exposure. This proposal would also require an air carrier's 
    approved continuous airworthiness maintenance program to incorporate 
    these inspection procedures. Air carriers with an approved continuous 
    airworthiness maintenance program would be allowed to either maintain 
    the records showing the current status of the inspections using the 
    record keeping system specified in the air carrier's maintenance 
    manual, or establish an acceptable alternate method of record keeping. 
    This proposal is prompted by an FAA study of in-service events 
    involving uncontained failures of critical rotating engine parts which 
    indicated the need for improved inspections. The improved inspections 
    are needed to identify those critical rotating parts with conditions, 
    that if allowed to continue in service, could result in uncontained 
    failures. The actions specified by this proposed AD are intended to 
    prevent critical life-limited rotating engine part failure, which could 
    result in an uncontained engine failure and damage to the airplane.
    
    DATES: Comments must be received by February 3, 1999.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), New England Region, Office of the Regional 
    Counsel, Attention: Rules Docket No. 98-ANE-66-AD, 12 New England 
    Executive Park,
    
    [[Page 59744]]
    
    Burlington, MA 01803-5299. Comments may also be sent via the Internet 
    using the following address: 9-ad-engineprop@faa.dot.gov''. Comments 
    sent via the Internet must contain the docket number in the subject 
    line. Comments may be inspected at this location between 8:00 a.m. and 
    4:30 p.m., Monday through Friday, except Federal holidays.
    
    FOR FURTHER INFORMATION CONTACT: Peter White, Aerospace Engineer, 
    Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
    New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
    238-7128, fax (781) 238-7199.
    
    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 should 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 98-ANE-66-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, New England Region, Office of the Regional Counsel, 
    Attention: Rules Docket No. 98-ANE-66-AD, 12 New England Executive 
    Park, Burlington, MA 01803-5299.
    
    Discussion
    
        A recent FAA study analyzing 15 years of accident data for 
    transport category airplanes identified several failure mode root 
    causes that can result in serious safety hazards to transport category 
    airplanes. This study identified uncontained failure of critical life-
    limited rotating engine parts as the leading engine-related safety 
    hazard to airplanes. Uncontained engine failures have resulted from 
    undetected cracks in rotating parts that initiated and propagated to 
    failure. Cracks can originate from causes such as unintended excessive 
    stress from the original design, or they may initiate from stresses 
    induced from material flaws, handling damage, or damage from machining 
    operations. The failure of rotating parts can present a significant 
    safety hazard to the airplanes by release of high energy fragments that 
    could injure passengers or crew by penetration of the cabin, damage 
    flight control surfaces, sever flammable fluid lines, or otherwise 
    compromise the airworthiness of the airplane.
        Accordingly, the FAA has developed an intervention strategy to 
    significantly reduce uncontained engine failures. This intervention 
    strategy was developed after consultation with industry and will be 
    used as a model for future initiatives. This intervention strategy is 
    to conduct enhanced, nondestructive inspections of fan disks which 
    could most likely result in a safety hazard to the airplane in the 
    event of a disk fracture. The need for additional rule making is also 
    being considered by the FAA. Future ADs may be issued introducing 
    additional intervention strategies to further reduce or eliminate 
    uncontained engine failures.
        Properly focused enhanced inspections require identification of the 
    parts whose failure presents the highest safety hazard to the airplane, 
    identifying the most critical features to inspect on these parts, and 
    utilizing inspection procedures and techniques that improve crack 
    detection. The FAA, with close cooperation of the engine manufacturers, 
    has completed a detailed analysis that identifies the most safety 
    significant parts and features, and the most appropriate inspection 
    methods.
        Critical life-limited high energy rotating parts are currently 
    subject to some form of recommended crack inspection when exposed 
    during engine maintenance or disassembly. As a result of this AD, the 
    inspections currently recommended by the manufacturer will become 
    mandatory for those parts listed in the compliance section. 
    Furthermore, the FAA intends that additional mandatory enhanced 
    inspections resulting from this AD serve as an adjunct to the existing 
    inspections. The FAA has determined that the enhanced inspections will 
    significantly improve the probability of crack detection while the 
    parts are disassembled during maintenance. All mandatory inspections 
    must be conducted in accordance with detailed inspection procedures 
    prescribed in the manufacturer's Engine Cleaning, Inspection, and 
    Repair (CIR) manuals.
        Additionally, this AD allows for air carriers operating under the 
    provisions of 14 CFR part 121 with an FAA-approved continuous 
    airworthiness maintenance program, and entities with whom those air 
    carriers make arrangements to perform this maintenance, to verify 
    performance of the enhanced inspections by retaining the maintenance 
    records that include the inspections resulting from this AD, provided 
    that the records include the date and signature of the person 
    performing the maintenance action. These records must be retained with 
    the maintenance records of the part, engine module, or engine until the 
    task is repeated. This will establish a method of record preservation 
    and retrieval typical to those in existing continuous airworthiness 
    maintenance programs. Instructions must be included in an air carrier's 
    maintenance manual providing procedures on how this record preservation 
    and retrieval system will be implemented and integrated into the air 
    carrier's record keeping system.
        For engines or engine modules that are approved for return to 
    service by an authorized FAA-certificated entity and that are acquired 
    by an operator after the effective date of this AD, the mandatory 
    enhanced inspections need not be accomplished until the next piece-part 
    opportunity. For example, there is no need for an operator to 
    disassemble to piece-part level an engine or module returned to service 
    by an FAA-certificated facility simply because that engine or module 
    was previously operated by an entity not required to comply with this 
    AD. Furthermore, the FAA intends for operators to perform the enhanced 
    inspections of these parts at the next piece-part opportunity following 
    the initial acquisition, installation, and removal of the part 
    following the effective date of this AD. For piece parts that have not 
    been approved for return to service prior to the effective date of this 
    AD, the FAA does intend that the mandatory enhanced inspections 
    required by this AD be performed before such parts are approved for 
    return to service. Piece parts that have been approved for return to 
    service prior to the effective date of this AD may be installed; 
    however,
    
    [[Page 59745]]
    
    enhanced inspection will be required at the next piece-part 
    opportunity.
        This proposal would require, within the next 30 days after the 
    effective date of this AD, revisions to the Time Limits Section (TLS) 
    of the Engine Manuals for PW4000 series turbofan engines, and, for air 
    carriers, the approved continuous airworthiness maintenance program. 
    Pratt & Whitney, the manufacturer of PW4000 series turbofan engines, 
    used on 14 CFR part 25 airplanes has provided the FAA with a detailed 
    proposal that identifies and prioritizes the critical life-limited 
    rotating engine parts with the highest potential to hazard the airplane 
    in the event of failure, along with instructions for enhanced, focused 
    inspection methods. The enhanced inspections resulting from this AD 
    will be conducted at piece-part opportunity, as defined below in the 
    compliance section, rather than specific time inspection intervals.
        There are approximately 1,900 engines of the affected design in the 
    worldwide fleet. The FAA estimates that 450 engines installed on 
    airplanes of U.S. registry would be affected by this proposed AD, that 
    it would take approximately 8 work hours for the fan disk inspection. 
    The average labor rate is $60 per work hour. Based on these figures, 
    and using recent shop visit rate data, the total cost impact of the 
    proposed AD on U.S. operators is estimated to be $70,000 per year.
        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 adding the following new 
    airworthiness directive:
    
    Pratt & Whitney: Docket 98-ANE-66-AD.
        Applicability: Pratt & Whitney PW4050, PW4052, PW4056, PW4060, 
    PW4060A, PW4062, PW4060C, PW4152, PW4156, PW4156A, PW4158, PW4160, 
    PW4460, PW4462, PW4164, PW4168, PW4074, PW4074D, PW4077, PW4077D, 
    PW4084, PW4084D, and PW4090 series turbofan engines, installed on 
    but not limited to Airbus A300, A310, and A330 series, Boeing 747, 
    767, 777 series, and McDonnell Douglas MD-11 series airplanes.
    
        Note 1: This airworthiness directive (AD) applies to each engine 
    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 engines 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 (c) 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 critical life-limited rotating engine part failure, 
    which could result in an uncontained engine failure and damage to 
    the airplane, accomplish the following:
        (a) Within the next 30 days after the effective date of this AD, 
    revise the manufacturer's Time Limits section of the manufacturer's 
    Engine Manual, Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822, 
    51A751, and 51A345, as applicable, for Pratt & Whitney PW4050, 
    PW4052, PW4056, PW4060, PW4060A, PW4062, PW4060C, PW4152, PW4156, 
    PW4156A, PW4158, PW4160, PW4460, PW4462, PW4164, PW4168, PW4074, 
    PW4074D, PW4077, PW4077D, PW4084, PW4084D, and PW4090 series 
    turbofan engines, and for air carrier operations revise the approved 
    continuous airworthiness maintenance program, by adding the 
    following:
    
    ``MANDATORY INSPECTIONS
    
        (1) Perform inspections of the following parts at each piece-part 
    opportunity in accordance with the instructions provided in the PW4000 
    series Engine Cleaning, Inspection, and Repair (CIR) Manuals:
    
    ----------------------------------------------------------------------------------------------------------------
                                                                                    Manual                    CIR
                     Part nomen                                P/N                 section     Inspection    manual
    ----------------------------------------------------------------------------------------------------------------
    Hub, LPC Assembly..........................  50B221 (50B201 Detail)........     72-31-07           02     51A357
    Hub, LPC Assembly..........................  50B321 (50B301 Detail)........     72-31-07           02     51A357
    Hub, LPC Assembly..........................  51B321 (51B301 Detail)........     72-31-07           02     51A357
    Hub, LPC Assembly..........................  52B021 (52B001 Detail)........     72-31-07           02     51A357
    Hub, LPC Assembly..........................  51B631 (50B601 Detail)........     72-31-07           02     51A750
    Hub, LPC Assembly..........................  51B821 (51B801 Detail)........     72-31-07           02     51A750
    Hub, LPC Assembly..........................  52B521 (52B501 Detail)........     72-31-07           02     51A750
    ----------------------------------------------------------------------------------------------------------------
    
        (2) For the purposes of these mandatory inspections, piece-part 
    opportunity means:
        (i) The part is considered completely disassembled when done in 
    accordance with the disassembly instructions in the engine 
    manufacturer's Engine Manual; and
        (ii) The part has accumulated more than 100 cycles in service since 
    the last piece-part opportunity inspection, provided that the part was 
    not damaged or related to the cause for its removal from the engine.''
    
        (b) Except as provided in paragraph (c) of this AD, and 
    notwithstanding contrary provisions in section 43.16 of the Federal 
    Aviation Regulations (14 CFR 43.16), these mandatory inspections 
    shall be performed only in accordance with the Time Limits
    
    [[Page 59746]]
    
    section of the applicable PW4000 series Engine Manuals.
        (c) 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 Engine Certification Office. Operators shall 
    submit their requests through an appropriate FAA Principal 
    Maintenance Inspector (PMI), who may add comments and then send it 
    to the Engine Certification Office.
    
        Note 2: Information concerning the existence of approved 
    alternative methods of compliance with this airworthiness directive, 
    if any, may be obtained from the Engine Certification Office.
    
        (d) 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.
        (e) The records of the mandatory inspections required as a 
    result of revising the Time Limits section of the PW4000 series 
    Engine Manuals and the air carrier's continuous airworthiness 
    maintenance program as provided by paragraph (a) of this AD shall be 
    maintained by FAA-certificated air carriers which have an approved 
    continuous airworthiness maintenance program in accordance with the 
    record keeping system currently specified in their manual required 
    by sections 121.369 of the Federal Aviation Regulations (14 CFR 
    121.369); or, in lieu of the record showing the current status of 
    each mandatory inspection required by sections 121.380(a)(2)(vi) of 
    the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)), 
    certificated air carriers may establish an approved alternate system 
    of record retention that provides a method for preservation and 
    retrieval of the maintenance records that include the inspections 
    resulting from this AD, and include the policy and procedures for 
    implementing this alternate method in the air carrier's maintenance 
    manual required by sections 121.369 (c) of the Federal Aviation 
    Regulations (14 CFR 121.369 (c)); however, the alternate system must 
    be accepted by the appropriate PMI and require the maintenance 
    records be maintained either indefinitely or until the work is 
    repeated.
    
        Note 3: These record keeping requirements apply only to the 
    records used to document the mandatory inspections required as a 
    result of revising the Time Limits section of the PW4000 series 
    Engine Manuals as provided in paragraph (a) of this AD, and do not 
    alter or amend the record keeping requirements for any other AD or 
    regulatory requirement.
    
        Issued in Burlington, Massachusetts, on October 30, 1998.
    David A. Downey,
    Assistant Manager, Engine and Propeller Directorate, Aircraft 
    Certification Service.
    [FR Doc. 98-29603 Filed 11-4-98; 8:45 am]
    BILLING CODE 4910-13-U
    
    
    

Document Information

Published:
11/05/1998
Department:
Federal Aviation Administration
Entry Type:
Proposed Rule
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
98-29603
Dates:
Comments must be received by February 3, 1999.
Pages:
59743-59746 (4 pages)
Docket Numbers:
Docket No. 98-ANE-66-AD
RINs:
2120-AA64: Airworthiness Directives
RIN Links:
https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives
PDF File:
98-29603.pdf
CFR: (1)
14 CFR 39.13