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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-1883; Project Identifier AD-2023-01120-E]
RIN 2120-AA64
Airworthiness Directives; General Electric Company Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to adopt a new airworthiness directive
(AD)
for all General Electric Company (GE) Model CF34-10E2A1, CF34-10E6,
CF34-10E6A1, CF34-10E7, and CF34-10E7-B engines with certain part-
numbered high-pressure turbine (HPT) shroud/low pressure turbine (LPT)
nozzle assemblies installed. This proposed AD was prompted by a report
of failed retention features of the inner and outer support air ducts
(commonly referred to as spoolies) discovered during engine
disassembly. This proposed AD would require a visual inspection of the
combustion case for wear and gouges, repair if necessary, and rework of
the affected HPT shroud/LPT nozzle assemblies. 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
26,
2024.
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 under
Docket No. FAA-2024-1883; 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, 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 that is incorporated
by reference 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: Alexei Marqueen, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone:
(781) 238-7178; email: alexei.t.marqueen@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-2024-1883; Project Identifier
AD-2023-01120-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
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
Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th
Street, Des Moines, WA 98198. 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 received a report from the manufacturer that during
disassembly, the retention features of the inner and outer support air
ducts on GE Model CF34-10E series engines were found to have failed.
The retention features include a retaining ring, which becomes
plastically deformed during installation. Vibrations loosen the
retaining ring until it disengages. With the retaining ring disengaged,
the outer support air duct has no radial constraint, and releases and
migrates due to gravity, impacting the inner wall of the combustion
case causing case wall damage. If this damage has been repaired in the
past and after the repair the support air duct liberates and causes
more damage, then the remaining wall thickness is not sufficient to
sustain the loading from a fan-blade-out or other extreme event. This
condition, if not addressed, could result in the inner surface of the
combustion case having reduced load carrying capability for fan blade
out or other extreme event with possible engine separation and loss of
the airplane.
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) 72-0351 R01, dated July
17, 2019, which provides instructions for a visual inspection of the
combustion case for wear and gouges, repair if necessary, and rework of
the affected HPT shroud/LPT nozzle assemblies. This service bulletin
also introduces a new HPT shroud/LPT nozzle assembly P/N 2205M38G07
with welded retaining rings. 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 requires a visual inspection of the combustion
case for wear and gouges, repair if necessary, and rework of the
affected HPT shroud/LPT nozzle assemblies to add a positive retention
of the support air duct.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 300 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
|
Action
|
Labor cost
|
Parts cost
|
Cost per
product
|
Cost on
U.S. operators
|
| Visual inspection of the combustion
case inner shell surface |
8 work-hours x $85 per hour =
$680 |
$0
|
$680
|
$204,000
|
| Rework of the affected HPT shroud/LPT
nozzle assembly
|
8 work-hours x $85 per hour =
$680 |
0
|
680
|
204,000
|
The FAA estimates the following costs
to do any necessary repairs
that would be required based on the results of the proposed inspection.
The agency has no way of determining the number of engines that might
need these repairs.
On-Condition Costs
|
Action
|
Labor cost
|
Parts cost
|
Cost per
product
|
| Repair the combustion case |
8 work-hours x $85 per hour =
$680 |
$0
|
$680
|
| Replace the combustion case |
8 work-hours x $85 per hour =
$680 |
647,000
|
647,680
|
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
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:
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