AD 47-10-33
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Aircraft Corporation | 49-46 | LOCKHEED Model 49 |
Unsafe Condition
Cylinder heads turning or unscrewing slightly on Wright 739C18BA1 and 2 engines with light type barrels, leading to potential valve clearance issues.
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Required Actions
Inspect and mark light barrel cylinders with yellow paint and scribe lines. Inspect scribe lines every 35 to 60 hours of operation. Replace cylinders if head turning exceeds 1/8 inch. Replace specific light barrel cylinders during first engine overhaul.
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Compliance Time
Prior to certification or next 60 hours of operation
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Affected Aircraft
Lockheed Model 49-46 aircraft with Wright 739C18BA1 and 2 engines having light type cylinder barrels.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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