Document ID: FAA-2021-1168-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: The Boeing Company Airplanes
Posted Date: 2022-02-23T05:00Z

[Federal Register Volume 87, Number 36 (Wednesday, February 23, 2022)]
[Proposed Rules]
[Pages 10110-10112]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-03804]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-1168; Project Identifier AD-2021-00825-T]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

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 certain The Boeing Company Model 737-8 airplanes. This proposed AD 
was prompted by a report that, during production, a small number of 
fasteners in certain locations of the center fuel tank were cap sealed 
on top of a black stripe of ink with a clear overcoat. This clear 
overcoat is not an approved surface for sealing and can potentially 
compromise sealant adhesion. Compromised sealant adhesion can, over 
time, affect the lightning-protection properties of the airplane. This 
proposed AD would require preparation of the affected surface areas to 
ensure that there is adequate sealant adhesion, and complete 
encapsulation of the discrepant fastener locations with the approved 
production sealant. 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 April 11, 
2022.

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 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. It is also available at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-
1168.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-1168; 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: Chris Baker, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3552; 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-2021-1168; Project Identifier 
AD-2021-00825-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 
this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other

[[Page 10111]]

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 Chris 
Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3552; email: [email protected]. 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 has received a report that, during production, a small 
number of fasteners common to upper wing panel stringers U-S1, U-S10, 
U-S12, U-S20, and U-S21 and lower wing panel stringer L-S14 were cap 
sealed on top of a black stripe of ink with a clear overcoat. The black 
stripe and clear overcoat were applied during airplane assembly to 
certain interior areas of the center fuel tank to ensure proper 
alignment of components, and this discrepancy was not identified by 
Boeing prior to the delivery of certain airplanes. The purpose of cap 
sealing is to provide a secondary layer of lightning protection to the 
metal-to-metal rivet installation bond, however, the clear overcoat is 
not an approved surface for sealing and can compromise sealant 
adhesion. Compromised sealant adhesion can, over time, affect the 
lightning-protection properties of the airplane. This condition, if not 
addressed, could result in ignition of fuel vapors and subsequent 
explosion of the fuel tank in the event of a lightning strike. The FAA 
expects, however, that the degree to which sealant adhesion is 
compromised under these circumstances, and therefore the risk, will 
initially be small, and increase gradually over a period of years as 
the adhesion begins to deteriorate. Additionally, the compliance time 
would allow operators to align this work with the typical schedule for 
maintenance into the airplane's fuel tank, which rarely exceeds once 
every ten years. Therefore, based on the evaluated risk, the FAA has 
determined that the related actions need to be completed within the 
timeframes identified in paragraph (g) of this proposed AD and in the 
manufacturer's 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 Special Attention Requirements Bulletin 
737-57-1352 RB, dated February 1, 2021. This service information 
specifies procedures for preparing the surface and completely 
encapsulating the black stripe of ink, the clear overcoat, and the 
existing sealant with the approved production (BMS5-45) sealant at 
upper stringer U-S1, U-S10, U-S12, U-S20, and U-S21, and lower stringer 
L-S14. The affected areas are all located on the portion of the 
stringers just outboard of the wing box.
    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 accomplishing the actions specified 
in the service information already described, 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-2021-1168.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 11 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
----------------------------------------------------------------------------------------------------------------
Apply Sealant.....................  106 work-hours x $85 per             $500           $9,510         $104,610
                                     hour = $9,010.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all 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

[[Page 10112]]

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:

The Boeing Company: Docket No. FAA-2021-1168; Project Identifier AD-
2021-00825-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by April 11, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-8 airplanes, 
certificated in any category, as identified in Boeing Special 
Attention Requirements Bulletin 737-57-1352 RB, dated February 1, 
2021.

(d) Subject

    Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report that, during production, a 
small number of fasteners in certain locations of the center fuel 
tank were cap sealed on top of a black stripe of ink with a clear 
overcoat. This clear overcoat is not an approved surface for sealing 
and can potentially compromise sealant adhesion. Compromised sealant 
adhesion can, over time, affect the lightning-protection properties 
of the airplane. The FAA is issuing this AD to address compromised 
sealant adhesion within the center fuel tank, which, if not 
addressed, could result in ignition of fuel vapors and subsequent 
explosion of the fuel tank in the event of a lightning strike.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Within 10 years after the date of issuance of the original 
airworthiness certificate or the original export certificate of 
airworthiness, do all applicable actions identified in, and in 
accordance with, the Accomplishment Instructions of Boeing Special 
Attention Requirements Bulletin 737-57-1352 RB, dated February 1, 
2021.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Special Attention Service 
Bulletin 737-57-1352, dated February 1, 2021, which is referred to 
in Boeing Special Attention Requirements Bulletin 737-57-1352 RB, 
dated February 1, 2021.

(h) 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: [email protected].
    (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.

(i) Related Information

    (1) For more information about this AD, contact Chris Baker, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3552; email: [email protected].
    (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 December 21, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2022-03804 Filed 2-22-22; 8:45 am]
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