AD 81-09-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12D | Airworthiness Directives; HILLER AVIATION Models UH-12D, UH-12E and UH-12E4 Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; HILLER AVIATION Models UH-12D, UH-12E and UH-12E4 Series Helicopters |
Unsafe Condition
Main rotor blade failure due to delamination of the skin at the blade tip.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove blade tip cap and visually inspect for skin bond separation in the tip cap area per Hiller Aviation Service Bulletin No. 51-8 dated March 25, 1981. If separation is detected, replace blade or repair with FAA approval. If no separation, replace tip cap and seal per the same service bulletin.
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Compliance Time
Prior to further flight after the effective date of this AD or receipt of the priority mail AD 81-09-08 issued April 27, 1981, whichever occurs first.
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Affected Aircraft
Hiller Aviation and Siam Hiller Holdings, Inc. Models UH-12D, UH-12E, UH-12E4 Series Helicopters, including military Models H-23F, OH-23G, and all models converted by STC SH178WE and STC SH177WE, equipped with main rotor blades Part No. 53200-03.
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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