AD 47-21-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sierra Hotel Aero, Inc. | Navion (Army L-17A) | Airworthiness Directives; Navion All Serials Up to and Including Number NAV-4-947 |
Unsafe Condition
Malfunctioning of the hydraulic system resulting in failure of components including actuating cylinders.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Rework the hydraulic power system to install manually controlled relief valve North American P/N 145-58027 and replace existing placard with 'Hyd. Power On'; install swivel head type nose gear actuating cylinder North American P/N 145-58014; visually inspect all flap and landing gear actuating cylinders for cracks or damage and replace damaged cylinders.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
prior to September 1, 1947
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Affected Aircraft
Navion All Serials Up to and Including Number NAV-4-947
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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