43406 Federal Register / Vol. 86, No. 150 / Monday, August 9, 2021 / Rules and Regulations 

(d) Subject 

Air Transport Association (ATA) of 

America Code 21, Air conditioning. 

(e) Unsafe Condition 

This AD was prompted by the 

determination that the aft cargo fire 

suppression capability is reduced if the 

airplane is dispatched or released with failed 

electronic flow control of air conditioning 

packs. The FAA is issuing this AD to address 

this condition, which can result in an 

uncontained aft cargo compartment fire due 

to insufficient cargo fire suppression 

capability. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Conditions for Prohibited Operation 

Beginning August 19, 2021, no person may 

dispatch or release an airplane with cargo in 

the aft cargo compartment with failed 

electronic flow control of air conditioning 

packs, unless the aft cargo compartment 

remains empty, or is verified by the operator 

to contain only non-combustible and/or nonflammable empty cargo handling equipment, 

ballast, and/or fly-away kits. 

Note 1 to paragraph (g): The operator’s 

existing FAA-approved minimum equipment 

list (MEL) defines which items are approved 

for inclusion in the fly-away kits, and which 

materials may be used as ballast. 

(h) Minimum Equipment List (MEL) Items 

The master minimum equipment list 

(MMEL) items specified in paragraphs (h)(1) 

and (2) of this AD are affected by the 

prohibition specified in paragraph (g) of this 

AD, and therefore may affect the operator’s 

existing FAA-approved MEL. 

(1) For Model 737–8, 737–9, and 737–8200 

airplanes: MMEL System No. 21, Sequence 

No. 51–02–01, ‘‘Electronic Flow Control.’’ 

(2) For Model 737–800 and 737–900ER 

series airplanes: MMEL System No. 21, 

Sequence No. 02–03, ‘‘Electronic Flow 

Control.’’ 

Note 2 to paragraph (h): The MMEL items 

specified in paragraph (h) of this AD can be 

found in the applicable FAA-approved 

MMEL: Boeing 737 (B–737–100/200/300/ 

400/500/600/700/800/900/900ER) MMEL, 

Revision 61, dated July 8, 2020; and Boeing 

737 MAX (B–737–8/–8200/–9) MMEL, 

Revision 3, dated April 12, 2021. These 

MMELs can be found on the Flight Standards 

Information Management System (FSIMS) 

website, https://fsims.faa.gov/PICResults

.aspx?mode=Publication&doctype=

MMELByModel. 

(i) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Seattle ACO 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 responsible Flight 

Standards 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. 

Information may be emailed to: 9-ANMSeattle-ACO-AMOC-Requests@faa.gov. 

(2) Before using any approved AMOC, 

notify your appropriate principal inspector, 

or lacking a principal inspector, the manager 

of the responsible Flight Standards Office. 

(3) An AMOC that provides an acceptable 

level of safety may be used for any repair, 

modification, or alteration required by this 

AD if it is approved by The Boeing Company 

Organization Designation Authorization 

(ODA) that has been authorized by the 

Manager, Seattle ACO Branch, FAA, to make 

those findings. To be approved, the repair 

method, modification deviation, or alteration 

deviation must meet the certification basis of 

the airplane, and the approval must 

specifically refer to this AD. 

(j) Related Information 

For more information about this AD, 

contact Sam Nalbandian, Aerospace 

Engineer, Cabin Safety and Environmental 

Systems Section, FAA, Seattle ACO Branch, 

2200 South 216th St., Des Moines, WA 

98198; phone and fax: 206–231–3993; email: 

Samuel.K.Nalbandian@faa.gov. 

(k) Material Incorporated by Reference 

None. 

Issued on July 29, 2021. 

Lance T. Gant, 

Director, Compliance & Airworthiness 

Division, Aircraft Certification Service. 

[FR Doc. 2021–16972 Filed 8–5–21; 11:15 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0619; Project 

Identifier AD–2021–00789–R; Amendment 

39–21678; AD 2021–15–51] 

RIN 2120–AA64 

Airworthiness Directives; Bell Textron 

Inc. (Type Certificate Previously Held 

by Bell Helicopter Textron Inc.) 

Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule; request for 

comments. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for certain 

Bell Textron Inc. (type certificate 

previously held by Bell Helicopter 

Textron Inc.) Model 204B, 205A, 205A– 

1, 205B, and 212 helicopters. This AD 

was prompted by a fatal accident in 

which an outboard main rotor hub strap 

pin (pin) sheared off during flight, 

resulting in the main rotor blade and the 

main rotor head detaching from the 

helicopter. This AD requires removing 

the pins from service before further 

flight and prohibits installing them on 

any helicopter. The FAA previously 

sent an emergency AD to all known U.S. 

owners and operators of these 

helicopters and is now issuing this AD 

to address the unsafe condition on these 

products. 

DATES: This AD is effective August 24, 

2021. Emergency AD 2021–15–51, 

issued on July 6, 2021, which contained 

the requirements of this amendment, 

was effective with actual notice. 

The FAA must receive comments on 

this AD by September 23, 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 final rule, contact Bell Textron, Inc., 

P.O. Box 482, Fort Worth, TX 76101; 

telephone (450) 437–2862 or (800) 363– 

8023; fax (450) 433–0272; email 

productsupport@bellflight.com; or at 

https://www.bellflight.com/support/ 

contact-support. You may view this 

service information at the FAA, Office 

of the Regional Counsel, Southwest 

Region, 10101 Hillwood Pkwy., Room 

6N–321, Fort Worth, TX 76177. For 

information on the availability of this 

material at the FAA, call (817) 222– 

5110. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA 2021–0619; 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 street address for 

Docket Operations is listed above. 

FOR FURTHER INFORMATION CONTACT: 

David Wilson, Aerospace Engineer, 

DSCO Branch, Compliance & 

Airworthiness Division, FAA, 10101 

Hillwood Pkwy., Fort Worth, TX 76177; 

telephone (817) 222–5786; email 

david.wilson@faa.gov. 

SUPPLEMENTARY INFORMATION: 


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Background 

On July 6, 2021, the FAA issued 

Emergency AD 2021–15–51 (Emergency 

AD 2021–15–51), which requires, before 

further flight, removing from service all 

part number (P/N) 204–012–104–005 

pins with a serial number (S/N) prefix 

‘‘FNFS’’. Emergency AD 2021–15–51 

also prohibits installing the pin on any 

helicopter as of the emergency AD’s 

effective date. The FAA sent Emergency 

AD 2021–15–51 to all known U.S. 

owners and operators of these 

helicopters. 

Emergency AD 2021–15–51 was 

prompted by a fatal accident on a Bell 

Textron Inc. Model 212 helicopter in 

which a pin P/N 204–012–104–005 with 

an S/N prefix ‘‘FNFS’’ sheared off 

during flight, which resulted in the 

main rotor blade and the main rotor 

head detaching from the helicopter. The 

pin had accumulated only 20 total hours 

time-in-service (TIS). An inspection of a 

different Model 212 helicopter revealed 

that another pin installed, and made by 

the same manufacturer and with the 

same S/N prefix, was deformed; this pin 

had accumulated only 29 total hours 

TIS. Failure of the pin could result in 

the main rotor blade detaching from the 

helicopter and subsequent loss of 

control of the helicopter. 

Prior to the FAA issuing Emergency 

AD 2021–15–51, Transport Canada, 

which is the aviation authority for 

Canada, issued Canadian Emergency AD 

CF–2021–23, dated July 5, 2021 

(Transport Canada Emergency AD CF– 

2021–23), to correct an unsafe condition 

for the following Bell Helicopter 

Textron Inc., helicopters: 

• Model 204B helicopters, S/Ns 2001 

through 2070 and 2196 through 2199; 

• Model 205A–1 helicopters, S/Ns 

30001 through 30065, 30067 through 

30165, 30167 through 30187, 30189 

through 30296, and 30298 through 

30332; 

• Model 205B helicopters, S/Ns 

30066, 30166, 30188, and 30297; and 

• Model 212 helicopters, S/Ns 30501 

through 30999, 31101 through 31311, 

32101 through 32142, and 35001 

through 35103. 

Transport Canada advises that during 

an investigation of a Bell Textron Inc., 

Model 212 fatal accident in Canada, it 

was discovered that a pin P/N 204–012– 

104–005 with an S/N prefix ‘‘FNFS’’, 

sheared off during flight, leading to 

detachment of the main rotor blade and 

the main rotor head. The pin had 

accumulated only 20 hours of service, 

and inspection of another Canadian Bell 

Textron Inc., Model 212 helicopter 

found a pin of the same P/N, made by 

the same manufacturer, with the same 

S/N prefix ‘‘FNFS’’, to be deformed after 

only approximately 29 hours in service. 

According to Transport Canada, failure 

of a main rotor hub strap pin will result 

in detachment of the main rotor blade 

and loss of control of the helicopter. 

Transport Canada also advises that, 

although the defective pins were only 

reported on Bell Textron Inc., Model 

212 helicopters, pins of the same P/N 

can also be installed on Bell Textron 

Inc., Model 204B, 205A–1, and 205B 

helicopters. While the cause of failure 

has not been determined, as a 

precautionary measure and to address 

the risk of detachment of main rotor hub 

strap pins in flight, Bell has issued Alert 

Service Bulletins to require replacing all 

pins with P/N 204–012–104–005 that 

have S/N prefix ‘‘FNFS’’. Accordingly, 

Transport Canada Emergency AD CF– 

2021–23 mandates replacement of 

affected pins. Transport Canada 

considers its emergency AD an interim 

action and states that further AD action 

may follow. 

FAA’s Determination 

The FAA is issuing this AD after 

evaluating all the relevant information 

and determining that the unsafe 

condition described previously is likely 

to exist or develop in other products of 

these same type designs. 

Related Service Information 

The FAA reviewed the following Bell 

Alert Service Bulletins (ASBs), each 

dated July 5, 2021: 

• ASB 204B–21–74 for Bell Textron 

Inc., Model 204B helicopters, S/Ns 2001 

through 2070 and 2196 through 2199; 

• ASB 205–21–117 for Bell Textron 

Inc., Model 205A and 205A–1 

helicopters, S/Ns 30001 through 30065, 

30067 through 30165, 30167 through 

30187, 30189 through 30296, and 30298 

through 30332; 

• ASB 205B–21–71 for Bell Textron 

Inc., Model 205B helicopters, S/ 

Ns30066, 30166, 30188 and 30297; and 

• ASB 212–21–165 for Bell Textron 

Inc., Model 212 helicopters, S/Ns 30501 

through 30999, 31101 through 31311, 

32101 through 32142, and 35001 

through 35103. 

The ASBs specify removing all P/N 

204–012–104–005 pins with an S/N 

prefix ‘‘FNFS’’ before further flight. The 

ASBs also specify that, although the 

investigation is still in progress, 

removing these pins from service is 

required. The ASBs state that these pins 

may not have been manufactured in 

accordance with the engineering design 

requirements and may therefore shear as 

a result of this nonconformance. 

AD Requirements 

This AD requires removing from 

service all P/N 204–012–104–005 pins 

with an S/N prefix ‘‘FNFS’’ before 

further flight. This AD also prohibits 

installing this pin on any helicopter as 

of the effective date of this AD. 

Interim Action 

The FAA considers this AD to be an 

interim action. If final action is later 

identified, the FAA might consider 

further rulemaking. 

Justification for Immediate Adoption 

and Determination of the Effective Date 

Section 553(b)(3)(B) of the 

Administrative Procedure Act (APA) (5 

U.S.C. 551 et seq.) authorizes agencies 

to dispense with notice and comment 

procedures for rules when the agency, 

for ‘‘good cause,’’ finds that those 

procedures are ‘‘impracticable, 

unnecessary, or contrary to the public 

interest.’’ Under this section, an agency, 

upon finding good cause, may issue a 

final rule without providing notice and 

seeking comment prior to issuance. 

Further, section 553(d) of the APA 

authorizes agencies to make rules 

effective in less than thirty days, upon 

a finding of good cause. 

An unsafe condition exists that 

required the immediate adoption of 

Emergency AD 2021–15–51, issued on 

July 6, 2021, to all known U.S. owners 

and operators of these helicopters. The 

FAA found that the risk to the flying 

public justified waiving notice and 

comment prior to adoption of this rule 

because an urgent unsafe condition 

existed and corrective action was 

required before further flight. This 

condition still exists, therefore, notice 

and opportunity for prior public 

comment are impracticable and contrary 

to the public interest pursuant to 5 

U.S.C. 553(b)(3)(B). 

In addition, the FAA finds that good 

cause exists pursuant to 5 U.S.C. 553(d) 

for making this amendment effective in 

less than 30 days, for the same reasons 

the FAA found good cause to forego 

notice and comment. 

Comments Invited 

The FAA invites you to send any 

written data, views, or arguments about 

this final rule. Send your comments to 

an address listed under ADDRESSES. 

Include the docket number FAA 2021– 

0619 and Project Identifier AD–2021– 

00789–R at the beginning of your 

comments. The most helpful comments 

reference a specific portion of the final 

rule, explain the reason for any 

recommended change, and include 

supporting data. The FAA will consider 

all comments received by the closing 


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date and may amend this final rule 

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 final rule. 

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 AD 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 AD, 

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 AD. Submissions containing CBI 

should be sent to David Wilson, 

Aerospace Engineer, DSCO Branch, 

Compliance & Airworthiness Division, 

FAA, 10101 Hillwood Pkwy., Fort 

Worth, TX 76177; telephone (817) 222– 

5786; email david.wilson@faa.gov. Any 

commentary that the FAA receives 

which is not specifically designated as 

CBI will be placed in the public docket 

for this rulemaking. 

Regulatory Flexibility Act 

The requirements of the Regulatory 

Flexibility Act (RFA) do not apply when 

an agency finds good cause pursuant to 

5 U.S.C. 553 to adopt a rule without 

prior notice and comment. Because the 

FAA has determined that it has good 

cause to adopt this rule without prior 

notice and comment, RFA analysis is 

not required. 

Costs of Compliance 

The FAA estimates that this AD 

affects 160 helicopters of U.S. registry. 

Labor rates are estimated at $85 per 

work-hour. Based on these numbers, the 

FAA estimates the following costs to 

comply with this AD. 

Replacing up to four pins takes about 

20 work-hours and parts cost about 

$1,756 for four pins for an estimated 

cost of up to $3,456 per helicopter. 

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, 

and 

(2) Will not affect intrastate aviation 

in Alaska. 

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 

■ 1. The authority citation for part 39 

continues to read as follows: 

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

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive: 

2021–15–51 Bell Textron Inc. (Type 

Certificate Previously Held by Bell 

Helicopter Textron Inc.): Amendment 

39–21678; Docket No. FAA 2021–0619; 

Project Identifier AD–2021–00789–R. 

(a) Effective Date 

This airworthiness directive (AD) is 

effective without actual notice on August 24, 

2021. Emergency AD 2021–15–51, issued on 

July 6, 2021, which contained the 

requirements of this amendment, was 

effective with actual notice. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to Bell Textron Inc. (type 

certificate previously held by Bell Helicopter 

Textron Inc.) Model 204B, 205A, 205A–1, 

205B, and 212 helicopters, certificated in any 

category, with an outboard main rotor hub 

strap pin (pin) part number 204–012–104– 

005 with a serial number prefix ‘‘FNFS’’ 

installed. 

(d) Subject 

Joint Aircraft System Component (JASC) 

Code/Air Transport Association (ATA) of 

America Code: 6200, Main rotor system. 

(e) Unsafe Condition 

This AD was prompted by a fatal accident 

in which a pin sheared off during flight, 

resulting in the main rotor blade and the 

main rotor head detaching from the 

helicopter. The FAA is issuing this AD to 

address this unsafe condition and prevent 

loss of control of the helicopter. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Required Actions 

(1) Before further flight, remove from 

service any pin that is identified in paragraph 

(c) of this AD. 

(2) As of the effective date of this AD, do 

not install any pin that is identified in 

paragraph (c) of this AD on any helicopter. 

(h) Special Flight Permits 

Special flight permits are prohibited. 

(i) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, DSCO 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 in paragraph (j)(1) of this AD. 

Information may be emailed to: 9-ASW-190- 

COS@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 

(1) For more information about this AD, 

contact David Wilson, Aerospace Engineer, 

DSCO Branch, Compliance & Airworthiness 

Division, FAA, 10101 Hillwood Pkwy., Fort 


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Worth, TX 76177; telephone (817) 222–5786; 

email david.wilson@faa.gov. 

(2) The subject of this AD is addressed in 

Transport Canada Emergency AD CF–2021– 

23, dated July 5, 2021. 

Issued on July 30, 2021. 

Ross Landes, 

Deputy Director for Regulatory Operations, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–17024 Filed 8–5–21; 4:15 pm] 

BILLING CODE 4910–13–P 

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. 

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 inservice 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. 


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