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Airworthiness directives › 2026-17-10

AD 2026-17-10 Airworthiness Directives; Lycoming Engines

2026-09-14
2026-08-28
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Engine
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Makes named: lycoming. Read the applicability below — it usually turns on serial or part numbers too.

Applicability*9

This AD applies to Lycoming Engines Model O-235, -A, -AP, -B, -BP, -C, -C1, -C1A, -C1B, -C1C, -C2A, -C2B, -C2C, -E1, -E1B, -E2A, -E2B, -F1, -F1B, -F2A, -F2B, -G1, -G1B, O-235-G2A, O-235-G2B, O-235-H2C, O-235-J2A, O-235-J2B, O-235-K2A, O-235-K2B, -K2C, -L2A, -L2C, -M1, -M2C, -M3C, -N2A, -N2C, -P1, -P2A, -P2C, and -P3C; O-540-A1A, -A1A5, -A1B5, -A1C5, -A1D, -A1D5, -A2B, -A3D5, -A4A5, -A4B5, -A4C5, -A4D5, -A4E5, -B1A5, -B1B5, -B1D5, -B2A5, -B2B5, -B2C5, -B4A5, -B4B5, -D1A5, -E4A5, -E4B5, -E4C5, -F1A5, -F1B5, -G1A5, -G2A5, -H1A5, -H1A5D, -H1B5D, -H2A5, -H2A5D, -H2B5D, -J1A5D, -J1B5D, -J1C5D, -J1D5D, -J2A5D, -J2B5D, -J2C5D, -J2D5D, -J3A5, -J3A5D, -J3C5D, and -L3C5D; IO-540-A1A5, -AA1A5, -AA1B5, -AB1A5, -AE1A5, -AC1A5, -AF1A5, -B1B5, -AG1A5, -B1A5, -B1C5, -C1B5, -C1C5, -C2C, -C4B5, -C4B5D, -C4C5, -C4D5, -C4D5D, -D4A5, -D4B5, -D4C5, -E1A5, -E1B5, -E1C5, -G1A5, -G1B5, -G1C5, -G1D5, -G1E5, -G1F5, -J4A5, -K1A5, -K1A5D, -K1B5, -K1B5D, -K1C5, -K1D5, -K1E5, -K1E5D, -K1F5, -K1F5D, -K1G5, -K1G5D, -K1H5, -K1J5, -K1J5D, -K1K5, -K2A5, -L1A5, -L1A5D, -L1B5D, -L1C5, -M1A5, -M1A5D, -M1B5D, -M1C5, -M2A5D, -N1A5, -P1A5, -R1A5, -S1A5, -T4A5D, -T4B5, -T4B5D, -T4C5D, -U1A5D, -U1B5D, -V4A5, -V4A5D, -W1A5, -W1A5D, and -W3A5D engines with a serial number listed in Table 2 or Table 3 of Lycoming Mandatory Service Bulletin No. (MSB) 667A, dated March 12, 2026 (Lycoming MSB 667A), and an installed piston pin having part number (P/N) LW-13445 with an FAA Form 8130-3 from the original equipment manufacturer for production dated between January 7, 2021 to December 15, 2025. If the production date on the FAA Form 8130-3 cannot be determined, or if the FAA Form 8130-3 is not available, this AD is applicable.

Compliance

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

Required actions

(1) For the purpose of this AD, a “part eligible for installation” is one of the following: (i) A piston pin that does not have P/N LW-13445. (ii) A piston pin having P/N LW-13445 with an FAA Form 8130-3 from the original equipment manufacturer for production that is not dated between January 7, 2021 to December 15, 2025. (2) For the purpose of this AD, an “affected piston pin” is a piston pin having P/N LW-13445 and one of the following: (i) An FAA Form 8130-3 from the original equipment manufacturer for production dated between January 7, 2021 to December 15, 2025. (ii) An FAA Form 8130-3 from the original equipment manufacturer for which the production date on the Form 8130-3 cannot be determined. (iii) An FAA Form 8130-3 that is not available.

Unsafe condition

This AD was prompted by reports from Lycoming of metal particulates found in the engine oil during oil change and two non-detectable engine failures. The FAA is issuing this AD to prevent failure of the piston pin. The unsafe condition, if not addressed, could result in engine failure, loss of thrust control, in-flight shutdown, damage to the airplane, and loss of control of the airplane.

Affected ADs

None.

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The directive text above is reproduced from the Federal Register, a work of the United States government and in the public domain. The separation into applicability, compliance and required actions is TrackAD's.*1