AD 79-03-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12D | Airworthiness Directives; Hiller Models UH-12D and UH-12E Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; Hiller Models UH-12D and UH-12E Helicopters |
Unsafe Condition
Repeated execution of emergency procedures involving unnecessary external load deployment and full autorotation following false low rotor speed warning system activation.
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Required Actions
Replace Globe Industries' P/N 22A571 or P/N 22A580 main rotor tachometer generator with P/N 22A623 in accordance with Soloy Conversions, Limited Service Bulletin 03-560 or later FAA approved revisions. Silicone sealing procedures from the bulletin must be followed.
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Compliance Time
Within the next 200-hours time in-service or 1 month calendar time, whichever occurs first after the effective date of this AD.
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Affected Aircraft
Hiller Models UH-12D and UH-12E helicopters converted to turbine power under Soloy Conversions STC Nos. SH177WE and SH178WE respectively.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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