[Federal Register Volume 86, Number 210 (Wednesday, November 3, 2021)]
[Rules and Regulations]
[Pages 60563-60565]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-23935]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1166; Project Identifier AD-2020-00906-T; 
Amendment 39-21737; AD 2021-19-19]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain The Boeing Company Model 737-9 airplanes. This AD was prompted 
by a report of missing sealant on the left and right wing leading edge 
outboard blowout door. This AD requires doing a fluid seal contact 
inspection and a detailed inspection for missing sealant on each 
blowout door and applying sealant if necessary. The FAA is issuing this 
AD to address the unsafe condition on these products.

DATES: This AD is effective December 8, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of December 8, 
2021.

ADDRESSES: For service information identified in this final rule, 
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-2020-1166.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2020-1166; 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: 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:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to The Boeing Company 
Model 737-9 airplanes having line numbers 6834, 6852, 6872, 6899, 6917, 
6935, 7096, 7173, 7196, 7201, 7208, 7216, 7246, 7253, 7261, 7268, 7306, 
7316, 7338, 7348, 7361, 7384, 7388, 7394, and 7428. The NPRM published 
in the Federal Register on January 21, 2021 (86 FR 6269). The NPRM was 
prompted by a report indicating that the application of sealant on the 
left wing and right wing leading edge outboard blowout door was missed 
during the airplane manufacturing process on some Model 737-9 
airplanes. In the NPRM, the FAA proposed to require doing a fluid seal 
contact inspection and a detailed inspection for missing sealant on 
each blowout door and applying sealant if necessary. The FAA is issuing 
this AD to address the missing sealant, which is intended to act as a 
fuel barrier. In the presence of a substantial fuel leak from the wing 
box, the unintended drain path could allow fuel to come into contact 
with the engine. This condition, if not addressed, could lead to a 
large ground fire.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from The Air Line Pilots Association, 
International (ALPA), Boeing, and an individual, who all stated that 
they supported the NPRM without change. The FAA also received comments 
from United Airlines (UAL) and two individuals. The following 
discussion presents those comments and the FAA's response.

Request To Use Alternative Products

    UAL suggested that the FAA work with Boeing on identifying 
acceptable alternatives to the developer specified in the service 
information. UAL stated that during initial accomplishment of the 
inspection there were difficulties sourcing the specified developer due 
to the requirement in Boeing Alert Requirements Bulletin 737-57A1350 RB 
to use the bulk material and not the aerosol spray. UAL stated it was 
ultimately able to procure the required bulk material.
    The FAA disagrees with the request to change the AD to allow the 
use of alternative developers. Use of the bulk developer identified in 
Boeing Alert Requirements Bulletin 737-57A1350 RB, dated April 23, 
2020, is needed for effective inspection. The aerosol spray form of the 
developer penetrates more aggressively than the bulk form, so it could 
cause existing sealants to swell. The use of bulk material avoids the 
potential for false readings of the gasket contact verification to be 
caused by sealant swelling.
    The commenter also did not identify any alternative developers in 
either bulk or aerosol spray that would be an acceptable alternative to 
the developer identified in Boeing Alert Requirements Bulletin 737-
57A1350 RB, dated April 23, 2020. However, operators may submit an 
alternative method of compliance (AMOC) request using the procedures 
specified in paragraph (i) of this AD; the request should include data 
that substantiates the alternative developer will ensure an effective 
inspection to determine if additional sealant is required. The FAA has 
not changed this AD as a result of this comment.

Request for Information on the Approval Process for Alternative 
Materials

    Two individuals asked about the approval process for alternative 
suitable materials (sealant) and procedures. In addition, the 
individuals questioned the role of the Boeing Company Organization 
Designation Authorization (ODA) in the approval process.
    In order to receive an AMOC to use an alternate sealant, the AMOC 
request would need to show that the alternate sealant meets or exceeds 
the performance or characteristics of the

[[Page 60564]]

current sealant that is identified in Boeing Alert Requirements 
Bulletin 737-57A1350 RB, dated April 23, 2020. While paragraph (i) of 
this AD indicates that AMOC authority may be delegated to the Boeing 
ODA, the ODA would still need to request that authority from the FAA 
and should include justification for why the authority should be 
granted. The FAA will then make the determination whether the ODA may 
grant AMOCs for this specific AD.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD. 
Except for minor editorial changes, this AD is adopted as proposed in 
the NPRM.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-57A1350 RB, 
dated April 23, 2020. The service information specifies procedures for 
doing a fluid seal contact inspection and a detailed inspection of the 
left and right wing leading edge outboard blowout door, at the inboard 
and outboard ends of the hinge, for missing sealant and applying 
sealant, if necessary. 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.

Costs of Compliance

    The FAA estimates that this AD affects 14 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Inspections...........................  4 work-hours x $85 per                $0            $340          $4,760
                                         hour = $340.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary repairs 
that would be required based on the results of the inspections. The FAA 
has no way of determining the number of aircraft that might need these 
on-condition actions.

                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
          Labor cost              Parts cost        Cost per product
------------------------------------------------------------------------
Up to 4 work-hours x $85 per   Up to $100.....  Up to $440.
 hour = Up to $340.
------------------------------------------------------------------------

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

    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,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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:

2021-19-19 The Boeing Company: Amendment 39-21737; Docket No. FAA-
2020-1166; Project Identifier AD-2020-00906-T.

(a) Effective Date

    This airworthiness directive (AD) is effective December 8, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-9 airplanes, 
certificated in any category, as identified in Boeing Alert 
Requirements Bulletin 737-57A1350 RB, dated April 23, 2020.

(d) Subject

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

[[Page 60565]]

(e) Unsafe Condition

    This AD was prompted by a report of missing sealant on the left 
and right wing leading edge outboard blowout door. The FAA is 
issuing this AD to address the missing sealant, which is intended to 
act as a fuel barrier. In the presence of a substantial fuel leak 
from the wing box, the unintended drain path could allow fuel to 
come into contact with the engine. This condition, if not addressed, 
could lead to a large ground fire.

(f) Compliance

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

(g) Required Actions

    Except as specified by paragraph (h) of this AD, at the 
applicable times specified in the Compliance paragraph of Boeing 
Alert Requirements Bulletin 737-57A1350 RB, dated April 23, 2020, do 
all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-57A1350 RB, dated April 23, 2020.

    Note 1 to paragraph (g):  Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-57A1350, dated April 23, 2020, which is referred to in Boeing 
Alert Requirements Bulletin 737-57A1350 RB, dated April 23, 2020.

(h) Exception to Service Information Specifications

    Where Boeing Alert Requirements Bulletin 737-57A1350 RB, dated 
April 23, 2020, refers to ``the Original Issue date of Requirements 
Bulletin 737-57A1350 RB,'' this AD requires using ``the effective 
date of this AD.''

(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 paragraph (j) of this AD. 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.

(j) Related Information

    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].

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Alert Requirements Bulletin 737-57A1350 RB, dated 
April 23, 2020.
    (ii) [Reserved]
    (3) 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.
    (4) 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.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on September 10, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-23935 Filed 11-2-21; 8:45 am]
BILLING CODE 4910-13-P


