AD 51-23-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-51 | Airworthiness Directives; Sikorsky Model S-51 Helicopters |
Unsafe Condition
Main rotor link assemblies (P/N S510348) with identification stamp 'F' in critical areas or exceeding 960 flight hours may fail, leading to loss of rotor control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect main rotor link assemblies (P/N S510348) for 'F' stamp location and flight time. Retire links with 'F' stamped on inner faces of ears or exceeding 960 flight hours. Polish noncritical 'F' stamps and return to service.
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Compliance Time
prior to next flight
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Affected Aircraft
All Sikorsky Model S-51 Helicopters with main rotor link assemblies (P/N S510348) received from the manufacturer between June 1 and September 6, inclusive.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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