Airworthiness Directives; General Electric Company Engines

[Federal Register Volume 90, Number 72 (Wednesday, April 16, 2025)]
[Rules and Regulations]
[Pages 15926-15929]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-06420]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2417; Project Identifier AD-2024-00336-E; 
Amendment 39-23012; AD 2025-07-10]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2020-20-17 
and AD 2021-15-05 for all General Electric Company (GE) Model GE90-
110B1 and GE90-115B engines. AD 2020-20-17 prohibits dispatch of an 
airplane if certain status messages are displayed on the engine 
indicating and crew alerting system (EICAS) and if certain conditions 
are present; and as terminating action, requires revision of the 
existing FAA-approved minimum equipment list (MEL) by incorporating the 
dispatch restrictions into the MEL. AD 2021-15-05 requires initial and 
repetitive replacement of the full authority digital engine control 
(FADEC) integrated circuit (MN4) microprocessor. Since the FAA issued 
AD 2020-20-17 and AD 2021-15-05, the manufacturer has developed a 
software revision for the electronic engine control (EEC) FADEC that 
further mitigates the unsafe condition. This AD retains all the actions 
of AD 2020-20-17 and AD 2021-15-05, and also requires upgrading the EEC 
FADEC software to an EEC FADEC software version eligible for 
installation as a terminating action. The FAA is issuing this AD to 
address the unsafe condition on these products.

DATES: This AD is effective May 21, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of May 21, 
2025.
    The Director of the Federal Register approved the incorporation by 
reference of certain other publications listed in this AD as of October 
23, 2020 (85 FR 63443, October 8, 2020); and September 13, 2021 (86 FR 
43409, August 9, 2021).

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-2417; 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 final rule, any comments received, and other 
information. The address for Docket Operations is U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
    Material Incorporated by Reference:
    <bullet> For GE material identified in this AD, contact GE, 1 
Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: 
ge.com">aviation.fleetsupport@ge.com; website: ge.com.
    <bullet> You may view this material 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. It is also available at 
regulations.gov under Docket No. FAA-2024-2417.

FOR FURTHER INFORMATION CONTACT: Alexander Thickstun, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
(202) 267-8292; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to supersede AD 2020-20-17, Amendment 39-21273 (85 FR 
63443, October 8, 2020) (AD 2020-20-17) and AD 2021-15-05, Amendment 
39-21652 (86 FR 43409, August 9, 2021) (AD 2021-15-05). AD 2020-20-17 
and AD 2021-15-05 applied to all GE Model GE90-110B1 and GE90-115B 
engines. The NPRM published in the Federal Register on November 1, 2024 
(89 FR 87317). The NPRM was prompted by an in-service occurrence of 
loss of engine thrust control resulting in uncommanded high thrust. 
Degradation of the MN4 integrated circuit microprocessor solder balls 
in the FADEC can result in the engine not following throttle commands. 
In the NPRM, the FAA proposed to continue to prohibit dispatch of an 
airplane if certain status messages are displayed on the EICAS and if 
certain conditions are present; and as terminating action, require 
revision of the existing FAA-approved MEL by incorporating the dispatch 
restrictions into the MEL. The FAA also proposed to continue to require 
initial and repetitive replacement of the FADEC MN4 microprocessor. In 
the NPRM, the FAA also proposed to require upgrading the EEC FADEC 
software to an EEC FADEC software version eligible for installation as 
a terminating action for the actions retained from AD 2020-20-17 and AD 
2021-15-05.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from five commenters. The commenters were 
the Air Line Pilots Association, International (ALPA), The Boeing 
Company (Boeing), FedEx Express (FedEx), GE Aerospace (GE), and United 
Airlines (UAL). The following presents the comments received on the 
NPRM and the FAA's response to each comment.

Support for the NPRM

    ALPA expressed support for the proposed AD. FedEx concurred with 
the intent and scope of the proposed AD and stated that the FedEx fleet 
has already upgraded the EEC FADEC software version to A.0.8.6. UAL 
indicated that it had no objections to the proposed AD.

Request for Updated Definition

    GE requested that the FAA update the Material Incorporated by 
Reference under 1 CFR part 51 paragraph and revise the definition 
specified in paragraph (i)(1)(ii) of the NPRM to include a later 
revision of the acceptable service information. GE mentioned that the 
FAA has approved a global alternative method of compliance (AMOC) to 
the corresponding paragraph in AD 2021-15-05, which allowed the use of 
the later service information. GE pointed out that including the later 
service information would prevent similar requests for AMOCs to the 
NPRM.
    The FAA agrees with the request. The FAA has revised the Material 
Incorporated by Reference under 1 CFR part 51 paragraph and paragraph 
(i)(1)(ii) of this AD to include reference to GE GE90-100 Service 
Bulletin 73-

[[Page 15927]]

0118 R02, dated November 15, 2024 (GE GE90-100 Service Bulletin 73-0118 
R02). Additionally, the FAA has added paragraph (n)(3) of this AD to 
allow AMOCs approved previously for AD 2021-15-05 as AMOCs for the 
corresponding provisions of this AD.

Request for Added Clarification of FADEC Software Version A.0.8.6

    GE requested that the FAA include a service bulletin reference (GE 
GE90-100 Service Bulletin 73-0122) in the required actions specified in 
paragraph (j) of the NPRM. GE pointed out that field configuration 
management is tracked with service bulletins that are used to release 
part numbers to the field, and that including reference to GE GE90-100 
Service Bulletin 73-0122 provides clarification.
    The FAA agrees and has updated the new required actions specified 
in paragraphs (j) and (l) of this AD to refer to GE GE90-100 Service 
Bulletin 73-0122.

Request for Credit

    GE requested that the FAA include credit for previous versions of 
GE GE90-100 Service Bulletin 73-0122. GE pointed out that including 
credit would help avoid confusion about compliance with the required 
action.
    The FAA disagrees with the request. The FAA has updated the new 
required actions specified in paragraphs (j) and (l) of this AD to 
include reference to GE GE90-100 Service Bulletin 73-0122. Since the 
reference is clarifying and does not require any action in accordance 
with the service information reference, there is no need for any credit 
related to the action. The FAA did not change this AD as a result of 
this comment.

Request for Clarification of the Unsafe Condition

    Boeing requested that the FAA revise the unsafe condition specified 
in paragraph (e) of the NPRM. Boeing requested that the unsafe 
condition be reworded to focus on describing the unsafe condition or to 
include the new mitigations provided in the NPRM. Boeing also included 
proposed language to revise paragraph (e) of the NPRM. Boeing noted 
that paragraph (e) of the NPRM does not describe the potentially unsafe 
condition in detail and does not discuss the new mitigations that were 
added in the NPRM.
    The FAA agrees to clarify. However, the FAA has determined that the 
unsafe condition described in paragraph (e) of this AD correctly 
describes the unsafe condition and is consistent with the verbiage used 
in the previous (superseded) ADs. Instead, the FAA has determined to 
include an additional clarifying sentence in the Background of this AD, 
which states: ``Degradation of the MN4 integrated circuit 
microprocessor solder balls in the FADEC can result in the engine not 
following throttle commands.''

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting the AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, and 
any other changes described previously, this AD is adopted as proposed 
in the NPRM. None of the changes will increase the economic burden on 
any operator.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed GE GE90-100 Service Bulletin 73-0118 R02, which 
specifies procedures for replacing the FADEC MN4 microprocessor, which 
describes procedures for checking for an inbound FADEC EICAS ``ENG EEC 
C1'' status message and corresponding conditions.
    The FAA also reviewed GE GE90-100 Service Bulletin 73-0117 R01, 
dated August 5, 2020, which the Director of the Federal Register 
approved for incorporation by reference as of October 23, 2020 (85 FR 
63443, October 8, 2020).
    The FAA also reviewed GE GE90-100 Service Bulletin 73-0118, 
Revision 01, dated April 27, 2021, which the Director of the Federal 
Register approved for incorporation by reference as of September 13, 
2021 (86 FR 43409, August 9, 2021).
    This material is reasonably available because the interested 
parties have access to it through their normal course of business or by 
the means identified in the ADDRESSES section.

Costs of Compliance

    The FAA estimates that this AD affects 330 engines installed on 
airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                       Cost per    Cost on U.S.
                  Action                            Labor cost           Parts cost    product       operators
----------------------------------------------------------------------------------------------------------------
Revise the existing MEL (Retained action   1 work-hour x $85 per hour            $0          $85         $28,050
 from AD 2020-20-17).                       = $85.
Remove and replace the FADEC (Retained     1 work-hour x 85 per hour =       25,200       25,285       8,344,050
 action from AD 2021-15-05).                85.
Upgrade the EEC FADEC software (New        1 work-hour x 85 per hour =            0           85          28,050
 Action).                                   85.
----------------------------------------------------------------------------------------------------------------

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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:

[[Page 15928]]

    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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 2020-20-17, Amendment 39-21273 (85 
FR 63443, October 8, 2020); and Airworthiness Directive 2021-15-05, 
Amendment 39-21652 (86 FR 43409, August 9, 2021); and
0
b. Adding the following new airworthiness directive:

2025-07-10 General Electric Company: Amendment 39-23012; Docket No. 
FAA-2024-2417; Project Identifier AD-2024-00336-E.

(a) Effective Date

    This airworthiness directive (AD) is effectiveMay 21, 2025.

(b) Affected ADs

    (1) This AD replaces AD 2020-20-17, Amendment 39-21273 (85 FR 
63443, October 8, 2020) (AD 2020-20-17).
    (2) This AD replaces AD 2021-15-05, Amendment 39-21652 (86 FR 
43409, August 9, 2021) (AD 2021-15-05).

(c) Applicability

    This AD applies to General Electric Company (GE) Model GE90-
110B1 and GE90-115B engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7320, Fuel 
Controlling System.

(e) Unsafe Condition

    This AD was prompted by an in-service occurrence of loss of 
engine thrust control resulting in uncommanded high thrust. The FAA 
is issuing this AD to prohibit dispatch of the airplane when certain 
faults caused by degradation of the MN4 integrated circuit in the 
full authority digital engine control (FADEC) are displayed and 
certain FADEC conditions are present, and to prevent failure of the 
electronic engine control (EEC) FADEC integrated circuit (MN4) 
microprocessor solder ball. The unsafe condition, if not addressed, 
could result in loss of engine thrust control and reduced control of 
the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Retained Actions From AD 2020-20-17, With No Changes

    (1) After October 23, 2020 (the effective date of AD 2020-20-
17), notwithstanding the provisions of the operator's minimum 
equipment list (MEL), dispatch of an airplane is prohibited if the 
engine indicating and crew alerting system (EICAS) displays the 
status message ``ENG EEC C1 L'' or ``ENG EEC C1 R'' and any 
condition is present that is listed in the Accomplishment 
Instructions, paragraphs 3.A.(2)(f), 3.A.3(a), or 3.A.(4) of GE 
GE90-100 Service Bulletin 73-0117 R01, dated August 5, 2020.
    (2) As terminating action for the requirements of paragraph 
(g)(1) of this AD, within 120 days of October 23, 2020 (the 
effective date of AD 2020-20-17), revise the existing FAA-approved 
MEL by incorporating into the MEL the dispatch restrictions listed 
in paragraph (g)(1) of this AD as a required operation or 
maintenance procedure. Specific alternative MEL wording to 
accomplish the actions specified in paragraph (g)(1) of this AD can 
be approved by the operator's principal operations or maintenance 
inspector.

(h) Retained Actions From AD 2021-15-05, With No Changes

    (1) Within the following compliance times after September 13, 
2021 (the effective date of AD 2021-15-05), replace the FADEC MN4 
microprocessor using an approved overhaul procedure:
    (i) For a FADEC MN4 microprocessor with 10,500 or more cycles 
since new (CSN), replace the FADEC MN4 microprocessor before 
accumulating 500 additional cycles on the FADEC MN4 microprocessor.
    (ii) For a FADEC MN4 microprocessor with 5,000 CSN or more, but 
fewer than 10,500 CSN, replace the FADEC MN4 microprocessor at the 
next FADEC component shop visit or before accumulating 11,000 CSN on 
the FADEC MN4 microprocessor, whichever occurs first.
    (2) Thereafter, repeat the replacement of the FADEC MN4 
microprocessor at the first FADEC component shop visit after 
accumulating 5,000 cycles since the last replacement but before 
accumulating 11,000 cycles since the last replacement.

(i) Retained Definitions From AD 2021-15-05, With an Updated Definition

    This paragraph restates the definitions of paragraph (h) of AD 
2021-15-05, with new service information included for the definition 
of paragraph (h)(1)(ii). For the purpose of this AD:
    (1) An ``approved overhaul procedure'' is one of the following:
    (i) Replacement of the FADEC MN4 microprocessor using FADEC 
International-approved maintenance procedures; or
    (ii) Replacement of the FADEC MN4 microprocessor using the 
Accomplishment Instructions, paragraph 3.A., of GE GE90-100 Service 
Bulletin 73-0118, Revision 01, dated April 27, 2021, or of GE GE90-
100 Service Bulletin 73-0118, Revision 02, dated November 15, 2024.
    (2) A ``FADEC component shop visit'' is the induction of the 
FADEC into a repair facility to perform internal maintenance on the 
FADEC.

(j) New Required Actions

    Within 180 days after the effective date of this AD, replace any 
EEC FADEC software version that is earlier than A.0.8.6 (prior to GE 
GE90-100 Service Bulletin 73-0122) with an EEC FADEC software 
version that is eligible for installation.

(k) Terminating Action

    The actions specified in paragraph (j) of this AD constitute 
terminating action for all the requirements of paragraphs (g) and 
(h) of this AD.

(l) Installation Prohibition

    As of the effective date of this AD, no person may install on 
any engine, an EEC FADEC software version that is earlier than 
A.0.8.6 (prior to GE GE90-100 Service Bulletin 73-0122).

(m) Definition

    For the purpose of this AD, an ``EEC FADEC software version that 
is eligible for installation'' is any software version that is 
A.0.8.6 or later.

(n) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520 Continued Operational Safety 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 AIR-520 Continued 
Operational Safety Branch, send it to the attention of the person 
identified in paragraph (o) of this AD and email to: [email protected].
    (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 2021-15-05 are approved as 
AMOCs for the corresponding provisions of this AD.

(o) Additional Information

    For more information about this AD, contact Alexander Thickstun, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: (202) 267-8292; email: 
[email protected].

(p) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the material listed in this 
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

[[Page 15929]]

    (2) You must use this material as applicable to do the actions 
required by this AD, unless the AD specifies otherwise.
    (3) The following material was approved for IBR on May 21, 2025.
    (i) General Electric Company (GE) GE90-100 Service Bulletin 73-
0118, Revision 02, dated November 15, 2024.
    (ii) [Reserved]
    (4) The following material was approved for IBR on October 23, 
2020 (85 FR 63443, October 8, 2020).
    (i) GE GE90-100 Service Bulletin 73-0117 R01, dated August 5, 
2020.
    (ii) [Reserved]
    (5) The following material was approved for IBR on September 13, 
2021 (86 FR 43409, August 9, 2021).
    (i) GE GE90-100 Service Bulletin 73-0118, Revision 01, dated 
April 27, 2021.
    (ii) [Reserved]
    (6) For GE material identified in this AD, contact GE, 1 Neumann 
Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: 
ge.com">aviation.fleetsupport@ge.com; website: ge.com.
    (7) You may view this material 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.
    (8) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on April 2, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2025-06420 Filed 4-15-25; 8:45 am]
BILLING CODE 4910-13-P

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