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Federal Register / Vol. 86, No. 87 / Friday, May 7, 2021 / Proposed Rules 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 202020
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 manufacturers service information. As a terminating action, AD 20202017 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 GE90100
Service Bulletin S/B 730118 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.
FAAs 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 GE90100 S/B
730118, 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
Action
Labor cost
Replace the FADEC MN4 microprocessor

1 work-hour $85 per hour = $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 FAAs 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 Agencys 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.

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Parts cost
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:

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Cost per product
$25,200

Cost on U.S.
operators
$25,285

$7,863,635

PART 39AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:

Authority: 49 U.S.C. 106g, 40113, 44701.
39.13

Amended
2. The FAA amends 39.13 by adding the following new airworthiness directive:

General Electric Company: Docket No. FAA
20210347; Project Identifier AD2020
01610E.
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 GE90110B1 and GE90115B
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
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