AD 66-22-04

final rule
Data completeness: 70%

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

AD Number
66-22-04
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

Failures of the mercury clutch due to cracking at the inner corners of driver lug slots in the side plates.

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

Required Actions

Visually inspect the side plates for cracks using at least 8-power magnification. If cracks are found, replace clutch before further flight with a clutch of the same part number that has been inspected and found free of cracks.

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

Compliance Time

within the next 100 hours' time in service after the effective date of this AD

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 equipped with Mercury Clutch Corporation P/N's 4578-6 and 4692-6, Clutch Serial Numbers 8584 through 9317.

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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