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[Federal Register Volume 89, Number 228 (Tuesday, November 26, 2024)]
[Proposed Rules]
[Pages 93228-93230]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-27664]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2540; Project Identifier AD-2024-00343-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Engines.

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain General Electric Company (GE) Model CT7-5A2, CT7-5A3, CT7-
7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, CT7-9C3, CT7-9D, and 
CT7-9D2 engines. This proposed AD was prompted by the manufacturer's 
determination that certain GE Model CT7 fleets have affected cooling 
plates installed that do not meet lifing guidelines. This proposed AD 
would require replacement of the stage 1 turbine forward cooling plate 
and the stage 2 turbine aft cooling plate. The FAA is proposing this AD 
to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by January 10, 
2025.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-2540; or in person at Docket Operations between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD 
docket contains this NPRM, any comments received, and other 
information. The street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Sungmo Cho, Aviation Safety Engineer, 
FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-
7241; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2024-2540; 
Project Identifier AD-2024-00343-E'' at the beginning of your comments. 
The most helpful comments reference a specific portion of the proposal, 
explain the reason for any recommended change, and include supporting 
data. The FAA will consider all comments received by the closing date 
and may revise this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this NPRM.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to 
Sungmo Cho, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des 
Moines, WA 98198. Any commentary that the FAA receives which is not 
specifically designated as CBI will be placed in the public docket for 
this rulemaking.

[[Page 93229]]

Background

    In 2004, the manufacturer notified the FAA of the identification of 
an analytic life shortfall on affected stage 1 turbine forward cooling 
plates and stage 2 turbine aft cooling plates installed on certain GE 
CT7 Model engines. As a result, GE published updated service material 
to remove affected parts at reduced cyclic limits. Based on the results 
of a 2019 fleet survey, the manufacturer determined that certain fleets 
still have affected cooling plates installed and in service which are 
above the recommended removal limits. Specifically, the affected fleet 
includes GE Model CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, 
CT7-9B2, CT7-9C, CT7-9C3, CT7-9D, and CT7-9D2 engines with an installed 
stage 1 turbine forward cooling plate having part number (P/N) 
6064T08P01, or with an installed stage 2 turbine aft cooling plate 
having P/N 6064T07P05 or P/N 6068T36P01. This condition, if not 
addressed, could result in the cooling plates failing and lead to 
uncontained engine failure and damage to the airplane.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Proposed AD Requirements in This NPRM

    This proposed AD would require replacement of the stage 1 turbine 
forward cooling plate having part number (P/N) 6064T08P01 and the stage 
2 turbine aft cooling plate having P/N 6064T07P05 or P/N 6068T36P01.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 228 engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                  Cost per        Cost on U.S.
              Action                        Labor cost           Parts cost        product         operators
----------------------------------------------------------------------------------------------------------------
Replace stage 1 turbine forward     8 work-hours x $85 per            $88,360         $89,040        $20,301,120
 cooling plate and stage 2 turbine   hour = $680.
 aft cooling plate.
----------------------------------------------------------------------------------------------------------------

    The above costs presume that the installed engine would require 
replacement of both the stage 1 turbine forward cooling plate and stage 
2 turbine aft cooling plate. It is possible that only one of these 
would need replacement, thus reducing the cost of the proposed AD.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect 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.
    For the reasons discussed above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

General Electric Company: Docket No. FAA-2024-2540; Project 
Identifier AD-2024-00343-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by January 10, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) Model CT7-5A2, 
CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, CT7-9C3, 
CT7-9D, and CT7-9D2 engines with an installed stage 1 turbine 
forward cooling plate having part number (P/N) 6064T08P01; or with 
an installed stage 2 turbine aft cooling plate having P/N 6064T07P05 
or P/N 6068T36P01.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7200, Engine 
(Turbine/Turboprop).

(e) Unsafe Condition

    This AD was prompted by the manufacturer's determination that 
certain GE Model CT7 fleets have affected cooling plates installed 
that do not meet lifing guidelines. The FAA is issuing this AD to 
prevent the failure of the stage 1 turbine forward cooling plate and 
stage 2 turbine aft cooling plate. The unsafe condition, if not 
addressed, could result in uncontained engine failure and damage to 
the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

[[Page 93230]]

(g) Required Actions

    (1) Within the compliance times specified in paragraphs 
(g)(1)(i) through (iii) of this AD, replace the affected stage 1 
turbine forward cooling plate or stage 2 turbine aft cooling plate, 
as applicable, with a replacement P/N eligible for installation, in 
accordance with Table 1 to paragraph (g)(1) of this AD:
    (i) For Group 1 engines with an affected part installed, replace 
the affected part at the next exposure of the gas generator stator 
assembly that occurs after the effective date of this AD.
    (ii) For Group 2 engines with an affected part installed having 
7,000 part cycles since new (PCSN) or less as of the effective date 
of this AD, replace the affected part at the next exposure of the 
gas generator stator assembly or within 2,000 flight cycles (FCs) 
but before reaching 7,500 PCSN, whichever occurs first after the 
effective date of this AD.
    (iii) For Group 2 engines with an affected part installed having 
more than 7,000 PCSN as of the effective date of this AD, replace 
the affected part at the next exposure of the gas generator stator 
assembly or within 500 FCs, whichever occurs first after the 
effective date of this AD.

                           Table 1 to Paragraph (g)(1): Cooling Plate Replacement P/Ns
----------------------------------------------------------------------------------------------------------------
             Engine group                        Part name               Affected P/N        Replacement P/N
----------------------------------------------------------------------------------------------------------------
1....................................  Stage 1 turbine forward               6064T08P01               6064T08P04
                                        cooling plate.
1....................................  Stage 2 turbine aft cooling           6064T07P05               6064T07P07
                                        plate.
1....................................  Stage 2 turbine aft cooling           6068T36P01               6068T36P04
                                        plate.
2....................................  Stage 1 turbine forward               6064T08P01            6064T08P03 or
                                        cooling plate.                                                6064T08P04
2....................................  Stage 2 turbine aft cooling           6064T07P05               6064T07P07
                                        plate.
2....................................  Stage 2 turbine aft cooling           6068T36P01               6068T36P04
                                        plate.
----------------------------------------------------------------------------------------------------------------

(h) Definitions

    For the purpose of this AD:
    (1) ``Group 1 engines'' are GE Model CT7-5A2, CT7-5A3, CT7-9B, 
CT7-9B1, CT7-9B2, CT7-9D, and CT7-9D2 engines.
    (2) ``Group 2 engines'' are GE Model CT7-7A, CT7-7A1, CT7-9C, 
and CT7-9C3 engines.
    (3) ``Exposure of the gas generator stator assembly'' is when 
the gas generator rotor and stator assembly are separated from the 
combustor module.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520 Continued Operational Safety Branch, 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the AIR-520 Continued 
Operational Safety Branch, send it to the attention of the person 
identified in paragraph (j) of this AD and email to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(j) Additional Information

    For more information about this AD, contact Sungmo Cho, Aviation 
Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; 
phone: (781) 238-7241; email: [email protected].

(k) Material Incorporated by Reference

    None.

    Issued on November 20, 2024.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2024-27664 Filed 11-25-24; 8:45 am]
BILLING CODE 4910-13-P
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