# 2025-15839: FAA Cracks Down on Helicopter Paint and Shaft Risks

2025-15839, Airworthiness Directives; Siam Hiller Holdings, Inc., is a Federal Register rule from Transportation Department, Federal Aviation Administration published 2025-08-20; PRIA reads it as touching household money (as of 2026-06-11).

- Canonical: https://policyrisk.com/federal-register/2025-15839
- As of: 2026-06-11
- Plain-text twin of the page above; the HTML and this file carry the same facts.

## Facts
- Document number: 2025-15839
- Title: Airworthiness Directives; Siam Hiller Holdings, Inc.
- Type: Rule
- Agencies: Transportation Department; Federal Aviation Administration
- Citation: 90 FR 40529
- Published: 2025-08-20
- Effective: unknown
- Comments close: not stated
- Significant: no
- Touches household money: yes
- Regulation identifier numbers: 2120-AA64
- Last updated: 2026-06-11

## In one line

FAA Cracks Down on Helicopter Paint and Shaft Risks

## Summary

If you own certain Siam Hiller helicopters, listen up! The FAA found cracks in some main rotor drive shafts and now requires inspections to keep things safe. You’ll need to check your parts soon, avoid using certain paint strippers, and follow new rules to keep flying without extra costs or delays.

## Abstract

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.

## Effects PRIA read

- Mandatory inspection for cracked drive shafts: cost, medium. If you own a Siam Hiller Model UH-12E (Army OH-23G and H-23F) or UH-12E-L helicopter, the FAA now requires inspecting certain main rotor (M/R) transmission drive shafts for cracks. You must perform these inspections to address reported cracks in the drive shaft before continuing normal operations.
- Installation blocked until inspection completed: cost, medium. The AD prohibits installing certain M/R drive shafts unless the required inspection for cracks has been completed. That means you cannot fit affected drive shafts into service until you follow the inspection steps mandated by the FAA.
- Certain paint strippers now prohibited: cost, low. The AD prohibits using certain paint strippers when working on the affected helicopters. Maintenance personnel and owners must avoid those specific paint strippers when servicing affected parts.

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## Sources
- [2025-15839 on federalregister.gov](https://www.federalregister.gov/documents/2025/08/20/2025-15839/airworthiness-directives-siam-hiller-holdings-inc)
- [2025-15839 as published (PDF)](https://www.govinfo.gov/content/pkg/FR-2025-08-20/pdf/2025-15839.pdf)

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Source: PRIA, https://policyrisk.com/federal-register/2025-15839 (as of 2026-06-11).