AD 68-08-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | IGSO-480-A1A6 | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | IGSO-480-A1B6 | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | IGSO-480-A1C6 | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | IGSO-480-A1F6 | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | IVO-360-A1A | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | IVO-540-A1A | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | TIVO-540-A2A | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-A1A | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-B1A | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-B1B | LYCOMING Model VO, IVO-360 Series: VO, TVO-435 Series Engines; IGSO-480 Series Engines; VO, IVO, TIVO-540 Series Engines |
Unsafe Condition
Valve failures due to the use of P/N 76289 hydraulic valve lifter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace hydraulic lifter P/N 76289 with P/N 78289 within specified time-in-service windows based on engine model and usage.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
(a) TVO-435, VO-540, IVO-540, and TIVO-540 Series engines: within 50 hours' time in service after AD effective date. (b) VO-360, VO-435, and IGSO-480 Series engines with <600 hours on P/N 76289: prior to 650 hours' time in service. (c) VO-360, IVO-360, VO-345, and IGSO-480 Series engines with ≥600 hours on P/N 76289: within next 50 hours' time in service.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Lycoming Engines: IGSO-480-A1A6, -A1B6, -A1C6, -A1F6; IVO-360-A1A; IVO-540-A1A; TIVO-540; VO-345, VO-360, VO-435, VO-540, TVO-435 Series engines with P/N 76289 hydraulic valve lifter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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