[Federal Register Volume 88, Number 89 (Tuesday, May 9, 2023)]
[Rules and Regulations]
[Pages 29815-29818]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-09737]



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 Rules and Regulations
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  Federal Register / Vol. 88, No. 89 / Tuesday, May 9, 2023 / Rules and 
Regulations  

[[Page 29815]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1422; Project Identifier AD-2022-01208-E; 
Amendment 39-22413; AD 2023-07-11]
RIN 2120-AA64


Airworthiness Directives; CFM International, S.A. Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain CFM International, S.A. (CFM) Model LEAP-1B engines. This AD 
was prompted by a report of multiple aborted takeoffs and air turn-
backs (ATBs) caused by high-pressure compressor (HPC) stall, which was 
induced by high levels of non-synchronous vibration (NSV). A subsequent 
investigation by the manufacturer revealed that wear on the No. 3 
bearing spring finger housing can lead to high levels of NSV. This AD 
requires repetitive calculations of the oil filter delta pressure 
(OFDP) data and, depending on the results of the calculation, 
replacement of the No. 3 bearing spring finger housing. This AD also 
prohibits installation of an engine with an affected No. 3 bearing 
spring finger housing onto an airplane that already has one engine with 
an affected No. 3 bearing spring finger housing installed. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective June 13, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of June 13, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov by 
searching for and locating Docket No. FAA-2022-1422; 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 address for Docket 
Operations is U.S. Department of Transportation, Docket Operations, M-
30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue 
SE, Washington, DC 20590.
    Material Incorporated by Reference:
     For CFM service information identified in this final rule, 
contact CFM International Inc., Aviation Operations Center, 1 Neumann 
Way, M/D Room 285, Cincinnati, OH 45215; phone: (877) 432-3272; email: 
[email protected].
     You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 1200 
District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call (817) 222-5110. It is 
also available at regulations.gov by searching for and locating Docket 
No. FAA-2022-1422.

FOR FURTHER INFORMATION CONTACT: Mehdi Lamnyi, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7743; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain CFM Model LEAP-
1B21, LEAP-1B23, LEAP-1B25, LEAP-1B27, LEAP-1B28, LEAP-1B28B1, LEAP-
1B28B2, LEAP-1B28B2C, LEAP-1B28B3, LEAP-1B28BBJ1, and LEAP-1B28BBJ2 
engines. The NPRM published in the Federal Register on December 1, 2022 
(87 FR 73686). The NPRM was prompted by a report of three aborted 
takeoffs and two ATBs caused by HPC stall, which was induced by high 
levels of NSV. A subsequent investigation by the manufacturer revealed 
that wear on the No. 3 bearing spring finger housing can lead to high 
levels of NSV, which could induce HPC stall. This wear manifests itself 
early on as higher than typical OFDP loading. As a result of its 
investigation, the manufacturer published service information that 
specifies procedures for calculating the OFDP data and replacing the 
affected No. 3 bearing spring finger housing. In the NPRM, the FAA 
proposed to require a calculation of the OFDP data and, depending on 
the results of the calculation, replacement of the No. 3 bearing spring 
finger housing. In the NPRM, the FAA also proposed to prohibit the 
installation of an engine with an affected No. 3 bearing spring finger 
housing onto an airplane that already has one engine with an affected 
No. 3 bearing spring finger housing installed. The FAA is issuing this 
AD to address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from four commenters. The commenters were 
Air Line Pilots Association, International (ALPA), American Airlines 
(AA), Lynx Air, and an anonymous commenter. ALPA and the anonymous 
commenter supported the proposed AD without change. AA and Lynx Air 
requested changes to the proposed AD. The following presents the 
comments received on the NPRM and the FAA's response to each comment.

Request To Include Additional Method To Correct Unsafe Condition

    AA requested that the FAA provide an additional solution using 
Original Equipment Manufacturer (OEM) provided data. AA stated that the 
OEM, who generates all data plots in CFM Fleet Monitor, should be 
required to generate a customer notification report (CNR) based on the 
points specified in the service bulletin (SB). AA stated that this 
solution would reduce human error of each operator required to access 
the data and manually complete the assessment. AA also noted that the 
automated process would provide a more robust and repeatable method for 
calculating the OFDP rate of change and allow OEM subject matter 
experts to review the data before releasing the CNR. AA also suggested 
that the My Fleet Monitor incorporate titles on the graphs to clarify 
which graph is applicable.

[[Page 29816]]

    In response to this comment, an operator may apply for an 
alternative method of compliance (AMOC) in accordance with paragraph 
(k) of this AD, along with substantiation data to show that the 
alternative method provides an acceptable level of safety. The FAA 
cannot require the type certificate holder (TCH) to implement specific 
actions with respect to an unsafe condition but can mandate that 
operators perform corrective actions to address an unsafe condition. 
The FAA did not change this AD as a result of this comment.

Request To Update Paragraph (g)(3)

    AA requested that the FAA update paragraph (g)(3) of this AD from: 
``during the calculation'' to ``at the time of calculation.'' AA stated 
that ``during the calculation'' was unclear.
    The FAA disagrees with the request to update paragraph (g)(3) of 
this AD because the language ``during the calculation'' is clear.

Request To Update Paragraphs (g)(1), (2), and (3) of This AD

    Lynx Air has requested that the FAA update paragraphs (g)(1) and 
(2) of this AD to mandate the engine OEM monitor and calculate the 
operator's OFDP data (similar to existing trend monitoring performed by 
the engine OEM and subsequent communication to customers via the 
existing CNR process). Lynx Air also requested that the FAA update 
paragraph (g)(3) of this AD to mandate the engine OEM notify operators 
about engines that must be replaced upon the recognition that an 
engine's OFDP data falls outside of the limits specified in CFM SB 
LEAP-1B-72-00-0369-01A-930A-D, Issue 001-00, dated August 22, 2022 (CFM 
SB LEAP-1B-72-00-0369-01A-930A-D). Additionally, Lynx Air has requested 
that the FAA update paragraph (g)(3) of this AD to require operators 
replace engines within 25 flight cycles (FCs) of the CNR by the engine 
OEM. Lynx Air reasoned that operators should not be responsible for 
engine trend monitoring or demonstration of engine trend monitoring at 
a defined interval. Instead, solely the engine OEM should manage engine 
trend monitoring. Lynx Air explained that there is an existing process 
for transmitting engine trend monitoring alerts from CFM to the engine 
operators; therefore, there should be no reason for the final rule to 
require data checks at defined intervals. Lynx Air stated that this AD 
should be limited to requiring operators to respond to CFM CNRs within 
an acceptable timeframe.
    The FAA disagrees with the request to update paragraphs (g)(1) 
through (3) of this AD to require the engine OEM monitor and calculate 
the operator's OFDP data. An operator may apply for an AMOC in 
accordance with paragraph (k) of this AD. The FAA cannot require the 
TCH to implement specific actions with respect to an unsafe condition 
but can mandate that operators perform actions to address an unsafe 
condition. The FAA did not change this AD as a result of this comment.

Request To Remove the Installation Prohibition Paragraph

    Lynx Air requested that the FAA remove paragraph (i), Installation 
Prohibition, specified in this AD. Lynx Air stated that an AD issued by 
the ECO Branch, which applies to an engine, should not establish 
installation restrictions at the aircraft level. If aircraft-level 
restrictions are to be mandated, the ACO Branch should issue a separate 
AD applicable to the airframe. Lynx Air reasoned that neither the CFM 
SB nor the proposed rule would drive the removal of an affected engine 
from an aircraft equipped with two affected engines as of the effective 
date of this AD. Lynx Air stated that it is understood that installing 
an affected engine onto an airplane already equipped with one affected 
engine would not introduce a less airworthy condition than that of an 
aircraft equipped with two affected engines installed before the 
effective date of this AD. Lynx Air clarified that if dual exposure 
already exists, as written, this AD will allow dual exposure to 
continue on one aircraft while prohibiting the introduction of dual 
exposure on a different aircraft.
    The FAA disagrees with the request to remove paragraph (i), 
Installation Prohibition. The requirement in paragraph (i), 
Installation Prohibition, which prevents installing an engine with an 
affected No. 3 bearing spring finger housing on an airplane that 
already has one engine with an affected No. 3 bearing spring finger 
housing installed, is part of the control plan to correct the unsafe 
condition. The OEM performed de-twinning as part of its early 
containment actions and subsequent investigation, which confirmed that 
there are no airplanes with two affected engines installed; hence, 
there is no need for a requirement to de-twin such airplanes to address 
the unsafe condition. The FAA did not change this AD as a result of 
this comment.

Request To Modify the Installation Prohibition Paragraph

    Lynx Air requested that if the FAA rejects the request to remove 
paragraph (i), Installation Prohibition, the FAA modify paragraph (i), 
Installation Prohibition, of this AD to allow the installation of an 
engine with an affected No. 3 bearing spring finger housing onto an 
airplane that already has one engine with an affected No. 3 bearing 
spring finger housing installed as long as the engine that is 
installed, or the opposite engine, has accrued at least 1,000 FCs since 
new. Lynx Air reasoned that the OEM explains within CFM SB LEAP-1B-72-
00-0369-01A-930A-D that the OFDP monitoring may cease after 1,000 FCs. 
Lynx Air stated that if this is the case, there should be no 
airworthiness concerns about the movement of an engine with an affected 
No. 3 bearing spring finger housing onto an airplane on which the other 
wing position has an engine with an affected No. 3 bearing spring 
finger housing installed, as long as the engine being installed has 
accrued at least 1,000 FCs since new. Lynx Air noted that neither 
paragraph (i), Installation Prohibition, nor paragraph (j), Definition, 
of this AD clearly define what an engine with a No. 3 bearing spring 
finger housing that has accrued more than 1,000 FCs refers to. Lynx Air 
commented that paragraph (i), Installation Prohibition, of the proposed 
AD is problematic as written, as an affected engine that has accrued 
more than 1,000 FCs should be eligible for installation onto the pylon 
opposite from an affected engine.
    The FAA disagrees with the request to modify paragraph (i), 
Installation Prohibition. Accumulating 1,000 FCs on an engine with an 
affected No. 3 bearing spring finger housing does not constitute a 
terminating action for that engine. The OFDP monitoring stops at 1,000 
FCs since new, due to the potential for false positives after that 
threshold is reached under normal engine wear. Therefore, the only 
terminating action is the removal and replacement of the affected No. 3 
bearing spring finger housing, as required by paragraphs (g)(3) and (4) 
of this AD. The FAA did not change this AD as a result of this comment.

Request To Revise Estimated Costs Section

    Lynx Air requested that the FAA modify the Estimated Costs section 
to predict the cost on U.S. operators more accurately. Lynx Air stated 
that the Estimated Costs section does not effectively capture the cost 
on U.S. operators. Lynx Air reasoned that the

[[Page 29817]]

estimated costs only consider the time to calculate the OFDP data in 
response to paragraph (g)(1) of the proposed AD and do not consider the 
time to calculate the OFDP data on a repetitive basis, as specified in 
paragraph (g)(2) of the proposed AD.
    The FAA notes that the Estimated Costs include the costs for a 
single calculation of OFDP data. In the case of a repetitive 
calculation, the FAA cannot predict how many repetitive calculations 
will be performed. The FAA did not change this AD as a result of this 
comment.

Request To Revise Paragraph (g)(4) of This AD

    Lynx Air requested that the FAA revise paragraph (g)(4) of this AD 
to more closely align with the parallel requirement of EASA AD 2022-
0215, paragraph (3). Lynx Air suggested that the FAA update this AD to 
state that affected engines may not be released from a qualified shop 
visit with an affected part installed. Lynx Air reasoned that using the 
words ``next shop visit after the effective date of this AD'' pose 
problems for owners and operators who obtain previously operated spare 
engines. Lynx Air noted that, traditionally, engine shop visit records 
include records that claim previous compliance with AD requirements but 
do not include the date of the shop visit or the sequential (1st, 2nd, 
3rd, etc.) occurrence at which a particular AD paragraph was complied 
with. Lynx Air reasoned that it becomes difficult, if not impossible, 
for an operator to demonstrate that a particular engine complied with 
paragraph (g)(4) of this AD at the next shop visit after the effective 
date of the AD, especially if the engine was not in their possession at 
the time in which the AD became effective.
    The FAA disagrees with the request to revise paragraph (g)(4) of 
this AD. Engine shop visit records should specify the date of the shop 
visit. An engine shop visit is the induction of an engine into the shop 
for maintenance involving the separation of pairs of major mating 
engine flanges. As discussed in a later comment reply, this definition 
of an engine shop visit has been added to this AD. The FAA did not 
change this AD as a result of this comment.

Request To Add a Definition of an ``Affected Engine''

    Lynx Air requested that the FAA add a definition of an ``affected 
engine'' to paragraph (j), Definitions, of this AD. Lynx Air reasoned 
that affected engines should no longer be considered affected after 
replacing affected parts. Lynx Air stated that given that Table 1 of 
CFM SB LEAP-1B-72-00-0369-01A-930A-D includes engine serial numbers (S/
Ns), the implication is that those engines remain ``affected'' even 
after the replacement of the affected No. 3 bearing spring finger 
housing.
    The FAA disagrees with the request to add a definition of 
``affected engine'' to paragraph (j), Definitions, of this AD. This AD 
does not use the term ``affected engine.'' The FAA did not change this 
AD as a result of this comment.

Request To Add a Definition of an ``Engine Shop Visit''

    Lynx Air requested that the FAA add a definition of an ``engine 
shop visit'' to paragraph (j), Definitions, of this AD. Lynx Air 
reasoned that operators need to understand what qualifies as a shop 
visit.
    The FAA agrees and has added paragraph (j)(2) to the Definitions 
paragraph of this AD to state: ``For the purpose of this AD, an 
``engine shop visit'' is the induction of an engine into the shop for 
maintenance involving the separation of pairs of major mating engine 
flanges. The separation of engine flanges solely for the purpose of 
transportation without subsequent engine maintenance does not 
constitute an engine shop visit.''

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, and 
any other changes described previously, this AD is adopted as proposed 
in the NPRM. None of the changes will increase the economic burden on 
any operator.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed CFM SB LEAP-1B-72-00-0369-01A-930A-D, Issue 001-
00, dated August 22, 2022. This service information specifies 
procedures for calculating the OFDP data and replacing the affected No. 
3 bearing spring finger housing. This service information also 
identifies the S/Ns of the affected No. 3 bearing spring finger 
housings installed on CFM Model LEAP-1B engines. 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.

Costs of Compliance

    The FAA estimates that this AD affects 8 engines installed on 
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
----------------------------------------------------------------------------------------------------------------
Calculate OFDP data...................  1 work-hour x $85 per                 $0             $85            $680
                                         hour = $85.
Replace No. 3 bearing spring finger     17 work-hours x $85 per           64,590          66,035         528,280
 housing.                                hour = $1,445.
----------------------------------------------------------------------------------------------------------------

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

[[Page 29818]]

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,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 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:

2023-07-11 CFM International, S.A.: Amendment 39-22413; Docket No. 
FAA-2022-1422; Project Identifier AD-2022-01208-E.

(a) Effective Date

    This airworthiness directive (AD) is effective June 13, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to CFM International, S.A. (CFM) Model LEAP-
1B21, LEAP-1B23, LEAP-1B25, LEAP-1B27, LEAP-1B28, LEAP-1B28B1, LEAP-
1B28B2, LEAP-1B28B2C, LEAP-1B28B3, LEAP-1B28BBJ1, and LEAP-1B28BBJ2 
engines with an installed No. 3 bearing spring finger housing, part 
number 2542M54G01, and serial number identified in Table 1 of CFM 
Service Bulletin LEAP-1B-72-00-0369-01A-930A-D, Issue 001-00, dated 
August 22, 2022 (CFM SB LEAP-1B-72-00-0369-01A-930A-D).

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section.

(e) Unsafe Condition

    This AD was prompted by a report of multiple aborted takeoffs 
and air turn-backs caused by high-pressure compressor (HPC) stall, 
which was induced by high levels of non-synchronous vibration, and a 
subsequent investigation by the manufacturer that revealed wear on 
the No. 3 bearing spring finger housing. The FAA is issuing this AD 
to prevent HPC stall. The unsafe condition, if not addressed, could 
result in engine power loss at a critical phase of flight such as 
takeoff or climb, loss of thrust control, reduced controllability of 
the airplane, and loss of the airplane.

(f) Compliance

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

(g) Required Actions

    (1) Before the affected No. 3 bearing spring finger housing 
accumulates 125 flight cycles (FCs) since new, but not before 
accumulating 75 FCs since new, or within 50 FCs after the effective 
date of this AD, whichever occurs later, calculate the oil filter 
delta pressure (OFDP) data in accordance with the Accomplishment 
Instructions, paragraphs 5.A.(1) through 5.A.(2) or 5.B.(1) through 
5.B.(2), of CFM SB LEAP-1B-72-00-0369-01A-930A-D.
    (2) Thereafter, at intervals not to exceed 100 FCs from the last 
calculation of the OFDP data, and until the affected No. 3 bearing 
spring finger housing accumulates 1,000 FCs since new, repeat the 
calculation required by paragraph (g)(1) of this AD.
    (3) If, during the calculation required by paragraph (g)(1) or 
(2) of this AD, the OFDP data exceed the limits specified in the 
Accomplishment Instructions, paragraph 5.A.(3) or 5.B.(3), of CFM SB 
LEAP-1B-72-00-0369-01A-930A-D, as applicable, within 25 FCs of 
performing the calculation, replace the affected No. 3 bearing 
spring finger housing with a part eligible for installation.
    (4) During the next engine shop visit after the effective date 
of this AD, replace the affected No. 3 bearing spring finger housing 
with a part eligible for installation.

(h) Terminating Action

    Replacement of the affected No. 3 bearing spring finger housing 
with a part eligible for installation, as specified in paragraphs 
(g)(3) and (4) of this AD, constitutes terminating action for the 
calculations required by paragraphs (g)(1) and (2) of this AD.

(i) Installation Prohibition

    After the effective date of this AD, do not install an engine 
with an affected No. 3 bearing spring finger housing onto an 
airplane that already has one engine with an affected No. 3 bearing 
spring finger housing installed.

(j) Definitions

    (1) For the purpose of this AD, a ``part eligible for 
installation'' is a No. 3 bearing spring finger housing that is not 
identified in Table 1 of CFM SB LEAP-1B-72-00-0369-01A-930A-D.
    (2) For the purpose of this AD, an ``engine shop visit'' is the 
induction of an engine into the shop for maintenance involving the 
separation of pairs of major mating engine flanges. The separation 
of engine flanges solely for the purpose of transportation without 
subsequent engine maintenance does not constitute an engine shop 
visit.

(k) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO 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 local Flight Standards District 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 (l) of this AD and email it to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(l) Related Information

    For more information about this AD, contact Mehdi Lamnyi, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7743; email: 
[email protected].

(m) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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) CFM Service Bulletin LEAP-1B-72-00-0369-01A-930A-D, Issue 
001-00, dated August 22, 2022
    (ii) [Reserved]
    (3) For CFM service information identified in this AD, contact 
CFM International Inc., Aviation Operations Center, 1 Neumann Way, 
M/D Room 285, Cincinnati, OH 45215; phone: (877) 432-3272; email: 
[email protected].
    (4) You may view this service information at FAA, Airworthiness 
Products Section, Operational Safety Branch, 1200 District Avenue, 
Burlington, MA 01803. For information on the availability of this 
material at the FAA, call (817) 222-5110.
    (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: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on April 8, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-09737 Filed 5-8-23; 8:45 am]
BILLING CODE 4910-13-P


