preamble attached >>>
ADs updated daily at www.Tdata.com
PROPOSED AD THE BOEING COMPANY: Docket No. FAA-2024-0028; Project Identifier AD-2023-00919-T.
(a) COMMENTS DUE DATE

    The FAA must receive comments on this airworthiness directive (AD)  by
    March 1, 2024.

(b) AFFECTED ADS

    This AD replaces AD 2021-09-06,  Amendment 39-21519  (86 FR 23595, May
    4, 2021) (AD 2021-09-06).

(c) APPLICABILITY

    This AD applies to all The Boeing Company  Model 737-600, -700, -700C,
    -800, -900, and -900ER series airplanes, certificated in any category.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 53, Fuselage.

(e) UNSAFE CONDITION

    This AD was prompted  by reports of cracking in the station (STA) 663.
    75 frame fitting outboard chords  and failsafe straps adjacent to  the
    stringer S-18A  area and  a determination  that additional inspections
    are needed to address the unsafe condition. The FAA is issuing this AD
    to address cracking  in the STA  663.75 frame fitting  outboard chords
    and failsafe straps adjacent to the stringer S-18A straps, which could
    result in failure of a  Principal Structural Element (PSE) to  sustain
    limit load. The  unsafe condition, if  not addressed, could  adversely
    affect the structural integrity of the airplane and result in loss  of
    control of the airplane.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready 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 737-53A1414 RB,  Revision 1,  dated November 20,
    2023, do all applicable actions identified in, and in accordance with,
    the Accomplishment Instructions of Boeing Alert Requirements  Bulletin
    737-53A1414 RB, Revision 1, dated November 20, 2023.

Note 1 to paragraph (g):  Guidance for accomplishing the actions  required
by this  AD can  be found  in Boeing  Alert Service  Bulletin 737-53A1414,
Revision 1, dated November 20, 2023, which is referred to in Boeing  Alert
Requirements Bulletin 737-53A1414 RB, Revision 1, dated November 20, 2023.

(h) EXCEPTIONS TO SERVICE INFORMATION SPECIFICATIONS

(1) Where the Condition  and  Compliance Time columns of the tables in the
    "Compliance" paragraph  of  Boeing  Alert  Requirements  Bulletin 737-
    53A1414 RB, Revision 1,  dated November 20, 2023,  use the phrase "the
    original issue date of Requirements Bulletin 737-53A1414 RB,"  or "the
    Revision 1 date of Requirements Bulletin 737-53A1414 RB,"  this AD re-
    quires using "the effective date of this AD."

(2) Where Boeing Alert Requirements  Bulletin 737-53A1414 RB,  Revision 1,
    dated November 20, 2023,  specifies  contacting  Boeing for repair in-
    structions:  This AD requires doing the repair using a method approved
    in accordance with the procedures  specified in paragraph (i)  of this
    AD.

(i) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The Manager,  AIR-520,  Continued Operational Safety 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)(1) of this AD. Information  may
    be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking a principal inspector,  the manager of the respon-
    sible 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, AIR-520,  Continued
    Operational  Safety  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

(1) For more information about this AD,  contact Owen Bley-Male,  Aviation
    Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; tel-
    ephone 206-231-3992; email owen.f.bley-male@faa.gov.

(2) Service information identified in this AD  that is not incorporated by
    reference is available at the addresses specified in paragraphs (k)(3)
    and (4) of this AD.

(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 this AD specifies otherwise.

(i) Boeing Alert Requirements Bulletin 737-53A1414 RB,  Revision 1,  dated
    November 20, 2023.

(ii) [Reserved]

(3) For service information identified in this AD,  contact Boeing Commer-
    cial Airplanes,  Attention:  Contractual & Data Services (C&DS),  2600
    Westminster Blvd., MC 110-SK57,  Seal Beach, CA 90740-5600;  telephone
    562-797-1717; website myboeingfleet.com.

(4) You may view this service information at the FAA,  Airworthiness Prod-
    ucts 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 material at the National Archives and Records Admin-
    istration (NARA). For information on the availability of this material
    at NARA,  visit www.archives.gov/federal-register/cfr/ibr-locations or
    email fr.inspection@nara.gov.

Issued on January 5, 2024.  Victor Wicklund, Deputy Director, Compliance &
Airworthiness Division, Aircraft Certification Service.

DATES: The FAA must receive comments on this proposed AD by March 1, 2024.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0028; Project Identifier AD-2023-00919-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)
2021-09-06, which applies to all The Boeing Company Model 737-600, -
700, -700C, -800, -900, and -900ER series airplanes. AD 2021-09-06
requires repetitive inspections for cracking of the left- and right-
hand side outboard chords of certain frame fittings and failsafe straps
at a certain station around eight fasteners, and repair if any cracking
is found. Since the FAA issued AD 2021-09-06, additional reports of
cracking in the area were received and it was determined that
additional inspections are needed to address the unsafe condition. This
proposed AD would require repetitive detailed and ultrasonic
inspections for cracking of the left-and right-hand sides of certain
frame fittings and failsafe straps, and repair if any cracking is
found. 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 March 1,
2024.

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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-0028; 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.
Material Incorporated by Reference:
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; website 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
regulations.gov by searching for and locating Docket No. FAA-2024-0028.

FOR FURTHER INFORMATION CONTACT: Owen Bley-Male, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone
206-231-3992; email owen.f.bley-male@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-2024-0028; Project Identifier
AD-2023-00919-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 information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
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 Owen
Bley-Male, Aviation Safety Engineer, FAA, 2200 South 216th St., Des
Moines, WA 98198; telephone 206-231-3992; email owen.f.bley-male@faa.gov. Any commentary that the FAA receives that is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.

Background

The FAA issued AD 2021-09-06, Amendment 39-21519 (86 FR 23595, May
4, 2021) (AD 2021-09-06), for all The Boeing Company Model 737-600, -
700, -700C, -800, -900, and -900ER series airplanes. AD 2021-09-06 was
prompted by reports of cracking discovered in the station (STA) 663.75
frame fitting outboard chords and failsafe straps adjacent to the
stringer S-18A straps and a determination that the initial inspection
threshold and repetitive inspection interval required by AD 2019-22-10,
Amendment 39-19789 (84 FR 61533, November 13, 2019), were inadequate to
address cracking in a timely manner. AD 2021-09-06 requires repetitive
inspections for cracking of the left- and right-hand side outboard
chords of frame fittings and failsafe straps at a certain station
around eight fasteners, repair if any cracking is
found, and an inspection report. The agency issued AD 2021-09-06 to
address cracking in the STA 663.75 frame fitting outboard chords and
failsafe straps adjacent to the stringer S-18A straps, which could
result in failure of a principal structural element (PSE) to sustain
limit load. This condition could adversely affect the structural
integrity of the airplane and result in loss of control of the
airplane.

Actions Since AD 2021-09-06 Was Issued

Since the FAA issued AD 2021-09-06, additional reports have been
made of several cracks in the STA 663.75 frame fittings and failsafe
straps. Cracks have also been found at the aft fastener common to the
failsafe strap upper row. Several cracks in the frame fitting were
found extending beyond the aft fastener hole to the forward fastener
hole. An additional report was made of a visible crack in the failsafe
strap without any visibly detectable crack in the frame fitting. These
additional reports led to a determination that the detailed visual
inspection required by AD 2021-09-06 might not be adequate to detect
STA 663.75 failsafe strap cracking.
Additionally, the preamble to AD 2021-09-06 explained that the FAA
considered the requirements ``interim action'' and was considering
further rulemaking. The FAA has now determined that further rulemaking
is indeed necessary and this proposed AD follows from that
determination.

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 Requirements Bulletin 737-53A1414 RB,
Revision 1, dated November 20, 2023. This service information specifies
procedures for repetitive internal detailed inspection for cracking of
the frame fitting and visible areas of the failsafe strap at STA 663.73
(left- and right-hand sides), repetitive external detailed and
ultrasonic inspections for cracking of the failsafe strap at STA 663.75
(left- and right-hand sides), and repair if any cracking is found. 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

Although this proposed AD does not explicitly restate the
requirements of AD 2021-09-06, this proposed AD would retain the
inspection requirements of AD 2021-09-06. 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 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 regulations.gov under Docket No. FAA-2024-0028.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 1,911 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 4 work-hours x $85 per hour = $340 per inspection cycle $0 $340 per inspection cycle $649,740 per inspection cycle

The FAA has received no definitive data on which to base the cost
estimates for the on-condition repairs specified in this proposed AD.
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 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive (AD) 2021-09-06, Amendment 39-21519
(86 FR 23595, May 4, 2021), and

b. Adding the following new AD: