AD 53-03-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sierra Hotel Aero, Inc. | Navion B | Airworthiness Directives; Navion All Model B Aircraft |
Unsafe Condition
Vibration characteristics of the Hartzell HC-12 X20-8C/9333C-0 propeller installed on the Lycoming GO-435 engine revealed hazardous vibration that could cause blade cracks and/or failures.
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Required Actions
Revise the existing r.p.m. restriction placard to state: 'Avoid continuous ground operation between 1675 and 2150 engine r.p.m.'
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Compliance Time
March 15, 1953
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Affected Aircraft
Sierra Hotel Aero, Inc. Navion B aircraft equipped with Hartzell HC-12 X20-8C/9333C-0 propellers.
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
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