AD 72-13-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12L | Airworthiness Directives: Fairchild Hiller Models UH-12L, UH-12L4 and UH-12E-L Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12L4 | Airworthiness Directives: Fairchild Hiller Models UH-12L, UH-12L4 and UH-12E-L Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E-L | Airworthiness Directives: Fairchild Hiller Models UH-12L, UH-12L4 and UH-12E-L Helicopters |
Unsafe Condition
Main rotor blades P/N 53100-01 with specific serial numbers (5, 21, 29, 66, 71, 74, 88, 125, 129, 130, 132, 142, 143, 158, 159, 160, 161, 162, 171, 176) may fail, resulting in loss of control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove and replace listed main rotor blades with non-listed serial numbers. Inspect and alter all other main rotor blades per Service Bulletin SBUH12L-51-1 or approved method within specified timeframes.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 10 hours in service after effective date (October 19, 1972) for removal and replacement. Within 30 hours time in service after effective date for inspection and alteration.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Fairchild Hiller Models UH-12L, UH-12L4, and UH-12E-L helicopters certificated in all categories.
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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