AD 2007-11-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky | Aircraft Corporation Model S-76A | Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters |
Unsafe Condition
Cracking in the main rotor shaft assembly (M/R shaft) due to inadequate cooling during heat treatment, which reduces ductility and increases the potential for cracking during cold-work forming.
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Required Actions
Perform a one-time ultrasonic inspection of the M/R shaft for cracking. Replace any cracked M/R shaft with an airworthy one before further flight. Reassemble the lower bearing housing assembly and perform a ground run leak test as instructed.
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Compliance Time
Within 75 hours time-in-service (TIS)
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Affected Aircraft
Sikorsky Aircraft Corporation Model S-76A, B, and C helicopters with specific main rotor shaft assemblies (P/N 76351-09630-041 and P/N 76351-09030-all dash numbers) installed.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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