AD 86-23-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61A | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61D | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61E | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61NM | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61V | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-61 Series Helicopters |
Unsafe Condition
Cracking of the main rotor hub lower plate, P/N S6110-23009-6 or -8, due to excessive time in service.
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Required Actions
Remove and replace the main rotor hub lower plate with a new or airworthy part of the same part number having less than 27,000 hours' time in service. The helicopter may be flown to a base for compliance under FAR sections 21.197 and 21.199. Alternate methods of compliance may be approved by the FAA.
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Compliance Time
Prior to further flight if the plate has more than 27,000 hours' time in service on the effective date (April 21, 1987), or prior to accumulating 27,000 hours' time in service if it has 27,000 or less hours. Thereafter, comply at intervals not exceeding 27,000 hours' time in service.
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Affected Aircraft
Sikorsky Aircraft Corporation Models S-61A, S-61D, S-61E, S-61L, S-61N, S-61NM, S-61R, S-61V with main rotor hub lower plate P/N S6110-23009-6 or -8 installed.
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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