DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0869; Project Identifier AD-2021-00176-E]
Airworthiness Directives; General Electric Company Turbofan
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for certain General Electric Company (GE) CF34-8C and CF34-8E model
turbofan engines. This proposed AD was prompted by a report of a
quality escape during the manufacturing of a high-pressure turbine
(HPT) rotor stage 1 disk. This proposed AD would require removing the
HPT rotor stage 1 disk from service and replacing the HPT rotor stage
disk with a part eligible for installation. The FAA is proposing this
AD to the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by November
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
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@example.com; 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 (781) 238-7759.
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0869; 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:
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-2021-0869; Project Identifier
AD-2021-00176-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 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.
The FAA was notified by GE of a quality escape that occurred during
the manufacturing of an HPT rotor stage 1 disk. The quality escape
occurred at a supplier that began production in August 2019. On
November 25, 2019, the supplier discovered tool gouges at the forward
chamfer of the air holes in an HPT rotor stage 1 disk. These gouges can
reduce the life of the HPT rotor stage 1 disk. This condition, if not
addressed, could result in uncontained disk release, damage to the
engine, and damage to the airplane.
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 CF34-8C Alert Service Bulletin (ASB) 72-A0344
R01 and GE CF34-8E ASB 72-A0228 R01, both dated December 19, 2019. The
ASBs describe procedures for removing the HPT rotor stage 1 disk. The
FAA also reviewed GE Repair Document RD #150-1811-P1, dated March 17,
2020. This document describes procedures for repairing the HPT rotor
stage 1 disk.
Proposed AD Requirements in This NPRM
This proposed AD would require removing a certain HPT rotor stage 1
disk from service and replacing the HPT rotor stage 1 disk with a part
eligible for installation.
Differences Between This Proposed AD and the Service Information
The ASBs instruct operators to perform a visual inspection of the
HPT rotor stage 1 disk and re-mark the HPT rotor stage 1 disk, while
this proposed AD would not mandate visual inspection or re-marking. The
ASBs also instruct operators to perform an inspection of the removed
HPT rotor stage 1 disk and send it to an authorized service center for
repair, while this proposed AD would require removal of the HPT rotor
stage 1 disk from service and replacement with a part eligible for
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 23 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
|Remove and replace HPT rotor
stage 1 disk
||812 work-hours x $85 per hour
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.
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
(1) Is not a ``significant regulatory action'' under Executive
(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
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 adding the following new airworthiness