# Airworthiness Directives; Bell Textron Canada Limited Helicopters
> **Rule** · Final rule; request for comments. · Published 2025-06-23 · Effective 2025-07-08 · 90 FR 26424
## Document
- **Document number:** 2025-11449
- **Category:** airworthiness
- **Manufacturer:** Bell Textron Canada Limited
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 90 FR 26424
- **Publication date:** 2025-06-23
- **Effective date:** 2025-07-08
- **FAA docket:** Docket No. FAA-2025-1111
## Abstract

The FAA is adopting a new airworthiness directive (AD) for all Bell Textron Canada Limited (BTCL) Model 407 and 427 helicopters. This AD was prompted by a report that certain expandable blade bolts installed on the main rotor blade may not have received the correct heat treatment, which could result in stress corrosion cracking of the expandable blade bolts. This AD requires removing the expandable blade bolts from service and replacing them with a part eligible for installation. This AD also prohibits the installation of an affected expandable blade bolt on any helicopter. The FAA is issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2025/06/23/2025-11449/airworthiness-directives-bell-textron-canada-limited-helicopters)
---
*AI Analytics · CC0 1.0*