AD Amdt-39-16408
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky | Aircraft Corporation Model S-76A | Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C Helicopters |
Unsafe Condition
Fatigue cracks in the tail rotor vertical stabilizer aft spar assembly web and outer caps could lead to increased vibrations, a fatigue crack, loss of a portion of the vertical stabilizer, and subsequent loss of control of the helicopter.
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Required Actions
Inspect the tail rotor vertical stabilizer aft spar assembly for cracks, loose or working fasteners, and corrosion. If any are found, inspect the vertical stabilizer forward spar assembly. Repair or replace any unairworthy part before further flight. Perform a recurring track-and-balance of the tail rotor. Install a vertical stabilizer modification kit as terminating action.
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Compliance Time
Within 30 days of the effective date, with recurring inspections and track-and-balance at specified intervals.
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Affected Aircraft
Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C helicopters with specified aft spar assembly part numbers, excluding serial numbers greater than 760578 but not including 762976.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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