Document ID: FAA-2021-0347-0007
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2021-08-09T04:00Z

[Federal Register Volume 86, Number 150 (Monday, August 9, 2021)]
[Rules and Regulations]
[Pages 43409-43411]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-16766]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0347; Project Identifier AD-2020-01610-E; 
Amendment 39-21652; AD 2021-15-05]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
General Electric Company (GE) GE90-110B1 and GE90-115B model turbofan 
engines. This AD was prompted by an in-service occurrence of loss of 
engine thrust control resulting in uncommanded high thrust. This AD 
requires initial and repetitive replacement of the full authority 
digital engine control (FADEC) integrated circuit (MN4) microprocessor. 
The FAA is issuing this AD to address the unsafe condition on these 
products.

DATES: This AD is effective September 13, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of September 
13, 2021.

ADDRESSES: For service information identified in this final rule, 
contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: aviation.fleetsupport@ae.ge.com; website: 
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. It is 
also available at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2021-0347.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0347; 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.

FOR FURTHER INFORMATION CONTACT: Stephen Elwin, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7236; fax: (781) 238-7199; email: 
Stephen.L.Elwin@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all GE GE90-110B1 and 
GE90-115B model turbofan engines. The NPRM published in the Federal 
Register on May 7, 2021 (86 FR 24554). The NPRM was prompted by an in-
service occurrence of loss of engine thrust control resulting in 
uncommanded high thrust. The FAA received a report from the 
manufacturer of an in-service loss of engine thrust control that 
occurred on October 27, 2019, resulting in uncommanded high thrust. 
Analysis by the manufacturer found accumulated thermal cycles of the 
MN4 integrated circuit in the FADEC, through normal operation, causes 
the solder ball joints to wear out and eventually fail over time. The 
FAA published AD 2020-20-17 (85 FR 63443, dated October 8, 2020) to 
prohibit dispatch of an airplane if certain status messages are 
displayed on the engine indicating and crew alerting system and if 
certain conditions are present per the manufacturer's service 
information. As a terminating action, AD 2020-20-17 also requires 
revision of the existing FAA-approved minimum equipment list (MEL) by 
incorporating into the MEL the dispatch restrictions listed in AD 2020-
20-17. Since the effective date of AD 2020-20-17, the manufacturer 
published GE GE90-100 Service Bulletin (SB) 73-0118 R00, dated November 
6, 2020, and Revision 01, dated April 27, 2021, to replace the FADEC 
MN4 microprocessor and solder. In the NPRM, the FAA proposed to require 
initial and repetitive replacement of the FADEC MN4 microprocessor 
using an approved overhaul procedure. The FAA is issuing this AD to 
address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from five commenters. Commenters included 
Air Line Pilots Association, International (ALPA), Boeing Commercial 
Airplanes (Boeing), Cathay Pacific Airways Limited (Cathay), FedEx 
Express (FedEx), and United Airlines, Inc. The following presents the 
comments received on the NPRM and the FAA's response to each comment.

Request To Revise Installation Prohibition

    Cathay requested the FAA revise paragraph (h), Installation 
Prohibition, of the NPRM that specifies no more than three replacements 
of the FADEC MN4 microprocessor may be performed on the same main 
channel board. Cathay suggested that the FAA revise proposed paragraph 
(h) to prohibit installation onto any engine of any FADEC that is not 
compliant with GE GE90-100 SB 73-0118. Cathay stated that the MN4 
processor replacements are managed by the original equipment 
manufacturer's (OEM) internal maintenance procedures and operators do 
not have visibility into the number of replacements that have been 
performed.
    The FAA partially agrees. As stated by Cathay, the MN4 processor 
replacements are managed by the OEM's internal maintenance procedures 
and, therefore, are not necessary in this AD. The FAA has removed 
paragraph (h), Installation Prohibition, from this AD. The subsequent 
paragraphs of this AD have been redesignated accordingly.

Request To Add Terminating Action

    FedEx requested the upcoming FADEC software revision (A085) be 
included in this AD as a terminating action. FedEx commented that this 
AD may no longer be necessary due to the development and pending 
release of GE's new and improved FADEC software upgrade (A085).
    The FAA disagrees. The new FADEC software revision (A085) has not 
been approved by the FAA. Therefore, this software is not eligible for 
installation and cannot be referenced in this AD. The FAA considers 
this AD to be an interim action. If terminating action is identified 
later, the FAA might consider additional rulemaking. The FAA did not 
change this AD.

[[Page 43410]]

Support for the AD

    ALPA and Boeing expressed support for the NPRM as written. United 
Airlines, Inc. stated they had no objections to the NPRM as proposed.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this 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.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed General Electric GE90-100 Service Bulletin (SB) 
73-0118, Revision 01, dated April 27, 2021. This SB specifies 
procedures for replacing the FADEC MN4 microprocessor. 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.

Interim Action

    The FAA considers this AD to be an interim action. If final action 
is later identified, the FAA may consider additional rulemaking.

Costs of Compliance

    The FAA estimates that this AD affects 311 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
----------------------------------------------------------------------------------------------------------------
Remove and replace FADEC..............  1 work-hour x $85 per            $25,200         $25,285      $7,863,635
                                         hour = $85.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some of the costs of this AD 
may be covered under warranty, thereby reducing the cost impact on 
affected individuals.

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:
    (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 adding the following new airworthiness 
directive:

2021-15-05 General Electric Company: Amendment 39-21652; Docket No. 
FAA-2021-0347; Project Identifier AD-2020-01610-E.

(a) Effective Date

    This airworthiness directive (AD) is effective September 13, 
2021.

(b) Affected ADs

    None.

(c) Applicability

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

(d) Subject

    Joint Aircraft System Component (JASC) Code 7600, Engine 
Controls.

(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 prevent failure of the full authority digital 
engine control (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) Required Actions

    (1) Within the following compliance times after the effective 
date of this AD, 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 CSN since the last replacement but before 
accumulating 11,000 CSN since the last replacement.

[[Page 43411]]

(h) Definition

    (1) For the purpose of this AD, 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.
    (2) For the purpose of this AD, a ``FADEC component shop visit'' 
is the induction of the FADEC into a repair facility to perform 
internal maintenance on the FADEC.

(i) 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 Related Information. You may email your request to: 
ANE-AD-AMOC@faa.gov.
    (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.

(j) Related Information

    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; fax: (781) 238-7199; 
email: Stephen.L.Elwin@faa.gov.

(k) 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) General Electric Company (GE) GE90-100 Service Bulletin 73-
0118, Revision 01, dated April 27, 2021.
    (ii) [Reserved]
    (3) For GE service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: aviation.fleetsupport@ae.ge.com; 
website: www.ge.com.
    (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 (781) 238-7759.
    (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: fedreg.legal@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on July 9, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-16766 Filed 8-6-21; 8:45 am]
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