[Federal Register Volume 86, Number 87 (Friday, May 7, 2021)]
[Proposed Rules]
[Pages 24554-24556]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-09291]


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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]
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 all General Electric Company GE90-110B1 and GE90-115B model 
turbofan engines. This proposed AD was prompted by an in-service 
occurrence of loss of engine thrust control resulting in uncommanded 
high thrust. This proposed AD would require initial and repetitive 
replacement of the full authority digital engine control (FADEC) 
integrated circuit (MN4) microprocessor. 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 June 21, 
2021.

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 https://www.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.
    For service information identified in this NPRM, contact General 
Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 
552-3272; email: [email protected]; 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.

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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.

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: 
[email protected].

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-2021-0347; Project Identifier 
AD-2020-01610-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 
https://www.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 
Stephen Elwin, Aviation Safety Engineer, ECO Branch, FAA, 1200 District 
Avenue, Burlington,

[[Page 24555]]

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 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 this AD. Since that AD, the manufacturer 
published GE GE90-100 Service Bulletin (S/B) 73-0118 R00, dated 
November 6, 2020, and Revision 01, dated April 27, 2021, to replace the 
FADEC MN4 microprocessor and solder. This condition, if not addressed, 
could result in loss of engine thrust control and reduced control 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 GE90-100 S/B 73-0118, Revision 01, dated April 
27, 2021. This S/B 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require initial and repetitive replacement 
of the FADEC MN4 microprocessor using an approved overhaul procedure.

Interim Action

    The FAA considers that this proposed AD would be an interim action. 
If final action is later identified, the FAA will consider further 
rulemaking.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 311 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
----------------------------------------------------------------------------------------------------------------
Replace the FADEC MN4                1 work-hour x $85 per hour          $25,200         $25,285      $7,863,635
 microprocessor.                      = $85.
----------------------------------------------------------------------------------------------------------------

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

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-2021-0347; Project 
Identifier AD-2020-01610-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by June 21, 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

[[Page 24556]]

the FADEC 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 full authority digital engine control 
(FADEC) integrated circuit (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.

(h) Installation Prohibition

    After the effective date of this AD, do not install onto any 
engine any FADEC with a main channel board that was subject to more 
than three replacements of the FADEC MN4 microprocessor.

(i) 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.

(j) 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: 
[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.

(k) 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; fax: (781) 238-7199; 
email: [email protected].
    (2) For service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: [email protected]; 
website: www.ge.com. You may view this referenced 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.

    Issued on April 28, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-09291 Filed 5-6-21; 8:45 am]
BILLING CODE 4910-13-P