Proposed Rule2022-23911
Airworthiness Directives; General Electric Company Turbofan Engines
Primary source
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Published
November 14, 2022
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for certain General Electric Company (GE) GE90-76B, GE90-85B, GE90-90B, and GE90-94B model turbofan engines. This proposed AD was prompted by a commanded in-flight shutdown (IFSD) due to cracking and rockback of the high-pressure turbine (HPT) stage 2 nozzles resulting in blade liberation, severe rotor imbalance, and liberation of the exhaust centerbody. This proposed AD would require initial and repetitive borescope inspections (BSIs) of the forward platforms of the HPT stage 2 blades or the leading edges of the HPT stage 2 nozzles and, depending on the results of the inspections, removal and replacement of the HPT stage 2 nozzles with a part eligible for installation. As a mandatory terminating action to the repetitive BSIs of the forward platforms of the HPT stage 2 blades or the leading edges of the HPT stage 2 nozzles, this proposed AD would require replacement of the HPT stage 2 nozzles. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 87 Issue 218 (Monday, November 14, 2022)</title>
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[Federal Register Volume 87, Number 218 (Monday, November 14, 2022)]
[Proposed Rules]
[Pages 68113-68116]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-23911]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-1240; Project Identifier AD-2022-00683-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 adopt a new airworthiness directive (AD)
for certain General Electric Company (GE) GE90-76B, GE90-85B, GE90-90B,
and GE90-94B model turbofan engines. This proposed AD was prompted by a
commanded in-flight shutdown (IFSD) due to cracking and rockback of the
high-pressure turbine (HPT) stage 2 nozzles resulting in blade
liberation, severe rotor imbalance, and liberation of the exhaust
centerbody. This proposed AD would require initial and repetitive
borescope inspections (BSIs) of the forward platforms of the HPT stage
2 blades or the leading edges of the HPT stage 2 nozzles and, depending
on the results of the inspections, removal and replacement of the HPT
stage 2 nozzles with a part eligible for installation. As a mandatory
terminating action to the repetitive BSIs of the forward platforms of
the HPT stage 2 blades or the leading edges of the HPT stage 2 nozzles,
this proposed AD would require replacement of the HPT stage 2 nozzles.
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
29, 2022.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> by
searching for and locating Docket No. FAA-2022-1240; 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 service information
identified in this NPRM, contact General Electric Company, GE Aviation,
Room 285, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272;
email: <a href="/cdn-cgi/l/email-protection#b6d7c0dfd7c2dfd9d898d0dad3d3c2c5c3c6c6d9c4c2f6d1d398d5d9db"><span class="__cf_email__" data-cfemail="d0b1a6b9b1a4b9bfbefeb6bcb5b5a4a3a5a0a0bfa2a490b7b5feb3bfbd">[email protected]</span></a>. 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: Stephen Elwin, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7236; email: <a href="/cdn-cgi/l/email-protection#7d2e09180d15181353315338110a14133d1b1c1c531a120b"><span class="__cf_email__" data-cfemail="e8bb9c8d98808d86c6a4c6ad849f8186a88e8989c68f879e">[email protected]</span></a>.
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-2022-1240; Project Identifier
AD-2022-00683-E'' at the beginning of your comments. The most helpful
comments reference a specific portion of the
[[Page 68114]]
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
<a href="http://regulations.gov">regulations.gov</a>, 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
Stephen Elwin, 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 received a report of a commanded IFSD of a GE90-85B model
turbofan engine installed on a Boeing Model 777-200ER airplane that
occurred on July 12, 2018. Subsequent investigation by the manufacturer
found that cracking and rockback of the HPT stage 2 nozzles, due to
thermal distress in the fillet radius of the leading edge, resulted in
rotor-stator contact with the HPT stage 2 blade platform. This
condition caused liberation of an HPT stage 2 blade and severe rotor
imbalance, leading to liberation of the exhaust centerbody from the
engine. This condition, if not addressed, could result in IFSD, failure
of the engine and exhaust centerbody, 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 GE90 Service Bulletin (SB) 72-1166, Revision 3,
dated February 14, 2019. This service information specifies procedures
for BSIs of the HPT stage 2 blade forward platforms for rub marks or
evidence of contact (circumferential grooves on the HPT stage 2 blade
platforms) with the HPT stage 2 nozzle angel wings. This service
information also specifies procedures for performing a 360-degree BSI
of the HPT stage 2 nozzles leading edges and specifies procedures for
removal and replacement of HPT stage 2 nozzles.
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 GE90 SB 72-1071, Revision 1, dated January 16,
2015. This service information specifies procedures for removal and
replacement of HPT stage 2 nozzles with HPT stage 2 nozzles that
incorporate a design change.
The FAA also reviewed GE GE90 SB 72-1216, Initial Issue, dated
August 22, 2022. This service information specifies inspection
procedures for affected HPT stage 2 nozzles.
Proposed AD Requirements in This NPRM
This proposed AD would require initial and repetitive borescope
inspections of the forward platforms of the HPT stage 2 blades or the
leading edges of the HPT stage 2 nozzles and, depending on the results
of the inspections, removal and replacement of the HPT stage 2 nozzles
with parts eligible for installation. As a mandatory terminating action
to the repetitive BSIs of the forward platforms of the HPT stage 2
blades or the leading edges of the HPT stage 2 nozzles, this proposed
AD would require replacement of the HPT stage 2 nozzles.
Differences Between This Proposed AD and the Service Information
GE GE90 SB 72-1166, Revision 3, dated February 14, 2019, specifies
BSIs be performed upon reaching the threshold of the analytical model
for the HPT stage 2 nozzles after GE Aviation issues a customer
notification report for any engine that reaches the analytical
threshold, while this proposed AD would require that BSIs be performed
based on the flight hours accrued on the HPT stage 2 nozzles since new
or since overhaul.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 8 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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BSI of HPT stage 2 nozzles or HPT 4 work-hours x $85 per $0 $340 $2,720
stage 2 blade interface. hour = $340.
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The FAA estimates the following costs to do any necessary
replacements 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 these replacements.
[[Page 68115]]
On-Condition Costs
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Cost per
Action Labor cost Parts cost product
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Replace full set of HPT stage 2 nozzles....... 8 work-hours x $85 per hour = $918,650 $919,330
$680.
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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 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
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 adding the following new airworthiness
directive:
General Electric Company: Docket No. FAA-2022-1240; Project
Identifier AD-2022-00683-E.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by December 29, 2022.
(b) Affected ADs
None.
(c) Applicability
This AD applies to General Electric Company (GE) GE90-76B, GE90-
85B, GE90-90B, and GE90-94B model turbofan engines, excluding those
engines with an installed full set of high-pressure turbine (HPT)
stage 2 nozzles with part numbers 1847M47G23 and 1847M47G24.
(d) Subject
Joint Aircraft System Component (JASC) Code 7250, Turbine
Section.
(e) Unsafe Condition
This AD was prompted by a commanded in-flight shutdown (IFSD)
due to cracking and rockback of the HPT stage 2 nozzles resulting in
blade liberation, severe rotor imbalance, and liberation of the
exhaust centerbody. The FAA is issuing this AD to prevent failure of
the HPT stage 2 nozzles, HPT stage 2 blades, and exhaust centerbody.
The unsafe condition, if not addressed, could result in IFSD,
failure of the engine and exhaust centerbody, and loss of the
airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within the compliance times specified in paragraphs
(g)(1)(i) and (ii) of this AD, perform an initial borescope
inspection (BSI) of the forward platforms of the HPT stage 2 blades,
or perform a 360 degree BSI of the leading edges of the HPT stage 2
nozzles (optional procedure) in accordance with the Accomplishment
Instructions, paragraph 3.A.(3)(a) of GE GE90 SB 72-1166, Revision
3, dated February 14, 2019 (the SB):
(i) For engines with HPT stage 2 nozzles that have accumulated
22,000 or more flight hours since new or since last overhaul as of
the effective date of this AD, perform the initial BSI before
accumulating 250 flight cycles (FCs) after the effective date of
this AD.
(ii) For engines with HPT stage 2 nozzles that have accumulated
less than 22,000 flight hours since new or since last overhaul as of
the effective date of this AD, perform the initial BSI before
accumulating 22,000 flight hours since new or since last overhaul,
or within 250 FCs after the effective date of this AD, whichever
occurs later.
(2) Thereafter, at intervals not to exceed 100 FCs from
performance of the last BSI of the forward platforms of the HPT
stage 2 blades, or at intervals not to exceed 500 FCs from the last
BSI of the leading edges of the HPT stage 2 nozzles, as applicable,
perform a repetitive BSI of the forward platforms of the HPT stage 2
blades or the leading edges of the HPT stage 2 nozzles in accordance
with the Accomplishment Instructions, paragraph 3.A.(3)(a) of the
SB.
(3) If, during any inspection required by paragraphs (g)(1) or
(g)(2) of this AD, rub marks, evidence of contact on the HPT stage 2
blade forward platform on three or more HPT stage 2 blades, or an
unserviceable HPT stage 2 nozzle is found, before further flight,
remove and replace the HPT stage 2 nozzles with a part eligible for
installation.
Note 1 to paragraph (g)(3): Serviceability criteria can be found
in the GE90 Boeing 777 Aircraft Maintenance Manual, 72-00-00,
INSPECTION/CHECK, Subtask 72-00-00-220-074-G00.
(h) Mandatory Terminating Action
As a mandatory terminating action to the repetitive inspections
required by paragraph (g)(2) of this AD, at the next engine shop
visit after reaching 22,000 flight hours since new or since last
overhaul, replace the HPT stage 2 nozzles with parts eligible for
installation.
(i) Definitions
(1) For the purpose of this AD, ``parts eligible for
installation'' is a full set of HPT stage 2 nozzles with part
numbers 1847M47G23 and 1847M47G24.
(2) For the purpose of this AD, an ``overhaul'' is the complete
refurbishment of the HPT stage 2 nozzle segments.
(3) For the purpose of this AD, and ``engine shop visit'' is the
induction of an engine into the shop for maintenance involving
separation of pairs of major mating engine case flanges, except for
the following situations, which do not constitute an engine shop
visit:
(i) Separation of engine flanges solely for the purposes of
transportation of the engine without subsequent maintenance; or
(ii) Separation of engine flanges solely for the purpose of
replacing the fan or propulsor without subsequent maintenance.
[[Page 68116]]
(j) Credit for Previous Actions
You may take credit for the initial inspection required by
paragraph (g)(1) of this AD if you performed the inspection before
the effective date of this AD using GE GE90 SB 72-1166, Revision 2,
dated October 13, 2017, or earlier revisions.
(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
identified in paragraph (l)(1) of this AD. Information may be
emailed to: <a href="/cdn-cgi/l/email-protection#5819161d75191c751915171b183e3939763f372e"><span class="__cf_email__" data-cfemail="bbfaf5fe96faff96faf6f4f8fbdddada95dcd4cd">[email protected]</span></a>.
(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
(1) For more information about this AD, contact Stephen Elwin,
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue,
Burlington, MA 01803; phone: (781) 238-7236; email:
<a href="/cdn-cgi/l/email-protection#bae9cedfcad2dfd494f694ffd6cdd3d4fadcdbdb94ddd5cc"><span class="__cf_email__" data-cfemail="683b1c0d18000d064624462d041f0106280e0909460f071e">[email protected]</span></a>.
(2) GE service information identified in this AD that is not
incorporated by reference is available at the addresses specified in
paragraph (m)(3) of this AD.
(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 GE90 Service Bulletin (SB) 72-1166, Revision 3, dated
February 14, 2019.
(ii) [Reserved]
(3) For GE service information identified in this AD, contact
General Electric Company, GE Aviation, Room 285, 1 Neumann Way,
Cincinnati, OH 45215; phone: (513) 552-3272; email:
<a href="/cdn-cgi/l/email-protection#99f8eff0f8edf0f6f7b7fff5fcfcedeaece9e9f6ebedd9fefcb7faf6f4"><span class="__cf_email__" data-cfemail="5637203f37223f393878303a333322252326263924221631337835393b">[email protected]</span></a>.
(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: <a href="/cdn-cgi/l/email-protection#c1a7b3efa8afb2b1a4a2b5a8aeaf81afa0b3a0efa6aeb7"><span class="__cf_email__" data-cfemail="4f293d6126213c3f2a2c3b2620210f212e3d2e61282039">[email protected]</span></a>, or go to: <a href="http://www.archives.gov/federal-register/cfr/ibr-locations.html">www.archives.gov/federal-register/cfr/ibr-locations.html</a>.
Issued on September 26, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2022-23911 Filed 11-10-22; 8:45 am]
BILLING CODE 4910-13-P
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