Proposed Rule2021-18069
Airworthiness Directives; The Boeing Company Airplanes
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 24, 2021
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, and -500 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that the frame splice between certain stringers is subject to widespread fatigue damage (WFD). This proposed AD would require an inspection of certain fuselage frame splices for existing repairs, repetitive inspections of certain fuselage frame splices for cracking, and applicable on-condition actions. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 86 Issue 161 (Tuesday, August 24, 2021)</title>
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[Federal Register Volume 86, Number 161 (Tuesday, August 24, 2021)]
[Proposed Rules]
[Pages 47255-47258]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-18069]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0609; Project Identifier AD-2021-00274-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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[[Page 47256]]
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain The Boeing Company Model 737-300, -400, and -500 series
airplanes. This proposed AD was prompted by an evaluation by the design
approval holder (DAH) indicating that the frame splice between certain
stringers is subject to widespread fatigue damage (WFD). This proposed
AD would require an inspection of certain fuselage frame splices for
existing repairs, repetitive inspections of certain fuselage frame
splices for cracking, and applicable on-condition actions. 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:
<bullet> Federal eRulemaking Portal: Go to <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the instructions for submitting comments.
<bullet> Fax: 202-493-2251.
<bullet> 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.
<bullet> 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 <a href="https://www.myboeingfleet.com">https://www.myboeingfleet.com</a>. 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 on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> by searching for and locating Docket No. FAA-2021-
0609.
Examining the AD Docket
You may examine the AD docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> by
searching for and locating Docket No. FAA-2021-0609; 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: Wayne Ha, Aerospace Engineer, Airframe
Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard,
Lakewood, CA 90712-4137; phone: 562-627-5238; fax: 562-627-5210; email:
<a href="/cdn-cgi/l/email-protection#c7b0a6bea9a2e9afa687a1a6a6e9a0a8b1"><span class="__cf_email__" data-cfemail="8bfceaf2e5eea5e3eacbedeaeaa5ece4fd">[email protected]</span></a>.
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-2021-0609; Project Identifier
AD-2021-00274-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
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, 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 Wayne
Ha, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch,
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5238;
fax: 562-627-5210; email: <a href="/cdn-cgi/l/email-protection#7403150d1a115a1c15341215155a131b02"><span class="__cf_email__" data-cfemail="e394829a8d86cd8b82a3858282cd848c95">[email protected]</span></a>. 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 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. 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),
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while providing operators with certainty regarding the LOV applicable
to their airplanes.
The FAA has received a report indicating that cracking is occurring
in the frame splice doubler and may occur in the upper frame at the
upper frame splice between stringer S-13 and S-14 on Boeing Model 737-
300, -400, and -500 airplanes at multiple frame locations. The doubler
cracking and possible upper frame cracking at the frame splice between
stringer S-13 and S-14 are the result of fatigue, caused by combined
cyclic loading from fuselage pressurization and flight loads. The FAA
is issuing this AD to address upper frame cracking common to the frame
splice between stringer S-13 and S-14, which could interact with
stringer S-14 skin lap splice lower fastener row cracking in lower
skin, and result in an uncontrolled decompression of the airplane and
loss of structural integrity.
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 737-53A1388 RB,
dated October 27, 2020. This service information specifies procedures
for a general visual inspection (GVI) of the fuselage frame splices
between stringer S-13 and S-14 station (STA) 360 to STA 520 and STA
727A to STA 907 for existing repairs, repetitive inspections of the
fuselage frame splices between stringer S-13 and S-14 from STA 360 to
STA 520 and STA 727A to STA 907 for cracking, and applicable on-
condition actions. On-condition actions include an open hole high
frequency eddy current (HFEC) inspection for cracking at all fastener
hole locations where a fastener was removed due to finding a cracked
doubler, repair, or replacement.
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 <a href="https://www.regulations.gov">https://www.regulations.gov</a> by searching for and
locating Docket No. FAA-2021-0609.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 66 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Repetitive Inspections......... Up to 267 work-hours x $0 Up to $22,695 per Up to $1,497,870
$85 per hour = Up to inspection cycle. per inspection
$22,695 inspection cycle.
cycle.
GVI............................ 2 work-hours x $85 per 0 $170.............. $11,220.
hour = $170.
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The FAA has received no definitive data on which to base the cost
estimates for the on-condition actions 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 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
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-2021-0609; Project Identifier AD-
2021-00274-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 The Boeing Company Model 737-300, -400, and -
500 series
[[Page 47258]]
airplanes, certificated in any category, as identified in Boeing
Alert Requirements Bulletin 737-53A1388 RB, dated October 27, 2020.
(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 (DAH) indicating that the frame splice between stringer S-13
and S-14 is subject to widespread fatigue damage (WFD). The FAA is
issuing this AD to address upper frame cracking common to the frame
splice between stringer S-13 and S-14, which could interact with
stringer S-14 skin lap splice lower fastener row cracking in lower
skin and result in an uncontrolled decompression of the airplane and
loss of structural integrity.
(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 737-53A1388 RB, dated October 27, 2020,
do all applicable actions identified in, and in accordance with, the
Accomplishment Instructions of Boeing Alert Requirements Bulletin
737-53A1388 RB, dated October 27, 2020.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
737-53A1388, dated October 27, 2020, which is referred to in Boeing
Alert Requirements Bulletin 737-53A1388 RB, dated October 27, 2020.
(h) Exceptions to Service Information Specifications
(1) Where Boeing Alert Requirements Bulletin 737-53A1388 RB,
dated October 27, 2020, uses the phrase ``the Original Issue date of
Requirements Bulletin 737-53A1388 RB,'' this AD requires using ``the
effective date of this AD,'' except where Alert Requirements
Bulletin 737-53A1388 RB, dated October 27, 2020, uses the phrase
``the Original Issue date of Requirements Bulletin 737-53A1388 RB,''
in a note or flag note.
(2) Where Boeing Alert Requirements Bulletin 737-53A1388 RB,
dated October 27, 2020, specifies contacting Boeing for repair
instructions or for alternative inspections: This AD requires doing
the repair, or doing the alternative inspections and applicable on-
condition actions 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, 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: <a href="/cdn-cgi/l/email-protection#b78e9af6f9fa9afbf6f6f4f89af6faf8f49ae5d2c6c2d2c4c3c4f7d1d6d699d0d8c1"><span class="__cf_email__" data-cfemail="685145292625452429292b27452925272b453a0d191d0d1b1c1b280e0909460f071e">[email protected]</span></a>.
(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.
(j) Related Information
(1) For more information about this AD, contact Wayne Ha,
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch,
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5238; fax: 562-627-5210; email: <a href="/cdn-cgi/l/email-protection#84f3e5fdeae1aaece5c4e2e5e5aae3ebf2"><span class="__cf_email__" data-cfemail="4631273f2823682e270620272768212930">[email protected]</span></a>.
(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 <a href="https://www.myboeingfleet.com">https://www.myboeingfleet.com</a>. 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 July 26, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification
Service.
[FR Doc. 2021-18069 Filed 8-23-21; 8:45 am]
BILLING CODE 4910-13-P
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