97-7595. Airworthiness Directives; General Electric Aircraft Engines CT7 Series Turboprop Engines  

  • [Federal Register Volume 62, Number 61 (Monday, March 31, 1997)]
    [Rules and Regulations]
    [Pages 15094-15096]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 97-7595]
    
    
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    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 39
    
    [Docket No. 96-ANE-34; Amendment 39-9956; AD 97-05-12]
    RIN 2120-AA64
    
    
    Airworthiness Directives; General Electric Aircraft Engines CT7 
    Series Turboprop Engines
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Final rule; request for comments.
    
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    SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
    is applicable to General Electric Aircraft Engines (GE) CT7 series 
    turboprop engines. This action requires eddy current inspection of disk 
    holes of stage 1 and 2 gas generator turbine (GGT) disks for cracks, 
    and, if necessary, replacement with serviceable parts. This amendment 
    is prompted by a report of a stage 2 GGT disk failure. The actions 
    specified in this AD are intended to prevent a stage 1 or 2 GGT disk 
    failure, which could result in an uncontained engine failure and damage 
    to the aircraft.
    
    DATES: Effective April 15, 1997.
        The incorporation by reference of certain publications listed in 
    the regulations is approved by the Director of the Federal Register as 
    of April 15, 1997.
        Comments for inclusion in the Rules Docket must be received on or 
    before May 30, 1997.
    
    ADDRESSES: Submit comments in triplicate to the Federal Aviation 
    Administration (FAA), New England Region, Office of the Assistant Chief 
    Counsel, Attention: Rules Docket No. 96-ANE-34, 12 New England 
    Executive Park, Burlington, MA 01803-5299.
        The service information referenced in this AD may be obtained from 
    GE Aircraft Engines, 1000 Western Ave., Lynn, MA 01910; telephone (617) 
    594-3140, fax (617) 594-4805. This information may be examined at the 
    FAA, New England Region, Office of the Assistant Chief Counsel, 12 New 
    England Executive Park, Burlington, MA; or at the Office of the Federal 
    Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    
    FOR FURTHER INFORMATION CONTACT: Dave Keenan, Aerospace Engineer, 
    Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
    New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
    238-7139, fax (617) 238-7199.
    
    SUPPLEMENTARY INFORMATION: The Federal Aviation Administration 
    (FAA) has received a report of a General Electric Aircraft Engines 
    (GE) CT7 series turboprop engine, installed on a SAAB-SCANIA SF340 
    aircraft, that experienced an uncontained stage 2 gas generator 
    turbine (GGT) failure during takeoff. The investigation revealed 
    that the failure was caused by a crack in a disk cooling hole. The 
    most likely cause of the cracking was machining damage to the disk 
    cooling hole during manufacturing. This condition, if not 
    corrected, could result in a stage 1 or 2 GGT disk failure, which 
    could result in an uncontained engine failure and damage to the 
    aircraft.
    
        The FAA has reviewed and approved the technical contents of GE 
    (CT7-TP Series) Alert Service Bulletin (SB) A72-393, dated November 26, 
    1996, that lists by serial number (S/N) affected stage 1 and 2 GGT 
    disks, and (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 
    1996, that describes the procedures for eddy current inspection (ECI) 
    of disk holes for cracks.
        Since an unsafe condition has been identified that is likely to 
    exist or develop on other engines of the same type design, this AD is 
    being issued to prevent stage 1 or 2 GGT disk failure, which could 
    result in an uncontained engine failure and damage to the aircraft. 
    This AD requires a one-time ECI for cracks of disk holes of stage 1 and 
    2 GGT disks, and, if necessary, replacement with serviceable parts. The 
    inspection compliance time is at the next GGT module removal, or 9 
    months after the effective date of this AD, whichever occurs first. The 
    actions are required to be accomplished in accordance with the SBs 
    described previously.
        Since a situation exists that requires the immediate adoption of 
    this regulation, it is found that notice and opportunity for prior 
    public comment hereon are impracticable, and that good
    
    [[Page 15095]]
    
    cause exists for making this amendment effective in less than 30 days.
    
    Comments Invited
    
        Although this action is in the form of a final rule that involves 
    requirements affecting flight safety and, thus, was not preceded by 
    notice and an opportunity for public comment, comments are invited on 
    this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
    communications received on or before the closing date for comments will 
    be considered, and this rule may be amended in light of the comments 
    received. Factual information that supports the commenter's ideas and 
    suggestions is extremely helpful in evaluating the effectiveness of the 
    AD action and determining whether additional rulemaking action would be 
    needed.
        Comments are specifically invited on the overall regulatory, 
    economic, environmental, and energy aspects of the rule that might 
    suggest a need to modify the 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 that 
    summarizes each FAA-public contact concerned with the substance of this 
    AD 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 96-ANE-34.'' The postcard will be date stamped and 
    returned to the commenter.
        The regulations adopted herein will 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 final 
    rule does not have sufficient federalism implications to warrant the 
    preparation of a Federalism Assessment.
        The FAA has determined that this regulation is an emergency 
    regulation that must be issued immediately to correct an unsafe 
    condition in aircraft, and is not a ``significant regulatory action'' 
    under Executive Order 12866. It has been determined further that this 
    action involves an emergency regulation under DOT Regulatory Policies 
    and Procedures (44 FR 11034, February 26, 1979). If it is determined 
    that this emergency regulation otherwise would be significant under DOT 
    Regulatory Policies and Procedures, a final regulatory evaluation will 
    be prepared and placed in the Rules Docket. A copy of it, if filed, may 
    be obtained from the Rules Docket at the location provided under the 
    caption ADDRESSES.
    
    List of Subjects in 14 CFR Part 39
    
        Air transportation, Aircraft, Aviation safety, Incorporation by 
    reference, Safety.
    
    Adoption of the Amendment
    
        Accordingly, pursuant to the authority delegated to me by the 
    Administrator, the Federal Aviation Administration amends 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:
    
    97-05-12 General Electric Aircraft Engines: Amendment 39-9956. 
    Docket 96-ANE-34.
    
        Applicability: General Electric Aircraft Engines (GE) Models 
    CT7-5A2, -7A, -9B, -9C turboprop engines, installed on but not 
    limited to Construcciones Aeronauticas, SA (CASA) CN-235 series and 
    SAAB-SCANIA SF340 series aircraft.
    
        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 (l) 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 a stage 1 or 2 gas generator turbine (GGT) disk 
    failure, which could result in an uncontained engine failure and 
    damage to the aircraft, accomplish the following:
        (a) For all stage 1 GGT disks, Part Number (P/N) 6064T06P01, 
    identified in Table 1 of GE (CT7-TP Series) SB A72-393, dated 
    November 26, 1996, that have accumulated 7,000 or more cycles since 
    new (CSN) on the effective date of this AD, perform a one time eddy 
    current inspection (ECI) for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    or not to exceed 9 months after the effective date of this AD, 
    whichever occurs first.
        (b) For all stage 1 GGT disks, P/N 6064T06P01, identified in 
    Table 1 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated less than 7,000 CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    but not to exceed 9,000 CSN.
        (c) For all stage 1 GGT disks, P/N 6064T06P01, identified in 
    Table 2 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated 10,000 or more CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    or not to exceed 9 months after the effective date of this AD, 
    whichever occurs first.
        (d) For all stage 1 GGT disks, P/N 6064T06P01, identified in 
    Table 2 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated less than 10,000 CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    but not to exceed 12,000 CSN.
        (e) For all stage 2 GGT disks, P/N 6064T12P01, identified in 
    Table 3 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated 7,000 or more CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    or not to exceed 9 months after the effective date of this AD, 
    whichever occurs first.
        (f) For all stage 2 GGT disks, P/N 6064T12P01, identified in 
    Table 3 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated less than 7,000 CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    but not to exceed 9,000 CSN.
        (g) For all stage 2 GGT disks, P/N 6064T12P01, identified in 
    Table 4 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated 10,000 or more CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-
    
    [[Page 15096]]
    
    390, Revision 1, dated December 11, 1996, at the next GGT module 
    removal, or not to exceed 9 months after the effective date of this 
    AD, whichever occurs first.
        (h) For all stage 2 GGT disks, P/N 6064T12P01, identified in 
    Table 4 of GE (CT7-TP Series) SB A72-393, dated November 26, 1996, 
    that have accumulated less than 10,000 CSN on the effective date of 
    this AD, perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    but not to exceed 12,000 CSN.
        (i) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2 
    GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of 
    GE (CT7-TP Series) SB A72-393, dated November 26, 1996, that have 
    accumulated 7,000 or more CSN on the effective date of this AD, 
    perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    or not to exceed 9 months after the effective date of this AD, 
    whichever occurs first.
        (j) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2 
    GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of 
    GE (CT7-TP Series) SB A72-393, dated November 26, 1996, that have 
    accumulated less than 7,000 CSN on the effective date of this AD, 
    perform a one time ECI for cracks in accordance with the 
    Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, 
    Revision 1, dated December 11, 1996, at the next GGT module removal, 
    but not to exceed 9,000 CSN.
        (k) Prior to further flight, remove from service cracked disks, 
    and replace with serviceable parts.
        (l) 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, Engine 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, 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.
    
        (m) 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 aircraft to a location where 
    the requirements of this AD can be accomplished.
        (n) The actions required by this AD shall be done in accordance 
    with the following GE (CT7-TP Series) SBs:
    
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                  Document No.                 Pages             Revision                         Date              
    ----------------------------------------------------------------------------------------------------------------
    A72-393.................................     1-16  Original...................  November 26, 1996.              
                                             ---------                                                              
        Total...............................       16                                                               
    72-390..................................      1-6  1..........................  December 11, 1996.              
                                             ---------                                                              
        Total...............................        6                                                               
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        This incorporation by reference was approved by the Director of 
    the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
    part 51. Copies may be obtained from GE Aircraft Engines, 1000 
    Western Ave., Lynn, MA 01910; telephone (617) 594-3140, fax (617) 
    594-4805. Copies may be inspected at the FAA, New England Region, 
    Office of the Assistant Chief Counsel, 12 New England Executive 
    Park, Burlington, MA; or at the Office of the Federal Register, 800 
    North Capitol Street, NW., suite 700, Washington, DC.
        (o) This amendment becomes effective on April 15, 1997.
    
        Issued in Burlington, Massachusetts, on February 24, 1997.
    James C. Jones,
    Acting Manager, Engine and Propeller Directorate, Aircraft 
    Certification Service.
    [FR Doc. 97-7595 Filed 3-28-97; 8:45 am]
    BILLING CODE 4910-13-U
    
    
    

Document Information

Effective Date:
4/15/1997
Published:
03/31/1997
Department:
Federal Aviation Administration
Entry Type:
Rule
Action:
Final rule; request for comments.
Document Number:
97-7595
Dates:
Effective April 15, 1997.
Pages:
15094-15096 (3 pages)
Docket Numbers:
Docket No. 96-ANE-34, Amendment 39-9956, AD 97-05-12
RINs:
2120-AA64: Airworthiness Directives
RIN Links:
https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives
PDF File:
97-7595.pdf
CFR: (1)
14 CFR 39.13