Document ID: FAA-2022-0690-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turboshaft Engines
Posted Date: 2022-06-21T04:00Z

[Federal Register Volume 87, Number 118 (Tuesday, June 21, 2022)]
[Proposed Rules]
[Pages 36781-36783]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-13154]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0690; Project Identifier AD-2021-01360-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turboshaft 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all General Electric Company (GE) CT7-8A model turboshaft engines. 
This proposed AD was prompted by the manufacturer revising the 
airworthiness limitations section (ALS) of the existing engine 
maintenance manual (EMM) to incorporate reduced life limits for certain 
stage 1 turbine aft cooling plates, stage 2 turbine forward cooling 
plates, turbine interstage seals, and stage 4 turbine disks. This 
proposed AD would require revising the ALS of the existing EMM and the 
operator's existing approved maintenance or inspection program, as 
applicable, to incorporate reduced life limits for these parts. 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 August 5, 
2022.

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 https://www.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.
    For service information identified in this NPRM, contact General 
Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 
552-3272; email: [email protected]; website: https://www.ge.com. You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 1200 
District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call (817) 222-5110.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2022-0690; 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, 
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 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 ADDRESSES. Include ``Docket No. FAA-2022-0690; Project Identifier 
AD-2021-01360-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 amend 
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 
https://www.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

[[Page 36782]]

should be sent to Sungmo Cho, Aviation Safety Engineer, ECO Branch, 
FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that 
the FAA receives which is not specifically designated as CBI will be 
placed in the public docket for this rulemaking.

Background

    The FAA was notified that the manufacturer revised the ALS of the 
existing EMM to incorporate reduced life limits for certain stage 1 
turbine aft cooling plates, stage 2 turbine forward cooling plates, 
turbine interstage seals, and stage 4 turbine disks (life-limited 
parts) installed on CT7-8A model turboshaft engines. Additionally, the 
manufacturer published service information that introduced the reduced 
life limits. The life limits were reduced by the manufacturer as the 
result of an analysis of the life management models for these parts. 
This condition, if not addressed, could result in uncontained part 
release, damage to the engine, damage to the helicopter, and possible 
loss of control of the helicopter.

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.

Related Service Information

    The FAA reviewed GE CT7-8 Service Bulletin 72-0062, Revision 01, 
dated December 22, 2021. This service information provides the reduced 
life limits for certain life-limited parts.

Proposed AD Requirements in This NPRM

    This proposed AD would require revising the ALS of the applicable 
GE CT7-8 EMM and the operator's existing approved maintenance or 
inspection program, as applicable, to incorporate reduced life limits 
for certain life-limited parts.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 126 engines installed on helicopters 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
----------------------------------------------------------------------------------------------------------------
Revise ALS of EMM and the operator's    1 work-hour x $85 per                 $0             $85         $10,710
 existing approved maintenance or        hour = $85.
 inspection program.
----------------------------------------------------------------------------------------------------------------

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-2022-0690; Project 
Identifier AD-2021-01360-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by August 5, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company CT7-8A model 
turboshaft engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7240, Turbine Engine 
Combustion Section; 7250, Turbine Section.

(e) Unsafe Condition

    This AD was prompted by the manufacturer revising the 
airworthiness limitations section (ALS) of the existing engine 
maintenance manual (EMM) to incorporate reduced life limits for 
certain stage 1 turbine aft cooling plates, stage 2 turbine forward 
cooling plates, turbine interstage seals, and stage 4 turbine disks. 
The FAA is issuing this AD to prevent failure of the stage 1 turbine 
aft cooling plates, stage 2 turbine forward cooling plates, turbine 
interstage seals, and stage 4 turbine disks. The unsafe condition, 
if not addressed, could result in uncontained part release, damage 
to the engine, damage to the helicopter, and possible loss of 
control of the helicopter.

(f) Compliance

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

(g) Required Actions

    (1) Within 90 days after the effective date of this AD, revise 
the ALS of the existing GE CT7-8 Turboshaft EMM and the operator's 
existing approved maintenance or inspection program, as applicable, 
by incorporating the following reduced life limits:
    (i) For stage 1 turbine aft cooling plate, part number (P/N) 
6064T09P02, change the life

[[Page 36783]]

limit cycles from 6,600 cycles since new (CSN) to 4,900 CSN;
    (ii) For stage 2 turbine forward cooling plate, P/N 4106T80P01, 
change the life limit cycles from 8,000 CSN to 7,200 CSN;
    (iii) For turbine interstage seal, P/N 4111T86P03, change the 
life limit cycles from 29,200 CSN to 19,000 CSN; and
    (iv) For stage 4 turbine disk, P/N 6068T32P04, change the life 
limit cycles from 24,100 CSN to 12,100 CSN.
    (2) After performing the actions required by paragraph (g)(1) of 
this AD, except as provided in paragraph (h) of this AD, no 
alternative life limits may be approved.

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO 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 
certification office, send it to the attention of the person 
identified in paragraph (i) 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.

(i) Related Information

    For more information about this AD, contact Sungmo Cho, Aviation 
Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, 
MA 01803; phone: (781) 238-7241; email: [email protected].

    Issued on June 14, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-13154 Filed 6-17-22; 8:45 am]
BILLING CODE 4910-13-P