DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0766; Project Identifier 2019-NE-23-AD; Amendment
39-22312; AD 2023-02-05]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
General Electric Company (GE) CF34-8C1, CF34-8C5, CF34-8C5A1, CF34-
8C5B1, CF34-8C5A2, CF34-8C5A3, CF34-8E2, CF34-8E2A1, CF34-8E5, CF34-
8E5A1, CF34-8E5A2, CF34-8E6, and CF34-8E6A1 model turbofan engines.
This AD was prompted by a predicted reduction in the cyclic life of the
combustion chamber assembly aft flange. This AD requires revisions to
the airworthiness limitations section (ALS) of the existing engine
manual (EM) and the operator's existing approved maintenance or
inspection program, as applicable, to incorporate initial and
repetitive fluorescent penetrant inspections (FPIs) of the combustion
chamber assembly. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective March 14, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 14,
2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov by
searching for and locating Docket No. FAA-2019-0766; 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 final rule, any
comments received, and other information. The address for Docket
Operations is U.S. Department of Transportation, Docket Operations, M-
30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue
SE, Washington, DC 20590.
Material Incorporated by Reference:
For GE service information identified in this final rule,
contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215;
phone: (513) 552-3272; email: aviation.fleetsupport@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. It is
also available at regulations.gov by searching for and locating Docket
No. FAA-2019-0766.

FOR FURTHER INFORMATION CONTACT: Scott Stevenson, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7132; email: Scott.M.Stevenson@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a supplemental notice of proposed rulemaking (SNPRM)
to amend 14 CFR part 39 by adding an AD that would apply to all GE
CF34-8C1, CF34-8C5, CF34-8C5A1, CF34-8C5B1, CF34-C5A2, CF34-8C5A3,
CF34-8E2, CF34-8E2A1, CF34-8E5, CF34-8E5A1, CF34-8E5A2, CF34-8E6, and
CF34-8E6A1 (CF34-8C and GE CF34-8E) model turbofan engines, including
engine models marked on the engine data plate as CF34-8C5/B, CF34-8C5/
M, CF34-8C5A1/B, CF34-8C5A1/M, CF34-8C5B1/B, CF34-8C5A2/B, and CF34-
8C5A2/M. The SNPRM published in the Federal Register on October 07,
2022 (87 FR 60944). The SNPRM was prompted by a predicted reduction in
the cyclic life of the combustion chamber assembly aft flange. As a
result, the manufacturer incorporated temporary revisions (TRs) into
the GE CF34-8C and GE CF34-8E EMs for a scheduled maintenance check. In
the SNPRM, the FAA proposed to require revisions to the ALS of the
existing EM and the operator's existing approved maintenance or
inspection program, as applicable, to incorporate initial and
repetitive FPIs of the combustion chamber assembly. The FAA is issuing
this AD to address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from three commenters. The commenters
were Horizon Air, Japan Airlines (JAL), and SkyWest Airlines (SkyWest).
The following presents the comments received on the SNPRM and the FAA's
response to each comment.

Request To Replace "ESM" Reference With "EM" Reference

Horizon Air requested that the FAA replace all references of
``ESM'' with ``EM'' in this final rule. Horizon Air reasoned that the
SNPRM only defines the acronym ``EM,'' and both acronyms are used
interchangeably in the SNPRM.
The FAA clarifies that the reference to ``ESM'' is not an acronym
defined by the FAA in the proposed AD and used interchangeably with
``EM.'' ``ESM'' is part of GE's chapter title within each task
reference and must be used for an accurate reference. The FAA did not
change this AD as a result of this comment.

Request To Add the Date of the Task in Paragraph (g)(3)

Horizon Air requested that the FAA include the task revision date
for ``TASK 05-21-03-200-801,'' referenced in paragraph (g)(3)(ii) of
the SNPRM. Horizon Air reasoned that adding the task revision date
would make the wording consistent with the dates of the tasks in
paragraphs (g)(1)(ii) and (2)(ii) of the SNPRM.
The FAA established a shorthand notation in paragraph (g)(2)(ii) of
the SNPRM, which contains the full citation, including the task
revision date, followed by the shorthand notation ``TASK 05-21-03-200-
801.'' The FAA then used the established shorthand notation to
reference the task in paragraph (g)(3)(ii) of the SNPRM. The FAA did
not change this AD as a result of this comment.

Request To Revise Paragraph (g)(1)(ii), (2)(ii), and (3)(ii) of the AD

Horizon Air requested that the FAA revise paragraphs (g)(1)(ii),
(2)(ii), and (3)(ii) of the AD, as those paragraphs do not clearly
include that performance of the inspection within 2,200 cycles from the
effective date of this AD is only applicable to those combustion
chamber assemblies that have exceeded the inspection threshold
specified in the tables referenced in TASK 05-21-03-200-801. Similarly,
JAL requested that the FAA revise paragraph (g)(1)(ii) for the same
reasons articulated by Horizon Air.
In response to these comments, the FAA has revised the language in
paragraphs (g)(1)(ii), (2)(ii), and (3)(ii) of this AD to clarify that
where the notes to Tables 801, 802, 803, 804, and 805, included in TASK
05-21-03-200-801, specify to perform the inspection within 2,200 cycles
from the issuance date of the TR, this AD requires performing the
inspection within 2,200 cycles from the effective date of this AD. The
FAA further clarifies that the notes are part of the task, and
therefore, has removed ``including the notes.''

Request To Correct an Incorrect Reference to a Task in Paragraph
(g)(2)(i)

SkyWest requested that the FAA correct an incorrect reference in
paragraph (g)(2)(i) of this AD. SkyWest noted that Table 802 does not
exist in TASK 05-11-25-200-801, which is specific to GE CF34-8C5 model
turbofan engines with/B minor model designation.
In response to this comment, the FAA has revised paragraph
(g)(2)(i) of this AD from ``Table 801 in TASK 05-11-05-200-801 and
Table 802 in TASK 05-11-25-200-801, dated November 3, 2020, from ESM
05-11-25 Static Structures--BJ Life Limits (TASK 05-11-25-200-801)'' to
``Tables 801 (for -8C1) and 802 (for -8C5) in TASK 05-11-05-200-801,
dated March 4, 2021, from ESM 05-11-05 Static Structures--Life Limits
(TASK 05-11-05-200-801).''

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, and
any other changes described previously, this AD is adopted as proposed
in the SNPRM. None of the changes will increase the economic burden on
any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following tasks:
TASK 05-11-05-200-801, dated March 4, 2021, from ESM 05-
11-05 Static Structures--Life Limits, of GE CF34-8C EM GEK105091, Rev
51, dated April 1, 2022;
TASK 05-11-05-200-801, dated March 4, 2021, from ESM 05-
11-05 Static Structures--Life Limits, of GE CF34-8E EM GEK112031, Rev
43, dated April 1, 2022; and
TASK 05-11-25-200-801, dated November 3, 2020, from ESM
05-11-25 Static Structures--BJ Life Limits, of GE CF34-8C EM GEK105091,
Rev 51, dated April 1, 2022.
These tasks, differentiated by GE CF34-8 turbofan engine model,
identify the combustion chamber assembly part number, life limit
cycles, and revised inspections.
The FAA also reviewed the following tasks:
TASK 05-21-03-200-801, dated April 1, 2019, from ESM 05-
21-03 Airworthiness Limitations--Mandatory Inspection 001, of GE CF34-
8C EM GEK105091, Rev 51, dated April 1, 2022; and
TASK 05-21-03-200-801, dated April 1, 2019, from ESM 05-
21-03 Airworthiness Limitations--Mandatory Inspection 001, of GE CF34-
8E EM GEK112031, Rev 43, dated April 1, 2022.
These tasks, differentiated by GE CF34-8 turbofan engine model,
describe revised inspection threshold limits and re-inspection interval
limits for the combustion chamber assembly.
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.

Costs of Compliance

The FAA estimates that this AD affects 1,633 GE CF34-8C turbofan
engine models and 857 GE CF34-8E turbofan engine models installed on
airplanes of U.S. registry.
The FAA estimates the following costs to comply with this AD:

Estimated Costs

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

This AD will not have federalism implications under Executive Order
13132. This AD will 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) 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.

List of Subjects in 14 CFR Part 39

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

The Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: