Proposed Rule2022-26579
Airworthiness Directives; General Electric Company Turbofan Engines
Primary source
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Published
December 8, 2022
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2012-02-07, which applies to certain General Electric Company (GE) CF6- 45 and CF6-50 series model turbofan engines with a specified low- pressure turbine (LPT) rotor stage 3 disk installed. AD 2012-02-07 requires inspections of high-pressure turbine (HPT) and LPT rotors, engine checks, vibration surveys, an optional LPT rotor stage 3 disk removal after a failed HPT blade borescope inspection (BSI) or a failed engine core vibration survey, establishes a lower life limit for the affected LPT rotor stage 3 disks, and requires removing these disks from service at times determined by a drawdown plan. Since the FAA issued AD 2012-02-07, four additional events of separation of the LPT rotor assembly have been reported resulting in the LPT rotor assembly departing the rear of the engine. The manufacturer has improved the design of the LPT rotor stage 3 disk. This proposed AD would continue to require inspections of HPT and LPT rotor stage 1 and stage 2 blades, vibration surveys, and use of a lower life limit for the affected LPT rotor stage 3 disks. As a terminating action to the inspections, engine checks, and vibration surveys, this proposed AD would require removal and replacement of the LPT rotor stage 3 disk with a redesigned LPT rotor stage 3 disk. This proposed AD would also revise the compliance time of the drawdown plan for the removal and replacement of the LPT rotor stage 3 disk. This proposed AD would also prohibit the installation or reinstallation of certain LPT rotor stage 3 disks. 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 235 (Thursday, December 8, 2022)</title>
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[Federal Register Volume 87, Number 235 (Thursday, December 8, 2022)]
[Proposed Rules]
[Pages 75181-75185]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-26579]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-1416; Project Identifier AD-2022-00725-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)
2012-02-07, which applies to certain General Electric Company (GE) CF6-
45 and CF6-50 series model turbofan engines with a specified low-
pressure turbine (LPT) rotor stage 3 disk installed. AD 2012-02-07
requires inspections of high-pressure turbine (HPT) and LPT rotors,
engine checks, vibration surveys, an optional LPT rotor stage 3 disk
removal after a failed HPT blade borescope inspection (BSI) or a failed
engine core vibration survey, establishes a lower life limit for the
affected LPT rotor stage 3 disks, and requires removing these disks
from service at times determined by a drawdown plan. Since the FAA
issued AD 2012-02-07, four additional events of separation of the LPT
rotor assembly have been reported resulting in the LPT rotor assembly
departing the rear of the engine. The manufacturer has improved the
design of the LPT rotor stage 3 disk. This proposed AD would continue
to require inspections of HPT and LPT rotor stage 1 and stage 2 blades,
vibration surveys, and use of a lower life limit for the affected LPT
rotor stage 3 disks. As a terminating action to the inspections, engine
checks, and vibration surveys, this proposed AD would require removal
and replacement of the LPT rotor stage 3 disk with a redesigned LPT
rotor stage 3 disk. This proposed AD would also revise the compliance
time of the drawdown plan for the removal and replacement of the LPT
rotor stage 3 disk. This proposed AD would also prohibit the
installation
[[Page 75182]]
or reinstallation of certain LPT rotor stage 3 disks. 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 January 23,
2023.
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-2022-1416; 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: Sungmo Cho, Aviation Safety Engineer,
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone:
(781) 238-7241; email: <a href="/cdn-cgi/l/email-protection#3467415a53595b1a701a775c5b745255551a535b42"><span class="__cf_email__" data-cfemail="9ccfe9f2fbf1f3b2d8b2dff4f3dcfafdfdb2fbf3ea">[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-2022-1416; Project Identifier
AD-2022-00725-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
<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
Sungmo Cho, 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 2012-02-07, Amendment 39-16930 (77 FR 4650,
January 31, 2012) (AD 2012-02-07), for GE CF6-45A, CF6-45A2, CF6-50A,
CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-50E,
CF6-50E1, CF6-50E2, and CF6-50E2B model turbofan engines, including
engines marked on the engine data plate as CF6-50C2-F and CF6-50C2-R,
with a specified LPT rotor stage 3 disk, identified by part number (P/
N), installed. AD 2012-02-07 superseded AD 2011-02-07, Amendment 39-
16580 (76 FR 6323, February 4, 2011) and AD 2011-18-01, Amendment 39-
16783 (76 FR 52213, August 22, 2011). AD 2012-02-07 was prompted by the
determination that a new lower life limit for the affected LPT rotor
stage 3 disks was necessary. AD 2012-02-07 retained the requirements of
the two superseded ADs, which required inspections of HPT and LPT
rotors, ultrasonic inspection (UI) of the LPT rotor stage 3 disk
forward spacer arm, exhaust gas temperature (EGT) resistance check, EGT
thermocouple inspection, cleaning, fluorescent-penetrant inspection
(FPI) of the LPT rotor stage 3 disk, engine checks, and vibration
surveys. AD 2012-02-07 also added an optional LPT rotor stage 3 disk
removal after a failed HPT BSI or a failed engine core vibration
survey, established a new lower life limit for the affected LPT rotor
stage 3 disks, and required removing those disks from service at times
determined by a drawdown plan. The agency issued AD 2012-02-07 to
prevent critical life-limited rotating engine part failure, which could
result in an uncontained engine failure and damage to the airplane.
Actions Since AD 2012-02-07 Was Issued
Since the FAA issued AD 2012-02-07, the FAA has received reports of
four additional events of separation of the LPT rotor assembly, which
resulted in the LPT rotor assembly departing the rear of the engine.
Following the most recent separation event, the FAA determined that due
to the complexity of AD 2012-02-07, the limitations of certain
operators to access required equipment and training needed to
accomplish the inspections, and the manufacturer's redesign of the LPT
rotor stage 3 disk, AD 2012-02-07 should be superseded. The redesigned
LPT rotor stage 3 disk, P/N 2453M80P01, has a thicker forward spacer
arm, which reduces stress on the forward arm area and increases its
high cycle fatigue alternating stress capability.
Accordingly, the FAA is proposing to require the replacement of the
affected LPT rotor stage 3 disk with a redesigned LPT rotor stage 3
disk, P/N 2453M80P01, as a terminating action to the HPT blade
inspection, vibration survey, UI, EGT resistance check, EGT
thermocouple inspection, cleaning, and FPI. This proposed AD would also
revise the installation prohibition for affected LPT rotor stage 3
disks. AD 2012-02-07 prohibited the installation or reinstallation of
an affected LPT rotor stage 3 disk if it had exceeded 6,200 cycles
since new. This proposed AD would prohibit installing an affected LPT
rotor stage 3 disk onto any engine.
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 designs.
Proposed AD Requirements in This NPRM
This proposed AD would retain certain requirements of AD 2012-02-
07. As a terminating action to the HPT blade inspection, vibration
survey, UI, EGT resistance check, EGT thermocouple inspection,
cleaning, and FPI of the LPT rotor stage 3 disk, this proposed AD would
require removal and replacement of the LPT rotor stage 3 disk with
improved design LPT rotor
[[Page 75183]]
stage 3 disk P/N 2453M80P01 within 18 months of the effective date of
the AD. This proposed AD would also prohibit the installation or
reinstallation of certain LPT rotor stage 3 disks on any engine.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 26 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
HPT blade inspection, vibration 28 work-hours x $85 per $0 $2,380 $61,880
survey, UI, EGT resistance check, EGT hour = $2,380.
thermocouple inspection, cleaning and
FPI of the LPT rotor stage 3 disk.
Remove and replace LPT rotor stage 3 620 work-hours x $85 per 276,300 329,000 8,554,000
disk. hour = $52,700.
----------------------------------------------------------------------------------------------------------------
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
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:
0
a. Removing Airworthiness Directive AD 2012-02-07, Amendment 39-16930
(77 FR 4650, January 31, 2012); and
0
b. Adding the following new airworthiness directive:
General Electric Company: Docket No. FAA-2022-1416; Project
Identifier AD-2022-00725-E.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) action by January 23, 2023.
(b) Affected ADs
This AD replaces AD 2012-02-07, Amendment 39-16930 (77 FR 4650,
January 31, 2012) (AD 2012-02-07).
(c) Applicability
This AD applies to General Electric Company (GE) CF6-45A, CF6-
45A2, CF6-50A, CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B,
CF6-50C2D, CF6-50E, CF6-50E1, CF6-50E2, and CF6-50E2B model turbofan
engines, including engines marked on the engine data plate as CF6-
50C2-F and CF6-50C2-R, with an installed low-pressure turbine (LPT)
rotor stage 3 disk having a part number listed in Table 1 to
paragraph (c) of this AD.
Table 1 to Paragraph (c)--Applicable LPT Rotor Stage 3 Disk Part Numbers
--------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------
9061M23P06 9061M23P07 9061M23P08 9061M23P09 9224M75P01
9061M23P10 1473M90P01 1473M90P02 1473M90P03 1473M90P04
9061M23P12 9061M23P14 9061M23P15 9061M23P16 1479M75P01
1479M75P02 1479M75P03 1479M75P04 1479M75P05 1479M75P06
1479M75P07 1479M75P08 1479M75P09 1479M75P11 1479M75P13
1479M75P14 N/A N/A N/A N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
(d) Subject
Joint Aircraft System Component (JASC) Code 7250, Turbine
Section.
(e) Unsafe Condition
This AD was prompted by the occurrence of four events of
separation of the LPT rotor assembly, occurring after the effective
date of AD 2012-02-07, which resulted in the LPT rotor assembly
departing the rear of the engine. The FAA is issuing this AD to
prevent critical life-limited rotating engine part failure. The
unsafe condition, if not addressed, could result in an uncontained
engine failure and damage to the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
[[Page 75184]]
(g) Required Actions
(1) Borescope Inspections (BSI) of High-Pressure Turbine (HPT)
Rotor Stage 1 and Stage 2 Blades:
For the BSIs required by paragraphs (g)(1)(i) through (iii) of
this AD, inspect the blades from the forward and aft directions.
Inspect all areas of the blade airfoil. The inspection must include
blade leading and trailing edges and their convex and concave
airfoil surfaces. Inspect for signs of impact, cracking, burning,
damage, and distress.
(i) Within 75 cycles since last inspection (CSLI) or before
further flight, whichever occurs later, perform an initial BSI of
the HPT rotor stage 1 and stage 2 blades.
(ii) Thereafter, within every 75 CSLI, repeat the BSI of the HPT
rotor stage 1 and stage 2 blades.
(iii) Within the cycle limits after the engine has experienced
any of the events specified in Table 1 to paragraph (g)(1) of this
AD, borescope-inspect the HPT rotor stage 1 and stage 2 blades.
(iv) If the engine fails any of the BSIs required by this AD,
before further flight, remove the engine from
service.[FEDREG][VOL]*[/VOL][NO]*[/NO][DATE]*[/
DATE][PRORULES][PRORULE][PREAMB][AGENCY]*[/AGENCY][SUBJECT]*[/
SUBJECT][/PREAMB][SUPLINF][HED]*[/HED][EXTRACT][P]*[/P]?>
Table 2 to Paragraph (g)(1)--Conditional BSI Criteria
------------------------------------------------------------------------
Then borescope
If the engine has experienced: inspect:
------------------------------------------------------------------------
(i) An exhaust gas temperature (EGT) above Within 10 cycles.
redline.
(ii) A shift in the smoothed EGT trending data Within 10 cycles.
that exceeds 18 [deg]F (10 [deg]C), but is less
than or equal to 36 [deg]F (20 [deg]C).
(iii) A shift in the smoothed EGT trending data Before further flight.
that exceeds 36 [deg]F (20 [deg]C).
(iv) Two consecutive raw EGT trend data points Within 10 cycles.
that exceed 18 [deg]F (10 [deg]C), but are less
than or equal to 36 [deg]F (20 [deg]C), above
the smoothed average.
(v) Two consecutive raw EGT trend data points Before further flight.
that exceed 36 [deg]F (20 [deg]C) above the
smoothed average.
------------------------------------------------------------------------
(2) Engines with Damaged HPT Rotor Blades:
For those engines that fail any BSI requirements of this AD,
before returning the engine to service, accomplish the actions
required by paragraph (g)(2)(i) or (ii) of this AD:
(i) Remove the LPT rotor stage 3 disk from service; or
(ii) Perform a fluorescent-penetrant inspection (FPI) of the
inner diameter surface forward cone body (forward spacer arm) of the
LPT rotor stage 3 disk as specified in paragraphs (g)(6)(i)(A)
through (C) of this AD.
(3) EGT Thermocouple Probe Inspections.
(i) Within 750 CSLI, or before further flight, whichever occurs
later, inspect the EGT thermocouple probe for damage.
Note 1 to paragraph (g)(3)(i): Damage to the EGT thermocouple
probe may be indicated by wear through the thermocouple guide sleeve
or contact between the turbine mid-frame liner and the EGT
thermocouple probe.
(ii) Thereafter, within every 750 CSLI, re-inspect the EGT
thermocouple probe for damage.
(iii) If any EGT thermocouple probe shows wear through the
thermocouple guide sleeve or contact between the turbine mid-frame
liner and the EGT thermocouple probe, before further flight, remove
and replace the EGT thermocouple probe and ensure the turbine mid-
frame liner does not contact the EGT thermocouple probe.
(4) EGT System Resistance Checks.
(i) Within 750 cycles since the last resistance check on the EGT
system or before further flight, whichever occurs later, perform an
EGT system resistance check.
(ii) Thereafter, within every 750 cycles since the last
resistance check, repeat the EGT system resistance check.
(iii) If an EGT system component fails the resistance system
check, before further flight, remove and replace, or repair the EGT
system component.
(5) Engine Core Vibration Survey.
(i) Within 350 cycles since the last engine core vibration
survey or before further flight, whichever occurs later, perform an
initial engine core vibration survey.
(ii) Use about a one-minute acceleration and a one-minute
deceleration of the engine between ground idle and 84% N2 (about
8,250 rpm) to perform the engine core vibration survey.
(iii) Use a spectral/trim balance analyzer or equivalent to
measure the N2 rotor vibration.
(iv) If the vibration level is above 5 mils Double Amplitude
then, before further flight, remove the engine from service.
(v) For those engines that fail any engine core vibration survey
requirements of this AD, then before returning the engine to
service:
(A) Remove the LPT rotor stage 3 disk from service; or
(B) Perform an FPI of the inner diameter surface forward spacer
arm of the LPT rotor stage 3 disk as specified in paragraph
(g)(6)(i)(A) through (C) of this AD.
(vi) Thereafter, within every 350 cycles since the last engine
core vibration survey, perform the engine core vibration survey as
required in paragraphs (g)(5)(i) through (v) of this AD.
(vii) If the engine has experienced any vibration reported by
maintenance or flight crew that is suspected to be caused by the
engine core (N2), within 10 cycles after the report, perform the
engine core vibration survey as required in paragraphs (g)(5)(i)
through (v) of this AD.
(viii) Vibration surveys carried out in an engine test cell as
part of an engine manual performance run fulfill the vibration
survey requirements of paragraphs (g)(5)(ii) and (iii) of this AD.
(6) Initial and Repetitive FPI of LPT Rotor Stage 3 Disk.
(i) At the next shop visit after accumulating 1,000 cycles since
the last FPI of the LPT rotor stage 3 disk forward spacer arm or
before further flight, whichever occurs later:
(A) Clean the LPT rotor stage 3 disk forward spacer arm,
including the use of a wet-abrasive blast, to eliminate residual or
background fluorescence.
(B) Perform an FPI of the LPT rotor stage 3 disk forward spacer
arm for cracks and for a band of fluorescence. Include all areas of
the disk forward spacer arm and the inner diameter surface forward
spacer arm of the LPT rotor stage 3 disk.
(C) If a crack or a band of fluorescence is present, before
further flight, remove the disk from service.
(ii) Thereafter, at each engine shop visit that occurs after
accumulating 1,000 cycles since the last FPI of the LPT rotor stage
3 disk forward spacer arm, clean and perform an FPI of the LPT rotor
stage 3 disk forward spacer arm, as specified in paragraph
(g)(6)(i)(A) through (C) of this AD.
(7) Removal of LPT Rotor Stage 3 Disk.
(i) For any installed LPT rotor stage 3 disk having a part
number listed in Table 1 to paragraph (c) of this AD, at the first
occurrence of any one of the conditions identified in paragraphs
(g)(7)(i)(A) through (C) of this AD, remove the LPT rotor stage 3
disk from service and replace with LPT rotor stage 3 disk part
number 2453M80P01.
(A) For a disk that has accumulated fewer than 3,200 cycles
since new (CSN) as of March 6, 2012 (the effective date of AD 2012-
02-07), remove the disk from service before accumulating 6,200 CSN.
(B) For a disk that accumulated 3,200 or more CSN as of March 6,
2012 (the effective date of AD 2012-02-07), do the actions required
by paragraphs (g)(7)(i)(B)(1) or (2) of this AD, as applicable to
your engine.
(1) If the engine has a shop visit before the disk accumulates
6,200 CSN, remove the disk from service at that shop visit.
(2) If the engine does not have a shop visit before the disk
accumulates 6,200 CSN, remove the disk from service at the next shop
visit after accumulating 6,200 CSN, not to exceed 3,000 cycles from
March 6, 2012 (the effective date of AD 2012-02-07).
(C) Before exceeding 18 months from the effective date of this
AD.
(h) Terminating Action
Replacement of the LPT rotor stage 3 disk in accordance with
paragraph (g)(7) of this AD constitutes terminating action for the
inspections, engine checks and vibration surveys required by
paragraphs (g)(1) through (6) of this AD.
[[Page 75185]]
(i) Installation Prohibition
After the effective date of this AD, do not install or reinstall
onto any engine an LPT rotor stage 3 disk listed in Table 1 to
paragraph (c) of this AD that has accumulated 6,200 CSN or more.
(j) Definitions
(1) For the purposes of this AD, an EGT above redline is a
confirmed over-temperature indication that is not a result of EGT
system error.
(2) For the purposes of this AD, a shift in the smoothed EGT
trending data is a shift in a rolling average of EGT readings that
can be confirmed by a corresponding shift in the trending of fuel
flow or fan speed/core speed (N1/N2) relationship. You can find
further guidance about evaluating EGT trend data in GE Company
Service Rep Tip 373 ''Guidelines For Parameter Trend Monitoring.''
(3) For the purposes of this AD, an engine shop visit is the
induction of an engine into the shop, where the separation of a
major engine flange occurs; except the following maintenance
actions, or any combination, are not considered engine shop visits:
(i) Induction of an engine into a shop solely for removal of the
compressor top or bottom case for airfoil maintenance or variable
stator vane bushing replacement.
(ii) Induction of an engine into a shop solely for removal or
replacement of the stage 1 fan disk.
(iii) Induction of an engine into a shop solely for replacement
of the turbine rear frame.
(iv) Induction of an engine into a shop solely for replacement
of the accessory gearbox or transfer gearbox, or both.
(v) Induction of an engine into a shop solely for replacement of
the fan forward case.
(4) For the purposes of this AD, a raw EGT trend data point
above the smoothed average is a confirmed temperature reading over
the rolling average of EGT readings that is not a result of EGT
system error.
(k) Credit for Previous Actions
You may take credit for the actions required by paragraph (g) of
this AD if they were performed before the effective date of this AD
using GE Service Bulletin (SB) No. CF6-50 SB 72-1315, Initial Issue,
dated June 3, 2011, or GE SB No. CF6-50 SB 72-1315, Revision 1,
dated June 30, 2011.
(l) 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 (m) of this AD and email it to: <a href="/cdn-cgi/l/email-protection#e1a0afa4cca0a5cca0acaea2a1878080cf868e97"><span class="__cf_email__" data-cfemail="377679721a76731a767a78747751565619505841">[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.
(3) AMOCs approved previously for AD 2010-12-10, Amendment 39-
16331 (75 FR 32649, June 9, 2010), AD 2011-02-07, Amendment 39-16580
(76 FR 6323, February 4, 2011), or AD 2011-18-01, Amendment 39-16783
(76 FR 52213, August 22, 2011) are approved as AMOCs for the
corresponding provisions of this AD.
(m) Related Information
For more information about this AD, contact Sungmo Cho, Aviation
Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington,
MA 01803; phone: (781) 238-7241; email: <a href="/cdn-cgi/l/email-protection#6536100b02080a4b214b260d0a250304044b020a13"><span class="__cf_email__" data-cfemail="4b183e252c2624650f650823240b2d2a2a652c243d">[email protected]</span></a>.
(n) Material Incorporated by Reference
None.
Issued on November 3, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2022-26579 Filed 12-7-22; 8:45 am]
BILLING CODE 4910-13-P
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