AD 85-17-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-58A | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58B | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58BT | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58C | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58D | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58DT | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58E | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58ET | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58F | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-58FT | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT, CH- 34, HH-34, SH-34, UH-34, and VH-34 Series Helicopters |
Unsafe Condition
Separation of the stationary star and rotating star in the main rotor head star assembly due to damaged or loose retainer bolts (Part Number MS20074-04-04 or AN74A4).
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Within 10 hours time in service after the AD's effective date, visually inspect the 12 main rotor head star assembly retainer bolts for damage and security. If damaged or loose bolts are found, perform fluorescent magnetic particle inspection for cracks and visually inspect threads for defects. Replace cracked or thread-damaged bolts with new zero-time bolts before further flight. Within 100 hours time in service, replace all 12 bolts with new zero-time bolts if not done in last 1,000 hours; thereafter, replace every 1,100 hours. Crush removed bolts to render unairworthy.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 10 hours time in service after the effective date of this AD, and thereafter at intervals not to exceed 25 hours time in service from the last inspection. Additionally, within the next 100 hours time in service after the effective date, unless already accomplished within the last 1,000 hours time in service; thereafter, install new bolts at intervals not to exceed 1,100 hours time in service.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Model S-58A, B, C, D, E, F, G, H, J, BT, DT, ET, FT, HT, JT helicopters in any category and CH-34, HH-34, SH-34, UH-34, VH-34 series helicopters in restricted 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
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.