AD 85-08-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Continental Motors | IO-470-C | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-G | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-K | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-L | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-M | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-R | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
| engine | Continental Motors | O-470-S | TELEDYNE CONTINENTAL MOTORS Model IO-470-C, O-470-K, O-470-L, O-470-M, O-470-R, O-470-S, O-470-G Engines |
Unsafe Condition
Valve stem wear, oil contamination, valve seizure, and total loss of engine power may occur due to cylinder assemblies with part numbers 646680A4 and 646680A5.
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Required Actions
Inspect engines and cylinder assemblies for part numbers 646680A4/A5. Remove and replace exhaust valve P/N 626540 with P/N 637781. Inspect and polish valve guides if metal transfer is present. Restamp cylinders with P/N 646680A7. Record compliance in maintenance logs.
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Compliance Time
Within the next 10 hours time in service for engines with the affected cylinders installed, or prior to installation for uninstalled cylinders.
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Affected Aircraft
Teledyne Continental Motors engines IO-470-C (S/N 242071-242076), O-470-K (S/N 49390-49394), O-470-L (S/N 69640-69643), O-470-M (S/N 54141-54142), O-470-R (specific S/N ranges), O-470-S (S/N 226443-226457), and cylinder assemblies P/N 646680A4/A5 installed since March 1984.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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