AD 51-24-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | GO-435-C2 (O-435-17) | LYCOMING Model GO-435-C2 Engines |
Unsafe Condition
Loosening of the exhaust valve seats in Lycoming GO-435-C2 engines installed in Navion Model B airplanes.
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Required Actions
Peen the exhaust valve seats in the cylinder head and stamp 'P' 1/8 inch high on the upper right-hand corner of the cylinder rocker box flange face near the exhaust push rod. Cylinders must be removed from the engine for this operation.
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Compliance Time
By June 1, 1952 or next overhaul, whichever occurs first.
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Affected Aircraft
Lycoming GO-435-C2 Engines serially numbered 1815-11 and below not having the letter 'P' stamped on the upper right-hand corner of each cylinder rocker box, installed in Navion Model B aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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