AD 86-22-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12D | Airworthiness Directives; ROGERSON HILLER CORP. Model UH-12D, UH-12E, and UH-12E4 Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; ROGERSON HILLER CORP. Model UH-12D, UH-12E, and UH-12E4 Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E-L | Airworthiness Directives; ROGERSON HILLER CORP. Model UH-12D, UH-12E, and UH-12E4 Series Helicopters |
Unsafe Condition
Main rotor blade failure due to cracking of the spar or delamination of the trailing edge skin from the spar.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually check main rotor blades for cracks daily before first flight. Conduct dye penetrant or magnaflux inspections every 25 hours' time in service. Perform visual and coin tap inspections for corrosion and voids every 100 hours' time in service. Overhaul blades within 100 hours if exceeding specified time in service, and thereafter every 1,000 hours. Replace blades with discrepancies exceeding service bulletin limits before further flight.
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Compliance Time
Prior to the first flight of each day after the effective date of this AD, and within the next 25/100/100 hours' time in service as specified, with subsequent intervals not exceeding the same units.
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Affected Aircraft
ROGERSON HILLER CORP. Model UH-12D, UH-12E, UH-12E4 series helicopters, including military Models OH-23F and OH-23G, and those converted under STC SH177WE or SH178WE, with main rotor blade assembly Parson's P/N 2253-1101-04 or 2253-1101-03.
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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