AD 62-26-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | C54-DC | Airworthiness Directives; DOUGLAS All C54-DC Series and DC-4 Aircraft |
| aircraft | The Boeing Company | DC-4 | Airworthiness Directives; DOUGLAS All C54-DC Series and DC-4 Aircraft |
Unsafe Condition
Vibration stresses in excess of allowable limits for continuous safe operation occur in Hamilton Standard 23E50/6507-0 propeller blades over a wider range of engine operating speeds than previously determined.
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Required Actions
Remove existing placard covering 1,600-1,700 r.p.m. range and install new placard warning against operation between 1,550-1,750 r.p.m. during flight and 1,550-1,800 r.p.m. on ground with blades off low pitch stops. Mark tachometers with red arc over 1,550-1,750 r.p.m. range. Revise Airplane Flight Manual to incorporate these limitations.
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Compliance Time
within the next 200 hours' time in service after the effective date of this AD
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Affected Aircraft
DOUGLAS All C54-DC Series and DC-4 Aircraft equipped with Pratt & Whitney Twin Wasp Series/R-2000 Series engines and Hamilton Standard 23E50/6507-0 propellers.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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