94-3237. Airworthiness Directives; Garrett Turbine Engine Company ATF3 Series Turbofan Engines  

  • [Federal Register Volume 59, Number 29 (Friday, February 11, 1994)]
    [Unknown Section]
    [Page 0]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 94-3237]
    
    
    [[Page Unknown]]
    
    [Federal Register: February 11, 1994]
    
    
    =======================================================================
    -----------------------------------------------------------------------
    
    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 39
    
    [Docket No. 93-ANE-39]
    
     
    
    Airworthiness Directives; Garrett Turbine Engine Company ATF3 
    Series Turbofan 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 Garrett Turbine Engine Company 
    ATF3 series turbofan engines. This proposal would require a one-time 
    inspection for cracks of the curvic and bore area of the high pressure 
    turbine (HPT) rotor assembly disk, and replacement, if necessary, with 
    a serviceable disk. This proposal is prompted by several reports of 
    cracks discovered during routine inspections of HPT rotor assembly 
    disks. The actions specified by the proposed AD are intended to prevent 
    an uncontained failure of the HPT rotor assembly disk.
    
    DATES: Comments must be received by April 12, 1994.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), New England Region, Office of the Assistant Chief 
    Counsel, Attention: Rules Docket No. 93-ANE-39, 12 New England 
    Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
    this location between 8 a.m. and 4:30 p.m., Monday through Friday, 
    except Federal holidays.
        The service information referenced in the proposed rule may be 
    obtained from AlliedSignal Propulsion Engines, Aviation Services 
    Division, Data Distribution, Dept. 64-3/2102-1M, P.O. Box 29003, 
    Phoenix, AZ 85038-9003. This information may be examined at the FAA, 
    New England Region, Office of the Assistant Chief Counsel, 12 New 
    England Executive Park, Burlington, MA.
    
    FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, Los 
    Angeles Aircraft Certification Office, FAA, Transport Airplane 
    Directorate, 3229 East Spring Street, Long Beach, CA 90806-2425; 
    telephone (310) 988-5246; 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 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 93-ANE-39.'' 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 Assistant Chief Counsel, 
    Attention: Rules Docket No. 93-ANE-39, 12 New England Executive Park, 
    Burlington, MA 01803-5299.
    
    Discussion
    
        The Federal Aviation Administration (FAA) has received reports of 
    cracks discovered during routine inspections of four high pressure 
    turbine (HPT) rotor assembly disks installed on Garrett Turbine Engine 
    Company Model ATF3-6 and -6A turbofan engines. The FAA has determined 
    that the cracks were created by a double strike forging and quench 
    process employed by a vendor in 1978. This process produced small 
    cracks in the curvic and bore area. These cracks became more prominent 
    during the forging and quenching operation and subsequently propagated 
    in fatigue during field service. Seventy five disks created using this 
    forging process have been identified by serial number in this 
    airworthiness directive (AD). This condition, if not corrected, could 
    result in an uncontained failure of the HPT rotor assembly disk.
        The FAA has reviewed and approved the technical contents of Allied-
    Signal Aerospace Company, Garrett Engine Division, Alert Service 
    Bulletin (ASB) No. ATF3-A72-6184, Revision 1, dated January 11, 1993, 
    that describes procedures for a one-time inspection for cracks of the 
    curvic and bore area of the HPT rotor assembly disk, and replacement, 
    if necessary, with a serviceable disk.
        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 a one-time inspection for cracks of the 
    curvic and bore area of HPT rotor assembly disks listed by serial 
    number in Table 1 of Allied-Signal Aerospace Company, Garrett Engine 
    Division, ASB No. ATF3-A72-6184, Revision 1, dated January 11, 1993. 
    The actions would be required to be accomplished in accordance with the 
    service bulletin described previously.
        There are approximately 75 engines of the affected design in the 
    worldwide fleet. The FAA estimates that 2 engines installed on aircraft 
    of U.S. registry would be affected by this proposed AD, that it would 
    take approximately 220 work hours per engine 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 $24,200.
        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:
    
    Garrett Turbine Engine Company: Docket No. 93-ANE-39.
    
        Applicability: Garrett Turbine Engine Company Model ATF3-6 and -
    6A turbofan engines equipped with high pressure turbine (HPT) rotor 
    assembly disk, Part Number (P/N) 3001765-1 and -2, listed by serial 
    numbers in Table 1 of Allied-Signal Aerospace Company, Garrett 
    Engine Division, Alert Service Bulletin (ASB) No. ATF3-A72-6184, 
    Revision 1, dated January 11, 1993. These engines are installed on 
    but not limited to Dassault Aviation Falcon Jet Falcon Series G 
    (Falcon 20G/HU-25) and Mystere-Falcon 200 aircraft.
        Compliance: Required as indicated, unless accomplished 
    previously.
        To prevent an uncontained failure of the HPT rotor assembly 
    disk, accomplish the following:
        (a) For engines with 1550 or more HPT rotor assembly disk cycles 
    since new (CSN) on the effective date of this AD, perform a one-time 
    inspection for cracks of the curvic and bore area of the HPT rotor 
    assembly disk, and replace if necessary, with a serviceable disk, in 
    accordance with Allied-Signal Aerospace Company, Garrett Engine 
    Division, ASB No. ATF3-A72-6184, Revision 1, dated January 11, 1993, 
    within 50 cycles in service (CIS) after the effective date of this 
    AD.
        (b) For engines with less than 1550 HPT rotor assembly disk CSN 
    on the effective date of this AD, perform a one-time inspection for 
    cracks of the curvic and bore area of the HPT rotor assembly disk, 
    and replace if necessary, with a serviceable disk, in accordance 
    with Allied-Signal Aerospace Company, Garrett Engine Division, ASB 
    No. ATF3-A72-6184, Revision 1, dated January 11, 1993, within 300 
    CIS after the effective date of this AD, or prior to accumulating 
    1600 CSN, whichever occurs first.
        (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 Manager, Los Angeles Aircraft Certification 
    Office. The request should be forwarded through an appropriate FAA 
    Principal Maintenance Inspector, who may add comments and then send 
    it to the Manager, Los Angeles Aircraft Certification Office.
    
        Note: Information concerning the existence of approved 
    alternative methods of compliance with this airworthiness directive, 
    if any, may be obtained from the Los Angeles Aircraft Certification 
    Office.
    
        (d) Special flight permits may be issued in accordance with FAR 
    21.197 and 21.199 to operate the airplane to a location where the 
    requirements of this AD can be accomplished.
    
        Issued in Burlington, Massachusetts, on February 3, 1994.
    Jay J. Pardee,
    Manager, Engine and Propeller Directorate, Aircraft Certification 
    Service.
    [FR Doc. 94-3237 Filed 2-10-94; 8:45 am]
    BILLING CODE 4910-13-P
    
    
    

Document Information

Published:
02/11/1994
Department:
Federal Aviation Administration
Entry Type:
Uncategorized Document
Action:
Notice of proposed rulemaking (NPRM).
Document Number:
94-3237
Dates:
Comments must be received by April 12, 1994.
Pages:
0-0 (1 pages)
Docket Numbers:
Federal Register: February 11, 1994, Docket No. 93-ANE-39
CFR: (1)
14 CFR 39.13