AD 47-50-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-51 | Airworthiness Directives; Sikorsky Model S-51 Helicopters |
Unsafe Condition
Failure of vertical hinge pins and bearings due to wear or damage could result in loss of main rotor control.
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Required Actions
Disassemble and inspect vertical hinge pins and bearings at each 200-hour inspection period. Replace Torrington No. 4479 bearings at each inspection. Inspect Smith 14TR-X1 bearings and replace only if wear or damage is found. Owners may rework to use Smith bearings instead of Torrington.
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Compliance Time
at each 200-hour inspection period
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Affected Aircraft
Sikorsky Model S-51 Helicopters using Torrington No. 4479 or Smith 14TR-X1 bearings at vertical hinge pins.
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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