AD 67-29-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-51 | Airworthiness Directives; Sikorsky Model S-51 Helicopters |
Unsafe Condition
Failure of sleeve and tube assembly P/N S535180 could lead to loss of tail rotor power.
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Required Actions
Perform torsional checks every 50 aircraft hours' time in service, including applying rotor brake, inducing torsional force on tail rotor drive shafting, and inspecting shaft ends for movement. Daily inspect for loose rivets indicated by black fretting residue or movement, and cracks at tube and sleeve joints. Replace assembly if movement or cracks are found; loose rivets may be replaced with specified rivets after drilling holes to specified diameters.
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Compliance Time
Immediately upon the effective date of this AD and every 50 aircraft hours' time in service thereafter
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Affected Aircraft
Sikorsky Model S-51 Helicopters, all serial numbers
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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