DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-1167; Project Identifier AD-2021-00823-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 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)
2019-22-05, which applies to all General Electric Company (GE) CF34-8C
model turbofan engines. AD 2019-22-05 requires initial and repetitive
inspections of the operability bleed valve (OBV) fuel tubes, OBV bleed
air manifold link rod assemblies, and the OBV fuel fittings. AD 2019-
22-05 also requires replacement of OBVs or related OBV hardware that
fail inspection. Since the FAA issued AD 2019-22-05, the manufacturer
has redesigned the OBV, which terminates the need for the repetitive
inspections. This proposed AD would require initial and repetitive
inspections of the OBV fuel tubes, OBV bleed air manifold link rod
assemblies, and the OBV fuel fittings. This proposed AD would also
require replacement of OBVs or related OBV hardware that fail
inspection. As a terminating action to the repetitive inspections, this
proposed AD would require replacement of certain OBVs installed on GE
CF34-8C and CF34-8E model turbofan engines. 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 February
14, 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: aviation.fleetsupport@ge.com; website: https://www.ge.com.
You may view this service information at the Airworthiness
Products Section, Operational Safety Branch, FAA, 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-2021-1167; 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: Scott Stevenson, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7132; fax: (781) 238-7199; email:
Scott.M.Stevenson@faa.gov.

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-2021-1167; Project Identifier
AD-2021-00823-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
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact we receive about this proposed AD.

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 Scott Stevenson,
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 2019-22-05, Amendment 39-19784 (84 FR 63569,
November 18, 2019), (AD 2019-22-05), for all GE CF34-8C1, CF34-8C5,
CF34-8C5A1, CF34-8C5B1, CF34-8C5A2, and CF34-8C5A3 model turbofan
engines. AD 2019-22-05 was prompted by multiple reports of fuel leaks,
some leading to engine fires, that have occurred as a result of
malfunctions related to the OBV. AD 2019-22-05 requires initial and
repetitive inspections of the OBV fuel tubes, OBV bleed air manifold
link rod assemblies, and the OBV fuel fittings. AD 2019-22-05 also
requires replacement of OBVs or related OBV hardware that fail
inspection. The agency issued AD 2019-22-05 to prevent failure of the
OBV.

Actions Since AD 2019-22-05 Was Issued

Since the FAA issued AD 2019-22-05, the manufacturer redesigned the
OBV to eliminate the need for the repetitive inspections of the OBV
fuel tubes, OBV bleed air manifold link rod assemblies, and the OBV
fuel fittings. The manufacturer has issued service information
specifying procedures to replace certain OBVs installed on CF34-8C1,
CF34-8C5, CF34-8C5A1, CF34-8C5B1, CF34-8C5A2, CF34-8C5A3 (CF34-8C), and
GE CF34-8E2, CF34-8E2A1, CF34-8E5, CF34-8E5A1, CF34-8E5A2, CF34-8E6,
and CF34-8E6A1 (CF34-8E) model turbofan engines. Additionally, the FAA
determined that the CF34-8E model turbofan engines are susceptible to
the same unsafe condition as the CF34-8C model turbofan engines, and
therefore, added the CF34-8E model turbofan engines to the
applicability of this proposed AD. The FAA is proposing to require
installation of the newly-designed OBV as a terminating action to the
repetitive inspections required for CF34-8C model turbofan engines. The
FAA is also proposing to require replacement of certain OBVs installed
on CF34-8E model turbofan engines.

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 CF34-8C Service Bulletin (SB) 75-0020 R04,
dated May 10, 2019 (GE SB 75-0020). The SB specifies procedures for
inspecting the bleed air manifold link rod assemblies; the supply,
return, and drain fuel fittings; and the fuel tubes on the OBV. The SB
also specifies procedures for performing corrective actions and
replacing any OBVs or related OBV hardware that fail the inspection
criteria. The Director of the Federal Register approved the
incorporation by reference of GE SB 75-0020 as of December 23, 2019 (84
FR 63569, November 18, 2019).
The FAA reviewed GE CF34-8C SB 75-0025 R01, dated August 1, 2019.
This SB describes procedures for replacing and upgrading the suspect
population of OBVs VIN 5000728-104 (part number (P/N) 4123T71P02), VIN
5000728-106 (P/N 4123T71P03), and VIN 5080046-101 (P/N 4123T71P04).
The FAA reviewed GE CF34-8E SB 75-0019 R01, dated August 1, 2019.
This SB describes procedures for replacing and upgrading the suspect
population of OBVs VIN 5000728-104 (P/N 4123T71P02), VIN 5000728-106
(P/N 4123T71P03), and VIN 5080046-101 (P/N 4123T71P04).
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.

Other Related Service Information

The FAA reviewed GE CF34-8C SB 75-0026 R00, dated February 21,
2020. This SB introduces OBV VIN 5080046-103 (P/N 4123T71P06).
The FAA also reviewed GE CF34-8E SB 75-0021 R00, dated February 21,
2020. This SB introduces OBV VIN 5080046-103 (P/N 4123T71P06).

Proposed AD Requirements in This NPRM

This proposed AD would retain certain requirements of AD 2019-22-
05. This proposed AD would require initial and repetitive inspections
of the OBV fuel tubes, OBV bleed air manifold link rod assemblies, and
the OBV fuel fittings and replacement of OBVs or related OBV hardware
that fail inspection. As a terminating action to the repetitive
inspections of the OBV fuel tubes, OBV bleed air manifold link rod
assemblies, and the OBV fuel fittings, this proposed AD would require
replacement of certain OBVs installed on GE CF34-8C model turbofan
engines. This proposed AD would also require replacement of certain
OBVs installed on CF34-8E model turbofan engines.

Differences Between This Proposed AD and the Service Information

GE SB 75-0020 specifies that the results of the inspections must be
documented in an inspection chart form and sent to GE Product Support
Engineering. This proposed AD would not mandate sending information to
GE Product Support Engineering.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 1,172 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs

The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
aircraft that might need this replacement.

On-Condition 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

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

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:
a. Removing Airworthiness Directive 2019-22-05, Amendment 39-19784
(84 FR 63569, November 18, 2019); and
b. Adding the following new airworthiness directive: