Proposed Rule2022-03968
Airworthiness Directives; The Boeing Company Airplanes
Primary source
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Published
February 25, 2022
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -700C, -800, and - 900 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that certain web lap splices in the center dome apex of the aft pressure bulkhead are subject to widespread fatigue damage (WFD). This proposed AD would require a general visual inspection for existing repairs at the aft pressure bulkhead, repetitive detailed, high frequency eddy current (HFEC), and low frequency eddy current (LFEC) inspections, and repair if necessary. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 87 Issue 38 (Friday, February 25, 2022)</title>
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[Federal Register Volume 87, Number 38 (Friday, February 25, 2022)]
[Proposed Rules]
[Pages 10755-10757]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-03968]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-0093; Project Identifier AD-2021-00987-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 737-600, -700, -700C, -800, and -
900 series airplanes. This proposed AD was prompted by an evaluation by
the design approval holder (DAH) indicating that certain web lap
splices in the center dome apex of the aft pressure bulkhead are
subject to widespread fatigue damage (WFD). This proposed AD would
require a general visual inspection for existing repairs at the aft
pressure bulkhead, repetitive detailed, high frequency eddy current
(HFEC), and low frequency eddy current (LFEC) inspections, and repair
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 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:
<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 at <a href="https://www.regulations.gov">https://www.regulations.gov</a> by searching for and locating Docket No. FAA-2022-
0093.
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-2022-0093; 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: Dirk Visser, Aerospace Engineer,
Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206-231-3994; email:
<a href="/cdn-cgi/l/email-protection#e8ac819a83c6a2c6be819b9b8d9aa88e8989c68f879e"><span class="__cf_email__" data-cfemail="317558435a1f7b1f675842425443715750501f565e47">[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-2022-0093; Project Identifier
AD-2021-00987-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 Dirk
Visser, Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch,
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3994; email: <a href="/cdn-cgi/l/email-protection#35715c475e1b7f1b635c46465047755354541b525a43"><span class="__cf_email__" data-cfemail="72361b00195c385c241b01011700321413135c151d04">[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
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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), while providing operators with
certainty regarding the LOV applicable to their airplanes.
The FAA has received an evaluation by the DAH indicating that
certain web lap splices in the center dome apex of the aft pressure
bulkhead are subject to WFD. During cycle tests of The Boeing Company
Model 737-800 series airplanes' Fatigue Test Article for the 0.032 inch
web (the configuration for The Boeing Company Model 737-600, -700, -
700C, -800, and -900 series airplane having line numbers (LN) 1 through
1166), cracks were found in three of the seven aft pressure bulkhead
web lap splices in several of the fastener rows common to the center
dome apex. The pull down stresses were caused by the single rivet
located in the area where each of the webs transition up 0.032 inches.
Airplanes having LN 1167 through 1755 inclusive have a different
fastener pattern than airplanes having LN 1 through 1166 inclusive, but
are subject to the same unsafe condition. There has been only one
reported finding on airplanes having LN 1167 through 1755 inclusive and
cracking was found in five of the seven webs. The FAA issued AD 2021-
21-09, Amendment 39-21769 (86 FR 61679, November 8, 2021) to address
fatigue cracks in the webs of the aft pressure bulkhead on The Boeing
Company Model 737-600, -700, -700C, -800, and -900 airplanes having LN
1 through 1755 inclusive.
The Boeing Company Model 737-600, -700, -700C, -800, and -900
airplanes having LN 1756 and subsequent (which are addressed in this
proposed AD) have a 0.040 inch web thickness. Following the findings in
the earlier LNs, supplemental testing showed an increase in the pull
down stress for the 0.040 inch aft pressure bulkhead configuration in
the same transition area as seen in the 0.032 inch configuration. The
aft pressure bulkhead web lap splice fasteners are subjected to
fuselage pressurization fatigue cycles and additional clamp-up stress
caused from the assembly process. The clamp up stresses, combined with
the pressurization, cause the existing airworthiness limitations
inspections for Principle Structural Element 53-80-01-3 (visible web
rows) and 53-80-01-7 (hidden web rows) to be inadequate. Therefore, the
FAA determined that additional inspections of the 0.040 inch thick web
lap splices at station 1016 aft pressure bulkhead center dome apex for
any crack are necessary to mitigate the identified unsafe condition.
This condition, if not addressed, could result in reduced structural
integrity of the airplane.
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 737-53A1403 RB,
dated August 26, 2021. This service information specifies procedures
for a general visual inspection for existing repairs at the aft
pressure bulkhead, repetitive detailed, HFEC, and LFEC inspections for
any crack, and repair. 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-2022-0093.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 1,187 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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Inspection for repairs......... 1 work-hour x $85 $0.................... $85.............. $100,895.
per hour = $85.
Repetitive detailed, HFEC, and Up to 9 work- Up to $0.............. Up to $765 per Up to $908,055
LFEC inspections. hours x $85 per inspection cycle. per inspection
hour = $765 per cycle.
inspection cycle.
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The FAA has received no definitive data on which to base the cost
estimates for the on-condition repairs 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
[[Page 10757]]
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-2022-0093; Project Identifier AD-
2021-00987-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 737-600, -700, -
700C, -800, and -900 series airplanes, certificated in any category,
as identified in Boeing Alert Requirements Bulletin 737-53A1403 RB,
dated August 26, 2021.
(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 certain web lap splices in the center
dome apex of the aft pressure bulkhead are subject to widespread
fatigue damage (WFD). The FAA is issuing this AD to address fatigue
cracks in the webs of the aft pressure bulkhead, which could result
in reduced structural integrity of the airplane.
(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 737-53A1403 RB, dated August 26, 2021,
do all applicable actions identified in, and in accordance with, the
Accomplishment Instructions of Boeing Alert Requirements Bulletin
737-53A1403 RB, dated August 26, 2021.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
737-53A1403, dated August 26, 2021, which is referred to in Boeing
Alert Requirements Bulletin 737-53A1403 RB, dated August 26, 2021.
(h) Exceptions to Service Information Specifications
(1) Where the Compliance Time column of the table in the
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
53A1403 RB, dated August 26, 2021, uses the phrase ``the original
issue date of the Requirements Bulletin 737-53A1403 RB,'' this AD
requires using ``the effective date of this AD.''
(2) Where Boeing Alert Requirements Bulletin 737-53A1403 RB,
dated August 26, 2021, 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, 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)(1) of this AD. Information may be
emailed to: <a href="/cdn-cgi/l/email-protection#645d49252a2949370105101008014925272b4925292b27493601151101171017240205054a030b12"><span class="__cf_email__" data-cfemail="f4cdd9b5bab9d9a7919580809891d9b5b7bbd9b5b9bbb7d9a691858191878087b4929595da939b82">[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, 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
(1) For more information about this AD, contact Dirk Visser,
Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200
South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3994;
email: <a href="/cdn-cgi/l/email-protection#8fcbe6fde4a1c5a1d9e6fcfceafdcfe9eeeea1e8e0f9"><span class="__cf_email__" data-cfemail="16527f647d385c38407f656573645670777738717960">[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 February 3, 2022.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification
Service.
[FR Doc. 2022-03968 Filed 2-24-22; 8:45 am]
BILLING CODE 4910-13-P
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