AD 78-20-05 R4
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61A | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61D | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61E | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61NM | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61V | Airworthiness Directives; Sikorsky Models S-61 Series Helicopters |
Unsafe Condition
Failure of main rotor spindles due to cracks in P/N S6112-23025-1 spindles (S6112-23027-006 spindle assemblies) and S6110-23325 series spindles (S6110-23327 series spindle assemblies).
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Conduct ultrasonic inspections within the next 20 hours' time in service (or within last 50 hours if already done), and thereafter every 70 hours' time in service. Replace cracked spindles before further flight. Report any cracks with details to the FAA.
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Compliance Time
Within the next 20 hours' time in service, unless already accomplished within the last 50 hours' time in service, after the effective date of this amendment, and thereafter at intervals not to exceed 70 hours time in service.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Models S-61A, S-61D, S-61E, S-61L, S-61N, S-61NM, S-61R, S-61V helicopters equipped with main rotor P/N S6112-23025-1 spindles (S6112-23027-006 spindle assemblies) and S6110-23325 series spindles (S6110-23327 series spindle assemblies).
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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