AD 95-10-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-58A | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58B | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58BT | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58C | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58D | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58DT | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58E | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58ET | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58F | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58FT | Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T Series Helicopters |
Unsafe Condition
Failure of the transmission main gear box ring gear (ring gear), failure of the main transmission, and subsequent loss of control of the helicopter due to slow-growth fatigue cracks.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the ring gear with an airworthy serialized ring gear within specified time intervals based on time-in-service (TIS) or time-since-last-overhaul (TSO). Create a component log and apply a serial number to the ring gear between the flanges as per Sikorsky Aircraft Alert Service Bulletin No. 58B35-32. Establish a retirement life of 2,500 hours TIS for the ring gear.
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 (TIS) after the effective date of this AD. Replacement must occur within 100 hours TIS or at reaching specified TIS/TSO thresholds.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Aircraft Model S-58 and S-58T series helicopters, certificated in any category.
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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