AD 82-16-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12L | Airworthiness Directives; HILLER AVIATION Model UH-12E, UH-12L, OH-23F and G Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12L4 | Airworthiness Directives; HILLER AVIATION Model UH-12E, UH-12L, OH-23F and G Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E | Airworthiness Directives; HILLER AVIATION Model UH-12E, UH-12L, OH-23F and G Series Helicopters |
| aircraft | Hiller Aviation | Siam Hiller Holdings, Inc. | UH-12E-L | Airworthiness Directives; HILLER AVIATION Model UH-12E, UH-12L, OH-23F and G Series Helicopters |
Unsafe Condition
Cracks in the engine drive torsional coupling assembly housings P/N 21047-9, -11 (S/N 704 through 766), and P/N 21047-15 (all serial numbers) could lead to failure of the assembly.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect the lower housing P/N 21046 in eight window areas adjacent to the engine attach flange using fluorescent penetrant inspection. Replace assemblies with cracked housings before further flight and install serviceable assemblies per maintenance manuals. Exclusions apply to helicopters with turbine engine installation via STC SH178WE.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 10 hours' time in service after the effective date of this AD and thereafter at intervals not to exceed 50 hours' time in service
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Hiller Aviation/Siam Hiller Holdings, Inc. models UH-12E, UH-12L, OH-23F and G Series helicopters equipped with engine drive torsional coupling assemblies P/N 21047-9 (S/N 704-766), P/N 21047-11 (S/N 704-766), and P/N 21047-15 (all serial numbers)
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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