AD 72-25-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61A | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61D | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61V | Airworthiness Directives; Sikorsky Models S-61A, S-61B, S-61D, S-61L, S-61N Series, S-61R, and S-61V Helicopters |
Unsafe Condition
Cracked primary servo mounting bracket retaining nuts could cause loss of main rotor control.
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Required Actions
Remove all MS21042-6 or MS20365-624C retaining nuts from the primary servo mounting brackets (P/N S613520249) and replace with P/N MS21045-6 retaining nuts in accordance with Sikorsky Service Bulletin No. 61B35-18. Equivalent methods of compliance require approval.
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Compliance Time
Within the next 25 hours time in service after the effective date of this Airworthiness Directive
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Affected Aircraft
Sikorsky Models S-61A, S-61B, S-61D, S-61L Series prior to SS No. 61454, S-61N Series prior to SS No. 61493, S-61R, S-61V helicopters.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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