AD 80-04-04 R1
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | IVO-540-A1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TIVO-540-A2A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-A1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-B1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-B1B | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-C1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-D1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-D1B | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-E1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
| engine | Lycoming Engines | TVO-435-F1A | AVCO LYCOMING Model VO and TVO-435 and VO, IVO, TVO and TIVO-540 Series Engines |
Unsafe Condition
Failure of the crankshaft flange bolts due to insufficient torque, fretting, galling, or metal transfer between mating surfaces.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Check crankshaft flange bolt nuts for 15 ft.-lbs. torque. Inspect flanges for cracks, fretting, galling, or metal transfer if torque is below 15 ft.-lbs. Remove deficient components and repair crankshaft bolt holes per Service Instruction 1209B. Install replacement bolts per Service Instruction 1209B. For engines without deficiencies, recheck torque every 600 hours until full compliance.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 50 hours in service after effective date of this AD
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
AVCO Lycoming VO and TVO-435 series engines and VO, IVO, TVO, TIVO-540 series engines
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
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.