Airworthiness directives › 2026-04-11
AD 2026-04-11 Airworthiness Directives; Lycoming Engines
Makes named: lycoming. Read the applicability below — it usually turns on serial or part numbers too.
Applicability*9
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 01/30/2009-09/09/2021 LW-11750 Connecting Rod Assembly 01/30/2009-09/09/2021 78030 Connecting Rod Assembly 01/30/2009-09/09/2021 LW-19332 Connecting Rod Assembly 01/30/2009-09/09/2021 LW-13865 Connecting Rod Assembly 01/30/2009-09/09/2021 77450 Connecting Rod Assembly 01/30/2009-09/09/2021 LW-13422 Connecting Rod Assembly 01/30/2009-09/09/2021 LW-13937 Connecting Rod Assembly 01/30/2009-09/09/2021 LW-15288 Connecting Rod Assembly 01/30/2009-09/09/2021 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, HIO-540-A1A, HO-360 series, IO-320 series, IO-360 series, IO-390 series, IO-540 series, IO-580 series, IO-720 series, IVO-360-A1A, IVO-540-A1A, LHIO-360 series, LIO-320 series, LIO-360 series, LO-360 series, LTIO-540 series, LTO-360 series, O-233-A1, O-235 series, O-290 series, O-320 series, O-340 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, TO-360 series, TVO-435 series, TVO-540-A1A, VO-360 series, VO-435 series, VO-540 series, and VSO-580-A1A engines.
Compliance
Comply with this AD within the compliance times specified, unless already done.
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 No. (MSB) 480F, dated May 25, 2017 (Lycoming 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 630B, dated June 11, 2025. Note 3 to paragraph (g)(2): Guidance for identifying the source of metallic contamination may be found in Table 3 of Lycoming 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.
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.
Affected ADs
This AD replaces AD 2024-21-02, Amendment 39-22869 (89 FR 86721, October 31, 2024); (AD 2024-21-02).
Read the original on the Federal Register →
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