[4910-13-P]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-1695; Project Identifier AD-2023-00783-E]
RIN 2120-AA64
Airworthiness Directives; Lycoming Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for
Lycoming Engines (Lycoming) model engines that have a certain connecting rod
assemblies installed. This proposed AD was prompted by several reports of connecting
rod failures, which resulted in uncontained engine failure and in-flight shutdowns
(IFSDs). This proposed AD would require repetitive oil inspections for bronze metal
particulates and, if found, additional inspections of the connecting rod bushings for
damage, proper fit, movement, and wear, and replacement if necessary. As terminating
action to the connecting rod bushing inspections, this proposed AD would require
replacement of the connecting rod bushings with parts eligible for installation. 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 [INSERT DATE 45
DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
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. FAA2024-1695; 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 service information, contact Lycoming Engines, 652 Oliver Street,
Williamsport, PA 17701; phone: (800) 258-3279; website:
lycoming.com/contact/knowledge-base/publications.
• 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.
FOR FURTHER INFORMATION CONTACT: James Delisio, Aviation Safety
Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (516) 2287321; email: james.delisio@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-2024-1695; Project Identifier AD-2023-00783-E” 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 James Delisio,
Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337. Any
commentary that the FAA receives which is not specifically designated as CBI will be
placed in the public docket for this rulemaking.
Background
The FAA received five reports of uncontained engine failures and IFSDs due to
failed connecting rods on various models of Lycoming reciprocating engines that were
overhauled or repaired using any replacement part listed in Table 2 of Lycoming
Mandatory Service Bulletin (MSB) No. 632B, dated August 4, 2017 (MSB 632B), which
was shipped from Lycoming during the dates listed in Table 2 of MSB 632B. As a result,
the FAA issued AD 2017-16-11, Amendment 39-18988 (82 FR 37296, August 10, 2017)
(AD 2017-16-11), which required an inspection of connecting rods and replacement of
affected connecting rod small end bushings.
Since the FAA issued AD 2017-16-11, a manufacturer investigation determined
that affected connecting rod small end bushings may be installed on additional
populations of Lycoming engines. The manufacturer also determined that degradation of
the connecting rod small end bushings is detectable during oil change inspections. This
condition, if not corrected, could result in connecting rod failure with consequent

uncontained engine failure, total engine power loss, IFSD, and possible loss 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 Lycoming MSB No. 630A, dated June 13, 2017, which
specifies procedures for inspection of the connecting rod bushings for damage, proper fit,
movement, and wear. 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 repetitive oil inspections for bronze metal
particulates and, if found, additional inspections of the connecting rod bushings for
damage (e.g. deterioration, missing metal), proper fit, movement, and wear, and
replacement if necessary. As terminating action to the connecting rod bushing
inspections, this proposed AD would require replacement of the connecting rod bushings
with parts eligible for installation.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would affect 16,000
engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
Estimated costs
Action

Labor Cost

Parts Cost

Inspect oil

2 work-hours
x $85 per
hour = $170
1 work-hour
x $85 per
hour = $85

Inspect connecting
rod bushings

$65

Cost per
product
$235

Cost on U.S.
operators
$3,760,000

$0

$85

$1,360,000

Replace connecting 4.5 workrod bushings (per
hours x $85
bushing)
per hour =
$382

$380

$762

$12,192,000

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.
§ 39.13 [Amended]
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
Lycoming Engines: Docket No. FAA-2024-1695; Project Identifier AD-2023-00783-E.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive (AD) by
[INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL
REGISTER].
(b) Affected ADs
None.
(c) Applicability
This AD applies to Lycoming Engines (Lycoming) model engines that have an
affected part and part number (P/N) installed and are assembled within the ship date
range, as specified in Table 1 to paragraph (c) of this AD.
Table 1 to Paragraph (c) - Affected P/Ns
P/N

Affected Part

Ship Date Range

LW-13923

Connecting Rod Bushing

01/30/2009 - 11/17/2015

LW-11750

Connecting Rod Assembly

01/30/2009 - 11/19/2015

Connecting Rod Assembly

01/30/2009 - 03/31/2016

LW-19332

Connecting Rod Assembly

01/30/2009 - 01/03/2016

LW-13865

Connecting Rod Assembly

01/30/2009 - 02/14/2017

Connecting Rod Assembly

01/30/2009 - 02/14/2017

LW-13422

Connecting Rod Assembly

01/30/2009 - 02/14/2017

LW-13937

Connecting Rod Assembly

01/30/2009 - 02/14/2017

LW-15288

Connecting Rod Assembly

01/30/2009 - 02/14/2017

Note 1 to paragraph (c): The affected parts are known to be installed on
Lycoming Model AEIO-320 series, AEIO-360 series, AEIO-390 series, AEIO-540 series,
AEIO-580-B1A, AIO-320 series, AIO-360 series, HIO-360 series, HIO-390-A1A, HIO540-A1A, HO-360 series, IO-320 series, IO-360 series, IO-390 series, IO-540 series,
IVO-360-A1A, IVO-540-A1A, LHIO-360 series, LIO-320 series, LIO-360 series, LO360 series, LTIO-540 series, LTO-360 series, O-233-A1, O-235 series, O-320 series, O340 series, O-360 series, O-435 series, O-540 series, SO-580 series, TEO-540 series,
TIGO-541 series, TIO-360 series, TIO-540 series, TIO-541 series, TIVO-540-A2A, TO360 series, TVO-435 series, TVO-540-A1A, VO-360 series, VO-435 series, VO-540
series, and VSO-580-A1A engines.
(d) Subject
Joint Aircraft System Component (JASC) Code 8500, Engine (Reciprocating).
(e) Unsafe Condition
This AD was prompted by several reports of connecting rod failures resulting in
uncontained engine failure and in-flight shutdowns (IFSDs). The FAA is issuing this AD
to prevent connecting rod failure. The unsafe condition, if not addressed, could result in
engine failure, an IFSD, and loss of control of the aircraft.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
(g) Required Actions
(1) At the next oil change or within 4 months after the effective date of this AD,
whichever occurs first, and thereafter at every oil change until the bushing replacement
required by either paragraph (g)(3) or (4) of this AD is done, perform a visual inspection
of the engine oil filter, oil pressure screen, and oil suction screen (depending on the
engine configuration) for bronze metal particulates. The actions required by this
paragraph may be performed by the owner/operator (pilot) holding at least a private pilot
certificate and must be entered into the aircraft records showing compliance with this AD

in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The record must be maintained
as required by 14 CFR 91.417, 121.380, or 135.439.
Note 2 to paragraph (g)(1): Guidance for engine oil filter, oil pressure screen,
and oil suction screen inspection instructions and identification of metallic solids may be
found in Lycoming Mandatory Service Bulletin (MSB) No. 480F, dated May 25, 2017
(MSB 480F).
(2) If, during any inspection required by paragraph (g)(1) of this AD, any bronze
metal particulates are found and the source is identified as the connecting rod bushings,
before further flight, inspect all affected connecting rod bushings for damage (e.g.
deterioration, missing metal), proper fit, movement, and wear in accordance with
“Connecting Rod Bushing Inspection,” of Lycoming MSB 630A, dated June 13, 2017.
Note 3 to paragraph (g)(2): Guidance for identifying the source of metallic
contamination may be found in Table 3 of MSB 480F.
(3) If the connecting rod bushings fail any inspection required by paragraph (g)(2)
of this AD, before further flight, replace the connecting rod bushings with parts eligible
for installation. This terminates the repetitive inspection required by paragraph (g)(1) of
this AD.
(4) At the next engine overhaul, replace the connecting rod bushings with parts
eligible for installation. This terminates the repetitive inspection required by paragraph
(g)(1) of this AD.
(h) Definition
For the purpose of this AD, a “part eligible for installation” is any connecting rod
bushing having P/N 01K28983.
(i) Credit for Previous Actions
You may take credit for the actions required by paragraph (g)(1) of this AD if you
performed those actions before the effective date of this AD using MSB 480F.
(j) Alternative Methods of Compliance (AMOCs)
(1) The Manager, East Certification 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 branch office, send it to the attention of the person identified in paragraph
(k)(1) of this AD and email to: 9-avs-nyaco-cos@faa.gov.
(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.
(k) Additional Information
(1) For more information about this AD, contact James Delisio, Aviation Safety
Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (516) 2287321; email: james.delisio@faa.gov.
(2) Service information identified in this AD that is not incorporated by reference
is available at the address specified in paragraph (l)(3) of this AD.
(l) 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) Lycoming Engines Mandatory Service Bulletin No. 630A, dated June 13,
2017.
(ii) [Reserved]
(3) For service information identified in this AD, contact Lycoming Engines, 652
Oliver Street, Williamsport, PA 17701; phone: (800) 258-3279; website:
lycoming.com/contact/knowledge-base/publications.
(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 material at the National Archives and Records
Administration (NARA). For information on the availability of this material at NARA,

visit www.archives.gov/federal-register/cfr/ibr-locations or email
fr.inspection@nara.gov.
Issued on June 21, 2024.

Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division,
Aircraft Certification Service.
[FR Doc. 2024-14100 Filed: 6/27/2024 8:45 am; Publication Date: 6/28/2024]