AD 59-25-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12 | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12A | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12B | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12C | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12D | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; Hiller Model UH-12, -12A, -12B, -12C, -12D, -12E Series Helicopters |
Unsafe Condition
Contact between the lower cyclic scissors and the filister head screws attaching the wobble plate shield can result in damage to the lower scissors and subsequent loss of cyclic control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Daily inspect the lower cyclic scissors (P/N 34158 or P/N 34141) for damage due to striking the wobble plate shield attachment screws. Replace damaged scissors prior to next flight. Replace filister head screws with AN 509-8R4 flush head screws by January 1, 1960, following Hiller Service Bulletins No. 87 or No. 2004.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Daily inspections required; screw replacement required not later than January 1, 1960. Damaged scissors must be replaced prior to next flight.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Hiller Model UH-12, UH-12A, UH-12B, UH-12C, all UH-12D serial numbers, and UH-12E serials 942, 954, and 2001 through 2018.
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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