Document ID: FAA-2023-0440-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: The Boeing Company Airplanes
Posted Date: 2023-03-27T04:00Z

[Federal Register Volume 88, Number 58 (Monday, March 27, 2023)]
[Rules and Regulations]
[Pages 18019-18023]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-06364]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0440; Project Identifier AD-2023-00245-T; 
Amendment 39-22396; AD 2023-06-10]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
The Boeing Company Model 737-8, -8200, and -9 airplanes. This AD was 
prompted by a report indicating that certain engine anti-ice (EAI) 
exhaust duct fasteners were inadequately torqued. This AD requires an 
inspection or records review to determine the serial number of each 
engine inlet; and if any affected engine inlet is found, an inspection 
of the EAI exhaust duct fasteners to determine the gap spacing and if 
all fasteners are installed, applicable related investigative and

[[Page 18020]]

corrective actions, and part marking. This AD also limits the 
installation of affected parts. The FAA is issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective April 11, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of April 11, 
2023.
    The FAA must receive comments on this AD by May 11, 2023.

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 by 
searching for and locating Docket No. FAA-2023-0440; 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 final rule, 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 final rule, 
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 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 
regulations.gov under Docket No. FAA-2023-0440.

FOR FURTHER INFORMATION CONTACT: Samuel Dorsey, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone: 206-231-3415; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written data, views, or arguments 
about this final rule. Send your comments to an address listed under 
ADDRESSES. Include Docket No. FAA-2023-0440 and Project Identifier AD-
2023-00245-T at the beginning of your comments. The most helpful 
comments reference a specific portion of the final rule, 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 final rule 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 final rule.

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 AD 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 AD, 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 AD. Submissions containing CBI should be sent to Samuel 
Dorsey, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-
3415; email: [email protected]. 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 has received a report indicating that during a pre-flight 
check, the flightcrew discovered a bolt protruding through a drain hole 
at the bottom of the engine inlet near the EAI exhaust vent. Boeing 
determined that some of the fasteners for EAI exhaust ducts were 
installed at the factory with inadequate torque due to the use of a 
prohibited yoke-style torque wrench adapter at a significant angle. 
When used at a sufficiently large angle, which is expected due to the 
restricted access in the area of the EAI exhaust duct, this adapter 
will produce a significant under-torque of the installed fasteners. 
Inadequately-torqued fasteners may loosen over time due to engine 
vibration, eventually causing the fastener to drop into the inlet inner 
barrel.
    The EAI system injects high-temperature bleed air from the engine 
into the interior of the inlet lip to prevent the formation of icing on 
the exterior of the inlet lip. This EAI exhaust air then exits the rear 
of the inlet lip through the EAI exhaust duct, which passes through the 
inlet inner barrel prior to exhausting air overboard. The composite 
construction of the inlet inner barrel structure is susceptible to heat 
damage at the temperatures of the EAI exhaust air should a leak occur.
    These inadequately torqued (loose or missing) fasteners for the EAI 
exhaust duct could allow EAI exhaust air to escape from the EAI exhaust 
duct via two scenarios. In the first scenario, the loose or missing 
fasteners allow the EAI exhaust duct to vibrate excessively, which, 
when combined with the redistribution of structural loads onto the 
other fasteners, may lead to fatigue cracking of the EAI exhaust duct. 
This fatigue cracking would ultimately progress to a rupture of the EAI 
exhaust duct. In the second scenario, the loose or missing fasteners 
may allow EAI exhaust air to escape from a limited location. This 
escaping air may impinge directly on the inner barrel structure, 
depending on which specific fasteners are loose or missing. In both 
scenarios, EAI exhaust air enters the inlet inner barrel causing heat 
damage, which will compromise the structural integrity of the inlet, 
eventually leading to inlet failure and separation under normal flight 
loads.
    Failure and separation of the inlet will lead to failure of the 
corresponding engine due to airflow disruption and ingestion of debris, 
and likely to failure and separation of the associated fan cowl. Damage 
to the engine and engine nacelle could result in a loss of engine 
thrust, increased nacelle drag, and disruption of airflow over the 
wing, which may excessively reduce the controllability and climb 
performance of the airplane; and damage from debris departing the 
engine and nacelle, which could impact the fuselage and empennage, 
could result in personal injury to passengers and loss of control of 
the airplane.
    The FAA is issuing this AD to address the unsafe condition on these 
products.

[[Page 18021]]

FAA's Determination

    The FAA is issuing this AD because the agency has determined the 
unsafe condition described previously is likely to exist or develop in 
other products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Service Letter 737-SL-71-081-A, Revision A, 
dated March 3, 2023. (Attachments I and II of this document are dated 
March 2, 2023.) The service information specifies procedures for an 
inspection to determine the serial number of each engine inlet, and if 
any affected engine inlet is found, an inspection of the EAI exhaust 
duct fasteners to determine the gap spacing and if all fasteners are 
installed, applicable related investigative and corrective actions, and 
part-marking the engine inlet. Related investigative actions include an 
inspection of the fasteners for proper torque, general visual and high 
frequency eddy current inspections of the EAI exhaust duct flange and 
fastener holes for cracking, and visual inspections of the inner barrel 
for thermal exposure (i.e., heat damage). Corrective actions include 
re-torque of fasteners, repairing or replacing EAI exhaust ducts, 
repairing thermal exposure, and replacing the engine inlet. 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.

AD Requirements

    This AD requires accomplishing the actions identified as ``(RC)'' 
(required for compliance) in the Work Instructions of Boeing Service 
Letter 737-SL-71-081-A, Revision A, dated March 3, 2023, described 
previously, except as discussed under ``Differences Between this AD and 
the Service Information,'' and except for any differences identified as 
exceptions in the regulatory text of this AD.
    For information on the procedures and compliance times, see this 
service information at regulations.gov under Docket No. FAA-2023-0440.

Differences Between This AD and the Service Information

    Boeing Service Letter 737-SL-71-081-A, Revision A, dated March 3, 
2023, specifies that the actions must be done on all airplanes. 
However, airplanes produced after a certain production line number were 
verified to have properly torqued EAI exhaust duct fasteners. 
Therefore, paragraph (g) of this AD only applies to airplanes with an 
original airworthiness certificate or original export certificate of 
airworthiness issued on or before the effective date of the AD. The 
parts installation limitation specified in paragraph (i) of this AD 
applies to all airplanes.
    Boeing Service Letter 737-SL-71-081-A, Revision A, dated March 3, 
2023, includes an inspection to verify the serial number of the inlet. 
This AD also allows a review of airplane maintenance records in lieu of 
the inspection to verify the serial number of the inlet if the serial 
number of the inlet can be conclusively determined from that review.

Interim Action

    The FAA considers this AD to be an interim action. The FAA is 
investigating if design changes may be needed to prevent a future 
common-cause failure of the EAI exhaust duct. If final action is later 
identified, the FAA might consider further rulemaking then.

Justification for Immediate Adoption and Determination of the Effective 
Date

    Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5 
U.S.C. 551 et seq.) authorizes agencies to dispense with notice and 
comment procedures for rules when the agency, for ``good cause,'' finds 
that those procedures are ``impracticable, unnecessary, or contrary to 
the public interest.'' Under this section, an agency, upon finding good 
cause, may issue a final rule without providing notice and seeking 
comment prior to issuance. Further, section 553(d) of the APA 
authorizes agencies to make rules effective in less than thirty days, 
upon a finding of good cause.
    An unsafe condition exists that requires the immediate adoption of 
this AD without providing an opportunity for public comments prior to 
adoption. The FAA has found that the risk to the flying public 
justifies forgoing notice and comment prior to adoption of this rule 
because loose or missing fasteners for the EAI exhaust duct might allow 
EAI exhaust air to enter the inlet interior causing heat damage, which 
could compromise the structural integrity of the inlet, eventually 
leading to inlet failure and separation under normal flight loads. 
Failure and separation of the inlet will lead to failure of the 
corresponding engine due to airflow disruption and ingestion of debris 
and likely failure and separation of the associated fan cowl. Damage to 
the engine and engine nacelle could result in a loss of engine thrust, 
increased nacelle drag, and disruption of airflow over the wing which 
may excessively reduce the controllability and climb performance of the 
airplane; and damage from debris departing the engine and nacelle, 
which could impact the fuselage and empennage, could result in personal 
injury to passengers and loss of control of the airplane. Accordingly, 
notice and opportunity for prior public comment are impracticable and 
contrary to the public interest pursuant to 5 U.S.C. 553(b)(3)(B).
    In addition, the FAA finds that good cause exists pursuant to 5 
U.S.C. 553(d) for making this amendment effective in less than 30 days, 
for the same reasons the FAA found good cause to forgo notice and 
comment.

Regulatory Flexibility Act

    The requirements of the Regulatory Flexibility Act (RFA) do not 
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt 
a rule without prior notice and comment. Because the FAA has determined 
that it has good cause to adopt this rule without notice and comment, 
RFA analysis is not required.

Costs of Compliance

    The FAA estimates that this AD affects 330 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Inspection or records review to         1 work-hour x $85 per                 $0             $85         $28,050
 determine serial number of engine       hour = $85.
 inlet.
Inspection of fastener gaps and to      2 work-hour x $85 per                  0             340         112,200
 determine if all fasteners are          hour = $170 per inlet
 installed, and engine inlet part-       (2 inlets per airplane).
 marking.
----------------------------------------------------------------------------------------------------------------

[[Page 18022]]

    The FAA estimates the following costs to do any necessary on-
condition actions that would be required based on the results of the 
inspection to of fastener gaps and to determine if all fasteners are 
installed. The FAA has no way of determining the number of aircraft 
that might need these actions:

                                              On-Condition Costs *
----------------------------------------------------------------------------------------------------------------
            Action                Labor cost                Parts cost                   Cost per product
----------------------------------------------------------------------------------------------------------------
Inspection of the fasteners    1 work-hour x     $0.............................  $85 per inlet.
 for proper torque.             $85 per hour =
                                $85 per inlet.
EAI exhaust duct inspection..  1 work-hour x     0..............................  85 per inlet.
                                $85 per hour =
                                $85 per inlet.
EAI exhaust duct replacement.  1 work-hour x     10,000 per inlet...............  10,085 per inlet.
                                $85 per hour =
                                $85 per inlet.
Inner barrel thermal exposure  1 work-hour x     0..............................  85 per inlet.
 inspection.                    $85 per hour =
                                $85 per inlet.
Inlet replacement............  12 work-hours x   1,741,000 per inlet............  1,742,020 per inlet.
                                $85 per hour =
                                $1,020 per
                                inlet.
Re-torquing..................  1 work-hour x     0..............................  85 per inlet.
                                $85 per hour =
                                $85 per inlet.
----------------------------------------------------------------------------------------------------------------
* For repair of the EAI exhaust duct and repairing thermal exposure, the FAA has no definitive data on which to
  base the cost estimate for those actions.

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this 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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866, and
    (2) Will not affect intrastate aviation in Alaska.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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:

2023-06-10 The Boeing Company: Amendment 39-22396; Docket No. FAA-
2023-0440; Project Identifier AD-2023-00245-T.

(a) Effective Date

    This airworthiness directive (AD) is effective April 11, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 737-8, -8200, 
and -9 airplanes, certificated in any category.

(d) Subject

    Air Transport Association (ATA) of America Code 30, Ice and Rain 
Protection; 71, Powerplant.

(e) Unsafe Condition

    This AD was prompted by a report indicating that certain engine 
anti-ice (EAI) exhaust duct fasteners were inadequately torqued 
during installation at the factory. The FAA is issuing this AD to 
address loose or missing fasteners for the EAI exhaust duct that may 
allow EAI exhaust air to enter the inlet inner barrel causing heat 
damage that will compromise the structural integrity of the inlet, 
eventually leading to inlet failure and separation under normal 
flight loads. The unsafe condition, if not addressed, will lead to 
failure of the corresponding engine due to airflow disruption and 
ingestion of debris and likely failure and separation of the 
associated fan cowl. Damage to the engine and engine nacelle could 
result in a loss of engine thrust, increased nacelle drag, and 
disruption of airflow over the wing, which may excessively reduce 
the controllability and climb performance of the airplane; and 
damage from debris departing the engine and nacelle, which could 
impact the fuselage and empennage, could result in personal injury 
to passengers and loss of control of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    For airplanes with an original airworthiness certificate or 
original export certificate of airworthiness issued on or before the 
effective date of the AD: Except as specified by paragraph (h) of 
this AD, at the applicable times specified in the ``Suggested 
Operator Action'' section of Boeing Service Letter 737-SL-71-081-A, 
Revision A, dated March 3, 2023, do all applicable actions 
identified as ``RC'' (required for compliance) in, and in accordance 
with, the Work Instructions of Boeing Service Letter 737-SL-71-081-
A, Revision A, dated March 3, 2023. Perform all applicable related 
investigative and corrective actions before further flight.

(h) Exceptions to Service Information Specifications

    (1) Where the ``Suggested Operator Action'' section of Boeing 
Service Letter 737-SL-71-081-A, Revision A, dated March 3, 2023, 
specifies doing ``the following actions within the given time from 
the publication of this service letter,'' this AD requires 
accomplishing the actions within the specified compliance times 
after ``the effective date of this AD.''
    (2) Where the ``Suggested Operator Action'' section of Boeing 
Service Letter 737-SL-71-081-A, Revision A, dated March 3, 2023, 
specifies ``corrective actions,'' for this AD, those actions include 
``corrective and related investigative actions.''

[[Page 18023]]

    (3) A review of airplane maintenance records is acceptable in 
lieu of the inspection to verify the serial number of the inlet 
specified in step A.1. of the Work Instructions of Boeing Service 
Letter 737-SL-71-081-A, Revision A, dated March 3, 2023, if the 
serial number of the inlet can be conclusively determined from that 
review.
    (4) Where Boeing Service Letter 737-SL-71-081-A, Revision A, 
dated March 3, 2023, specifies contacting Boeing for repair or 
further instructions: This AD requires doing the repair and 
applicable instructions before further flight using a method 
approved in accordance with the procedures specified in paragraph 
(l) of this AD.
    (5) Where the Work Instructions of Boeing Service Letter 737-SL-
71-081-A, Revision A, dated March 3, 2023, refers to the structural 
repair manual, replace the text ``737-8/8200/9 Structural Repair 
Manual (SRM) 51-40-04, Revision 18/9/15,'' with ``737-8 Structural 
Repair Manual (SRM) 51-40-04, Revision 18 or 19; 737-8200 SRM 51-40-
04, Revision 9 or 10; or 737-9 SRM 51-40-04, Revision 15 or 16.''

(i) Parts Installation Limitation

    As of the effective date of this AD, no person may install an 
engine inlet assembly with a serial number listed in Attachment I of 
Boeing Service Letter 737-SL-71-081-A, Revision A, dated March 3, 
2023, on any airplane unless all applicable actions required by 
paragraph (g) of this AD have been done for that inlet.

(j) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Service Letter 737-SL-71-081, 
dated February 20, 2023, provided the conditions specified in 
paragraphs (j)(1) and (2) of this AD are met.
    (1) An inspection or records review has been done to verify the 
inlet serial number is not included in the additional serial numbers 
identified in Attachment I of Boeing Service Letter 737-SL-71-081-A, 
Revision A, dated March 3, 2023; and the serial number of the inlet 
can be conclusively determined from that inspection or review.
    (2) Where the Work Instructions of Boeing Service Letter 737-SL-
71-081, dated February 20, 2023, refer to the structural repair 
manual (SRM) to apply torque, the applicable SRM identified in 
paragraph (j)(2)(i), (ii), or (iii) of this AD was used to apply the 
torque.
    (i) Boeing 737-8 SRM 51-40-04, Revision 18, dated November 10, 
2022; or Revision 19, dated March 10, 2023.
    (ii) Boeing 737-8200 SRM 51-40-04, Revision 9, dated November 
10, 2022; or Revision 10, dated March 10, 2023.
    (iii) Boeing 737-9 SRM 51-40-04, Revision 15, dated November 10, 
2022; or Revision 16, dated March 10, 2023.

(k) Special Flight Permit

    (1) Special flight permits, as described in 14 CFR 21.197 and 
21.199, may be issued to move the airplane to a maintenance facility 
prior to performing the required inspections.
    (2) If, during the inspections required by paragraph (g) of this 
AD, only one engine is found with an inlet having any crack or 
thermal damage: Special flight permits, as described in 14 CFR 
21.197 and 21.199, may be issued to operate the airplane to a 
location where the requirements of this AD can be accomplished 
provided the conditions specified in paragraph (k)(2)(i) and (ii) of 
this AD, as applicable, are met.
    (i) The EAI is deactivated on the affected engine in accordance 
with the operator's existing Minimum Equipment List.
    (ii) For any inlet with any thermal exposure (i.e., heat damage) 
on the inner barrel, The Boeing Company Organization Designation 
Authorization (ODA) is contacted to obtain concurrence for issuance 
of a special flight permit and The Boeing Company ODA concurs. 
Operators must comply with any flight limitations provided by The 
Boeing Company ODA. The concurrence with any limitations must 
specifically refer to this AD.
    (3) If, during the inspections required by paragraph (g) of this 
AD, both engines are found with inlets having any crack or thermal 
exposure: Special flight permits, as described in 14 CFR 21.197 and 
21.199, are not allowed.

(l) 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 (m) of this AD. Information may be emailed 
to: [email protected].
    (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 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.
    (4) Except as required by paragraph (h) of this AD: For service 
information that contains steps that are labeled as Required for 
Compliance (RC), the provisions of paragraphs (l)(4)(i) and (ii) of 
this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. If a step or substep is labeled ``RC Exempt,'' then the 
RC requirement is removed from that step or substep. An AMOC is 
required for any deviations to RC steps, including substeps and 
identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(m) Related Information

    For more information about this AD, contact Samuel Dorsey, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3415; 
email: [email protected].

(n) 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 the AD specifies otherwise.
    (i) Boeing Service Letter 737-SL-71-081-A, Revision A, dated 
March 3, 2023.
    Note 1 to paragraph (n)(2)(i): Attachments I and II of this 
document are dated March 2, 2023.
    (ii) [Reserved]
    (3) 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; website myboeingfleet.com.
    (4) 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.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on March 17, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-06364 Filed 3-23-23; 4:15 pm]
BILLING CODE 4910-13-P