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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-2315; Project Identifier AD-2023-00537-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 737-800 series airplanes. This
proposed AD was prompted by a determination that the compliance time
for the initial ultrasonic inspection required by AD 2019-11-06 is
insufficient for certain airplanes. This proposed AD would require
reducing the compliance time for the ultrasonic inspection of the skin
under the drag link assembly. 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 November
12, 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-2024-2315; 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 Boeing material 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 material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St., Des
Moines, WA.
FOR FURTHER INFORMATION CONTACT: Owen Bley-Male, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 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-2024-2315; Project Identifier
AD-2023-00537-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; phone: 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 2019-11-06, Amendment 39-19652 (84 FR 27193, June
12, 2019) (AD 2019-11-06) for certain The Boeing Company Model 737-600,
737-700, 737-700C, 737-800, 737-900, and 737-900ER series airplanes. AD
2019-11-06 requires ultrasonic inspections of the skin under the drag
link assembly for cracks and applicable on-condition actions. The FAA
issued AD 2019-11-06 to address cracking in the station (STA) 540
bulkhead chord or skin, which could result in the inability of a
primary structural element to sustain limit load.
Since issuing AD 2019-11-06, the FAA has received a report that,
for Model 737-800 series airplanes that have been modified to a
freighter configuration using Boeing Drawing 800A0003, an evaluation of
structural stresses using revised stress level calculations found that
the inspection thresholds required by AD 2019-11-06 were insufficient.
Those airplanes are subject to additional structural stresses due to
the modifications done during conversion to a freighter configuration.
Therefore, the compliance times for the initial inspections required by
AD 2019-11-06 could be performed on those airplanes after the
appropriate inspection threshold has passed, which could result in
undetected cracking in the STA 540 bulkhead chord or skin. The FAA
determined that, for those airplanes, a reduced compliance time is
needed to address the unsafe condition. Accomplishing the actions
required by this proposed AD would replace the initial ultrasonic
inspections required by paragraph (g) of AD 2019-11-06 for Model 737-
800 airplanes converted to a freighter configuration using Boeing
Drawing 800A0003.
This condition, if not addressed, could lead to undetected cracking
in the STA 540 bulkhead chord or skin, which could result in possible
rapid decompression and loss of 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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Boeing Alert Service Bulletin 737-53A1368, dated
February 27, 2018. This material specifies an ultrasonic inspection of
the skin under the drag link assembly and repair for any cracks;
repetitive inspections for any cracks, including ultrasonic
inspections, high frequency eddy current inspections, low frequency
eddy current inspections, and detailed inspections; and a preventative
modification if no crack is found.
The FAA also reviewed Boeing 737-800BCF Airworthiness Limitations,
D140A006, Revision L, dated April 1, 2021. This material contains
required inspections for principal structural element items. Section
5.2.1 of this material identifies the airplanes affected by this
proposed AD.
This material 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 reduce the compliance time for the initial
ultrasonic inspection required by AD 2019-11-06 for Model 737-800
series airplanes that have been converted to a freighter configuration
using Boeing Drawing 800A0003.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 18 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
Estimated Costs for Required Actions
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ACTION
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LABOR COST
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PARTS COST
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COST PER PRODUCT
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COST ON U.S. OPERATORS
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| Initial inspection |
Up to 23 work-hours x $85 per hour = $1,955. |
$0
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$1,955
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Up to $35,190.
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The FAA estimates the following costs to do any on-condition
actions that would be required based on the results of the proposed
inspection. The agency has no way of determining the number of
airplanes that might need these actions:
Estimated Costs for On-Condition Actions
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LABOR COST
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PARTS COST
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COST PER PRODUCT
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| Up to 56 work-hours x $85 per hour = $4,760. |
$24,020
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Up to $28,780.
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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 adding the following new airworthiness
directive:
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