AD 86-17-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12D | Airworthiness Directives; ROGERSON HILLER CORP Model UH-12D, UH-12E, UH-12E4 Series and Military OH-23F and OH-23G Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; ROGERSON HILLER CORP Model UH-12D, UH-12E, UH-12E4 Series and Military OH-23F and OH-23G Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E-L | Airworthiness Directives; ROGERSON HILLER CORP Model UH-12D, UH-12E, UH-12E4 Series and Military OH-23F and OH-23G Helicopters |
Unsafe Condition
Cracks and failures in the main rotor blade fork P/N 52110-3 at the outboard tension-torsion bar retention bolt hole.
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Required Actions
Verify each installed P/N 52110-3 fork has a serial number displayed; perform daily visual checks for cracks; conduct dye penetrant inspections every 100 hours' time in service, with initial inspections within 10 hours' time in service for forks with 240+ hours and prior to 250 hours' time in service for those with less. Replace cracked forks before flight.
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Compliance Time
Within the next 10 hours' time in service after the effective date, and recurring intervals as specified.
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Affected Aircraft
ROGERSON HILLER CORP Model UH-12D, UH-12E, UH-12E4 Series, Military OH-23F and OH-23G helicopters, including those converted under STC SH177WE and SH178WE, equipped with main rotor blade fork P/N 52110-3.
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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