Document ID: FAA-2022-1314-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turboprop Engines
Posted Date: 2022-11-01T04:00Z

[Federal Register Volume 87, Number 210 (Tuesday, November 1, 2022)]
[Proposed Rules]
[Pages 65694-65700]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-23385]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1314; Project Identifier AD-2021-00811-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turboprop 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2018-03-13, which applies to certain General Electric Company (GE) CT7-
5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and 
CT7-9C3 model turboprop engines. AD 2018-03-13 requires initial and 
repetitive visual inspections and fluorescent penetrant inspections 
(FPIs) of the main propeller shaft. Since the FAA issued AD 2018-03-13, 
the manufacturer detected two additional cracks on a main propeller 
shaft during its ongoing investigation and subsequently published 
service information that introduced reduced inspection thresholds for 
initial and repetitive visual inspections, FPIs, and added initial and 
repetitive ultrasonic inspections (USIs) of the main propeller shaft. 
Additionally, the manufacturer revised the airworthiness limitations 
section (ALS) of the maintenance manual (MM) to incorporate initial and 
repetitive USIs to inspect for cracks on the main propeller shaft. This 
proposed AD would require initial and repetitive visual inspections, 
FPIs, and USIs of the main propeller shaft. Depending on the results of 
these inspections, this proposed AD would require replacement of the 
main propeller shaft. As an optional terminating action to these 
inspections, this proposed AD would require revising the ALS of the 
existing MM and the operator's existing approved maintenance program or 
inspection program, as applicable, to incorporate the tasks and reduced 
inspection thresholds for the main propeller shaft. 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 December 
16, 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 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 by 
searching for and locating Docket No. FAA-2022-1314; 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.
    Material Incorporated by Reference:
     For GE service information identified in this NPRM, 
contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: ge.com">[email protected]ge.com; website: 
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.

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-2022-1314; Project Identifier 
AD-2021-00811-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 
the 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

[[Page 65695]]

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, 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 issued AD 2018-03-13, Amendment 39-19186 (83 FR 6125, 
February 13, 2018) (AD 2018-03-13), for certain GE CT7-5A2, CT7-5A3, 
CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 model 
turboprop engines with main propeller shaft, part number 77581-11, 
installed. AD 2018-03-13 was prompted by an in-flight failure of a main 
propeller shaft on a GE CT7-9B model turboprop engine, resulting in the 
loss of the propeller. The manufacturer determined the failure of the 
main propeller shaft was caused by cracks initiating from undiscovered 
corrosion in the dowel pin holes on the flange of the main propeller 
shaft. AD 2018-03-13 requires visually inspecting the main propeller 
shaft for wear, corrosion, and cracking and performing FPI for cracks. 
The agency issued AD 2018-03-13 to prevent failure of the main 
propeller shaft. The unsafe condition, if not addressed, could result 
in in-flight loss of the propeller, loss of engine thrust control, and 
damage to the airplane.

Actions Since AD 2018-03-13 Was Issued

    Since the FAA issued AD 2018-03-13, the manufacturer detected two 
additional cracks on a main propeller shaft during its ongoing 
investigation and subsequently published service information that 
introduced reduced inspection thresholds for initial and repetitive 
visual inspections, FPIs, and added initial and repetitive USIs of the 
main propeller shaft. Additionally, the manufacturer revised the ALS of 
the MM to incorporate initial and repetitive USIs to inspect for cracks 
on the main propeller shaft.

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 Under 1 CFR Part 51

    The FAA reviewed GE Service Bulletin (SB) CT7-TP 72-0541 R01, dated 
November 18, 2021 (GE SB CT7-TP 72-0541). This service information 
specifies procedures for performing initial and repetitive visual 
inspections, FPIs, and USIs of the main propeller shaft.
    This service information is reasonably available because the 
interested parties have access to it through their normal course of 
business or by the means identified in ADDRESSES.

Proposed AD Requirements in This NPRM

    This proposed AD would retain none of the requirements of AD 2018-
03-13. This proposed AD would require initial and repetitive visual 
inspections, FPIs, and USIs of the main propeller shaft. Depending on 
the results of these inspections, this proposed AD would require 
replacement of the main propeller shaft. As an optional terminating 
action to these inspections, this proposed AD would require revising 
the ALS of the existing MM and the operator's existing approved 
maintenance program or inspection program, as applicable, to 
incorporate incorporating the tasks and reduced inspection thresholds 
for the main propeller shaft. An owner/operator (pilot) holding at 
least at least a private pilot certificate may revise the ALS of the 
existing MM, and the owner/operator must enter compliance with the 
applicable paragraphs of the AD into the aircraft records in accordance 
with 14 CFR 43.9(a) and 14 CFR 91.417(a)(2)(v). The record must be 
maintained as required by 14 CFR 91.417, 14 CFR 121.380, or 14 CFR 
135.439. This is an exception to the FAA's standard maintenance 
regulations.

Differences Between This Proposed AD and the Service Information

    GE SB CT7-TP 72-0541 uses the term ``UTI,'' while this proposed AD 
uses the term ``USI.''

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 176 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
----------------------------------------------------------------------------------------------------------------
Visually inspect, FPI, and USI the      2 work-hours x $85 per                $0            $170         $29,920
 main propeller shaft.                   hour = $170.
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    The FAA estimates the following costs to do any necessary 
replacement that would be required based on the results of the proposed 
inspections. The agency has no way of determining the number of 
aircraft that might need this replacement:

[[Page 65696]]

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace the main propeller shaft..............  8 work-hours x $85 per hour =            $48,360         $49,040
                                                 $680.
Revise the ALS of the MM......................  1 work-hour x $85 per hour = $85               0              85
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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 that the 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:
0
a. Removing Airworthiness Directive 2018-03-13, Amendment 39-19186 (83 
FR 6125, February 13, 2018); and
0
b. Adding the following new airworthiness directive:

General Electric Company: Docket No. FAA-2022-1314; Project 
Identifier AD-2021-00811-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) action by December 16, 2022.

(b) Affected ADs

    This AD replaces AD 2018-03-13, Amendment 39-19186 (83 FR 6125, 
February 13, 2018).

(c) Applicability

    This AD applies to General Electric Company (GE) CT7-5A2, CT7-
5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 
model turboprop engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7210, Turbine Engine 
Reduction Gear.

(e) Unsafe Condition

    This AD was prompted by an in-flight failure of a main propeller 
shaft on a GE CT7-9B model turboprop engine, resulting in the loss 
of the propeller. The FAA is issuing this AD to prevent failure of 
the main propeller shaft. The unsafe condition, if not addressed, 
could result in in-flight loss of the propeller, loss of engine 
thrust control, and damage to the airplane.

(f) Compliance

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

(g) Required Actions

    (1) For affected CT7-5A2, CT7-5A3, CT7-7A, and CT7-7A1 model 
turboprop engines, using the compliance times specified in Figure 1 
to paragraph (g)(1) of this AD, perform initial and repetitive 
visual inspections, fluorescent penetrant inspections (FPIs), and 
ultrasonic inspections (USIs) of the main propeller shaft.
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[[Page 65697]]

[GRAPHIC] [TIFF OMITTED] TP01NO22.046

    (2) For affected CT7-9B, CT7-B1, CT7-9B2, CT7-9C, and CT7-9C3 
model turboprop engines, using the compliance times specified in 
Figure 2 to paragraph (g)(2) of this AD, perform initial and 
repetitive visual inspections, FPIs, and USIs of the main propeller 
shaft.
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[GRAPHIC] [TIFF OMITTED] TP01NO22.047

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[[Page 65698]]

    (3) Perform the visual inspections, FPIs, and USIs required by 
paragraphs (g)(1) and (2) of this AD as follows:
    (i) Prior to performance of the inspections, clean the main 
propeller shaft flange using the Accomplishment Instructions, 
paragraph 3.B., of GE Service Bulletin (SB) CT7-TP 72-0541 R01, 
dated November 18, 2021 (GE SB CT7-TP 72-0541).
    (ii) Visually inspect the main propeller shaft for wear, 
corrosion, and cracking using the Accomplishment Instructions, 
paragraph 3.C.(1), of GE SB CT7-TP 72-0541.
    (iii) Spot-FPI the area on the main propeller shaft flange face 
using the Accomplishment Instructions, paragraph 3.C.(2)(a), of GE 
SB CT7-TP 72-0541.
    (iv) USI the two dowel pin holes of the main propeller shaft 
using the Accomplishment Instructions, paragraph 3.C.(3)(a), of GE 
SB CT7-TP 72-0541.
    (4) If a crack or rejectable indication is found during the 
initial and repetitive visual inspections, FPIs, or USIs required by 
paragraphs (g)(1) through (3) of this AD, before further flight, 
remove the main propeller shaft from service and replace it with a 
part eligible for installation.
    (5) For all affected engines, if the main propeller shaft CSN is 
unknown, use the propeller gearbox (PGB) CSN. If the PGB CSN is 
unknown, assume the inspection threshold is exceeded.

(h) Optional Terminating Action

    Accomplishing the actions in paragraphs (h)(1) through (4) of 
this AD, as applicable by engine model, constitutes terminating 
action for the inspections required by paragraphs (g)(1) through (3) 
of this AD.
    (1) For affected CT7-5A2, CT7-5A3, CT7-7A, and CT7-7A1 model 
turboprop engines, revise the airworthiness limitations section 
(ALS) of the existing maintenance manual (MM) and the operator's 
existing approved maintenance program or inspection program, as 
applicable, by incorporating the information in Figure 3 to 
paragraph (h)(1) of this AD.
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[GRAPHIC] [TIFF OMITTED] TP01NO22.048

[[Page 65699]]

    (2) For affected CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 
model turboprop engines, revise the ALS of the existing MM and the 
operator's existing approved maintenance program or inspection 
program, as applicable, by incorporating the information in Figure 4 
to paragraph (h)(2) of this AD.
[GRAPHIC] [TIFF OMITTED] TP01NO22.049

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    (3) Thereafter, except as provided in paragraph (k) of this AD, 
no alternative inspection times or intervals may be approved for 
this main propeller shaft.
    (4) The optional terminating actions in paragraphs (h)(1) and 
(2) of this AD may be performed by the owner/operator (pilot) 
holding at least a private pilot certificate and must be entered 
into the aircraft records showing compliance with this AD in 
accordance with 14 CFR 43.9(a) and 14 CFR 91.417(a)(2)(v). The 
record must be maintained as required by 14 CFR 91.417, 14 CFR 
121.380, or 14 CFR 135.439.

(i) Definition

    For the purpose of this AD, a ``part eligible for installation'' 
is a main propeller shaft that has been inspected in accordance with 
paragraphs (g)(1) or (2) and (3) of this AD, and a crack or 
rejectable indication was not found.

(j) Credit for Previous Actions

    You may take credit for the initial visual inspection, FPI, and 
USI required by paragraphs (g)(1) through (3) of this AD if you 
performed these initial inspections before the effective date of 
this AD in accordance with GE SB CT7-TP 72-0541 R00, dated September 
9, 2021.

(k) 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

[[Page 65700]]

identified in paragraph (l) of this AD and email it 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.

(l) 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].

(m) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) GE Service Bulletin CT7-TP 72-0541 R01, dated November 18, 
2021.
    (ii) [Reserved]
    (3) For GE service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: ge.com">[email protected]ge.com; 
website: ge.com.
    (4) You may view this service information at 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.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on October 21, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-23385 Filed 10-31-22; 8:45 am]
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