AD 81-07-51 R1
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-76A | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-76A Series Helicopters |
Unsafe Condition
Fracture of main rotor spindles, P/N 76102-08001-041 series, due to cracks or excessive diametrical clearance in spindle bearings, which could result in loss of main rotor control.
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Required Actions
Inspect main rotor spindles for cracks via fluorescent penetrant inspection and replace if cracks are found. Replace spindles exceeding 700 hours time in service. Inspect shear bearing inner/outer races for diametrical clearance exceeding 0.015 inches and replace spindles if necessary. Replace spindle/cuff assemblies with P/N 76102-08001-043 and specific preload bolts by December 15, 1981.
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Compliance Time
Prior to further flight, within the next 5 hours time in service after March 20, 1981, within the next 25 hours time in service after March 20, 1981, or before December 15, 1981, depending on specific requirements. Thereafter, at intervals not to exceed 350 hours time in service or upon removal/replacement of components.
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Affected Aircraft
Sikorsky Aircraft Corporation Model S-76A series helicopters certificated in all categories.
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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