AD 63-04-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | UH-12 | Airworthiness Directives; Hiller Models UH-12, UH-12A, UH-12B amd UH-12C Helicopters |
| aircraft | Hiller Aviation | UH-12A | Airworthiness Directives; Hiller Models UH-12, UH-12A, UH-12B amd UH-12C Helicopters |
| aircraft | Hiller Aviation | UH-12B | Airworthiness Directives; Hiller Models UH-12, UH-12A, UH-12B amd UH-12C Helicopters |
| aircraft | Hiller Aviation | UH-12C | Airworthiness Directives; Hiller Models UH-12, UH-12A, UH-12B amd UH-12C Helicopters |
Unsafe Condition
Failures of P/N's 55008 and 55012 tail rotor blades due to cracks in the outer tension torsion bar retention bolt area and adjacent rivet pattern.
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Required Actions
Replace P/N's 55008 and 55012 tail rotor blades with P/N 55064 blades within 50 hours' time in service. Install stabilizer struts per Hiller Service Bulletins 75B (for P/N 37003) and 83 (for P/N 37001). Visually inspect blades before each flight and refueling for cracks in specified areas until replacement is done.
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Compliance Time
Within the next 50 hours' time in service
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Affected Aircraft
Hiller Models UH-12, UH-12A, UH-12B, and UH-12C Helicopters with P/N's 55008 and 55012 Tail Rotor Blades.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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