AD 78-12-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | O-320-H1AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H1BD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H2AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H2BD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H3AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H3BD | AVCO LYCOMING Model O-320-H Series Engines |
Unsafe Condition
Oil pump failures due to insufficient clearance between the oil pump driving and driven impellers.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove, inspect, and alter the oil pump body. Replace the oil pump driving impeller with P/N LW-15998 and the driven impeller with P/N LW-15999 per AVCO Lycoming Service Bulletin No. 423 or FAA-approved equivalent.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 10 hours in service
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
AVCO Lycoming Model O-320-H series engines with serial numbers L-101-76 through L-3829-76, L-3831-76, L-3843-76 through L-3859-76, L-3864-76, L-3866-76, L-3871-76, L-3902-76 through L-3907-76 and all O-320-H series engines overhauled (remanufactured by Lycoming) before March 24, 1978.
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.