AD 58-02-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | UH-12 | Airworthiness Directives; Hiller Model UH-12 Series Helicopters |
| aircraft | Hiller Aviation | UH-12A | Airworthiness Directives; Hiller Model UH-12 Series Helicopters |
| aircraft | Hiller Aviation | UH-12B | Airworthiness Directives; Hiller Model UH-12 Series Helicopters |
| aircraft | Hiller Aviation | UH-12C | Airworthiness Directives; Hiller Model UH-12 Series Helicopters |
| aircraft | Hiller Aviation | UH-12D | Airworthiness Directives; Hiller Model UH-12 Series Helicopters |
Unsafe Condition
With a Marvel-Schebler Model MA-4-5AA carburetor installed, it is possible to start and run the engine with the carburetor mixture control in the idle cutoff position if the throttle is partially or fully opened. However, as soon as the throttle is fully closed, the idle cutoff will operate and shut off the engine.
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Required Actions
Delete the carburetor mixture control from the cockpit and secure the carburetor setting at 'ALT.COMP' at the carburetor. An appropriate FAA approved Helicopter Flight Manual revision is required.
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Compliance Time
June 1, 1958
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Affected Aircraft
Hiller Model UH-12 Series Helicopters equipped with Marvel-Schebler Automatic Altitude Compensating Carburetor Model MA-4-5AA (Aircooled P/N 19588)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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