20 Aug 2025

🚁New Airworthiness Directive for Siam Hiller Helicopters Issued

Airworthiness Directives; Siam Hiller Holdings, Inc.

Summary

The FAA is adopting a new airworthiness directive (AD) for certain Siam Hiller Holdings, Inc. (Siam Hiller), Model UH-12E (Army OH-23G and H-23F) and UH-12E-L helicopters. This AD was prompted by reports of cracks found in a main rotor (M/R) transmission drive shaft (drive shaft). This AD requires inspecting certain M/R drive shafts for a crack, prohibits installing certain M/R drive shafts unless the inspection is done, and prohibits using certain paint strippers. The FAA is issuing this AD to address the unsafe condition on these products.

Agencies

  • Transportation Department
  • Federal Aviation Administration

Business Impact ?

$$$ - High

The content outlines airworthiness directives (AD) that require compliance inspections, impacting operational costs and maintenance schedules for affected helicopter models. Businesses may face increased inspections and associated labor costs estimated at $2,402.50 per helicopter, with a total impact of up to $264,275 for the U.S. fleet, indicating financial implications.

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