AD 75-10-01

final rule
Data completeness: 70%

Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters

AD Number
75-10-01
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Unknown
FR Citation
This information is not available.

Applicability

TypeManufacturerModelDetails
aircraft Hiller Aviation | Siam Hiller Holdings, Inc. UH-12D Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters
aircraft Hiller Aviation | Siam Hiller Holdings, Inc. UH-12L Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters
aircraft Hiller Aviation | Siam Hiller Holdings, Inc. UH-12L4 Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters
aircraft Hiller Aviation | Siam Hiller Holdings, Inc. UH-12E Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters
aircraft Hiller Aviation | Siam Hiller Holdings, Inc. UH-12E-L Airworthiness Directives; Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters

Unsafe Condition

Power loss due to slippage of the mercury clutch in the rotor drive system.

AI-generated summary from the source AD text. Verify against the official source before acting.

Required Actions

Remove the existing placard stating 'No further flight if clutch engagement time exceeds 25 seconds', install decal placard part number 81426-7 on the instrument panel, and incorporate Hiller Rotorcraft Flight Manual Revision dated April 15, 1975.

AI-generated summary from the source AD text. Verify against the official source before acting.

Compliance Time

within 50 hours' time in service after the effective date of this AD unless already accomplished

AI-generated summary from the source AD text. Verify against the official source before acting.

Affected Aircraft

Hiller Models UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 helicopters except those modified with Allison 250 series engines under STC SH177WE or SH178WE.

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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View Official Source ↗ Find More ADs for Hiller Aviation | Siam Hiller Holdings, Inc. UH-12D

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