DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0504; Project Identifier AD-2020-01380-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 supersede Airworthiness Directive (AD)
2019-03-26, which applies to certain The Boeing Company Model 737-600,
-700, -700C, -800, -900, and -900ER series airplanes. AD 2019-03-26
requires modifying the passenger service units (PSUs) and life vest
panels by replacing the existing inboard lanyard and installing two new
lanyards on the outboard edge of the PSUs and life vest panels;
measuring the distance between the hooks of the torsion spring of the
lanyard assembly; replacing discrepant lanyard assemblies; and re-
identifying serviceable lanyard assemblies. Since the FAA issued AD
2019-03-26, it has been determined that certain airplanes are listed in
the wrong configuration and certain PSUs have not been correctly re-
identified. This proposed AD would retain the requirements of AD 2019-
03-26, and, for certain airplanes, would require an inspection to
determine if the re-identified PSU part number is correct, and further
re-identification if necessary. 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 August 16,
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-2021-0504.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0504; 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: Tony Koung, Aerospace Engineer, Cabin
Safety and Environmental Systems Section, FAA, Seattle ACO Branch, 2200
South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3985;
email: tony.koung@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-2021-0504; Project Identifier
AD-2020-01380-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 Tony
Koung, Aerospace Engineer, Cabin Safety and Environmental Systems
Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA
98198; phone and fax: 206-231-3985; email: tony.koung@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

The FAA issued AD 2019-03-26, Amendment 39-19578 (84 FR 7266, March
4, 2019) (AD 2019-03-26), for certain The Boeing Company Model 737-600,
-700, -700C, -800, -900, and -900ER series airplanes. AD 2019-03-26 was
prompted by reports of PSUs becoming detached from the supporting
airplane structure in several Model 737 series airplanes. AD 2019-03-26
requires modifying the PSUs and life vest panels by replacing the
existing inboard lanyard and installing two new lanyards on the
outboard edge of the PSUs and life vest panels; measuring the distance
between the hooks of the torsion spring of the lanyard assembly;
replacing discrepant lanyard assemblies; and re-identifying serviceable
lanyard assemblies. The agency issued AD 2019-03-26 to address PSUs and
life vest panels detaching from the supporting airplane structure,
which could lead to passenger injuries and impede passenger and crew
egress during evacuation.

Actions Since AD 2019-03-26 Was Issued

Since the FAA issued AD 2019-03-26, Boeing found that, in the
service information required by AD 2019-03-26, some airplanes were not
assigned to the correct group and configuration. In addition, Boeing
determined that the service information had missing or incorrect re-
identification part numbers for those PSUs that were modified using
Boeing Service Bulletin 737-35-1107. The FAA determined that the new
requirements in this proposed AD would take a minimal amount of time to
accomplish. Therefore, the proposed compliance time would remain the
same as the time required by AD 2019-03-26 (within 60 months after
April 8, 2019 (the effective date of AD 2019-03-26)).

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 Service Bulletin 737-25-
1707, Revision 2, dated July 27, 2020. This service information
specifies procedures for modifying the PSUs and life vest panels by:
Replacing the existing inboard lanyard and installing two new lanyards
on the outboard edge of the PSUs and life vest panels (secondary
retention features); measuring the distance between the hooks of the
torsion spring of the lanyard assembly; replacing any discrepant
lanyard assemblies; and re-identifying serviceable lanyard assemblies.
For some airplanes, the service information specifies procedures for
inspecting PSUs for correct re-identification part numbers and, if
necessary, re-identifying the PSU. 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 2019-03-26, this proposed AD would retain all of the
requirements of AD 2019-03-26. Those requirements are referenced in the
service information identified previously, which, in turn, is
referenced in paragraph (g) of this proposed AD. This proposed AD would
add additional actions for certain airplanes. This proposed AD would
also require accomplishment of the actions identified as "RC"
(required for compliance) in the Accomplishment Instructions of Boeing
Special Attention Service Bulletin 737-25-1707, Revision 2, dated July
27, 2020, described previously, except as discussed under
"Differences Between the Proposed AD and the Service Information."

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-2021-0504.

Differences Between This Proposed AD and the Service Information

The effectivity of Boeing Special Attention Service Bulletin 737-
25-1707, Revision 2, dated July 27, 2020, is limited to Model 737-600,
-700, -700C, -800, -900, and -900ER series airplanes, having certain
line numbers, without a Boeing Sky Interior (BSI). However, the
applicability of this proposed AD includes all Boeing Model 737-600,
-700, -700C, -800, -900, and -900ER series airplanes without a BSI.
Because the affected lanyard assemblies are rotable parts, the FAA has
determined that these affected parts could later be installed on
airplanes that were initially delivered with acceptable lanyard
assemblies, thereby subjecting those airplanes to the unsafe condition.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 2,045 airplanes of U.S. registry. The FAA estimates the
following costs to comply with this proposed AD:

Estimated Costs

The FAA estimates the following costs to do any necessary
replacements or re-identifications 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 replacements or re-
identifications:

On-Condition Costs

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.

Authority for This Rulemaking

Title 49 of the United States Code specifies the 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive (AD) 2019-03-26, Amendment 39-19578
(84 FR 7266, March 4, 2019), and

b. Adding the following new AD: