47260 Federal Register / Vol. 86, No. 161 / Tuesday, August 24, 2021 / Proposed Rules 

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 

■ 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: 

De Havilland Aircraft of Canada Limited 

(Type Certificate Previously Held by 

Bombardier, Inc.): Docket No. FAA– 

2021–0694; Project Identifier MCAI– 

2021–00305–T. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) by October 8, 

2021. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to De Havilland Aircraft 

of Canada Limited Model DHC–8–401 and 

–402 airplanes, certificated in any category, 

serial numbers 4001 and 4003 through 4628 

inclusive. 

(d) Subject 

Air Transport Association (ATA) of 

America Code 57, Wings. 

(e) Unsafe Condition 

This AD was prompted by reports of a 

possible hard contact between the #2 top 

high level sensor (HLS) terminal screw head 

and the #6 outer wing fuel access panel 

stiffener flange. The FAA is issuing this AD 

to address the possibility of electrical arcing 

during a lightning strike, which could be a 

source of ignition inside the fuel tank. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Required Actions 

Within 8,000 flight hours after the effective 

date of this AD: Do the actions specified in 

paragraph (g)(1) or (2) of this AD. 

(1) Replace the #6 outer wing fuel access 

panel assembly in accordance with Section 

3.B., Part A, of the Accomplishment 

Instructions of De Havilland Aircraft of 

Canada Limited Service Bulletin 84–57–35, 

Revision A, dated February 11, 2021. 

(2) Rework the #6 outer wing fuel access 

panel assembly, including an eddy current or 

fluorescent liquid penetrant inspection for 

crack indications of the rework area, in 

accordance with Section 3.B., Part B, of the 

Accomplishment Instructions of De 

Havilland Aircraft of Canada Limited Service 

Bulletin 84–57–35, Revision A, dated 

February 11, 2021. If any crack indication is 

found, before further flight, repair using a 

method approved in accordance with the 

procedures specified in paragraph (j)(2) of 

this AD. 

(h) Parts Installation Prohibition 

As of the effective date of this AD, no 

person may install a #6 outer wing fuel 

access panel assembly, part numbers (P/Ns) 

85714233–003/–004 and 85714233–005/– 

006, on any airplane. 

(i) Credit for Previous Actions 

This paragraph provides credit for actions 

required by paragraph (g) of this AD, if those 

actions were performed before the effective 

date of this AD using De Havilland Aircraft 

of Canada Limited Service Bulletin 84–57– 

35, dated October 1, 2020. 

(j) Other FAA AD Provisions 

The following provisions also apply to this 

AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York 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 ATTN: Program Manager, 

Continuing Operational Safety, FAA, New 

York ACO Branch, 1600 Stewart Avenue, 

Suite 410, Westbury, NY 11590; telephone 

516–228–7300; fax 516–794–5531. Before 

using any approved AMOC, notify your 

appropriate principal inspector, or lacking a 

principal inspector, the manager of the 

responsible Flight Standards Office. 

(2) Contacting the Manufacturer: For any 

requirement in this AD to obtain instructions 

from a manufacturer, the instructions must 

be accomplished using a method approved 

by the Manager, New York ACO Branch, 

FAA; or Transport Canada Civil Aviation 

(TCCA); or De Havilland Aircraft of Canada 

Limited’s TCCA Design Approval 

Organization (DAO). If approved by the DAO, 

the approval must include the DAOauthorized signature. 

(k) Related Information 

(1) Refer to Mandatory Continuing 

Airworthiness Information (MCAI) TCCA AD 

CF–2021–08, dated March 9, 2021, for related 

information. This MCAI may be found in the 

AD docket on the internet at https://

www.regulations.gov by searching for and 

locating Docket No. FAA–2021–0694. 

(2) For more information about this AD, 

contact Thomas Niczky, Aerospace Engineer, 

Avionics and Electrical Systems Section, 

FAA, New York ACO Branch, 1600 Stewart 

Avenue, Suite 410, Westbury, NY 11590; 

telephone 516–228–7347; fax 516–794–5531; 

email 9-avs-nyaco-cos@faa.gov. 

(3) For service information identified in 

this AD, contact De Havilland Aircraft of 

Canada Limited, Q-Series Technical Help 

Desk, 123 Garratt Boulevard, Toronto, 

Ontario M3K 1Y5, Canada; telephone 416– 

375–4000; fax 416–375–4539; email thd@

dehavilland.com; internet https://

dehavilland.com. You may view this service 

information at the FAA, Airworthiness 

Products Section, Operational Safety Branch, 

2200 South 216th St., Des Moines, WA. For 

information on the availability of this 

material at the FAA, call 206–231–3195. 

Issued on August 18, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–18111 Filed 8–23–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0665; Project 

Identifier AD–2021–00270–T] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede Airworthiness Directive (AD) 

2017–23–02, which applies to certain 

The Boeing Company Model 737–200, 

–200C, –300, –400, and –500 series 

airplanes. AD 2017–23–02 requires 


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repetitive inspections, replacement, and 

applicable on-condition actions for 

certain fuselage crown skin panels. 

Since the FAA issued AD 2017–23–02, 

certain airplane configurations and 

inspection locations have been revised 

and additional airplanes have been 

determined to be subject to the unsafe 

condition. This proposed AD would 

retain the actions in AD 2017–23–02, 

revise certain airplane configurations 

and inspection locations, and add 

airplanes to the applicability. 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 October 8, 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 Boeing Commercial 

Airplanes, Attention: Contractual & Data 

Services (C&DS), 2600 Westminster 

Blvd., MC 110–SK57, Seal Beach, CA 

90740–5600; telephone 562–797–1717; 

internet https://

www.myboeingfleet.com. You may view 

this service information at the FAA, 

Airworthiness Products Section, 

Operational Safety Branch, 2200 South 

216th St., Des Moines, WA. For 

information on the availability of this 

material at the FAA, call 206–231–3195. 

It is also available at https://

www.regulations.gov by searching for 

and locating Docket No. FAA–2021– 

0665. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0665; 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: 

James Guo, Aerospace Engineer, 

Airframe Section, FAA, Los Angeles 

ACO Branch, 3960 Paramount 

Boulevard, Lakewood, CA 90712–4137; 

phone: 562–627–5357; fax: 562–627– 

5210; email: james.guo@faa.gov. 

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–2021–0665; Project Identifier AD– 

2021–00270–T’’ 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 the 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 proposed 

AD. 

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 James Guo, Aerospace 

Engineer, Airframe Section, FAA, Los 

Angeles ACO Branch, 3960 Paramount 

Boulevard, Lakewood, CA 90712–4137; 

phone: 562–627–5357; fax: 562–627– 

5210; email: james.guo@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. 

Background 

Fatigue damage can occur locally, in 

small areas or structural design details, 

or globally, in widespread areas. 

Multiple-site damage is widespread 

damage that occurs in a large structural 

element such as a single rivet line of a 

lap splice joining two large skin panels. 

Widespread damage can also occur in 

multiple elements such as adjacent 

frames or stringers. Multiple-site 

damage and multiple-element damage 

cracks are typically too small initially to 

be reliably detected with normal 

inspection methods. Without 

intervention, these cracks will grow, 

and eventually compromise the 

structural integrity of the airplane. This 

condition is known as widespread 

fatigue damage (WFD). It is associated 

with general degradation of large areas 

of structure with similar structural 

details and stress levels. As an airplane 

ages, WFD will likely occur, and will 

certainly occur if the airplane is 

operated long enough without any 

intervention. 

An FAA final rule (‘‘Aging Airplane 

Program: Widespread Fatigue Damage;’’ 

75 FR 69746, November 15, 2010) 

became effective on January 14, 2011, 

and amended 14 CFR parts 25, 26, 121, 

and 129 (commonly known as the WFD 

rule). The WFD rule requires certain 

actions to prevent structural failure due 

to WFD throughout the operational life 

of certain existing transport category 

airplanes and all of these airplanes that 

will be certificated in the future. Design 

approval holders (DAHs) of existing and 

future airplanes subject to the WFD rule 

are required to establish a limit of 

validity (LOV) of the engineering data 

that support the structural maintenance 

program. Operators affected by the WFD 

rule may not fly an airplane beyond its 

LOV, unless an extended LOV is 

approved. 

The WFD rule does not require 

identifying and developing maintenance 

actions if the DAHs can show that such 

actions are not necessary to prevent 

WFD before the airplane reaches the 

LOV. Many LOVs, however, do depend 

on accomplishment of future 

maintenance actions. As stated in the 

WFD rule, any maintenance actions 

necessary to reach the LOV will be 

mandated by airworthiness directives 

through separate rulemaking actions. 

In the context of WFD, this action is 

necessary to enable DAHs to propose 

LOVs that allow operators the longest 

operational lives for their airplanes, and 

still ensure that WFD will not occur. 

This approach allows for an 

implementation strategy that provides 

flexibility to DAHs in determining the 

timing of service information 

development (with FAA approval), 

while providing operators with certainty 


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47262 Federal Register / Vol. 86, No. 161 / Tuesday, August 24, 2021 / Proposed Rules 

regarding the LOV applicable to their 

airplanes. 

The FAA issued AD 2017–23–02, 

Amendment 39–19096 (82 FR 52835, 

November 15, 2017) (AD 2017–23–02), 

for certain The Boeing Company Model 

737–200, –200C, –300, –400, and –500 

series airplanes. AD 2017–23–02 was 

prompted by an evaluation by the DAH 

indicating that the fuselage crown skin 

panels are subject to WFD. AD 2017– 

23–02 requires repetitive inspections, 

replacement, and applicable oncondition actions for certain fuselage 

crown skin panels. The agency issued 

AD 2017–23–02 to address cracking in 

the fuselage crown skin panels. Multiple 

adjacent cracks in the fuselage crown 

skin could link up and lead to 

decompression or loss of structural 

integrity of the airplane. 

Actions Since AD 2017–23–02 Was 

Issued 

Since the FAA issued AD 2017–23– 

02, errors were found in Boeing Alert 

Service Bulletin 737–53A1358, dated 

April 27, 2017, which is referenced in 

AD 2017–23–02. These errors include 

airplanes that are incorrectly identified 

as being in certain groups, and 

inspection figures that show incorrect 

chem-mill locations. Additional 

airplanes were also identified as being 

subject to the unsafe condition. These 

errors affect operators’ ability to comply 

with AD 2017–23–02, and the FAA 

determined that a supersedure was 

needed to require corrected service 

information. 

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 Boeing Alert 

Service Bulletin 737–53A1358, Revision 

1, dated February 26, 2021. This service 

information specifies procedures for 

repetitive non-destructive inspections 

for cracking, replacement of certain 

fuselage crown skin panels, and 

applicable on-condition actions. Oncondition actions include a general 

visual inspection of certain repairs for 

any loose or missing fasteners, a low 

frequency eddy current (LFEC) 

inspection of certain repairs for 

cracking, and repair. 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 the ADDRESSES section. 

Proposed AD Requirements in This 

NPRM 

Although this proposed AD does not 

explicitly restate the requirements of AD 

2017–23–02, this AD would retain all of 

the requirements of AD 2017–23–02. 

Those requirements are referenced in 

the service information identified 

previously, which, in turn, is referenced 

in paragraph (h) of this proposed AD. 

This proposed AD would revise certain 

airplane configurations and inspection 

locations, and add airplanes to the 

applicability. This proposed AD would 

also require accomplishment of the 

actions identified as ‘‘RC’’ (required for 

compliance) in the Accomplishment 

Instructions of Boeing Alert Service 

Bulletin 737–53A1358, Revision 1, 

dated February 26, 2021, described 

previously, except for any differences 

identified as exceptions in the 

regulatory text of this proposed AD. 

For information on the procedures 

and compliance times, see this service 

information at https://

www.regulations.gov by searching for 

and locating Docket No. FAA–2021– 

0665. 

Explanation of Proposed Compliance 

Time 

The compliance time for the 

replacement specified in this proposed 

AD for addressing WFD was established 

to ensure that discrepant structure is 

replaced before WFD develops in 

airplanes. Standard inspection 

techniques cannot be relied on to detect 

WFD before it becomes a hazard to 

flight. The FAA will not grant any 

extensions of the compliance time to 

complete any AD-mandated service 

bulletin related to WFD without 

extensive new data that would 

substantiate and clearly warrant such an 

extension. 

Explanation of Proposed Applicability 

Model 737 airplanes having line 

numbers 1 through 291 have an LOV of 

34,000 total flight cycles, and the 

actions proposed in this NPRM, as 

specified in Boeing Alert Service 

Bulletin 737–53A1358, Revision 1, 

dated February 26, 2021, would be 

required at a compliance time occurring 

after that LOV. Although operation of an 

airplane beyond its LOV is prohibited 

by 14 CFR 121.1115 and 129.115, this 

NPRM would include those airplanes in 

the applicability so that these airplanes 

are tracked in the event the LOV is 

extended in the future. 

Costs of Compliance 

The FAA estimates that this AD, if 

adopted as proposed, would affect 143 

airplanes of U.S. registry. The FAA 

estimates the following costs to comply 

with this proposed AD: 

ESTIMATED COSTS

Action Labor cost Parts cost Cost per 

product Cost on U.S. operators 

Inspection ...................... Up to 507 work-hours × $85 per hour = Up to 

$43,095 per inspection cycle.

$0 Up to $43,095 per inspection cycle.Up to $6,162,585 per 

inspection cycle. 

Replacement ................. 304 work-hours × $85 per hour = $25,840 per 

skin panel.

95,000 $120,840 per skin 

panel.

$17,280,120 per skin 

panel. 

The FAA estimates the following 

costs to do any necessary inspections 

that would be required based on the 

results of the proposed inspection. The 

FAA has no way of determining the 

number of aircraft that might need these 

inspections: 

ON-CONDITION COSTS

Action Labor cost Parts cost Cost per 

product 

LFEC inspection ........................................................... 1 work-hours × $85 per hour = $85 ............................. $0 $85 


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Federal Register / Vol. 86, No. 161 / Tuesday, August 24, 2021 / Proposed Rules 47263 

ON-CONDITION COSTS—Continued 

Action Labor cost Parts cost Cost per 

product 

General visual inspection ............................................. 1 work-hour × $85 per hour = $85 ............................... 0 85 

The FAA has received no definitive 

data on which to base the cost estimates 

for the on-condition repairs specified in 

this proposed AD. 

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 has 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 that the 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 

■ 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: 

■ a. Removing Airworthiness Directive 

(AD) 2017–23–02, Amendment 39– 

19096 (82 FR 52835, November 15, 

2017), and 

■ b. Adding the following new AD: 

The Boeing Company: Docket No. FAA– 

2021–0665; Project Identifier AD–2021– 

00270–T. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) action by 

October 8, 2021. 

(b) Affected ADs 

This AD replaces AD 2017–23–02, 

Amendment 39–19096 (82 FR 52835, 

November 15, 2017) (AD 2017–23–02). 

(c) Applicability 

This AD applies to The Boeing Company 

Model 737–100, –200, –200C, –300, –400, 

and –500 series airplanes, certificated in any 

category, as identified in Boeing Alert 

Service Bulletin 737–53A1358, Revision 1, 

dated February 26, 2021. 

(d) Subject 

Air Transport Association (ATA) of 

America Code 53, Fuselage. 

(e) Unsafe Condition 

This AD was prompted by an evaluation by 

the design approval holder indicating that 

the fuselage crown skin panels are subject to 

widespread fatigue damage. This AD was 

also prompted by a determination that 

certain airplane configurations and 

inspection locations need to be revised, and 

that additional airplanes are subject to the 

unsafe condition. The FAA is issuing this AD 

to address cracking in the fuselage crown 

skin panels. Multiple adjacent cracks in the 

fuselage crown skin could link up and lead 

to decompression or loss of structural 

integrity of the airplane. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Actions for Group 43 Airplanes 

For airplanes identified as Group 43 in 

Boeing Alert Service Bulletin 737–53A1358, 

Revision 1, dated February 26, 2021, within 

120 days after the effective date of this AD, 

inspect the airplane and do all applicable oncondition actions using a method approved 

in accordance with the procedures specified 

in paragraph (j) of this AD 

(h) Required Actions for Groups 1 Through 

42 Airplanes 

For airplanes identified as Groups 1 

through 42 in Boeing Alert Service Bulletin 

737–53A1358, Revision 1, dated February 26, 

2021, except as specified by paragraph (i) of 

this AD: At the applicable times specified in 

paragraph 1.E., ‘‘Compliance,’’ of Boeing 

Alert Service Bulletin 737–53A1358, 

Revision 1, dated February 26, 2021, do all 

applicable actions identified as ‘‘RC’’ 

(required for compliance) in, and in 

accordance with, the Accomplishment 

Instructions of Boeing Alert Service Bulletin 

737–53A1358, Revision 1, dated February 26, 

2021. Actions identified as terminating 

action in Boeing Alert Service Bulletin 737– 

53A1358, Revision 1, dated February 26, 

2021, terminate the applicable required 

actions of this AD, provided the terminating 

action is done in accordance with the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 737–53A1358, Revision 1, 

dated February 26, 2021. 

(i) Exceptions to Service Information 

Specifications 

(1) Where Boeing Alert Service Bulletin 

737–53A1358, Revision 1, dated February 26, 

2021, uses the phrase ‘‘the original issue date 

of this service bulletin,’’ this AD requires 

using ‘‘December 20, 2017’’ (the effective 

date of AD 2017–23–02). 

(2) Where Boeing Alert Service Bulletin 

737–53A1358, Revision 1, dated February 26, 

2021, specifies contacting Boeing for repair 

instructions or for work instructions, this AD 

requires doing the repair, or doing the work 

instructions and applicable on-condition 

actions using a method approved in 

accordance with the procedures specified in 

paragraph (j) of this AD. 

(3) Part 7 of Boeing Alert Service Bulletin 

737–53A1358, Revision 1, dated February 26, 

2021, specifies post-modification 

airworthiness limitation inspections in 

compliance with 14 CFR 25.571(a)(3) at the 

modified locations to support compliance 

with 14 CFR 121.1109(c)(2) or 129.109(b)(2). 

Although Part 7 is identified as RC, this AD 

does not require accomplishment of Part 7. 

As airworthiness limitations, these 

inspections are required by maintenance and 

operational rules. It is, therefore, unnecessary 

to mandate them in this AD. Deviations from 

these inspections require FAA approval, but 

do not require an alternative method of 

compliance. 


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(j) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Los Angeles 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-ANMLAACO-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, Los Angeles 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. 

(4) AMOCs approved for AD 2017–23–02 

are approved as AMOCs for the 

corresponding provisions of Boeing Alert 

Service Bulletin 737–53A1358, Revision 1, 

dated February 26, 2021, that are required by 

paragraph (h) of this AD. 

(5) Except as specified by paragraph (i)(2) 

of this AD: For service information that 

contains steps that are labeled as Required 

for Compliance (RC), the provisions of 

paragraphs (j)(5)(i) and (ii) of this AD apply. 

(i) The steps labeled as RC, including 

substeps under an RC step and any figures 

identified in an RC step, must be done to 

comply with the AD. If a step or substep is 

labeled ‘‘RC Exempt,’’ then the RC 

requirement is removed from that step or 

substep. An AMOC is required for any 

deviations to RC steps, including substeps 

and identified figures. 

(ii) Steps not labeled as RC may be 

deviated from using accepted methods in 

accordance with the operator’s maintenance 

or inspection program without obtaining 

approval of an AMOC, provided the RC steps, 

including substeps and identified figures, can 

still be done as specified, and the airplane 

can be put back in an airworthy condition. 

(k) Related Information 

(1) For more information about this AD, 

contact James Guo, Aerospace Engineer, 

Airframe Section, FAA, Los Angeles ACO 

Branch, 3960 Paramount Boulevard, 

Lakewood, CA 90712–4137; phone: 562–627– 

5357; fax: 562–627–5210; email: james.guo@

faa.gov. 

(2) For service information identified in 

this AD, contact Boeing Commercial 

Airplanes, Attention: Contractual & Data 

Services (C&DS), 2600 Westminster Blvd., 

MC 110–SK57, Seal Beach, CA 90740–5600; 

telephone 562–797–1717; internet https://

www.myboeingfleet.com. You may view this 

referenced service information at the FAA, 

Airworthiness Products Section, Operational 

Safety Branch, 2200 South 216th St., Des 

Moines, WA. For information on the 

availability of this material at the FAA, call 

206–231–3195. 

Issued on August 7, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division,Aircraft 

Certification Service. 

[FR Doc. 2021–18068 Filed 8–23–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0699; Project 

Identifier AD–2020–01685–E] 

RIN 2120–AA64 

Airworthiness Directives; General 

Electric Company Turbofan Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for 

certain General Electric Company (GE) 

CF34–10E model turbofan engines. This 

proposed AD was prompted by a 

manufacturer investigation that revealed 

Teflon material in the A-sump oil 

strainer (strainer assembly) screen after 

several reports of in-flight shutdowns 

(IFSDs) and unscheduled engine 

removals (UERs). This proposed AD 

would require initial and repetitive 

visual inspections of the strainer 

assembly screen. As a terminating 

action to the initial and repetitive visual 

inspections, this proposed AD would 

require the replacement of the stationary 

oil seal at the No. 1 forward bearing. 

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 October 8, 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, GE Aviation, Room 285, 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. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0699; 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: 

Scott Stevenson, Aviation Safety 

Engineer, ECO Branch, FAA, 1200 

District Avenue, Burlington, MA 01803; 

phone: (781) 238–7132; fax: (781) 238– 

7199; email: Scott.M.Stevenson@faa.gov. 

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–2021–0699; Project Identifier AD– 

2020–01685–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 


lotter on DSK11XQN23PROD with PROPOSALS1