EASA AD CF-2025-21R1
Main Rotor — Expandable Blade Bolt incorrect heat treatment
Canadian Airworthiness Directive CF-2025-21R1 addresses an issue with expandable blade bolts, part number 406-310-103-103, installed on Bell Textron Canada Limited model 407 and 427 helicopters. The directive identifies that some bolts may have incorrect heat treatment, which could lead to stress corrosion cracking and potential main rotor blade detachment. This directive mandates inspection and replacement of affected bolts to ensure continued airworthiness.