AD 84-01-51
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61A | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61D | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61E | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61NM | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
| aircraft | Sikorsky Aircraft Corporation | S-61V | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Aircraft |
Unsafe Condition
Crack in rotary wing head shaft nut with improper Rockwell hardness due to possible incomplete processing of nuts, part number S6110-21082-0.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Fluorescent magnetic particle inspect and Rockwell hardness test the nut per Sikorsky Service Bulletin 61B10-14 and message CST-P-83-171. Replace cracked or out-of-hardness nuts before further flight with compliant nuts. Bake and mark acceptable nuts at 375°F±25°F for 3 hours.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 25 hours time in service after the effective date of this AD
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Affected Aircraft
Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, S-61L, S-61N, S-61NM, S-61R, S-61V aircraft 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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